1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_SUPPORTS_PER_VMA_LOCK
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
63 select ARCH_32BIT_OFF_T if X86_32
64 select ARCH_CLOCKSOURCE_INIT
65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
72 select ARCH_HAS_CACHE_LINE_SIZE
73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
74 select ARCH_HAS_CPU_FINALIZE_INIT
75 select ARCH_HAS_CURRENT_STACK_POINTER
76 select ARCH_HAS_DEBUG_VIRTUAL
77 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
78 select ARCH_HAS_DEVMEM_IS_ALLOWED
79 select ARCH_HAS_EARLY_DEBUG if KGDB
80 select ARCH_HAS_ELF_RANDOMIZE
81 select ARCH_HAS_FAST_MULTIPLIER
82 select ARCH_HAS_FORTIFY_SOURCE
83 select ARCH_HAS_GCOV_PROFILE_ALL
84 select ARCH_HAS_KCOV if X86_64
85 select ARCH_HAS_MEM_ENCRYPT
86 select ARCH_HAS_MEMBARRIER_SYNC_CORE
87 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
88 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
89 select ARCH_HAS_PMEM_API if X86_64
90 select ARCH_HAS_PTE_DEVMAP if X86_64
91 select ARCH_HAS_PTE_SPECIAL
92 select ARCH_HAS_HW_PTE_YOUNG
93 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
94 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
95 select ARCH_HAS_COPY_MC if X86_64
96 select ARCH_HAS_SET_MEMORY
97 select ARCH_HAS_SET_DIRECT_MAP
98 select ARCH_HAS_STRICT_KERNEL_RWX
99 select ARCH_HAS_STRICT_MODULE_RWX
100 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
101 select ARCH_HAS_SYSCALL_WRAPPER
102 select ARCH_HAS_UBSAN_SANITIZE_ALL
103 select ARCH_HAS_DEBUG_WX
104 select ARCH_HAS_ZONE_DMA_SET if EXPERT
105 select ARCH_HAVE_NMI_SAFE_CMPXCHG
106 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
107 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
108 select ARCH_MIGHT_HAVE_PC_PARPORT
109 select ARCH_MIGHT_HAVE_PC_SERIO
110 select ARCH_STACKWALK
111 select ARCH_SUPPORTS_ACPI
112 select ARCH_SUPPORTS_ATOMIC_RMW
113 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
114 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
115 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
116 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
117 select ARCH_SUPPORTS_CFI_CLANG if X86_64
118 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
119 select ARCH_SUPPORTS_LTO_CLANG
120 select ARCH_SUPPORTS_LTO_CLANG_THIN
121 select ARCH_USE_BUILTIN_BSWAP
122 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
123 select ARCH_USE_MEMTEST
124 select ARCH_USE_QUEUED_RWLOCKS
125 select ARCH_USE_QUEUED_SPINLOCKS
126 select ARCH_USE_SYM_ANNOTATIONS
127 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
128 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
129 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
130 select ARCH_WANTS_NO_INSTR
131 select ARCH_WANT_GENERAL_HUGETLB
132 select ARCH_WANT_HUGE_PMD_SHARE
133 select ARCH_WANT_LD_ORPHAN_WARN
134 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
135 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
136 select ARCH_WANTS_THP_SWAP if X86_64
137 select ARCH_HAS_PARANOID_L1D_FLUSH
138 select BUILDTIME_TABLE_SORT
140 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
141 select CLOCKSOURCE_WATCHDOG
142 # Word-size accesses may read uninitialized data past the trailing \0
143 # in strings and cause false KMSAN reports.
144 select DCACHE_WORD_ACCESS if !KMSAN
145 select DYNAMIC_SIGFRAME
146 select EDAC_ATOMIC_SCRUB
148 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
149 select GENERIC_CLOCKEVENTS_MIN_ADJUST
150 select GENERIC_CMOS_UPDATE
151 select GENERIC_CPU_AUTOPROBE
152 select GENERIC_CPU_DEVICES
153 select GENERIC_CPU_VULNERABILITIES
154 select GENERIC_EARLY_IOREMAP
157 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
158 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
159 select GENERIC_IRQ_MIGRATION if SMP
160 select GENERIC_IRQ_PROBE
161 select GENERIC_IRQ_RESERVATION_MODE
162 select GENERIC_IRQ_SHOW
163 select GENERIC_PENDING_IRQ if SMP
164 select GENERIC_PTDUMP
165 select GENERIC_SMP_IDLE_THREAD
166 select GENERIC_TIME_VSYSCALL
167 select GENERIC_GETTIMEOFDAY
168 select GENERIC_VDSO_TIME_NS
169 select GUP_GET_PXX_LOW_HIGH if X86_PAE
170 select HARDIRQS_SW_RESEND
171 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
173 select HAVE_ACPI_APEI if ACPI
174 select HAVE_ACPI_APEI_NMI if ACPI
175 select HAVE_ALIGNED_STRUCT_PAGE
176 select HAVE_ARCH_AUDITSYSCALL
177 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
178 select HAVE_ARCH_HUGE_VMALLOC if X86_64
179 select HAVE_ARCH_JUMP_LABEL
180 select HAVE_ARCH_JUMP_LABEL_RELATIVE
181 select HAVE_ARCH_KASAN if X86_64
182 select HAVE_ARCH_KASAN_VMALLOC if X86_64
183 select HAVE_ARCH_KFENCE
184 select HAVE_ARCH_KMSAN if X86_64
185 select HAVE_ARCH_KGDB
186 select HAVE_ARCH_MMAP_RND_BITS if MMU
187 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
188 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
189 select HAVE_ARCH_PREL32_RELOCATIONS
190 select HAVE_ARCH_SECCOMP_FILTER
191 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
192 select HAVE_ARCH_STACKLEAK
193 select HAVE_ARCH_TRACEHOOK
194 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
195 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
196 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
197 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
198 select HAVE_ARCH_VMAP_STACK if X86_64
199 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
200 select HAVE_ARCH_WITHIN_STACK_FRAMES
201 select HAVE_ASM_MODVERSIONS
202 select HAVE_CMPXCHG_DOUBLE
203 select HAVE_CMPXCHG_LOCAL
204 select HAVE_CONTEXT_TRACKING_USER if X86_64
205 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
206 select HAVE_C_RECORDMCOUNT
207 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
208 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
209 select HAVE_BUILDTIME_MCOUNT_SORT
210 select HAVE_DEBUG_KMEMLEAK
211 select HAVE_DMA_CONTIGUOUS
212 select HAVE_DYNAMIC_FTRACE
213 select HAVE_DYNAMIC_FTRACE_WITH_REGS
214 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
215 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
216 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
217 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
219 select HAVE_EFFICIENT_UNALIGNED_ACCESS
221 select HAVE_EXIT_THREAD
223 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
224 select HAVE_FTRACE_MCOUNT_RECORD
225 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
226 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
227 select HAVE_FUNCTION_TRACER
228 select HAVE_GCC_PLUGINS
229 select HAVE_HW_BREAKPOINT
230 select HAVE_IOREMAP_PROT
231 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
232 select HAVE_IRQ_TIME_ACCOUNTING
233 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
234 select HAVE_KERNEL_BZIP2
235 select HAVE_KERNEL_GZIP
236 select HAVE_KERNEL_LZ4
237 select HAVE_KERNEL_LZMA
238 select HAVE_KERNEL_LZO
239 select HAVE_KERNEL_XZ
240 select HAVE_KERNEL_ZSTD
242 select HAVE_KPROBES_ON_FTRACE
243 select HAVE_FUNCTION_ERROR_INJECTION
244 select HAVE_KRETPROBES
247 select HAVE_LIVEPATCH if X86_64
248 select HAVE_MIXED_BREAKPOINTS_REGS
249 select HAVE_MOD_ARCH_SPECIFIC
252 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
254 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
255 select HAVE_OBJTOOL if X86_64
256 select HAVE_OPTPROBES
257 select HAVE_PCSPKR_PLATFORM
258 select HAVE_PERF_EVENTS
259 select HAVE_PERF_EVENTS_NMI
260 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
262 select HAVE_PERF_REGS
263 select HAVE_PERF_USER_STACK_DUMP
264 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
265 select MMU_GATHER_MERGE_VMAS
266 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
267 select HAVE_REGS_AND_STACK_ACCESS_API
268 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
269 select HAVE_FUNCTION_ARG_ACCESS_API
270 select HAVE_SETUP_PER_CPU_AREA
271 select HAVE_SOFTIRQ_ON_OWN_STACK
272 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
273 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
274 select HAVE_STATIC_CALL
275 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
276 select HAVE_PREEMPT_DYNAMIC_CALL
278 select HAVE_RUST if X86_64
279 select HAVE_SYSCALL_TRACEPOINTS
280 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
281 select HAVE_UNSTABLE_SCHED_CLOCK
282 select HAVE_USER_RETURN_NOTIFIER
283 select HAVE_GENERIC_VDSO
284 select HOTPLUG_PARALLEL if SMP && X86_64
285 select HOTPLUG_SMT if SMP
286 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
287 select IRQ_FORCED_THREADING
288 select LOCK_MM_AND_FIND_VMA
289 select NEED_PER_CPU_EMBED_FIRST_CHUNK
290 select NEED_PER_CPU_PAGE_FIRST_CHUNK
291 select NEED_SG_DMA_LENGTH
292 select PCI_DOMAINS if PCI
293 select PCI_LOCKLESS_CONFIG if PCI
296 select RTC_MC146818_LIB
298 select SYSCTL_EXCEPTION_TRACE
299 select THREAD_INFO_IN_TASK
300 select TRACE_IRQFLAGS_SUPPORT
301 select TRACE_IRQFLAGS_NMI_SUPPORT
302 select USER_STACKTRACE_SUPPORT
303 select HAVE_ARCH_KCSAN if X86_64
304 select PROC_PID_ARCH_STATUS if PROC_FS
305 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
306 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
307 select FUNCTION_ALIGNMENT_4B
308 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
309 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
311 config INSTRUCTION_DECODER
313 depends on KPROBES || PERF_EVENTS || UPROBES
317 default "elf32-i386" if X86_32
318 default "elf64-x86-64" if X86_64
320 config LOCKDEP_SUPPORT
323 config STACKTRACE_SUPPORT
329 config ARCH_MMAP_RND_BITS_MIN
333 config ARCH_MMAP_RND_BITS_MAX
337 config ARCH_MMAP_RND_COMPAT_BITS_MIN
340 config ARCH_MMAP_RND_COMPAT_BITS_MAX
346 config GENERIC_ISA_DMA
348 depends on ISA_DMA_API
352 default y if KMSAN || KASAN
357 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
359 config GENERIC_BUG_RELATIVE_POINTERS
362 config ARCH_MAY_HAVE_PC_FDC
364 depends on ISA_DMA_API
366 config GENERIC_CALIBRATE_DELAY
369 config ARCH_HAS_CPU_RELAX
372 config ARCH_HIBERNATION_POSSIBLE
375 config ARCH_SUSPEND_POSSIBLE
381 config KASAN_SHADOW_OFFSET
384 default 0xdffffc0000000000
386 config HAVE_INTEL_TXT
388 depends on INTEL_IOMMU && ACPI
392 depends on X86_64 && SMP
394 config ARCH_SUPPORTS_UPROBES
397 config FIX_EARLYCON_MEM
400 config DYNAMIC_PHYSICAL_MASK
403 config PGTABLE_LEVELS
405 default 5 if X86_5LEVEL
410 config CC_HAS_SANE_STACKPROTECTOR
412 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
413 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
415 We have to make sure stack protector is unconditionally disabled if
416 the compiler produces broken code or if it does not let us control
417 the segment on 32-bit kernels.
419 menu "Processor type and features"
422 bool "Symmetric multi-processing support"
424 This enables support for systems with more than one CPU. If you have
425 a system with only one CPU, say N. If you have a system with more
428 If you say N here, the kernel will run on uni- and multiprocessor
429 machines, but will use only one CPU of a multiprocessor machine. If
430 you say Y here, the kernel will run on many, but not all,
431 uniprocessor machines. On a uniprocessor machine, the kernel
432 will run faster if you say N here.
434 Note that if you say Y here and choose architecture "586" or
435 "Pentium" under "Processor family", the kernel will not work on 486
436 architectures. Similarly, multiprocessor kernels for the "PPro"
437 architecture may not work on all Pentium based boards.
439 People using multiprocessor machines who say Y here should also say
440 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
441 Management" code will be disabled if you say Y here.
443 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
444 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
445 <http://www.tldp.org/docs.html#howto>.
447 If you don't know what to do here, say N.
450 bool "Support x2apic"
451 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
453 This enables x2apic support on CPUs that have this feature.
455 This allows 32-bit apic IDs (so it can support very large systems),
456 and accesses the local apic via MSRs not via mmio.
458 Some Intel systems circa 2022 and later are locked into x2APIC mode
459 and can not fall back to the legacy APIC modes if SGX or TDX are
460 enabled in the BIOS. They will boot with very reduced functionality
461 without enabling this option.
463 If you don't know what to do here, say N.
466 bool "Enable MPS table" if ACPI
468 depends on X86_LOCAL_APIC
470 For old smp systems that do not have proper acpi support. Newer systems
471 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
475 depends on X86_GOLDFISH
477 config X86_CPU_RESCTRL
478 bool "x86 CPU resource control support"
479 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
481 select PROC_CPU_RESCTRL if PROC_FS
483 Enable x86 CPU resource control support.
485 Provide support for the allocation and monitoring of system resources
488 Intel calls this Intel Resource Director Technology
489 (Intel(R) RDT). More information about RDT can be found in the
490 Intel x86 Architecture Software Developer Manual.
492 AMD calls this AMD Platform Quality of Service (AMD QoS).
493 More information about AMD QoS can be found in the AMD64 Technology
494 Platform Quality of Service Extensions manual.
500 bool "Support for big SMP systems with more than 8 CPUs"
503 This option is needed for the systems that have more than 8 CPUs.
505 config X86_EXTENDED_PLATFORM
506 bool "Support for extended (non-PC) x86 platforms"
509 If you disable this option then the kernel will only support
510 standard PC platforms. (which covers the vast majority of
513 If you enable this option then you'll be able to select support
514 for the following (non-PC) 32 bit x86 platforms:
515 Goldfish (Android emulator)
518 SGI 320/540 (Visual Workstation)
519 STA2X11-based (e.g. Northville)
520 Moorestown MID devices
522 If you have one of these systems, or if you want to build a
523 generic distribution kernel, say Y here - otherwise say N.
527 config X86_EXTENDED_PLATFORM
528 bool "Support for extended (non-PC) x86 platforms"
531 If you disable this option then the kernel will only support
532 standard PC platforms. (which covers the vast majority of
535 If you enable this option then you'll be able to select support
536 for the following (non-PC) 64 bit x86 platforms:
541 If you have one of these systems, or if you want to build a
542 generic distribution kernel, say Y here - otherwise say N.
544 # This is an alphabetically sorted list of 64 bit extended platforms
545 # Please maintain the alphabetic order if and when there are additions
547 bool "Numascale NumaChip"
549 depends on X86_EXTENDED_PLATFORM
552 depends on X86_X2APIC
553 depends on PCI_MMCONFIG
555 Adds support for Numascale NumaChip large-SMP systems. Needed to
556 enable more than ~168 cores.
557 If you don't have one of these, you should say N here.
561 select HYPERVISOR_GUEST
563 depends on X86_64 && PCI
564 depends on X86_EXTENDED_PLATFORM
567 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
568 supposed to run on these EM64T-based machines. Only choose this option
569 if you have one of these machines.
572 bool "SGI Ultraviolet"
574 depends on X86_EXTENDED_PLATFORM
577 depends on KEXEC_CORE
578 depends on X86_X2APIC
581 This option is needed in order to support SGI Ultraviolet systems.
582 If you don't have one of these, you should say N here.
584 # Following is an alphabetically sorted list of 32 bit extended platforms
585 # Please maintain the alphabetic order if and when there are additions
588 bool "Goldfish (Virtual Platform)"
589 depends on X86_EXTENDED_PLATFORM
591 Enable support for the Goldfish virtual platform used primarily
592 for Android development. Unless you are building for the Android
593 Goldfish emulator say N here.
596 bool "CE4100 TV platform"
598 depends on PCI_GODIRECT
599 depends on X86_IO_APIC
601 depends on X86_EXTENDED_PLATFORM
602 select X86_REBOOTFIXUPS
604 select OF_EARLY_FLATTREE
606 Select for the Intel CE media processor (CE4100) SOC.
607 This option compiles in support for the CE4100 SOC for settop
608 boxes and media devices.
611 bool "Intel MID platform support"
612 depends on X86_EXTENDED_PLATFORM
613 depends on X86_PLATFORM_DEVICES
615 depends on X86_64 || (PCI_GOANY && X86_32)
616 depends on X86_IO_APIC
621 Select to build a kernel capable of supporting Intel MID (Mobile
622 Internet Device) platform systems which do not have the PCI legacy
623 interfaces. If you are building for a PC class system say N here.
625 Intel MID platforms are based on an Intel processor and chipset which
626 consume less power than most of the x86 derivatives.
628 config X86_INTEL_QUARK
629 bool "Intel Quark platform support"
631 depends on X86_EXTENDED_PLATFORM
632 depends on X86_PLATFORM_DEVICES
636 depends on X86_IO_APIC
641 Select to include support for Quark X1000 SoC.
642 Say Y here if you have a Quark based system such as the Arduino
643 compatible Intel Galileo.
645 config X86_INTEL_LPSS
646 bool "Intel Low Power Subsystem Support"
647 depends on X86 && ACPI && PCI
652 Select to build support for Intel Low Power Subsystem such as
653 found on Intel Lynxpoint PCH. Selecting this option enables
654 things like clock tree (common clock framework) and pincontrol
655 which are needed by the LPSS peripheral drivers.
657 config X86_AMD_PLATFORM_DEVICE
658 bool "AMD ACPI2Platform devices support"
663 Select to interpret AMD specific ACPI device to platform device
664 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
665 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
666 implemented under PINCTRL subsystem.
669 tristate "Intel SoC IOSF Sideband support for SoC platforms"
672 This option enables sideband register access support for Intel SoC
673 platforms. On these platforms the IOSF sideband is used in lieu of
674 MSR's for some register accesses, mostly but not limited to thermal
675 and power. Drivers may query the availability of this device to
676 determine if they need the sideband in order to work on these
677 platforms. The sideband is available on the following SoC products.
678 This list is not meant to be exclusive.
683 You should say Y if you are running a kernel on one of these SoC's.
685 config IOSF_MBI_DEBUG
686 bool "Enable IOSF sideband access through debugfs"
687 depends on IOSF_MBI && DEBUG_FS
689 Select this option to expose the IOSF sideband access registers (MCR,
690 MDR, MCRX) through debugfs to write and read register information from
691 different units on the SoC. This is most useful for obtaining device
692 state information for debug and analysis. As this is a general access
693 mechanism, users of this option would have specific knowledge of the
694 device they want to access.
696 If you don't require the option or are in doubt, say N.
699 bool "RDC R-321x SoC"
701 depends on X86_EXTENDED_PLATFORM
703 select X86_REBOOTFIXUPS
705 This option is needed for RDC R-321x system-on-chip, also known
707 If you don't have one of these chips, you should say N here.
709 config X86_32_NON_STANDARD
710 bool "Support non-standard 32-bit SMP architectures"
711 depends on X86_32 && SMP
712 depends on X86_EXTENDED_PLATFORM
714 This option compiles in the bigsmp and STA2X11 default
715 subarchitectures. It is intended for a generic binary
716 kernel. If you select them all, kernel will probe it one by
717 one and will fallback to default.
719 # Alphabetically sorted list of Non standard 32 bit platforms
721 config X86_SUPPORTS_MEMORY_FAILURE
723 # MCE code calls memory_failure():
725 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
726 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
727 depends on X86_64 || !SPARSEMEM
728 select ARCH_SUPPORTS_MEMORY_FAILURE
731 bool "STA2X11 Companion Chip Support"
732 depends on X86_32_NON_STANDARD && PCI
737 This adds support for boards based on the STA2X11 IO-Hub,
738 a.k.a. "ConneXt". The chip is used in place of the standard
739 PC chipset, so all "standard" peripherals are missing. If this
740 option is selected the kernel will still be able to boot on
741 standard PC machines.
744 tristate "Eurobraille/Iris poweroff module"
747 The Iris machines from EuroBraille do not have APM or ACPI support
748 to shut themselves down properly. A special I/O sequence is
749 needed to do so, which is what this module does at
752 This is only for Iris machines from EuroBraille.
756 config SCHED_OMIT_FRAME_POINTER
758 prompt "Single-depth WCHAN output"
761 Calculate simpler /proc/<PID>/wchan values. If this option
762 is disabled then wchan values will recurse back to the
763 caller function. This provides more accurate wchan values,
764 at the expense of slightly more scheduling overhead.
766 If in doubt, say "Y".
768 menuconfig HYPERVISOR_GUEST
769 bool "Linux guest support"
771 Say Y here to enable options for running Linux under various hyper-
772 visors. This option enables basic hypervisor detection and platform
775 If you say N, all options in this submenu will be skipped and
776 disabled, and Linux guest support won't be built in.
781 bool "Enable paravirtualization code"
782 depends on HAVE_STATIC_CALL
784 This changes the kernel so it can modify itself when it is run
785 under a hypervisor, potentially improving performance significantly
786 over full virtualization. However, when run without a hypervisor
787 the kernel is theoretically slower and slightly larger.
792 config PARAVIRT_DEBUG
793 bool "paravirt-ops debugging"
794 depends on PARAVIRT && DEBUG_KERNEL
796 Enable to debug paravirt_ops internals. Specifically, BUG if
797 a paravirt_op is missing when it is called.
799 config PARAVIRT_SPINLOCKS
800 bool "Paravirtualization layer for spinlocks"
801 depends on PARAVIRT && SMP
803 Paravirtualized spinlocks allow a pvops backend to replace the
804 spinlock implementation with something virtualization-friendly
805 (for example, block the virtual CPU rather than spinning).
807 It has a minimal impact on native kernels and gives a nice performance
808 benefit on paravirtualized KVM / Xen kernels.
810 If you are unsure how to answer this question, answer Y.
812 config X86_HV_CALLBACK_VECTOR
815 source "arch/x86/xen/Kconfig"
818 bool "KVM Guest support (including kvmclock)"
820 select PARAVIRT_CLOCK
821 select ARCH_CPUIDLE_HALTPOLL
822 select X86_HV_CALLBACK_VECTOR
825 This option enables various optimizations for running under the KVM
826 hypervisor. It includes a paravirtualized clock, so that instead
827 of relying on a PIT (or probably other) emulation by the
828 underlying device model, the host provides the guest with
829 timing infrastructure such as time of day, and system time
831 config ARCH_CPUIDLE_HALTPOLL
833 prompt "Disable host haltpoll when loading haltpoll driver"
835 If virtualized under KVM, disable host haltpoll.
838 bool "Support for running PVH guests"
840 This option enables the PVH entry point for guest virtual machines
841 as specified in the x86/HVM direct boot ABI.
843 config PARAVIRT_TIME_ACCOUNTING
844 bool "Paravirtual steal time accounting"
847 Select this option to enable fine granularity task steal time
848 accounting. Time spent executing other tasks in parallel with
849 the current vCPU is discounted from the vCPU power. To account for
850 that, there can be a small performance impact.
852 If in doubt, say N here.
854 config PARAVIRT_CLOCK
857 config JAILHOUSE_GUEST
858 bool "Jailhouse non-root cell support"
859 depends on X86_64 && PCI
862 This option allows to run Linux as guest in a Jailhouse non-root
863 cell. You can leave this option disabled if you only want to start
864 Jailhouse and run Linux afterwards in the root cell.
867 bool "ACRN Guest support"
869 select X86_HV_CALLBACK_VECTOR
871 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
872 a flexible, lightweight reference open-source hypervisor, built with
873 real-time and safety-criticality in mind. It is built for embedded
874 IOT with small footprint and real-time features. More details can be
875 found in https://projectacrn.org/.
877 config INTEL_TDX_GUEST
878 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
879 depends on X86_64 && CPU_SUP_INTEL
880 depends on X86_X2APIC
882 select ARCH_HAS_CC_PLATFORM
883 select X86_MEM_ENCRYPT
885 select UNACCEPTED_MEMORY
887 Support running as a guest under Intel TDX. Without this support,
888 the guest kernel can not boot or run under TDX.
889 TDX includes memory encryption and integrity capabilities
890 which protect the confidentiality and integrity of guest
891 memory contents and CPU state. TDX guests are protected from
892 some attacks from the VMM.
894 endif # HYPERVISOR_GUEST
896 source "arch/x86/Kconfig.cpu"
900 prompt "HPET Timer Support" if X86_32
902 Use the IA-PC HPET (High Precision Event Timer) to manage
903 time in preference to the PIT and RTC, if a HPET is
905 HPET is the next generation timer replacing legacy 8254s.
906 The HPET provides a stable time base on SMP
907 systems, unlike the TSC, but it is more expensive to access,
908 as it is off-chip. The interface used is documented
909 in the HPET spec, revision 1.
911 You can safely choose Y here. However, HPET will only be
912 activated if the platform and the BIOS support this feature.
913 Otherwise the 8254 will be used for timing services.
915 Choose N to continue using the legacy 8254 timer.
917 config HPET_EMULATE_RTC
919 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
921 # Mark as expert because too many people got it wrong.
922 # The code disables itself when not needed.
925 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
926 bool "Enable DMI scanning" if EXPERT
928 Enabled scanning of DMI to identify machine quirks. Say Y
929 here unless you have verified that your setup is not
930 affected by entries in the DMI blacklist. Required by PNP
934 bool "Old AMD GART IOMMU support"
938 depends on X86_64 && PCI && AMD_NB
940 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
941 GART based hardware IOMMUs.
943 The GART supports full DMA access for devices with 32-bit access
944 limitations, on systems with more than 3 GB. This is usually needed
945 for USB, sound, many IDE/SATA chipsets and some other devices.
947 Newer systems typically have a modern AMD IOMMU, supported via
948 the CONFIG_AMD_IOMMU=y config option.
950 In normal configurations this driver is only active when needed:
951 there's more than 3 GB of memory and the system contains a
952 32-bit limited device.
956 config BOOT_VESA_SUPPORT
959 If true, at least one selected framebuffer driver can take advantage
960 of VESA video modes set at an early boot stage via the vga= parameter.
963 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
964 depends on X86_64 && SMP && DEBUG_KERNEL
965 select CPUMASK_OFFSTACK
967 Enable maximum number of CPUS and NUMA Nodes for this architecture.
971 # The maximum number of CPUs supported:
973 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
974 # and which can be configured interactively in the
975 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
977 # The ranges are different on 32-bit and 64-bit kernels, depending on
978 # hardware capabilities and scalability features of the kernel.
980 # ( If MAXSMP is enabled we just use the highest possible value and disable
981 # interactive configuration. )
984 config NR_CPUS_RANGE_BEGIN
986 default NR_CPUS_RANGE_END if MAXSMP
990 config NR_CPUS_RANGE_END
993 default 64 if SMP && X86_BIGSMP
994 default 8 if SMP && !X86_BIGSMP
997 config NR_CPUS_RANGE_END
1000 default 8192 if SMP && CPUMASK_OFFSTACK
1001 default 512 if SMP && !CPUMASK_OFFSTACK
1004 config NR_CPUS_DEFAULT
1007 default 32 if X86_BIGSMP
1011 config NR_CPUS_DEFAULT
1014 default 8192 if MAXSMP
1019 int "Maximum number of CPUs" if SMP && !MAXSMP
1020 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1021 default NR_CPUS_DEFAULT
1023 This allows you to specify the maximum number of CPUs which this
1024 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1025 supported value is 8192, otherwise the maximum value is 512. The
1026 minimum value which makes sense is 2.
1028 This is purely to save memory: each supported CPU adds about 8KB
1029 to the kernel image.
1031 config SCHED_CLUSTER
1032 bool "Cluster scheduler support"
1036 Cluster scheduler support improves the CPU scheduler's decision
1037 making when dealing with machines that have clusters of CPUs.
1038 Cluster usually means a couple of CPUs which are placed closely
1039 by sharing mid-level caches, last-level cache tags or internal
1047 prompt "Multi-core scheduler support"
1050 Multi-core scheduler support improves the CPU scheduler's decision
1051 making when dealing with multi-core CPU chips at a cost of slightly
1052 increased overhead in some places. If unsure say N here.
1054 config SCHED_MC_PRIO
1055 bool "CPU core priorities scheduler support"
1056 depends on SCHED_MC && CPU_SUP_INTEL
1057 select X86_INTEL_PSTATE
1061 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1062 core ordering determined at manufacturing time, which allows
1063 certain cores to reach higher turbo frequencies (when running
1064 single threaded workloads) than others.
1066 Enabling this kernel feature teaches the scheduler about
1067 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1068 scheduler's CPU selection logic accordingly, so that higher
1069 overall system performance can be achieved.
1071 This feature will have no effect on CPUs without this feature.
1073 If unsure say Y here.
1077 depends on !SMP && X86_LOCAL_APIC
1080 bool "Local APIC support on uniprocessors" if !PCI_MSI
1082 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1084 A local APIC (Advanced Programmable Interrupt Controller) is an
1085 integrated interrupt controller in the CPU. If you have a single-CPU
1086 system which has a processor with a local APIC, you can say Y here to
1087 enable and use it. If you say Y here even though your machine doesn't
1088 have a local APIC, then the kernel will still run with no slowdown at
1089 all. The local APIC supports CPU-generated self-interrupts (timer,
1090 performance counters), and the NMI watchdog which detects hard
1093 config X86_UP_IOAPIC
1094 bool "IO-APIC support on uniprocessors"
1095 depends on X86_UP_APIC
1097 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1098 SMP-capable replacement for PC-style interrupt controllers. Most
1099 SMP systems and many recent uniprocessor systems have one.
1101 If you have a single-CPU system with an IO-APIC, you can say Y here
1102 to use it. If you say Y here even though your machine doesn't have
1103 an IO-APIC, then the kernel will still run with no slowdown at all.
1105 config X86_LOCAL_APIC
1107 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1108 select IRQ_DOMAIN_HIERARCHY
1112 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1114 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1115 bool "Reroute for broken boot IRQs"
1116 depends on X86_IO_APIC
1118 This option enables a workaround that fixes a source of
1119 spurious interrupts. This is recommended when threaded
1120 interrupt handling is used on systems where the generation of
1121 superfluous "boot interrupts" cannot be disabled.
1123 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1124 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1125 kernel does during interrupt handling). On chipsets where this
1126 boot IRQ generation cannot be disabled, this workaround keeps
1127 the original IRQ line masked so that only the equivalent "boot
1128 IRQ" is delivered to the CPUs. The workaround also tells the
1129 kernel to set up the IRQ handler on the boot IRQ line. In this
1130 way only one interrupt is delivered to the kernel. Otherwise
1131 the spurious second interrupt may cause the kernel to bring
1132 down (vital) interrupt lines.
1134 Only affects "broken" chipsets. Interrupt sharing may be
1135 increased on these systems.
1138 bool "Machine Check / overheating reporting"
1139 select GENERIC_ALLOCATOR
1142 Machine Check support allows the processor to notify the
1143 kernel if it detects a problem (e.g. overheating, data corruption).
1144 The action the kernel takes depends on the severity of the problem,
1145 ranging from warning messages to halting the machine.
1147 config X86_MCELOG_LEGACY
1148 bool "Support for deprecated /dev/mcelog character device"
1151 Enable support for /dev/mcelog which is needed by the old mcelog
1152 userspace logging daemon. Consider switching to the new generation
1155 config X86_MCE_INTEL
1157 prompt "Intel MCE features"
1158 depends on X86_MCE && X86_LOCAL_APIC
1160 Additional support for intel specific MCE features such as
1161 the thermal monitor.
1165 prompt "AMD MCE features"
1166 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1168 Additional support for AMD specific MCE features such as
1169 the DRAM Error Threshold.
1171 config X86_ANCIENT_MCE
1172 bool "Support for old Pentium 5 / WinChip machine checks"
1173 depends on X86_32 && X86_MCE
1175 Include support for machine check handling on old Pentium 5 or WinChip
1176 systems. These typically need to be enabled explicitly on the command
1179 config X86_MCE_THRESHOLD
1180 depends on X86_MCE_AMD || X86_MCE_INTEL
1183 config X86_MCE_INJECT
1184 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1185 tristate "Machine check injector support"
1187 Provide support for injecting machine checks for testing purposes.
1188 If you don't know what a machine check is and you don't do kernel
1189 QA it is safe to say n.
1191 source "arch/x86/events/Kconfig"
1193 config X86_LEGACY_VM86
1194 bool "Legacy VM86 support"
1197 This option allows user programs to put the CPU into V8086
1198 mode, which is an 80286-era approximation of 16-bit real mode.
1200 Some very old versions of X and/or vbetool require this option
1201 for user mode setting. Similarly, DOSEMU will use it if
1202 available to accelerate real mode DOS programs. However, any
1203 recent version of DOSEMU, X, or vbetool should be fully
1204 functional even without kernel VM86 support, as they will all
1205 fall back to software emulation. Nevertheless, if you are using
1206 a 16-bit DOS program where 16-bit performance matters, vm86
1207 mode might be faster than emulation and you might want to
1210 Note that any app that works on a 64-bit kernel is unlikely to
1211 need this option, as 64-bit kernels don't, and can't, support
1212 V8086 mode. This option is also unrelated to 16-bit protected
1213 mode and is not needed to run most 16-bit programs under Wine.
1215 Enabling this option increases the complexity of the kernel
1216 and slows down exception handling a tiny bit.
1218 If unsure, say N here.
1222 default X86_LEGACY_VM86
1225 bool "Enable support for 16-bit segments" if EXPERT
1227 depends on MODIFY_LDT_SYSCALL
1229 This option is required by programs like Wine to run 16-bit
1230 protected mode legacy code on x86 processors. Disabling
1231 this option saves about 300 bytes on i386, or around 6K text
1232 plus 16K runtime memory on x86-64,
1236 depends on X86_16BIT && X86_32
1240 depends on X86_16BIT && X86_64
1242 config X86_VSYSCALL_EMULATION
1243 bool "Enable vsyscall emulation" if EXPERT
1247 This enables emulation of the legacy vsyscall page. Disabling
1248 it is roughly equivalent to booting with vsyscall=none, except
1249 that it will also disable the helpful warning if a program
1250 tries to use a vsyscall. With this option set to N, offending
1251 programs will just segfault, citing addresses of the form
1254 This option is required by many programs built before 2013, and
1255 care should be used even with newer programs if set to N.
1257 Disabling this option saves about 7K of kernel size and
1258 possibly 4K of additional runtime pagetable memory.
1260 config X86_IOPL_IOPERM
1261 bool "IOPERM and IOPL Emulation"
1264 This enables the ioperm() and iopl() syscalls which are necessary
1265 for legacy applications.
1267 Legacy IOPL support is an overbroad mechanism which allows user
1268 space aside of accessing all 65536 I/O ports also to disable
1269 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1270 capabilities and permission from potentially active security
1273 The emulation restricts the functionality of the syscall to
1274 only allowing the full range I/O port access, but prevents the
1275 ability to disable interrupts from user space which would be
1276 granted if the hardware IOPL mechanism would be used.
1279 tristate "Toshiba Laptop support"
1282 This adds a driver to safely access the System Management Mode of
1283 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1284 not work on models with a Phoenix BIOS. The System Management Mode
1285 is used to set the BIOS and power saving options on Toshiba portables.
1287 For information on utilities to make use of this driver see the
1288 Toshiba Linux utilities web site at:
1289 <http://www.buzzard.org.uk/toshiba/>.
1291 Say Y if you intend to run this kernel on a Toshiba portable.
1294 config X86_REBOOTFIXUPS
1295 bool "Enable X86 board specific fixups for reboot"
1298 This enables chipset and/or board specific fixups to be done
1299 in order to get reboot to work correctly. This is only needed on
1300 some combinations of hardware and BIOS. The symptom, for which
1301 this config is intended, is when reboot ends with a stalled/hung
1304 Currently, the only fixup is for the Geode machines using
1305 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1307 Say Y if you want to enable the fixup. Currently, it's safe to
1308 enable this option even if you don't need it.
1313 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1315 config MICROCODE_INITRD32
1317 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1319 config MICROCODE_LATE_LOADING
1320 bool "Late microcode loading (DANGEROUS)"
1322 depends on MICROCODE && SMP
1324 Loading microcode late, when the system is up and executing instructions
1325 is a tricky business and should be avoided if possible. Just the sequence
1326 of synchronizing all cores and SMT threads is one fragile dance which does
1327 not guarantee that cores might not softlock after the loading. Therefore,
1328 use this at your own risk. Late loading taints the kernel unless the
1329 microcode header indicates that it is safe for late loading via the
1330 minimal revision check. This minimal revision check can be enforced on
1331 the kernel command line with "microcode.minrev=Y".
1333 config MICROCODE_LATE_FORCE_MINREV
1334 bool "Enforce late microcode loading minimal revision check"
1336 depends on MICROCODE_LATE_LOADING
1338 To prevent that users load microcode late which modifies already
1339 in use features, newer microcode patches have a minimum revision field
1340 in the microcode header, which tells the kernel which minimum
1341 revision must be active in the CPU to safely load that new microcode
1342 late into the running system. If disabled the check will not
1343 be enforced but the kernel will be tainted when the minimal
1344 revision check fails.
1346 This minimal revision check can also be controlled via the
1347 "microcode.minrev" parameter on the kernel command line.
1352 tristate "/dev/cpu/*/msr - Model-specific register support"
1354 This device gives privileged processes access to the x86
1355 Model-Specific Registers (MSRs). It is a character device with
1356 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1357 MSR accesses are directed to a specific CPU on multi-processor
1361 tristate "/dev/cpu/*/cpuid - CPU information support"
1363 This device gives processes access to the x86 CPUID instruction to
1364 be executed on a specific processor. It is a character device
1365 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1369 prompt "High Memory Support"
1376 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1377 However, the address space of 32-bit x86 processors is only 4
1378 Gigabytes large. That means that, if you have a large amount of
1379 physical memory, not all of it can be "permanently mapped" by the
1380 kernel. The physical memory that's not permanently mapped is called
1383 If you are compiling a kernel which will never run on a machine with
1384 more than 1 Gigabyte total physical RAM, answer "off" here (default
1385 choice and suitable for most users). This will result in a "3GB/1GB"
1386 split: 3GB are mapped so that each process sees a 3GB virtual memory
1387 space and the remaining part of the 4GB virtual memory space is used
1388 by the kernel to permanently map as much physical memory as
1391 If the machine has between 1 and 4 Gigabytes physical RAM, then
1394 If more than 4 Gigabytes is used then answer "64GB" here. This
1395 selection turns Intel PAE (Physical Address Extension) mode on.
1396 PAE implements 3-level paging on IA32 processors. PAE is fully
1397 supported by Linux, PAE mode is implemented on all recent Intel
1398 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1399 then the kernel will not boot on CPUs that don't support PAE!
1401 The actual amount of total physical memory will either be
1402 auto detected or can be forced by using a kernel command line option
1403 such as "mem=256M". (Try "man bootparam" or see the documentation of
1404 your boot loader (lilo or loadlin) about how to pass options to the
1405 kernel at boot time.)
1407 If unsure, say "off".
1412 Select this if you have a 32-bit processor and between 1 and 4
1413 gigabytes of physical RAM.
1417 depends on X86_HAVE_PAE
1420 Select this if you have a 32-bit processor and more than 4
1421 gigabytes of physical RAM.
1426 prompt "Memory split" if EXPERT
1430 Select the desired split between kernel and user memory.
1432 If the address range available to the kernel is less than the
1433 physical memory installed, the remaining memory will be available
1434 as "high memory". Accessing high memory is a little more costly
1435 than low memory, as it needs to be mapped into the kernel first.
1436 Note that increasing the kernel address space limits the range
1437 available to user programs, making the address space there
1438 tighter. Selecting anything other than the default 3G/1G split
1439 will also likely make your kernel incompatible with binary-only
1442 If you are not absolutely sure what you are doing, leave this
1446 bool "3G/1G user/kernel split"
1447 config VMSPLIT_3G_OPT
1449 bool "3G/1G user/kernel split (for full 1G low memory)"
1451 bool "2G/2G user/kernel split"
1452 config VMSPLIT_2G_OPT
1454 bool "2G/2G user/kernel split (for full 2G low memory)"
1456 bool "1G/3G user/kernel split"
1461 default 0xB0000000 if VMSPLIT_3G_OPT
1462 default 0x80000000 if VMSPLIT_2G
1463 default 0x78000000 if VMSPLIT_2G_OPT
1464 default 0x40000000 if VMSPLIT_1G
1470 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1473 bool "PAE (Physical Address Extension) Support"
1474 depends on X86_32 && X86_HAVE_PAE
1475 select PHYS_ADDR_T_64BIT
1478 PAE is required for NX support, and furthermore enables
1479 larger swapspace support for non-overcommit purposes. It
1480 has the cost of more pagetable lookup overhead, and also
1481 consumes more pagetable space per process.
1484 bool "Enable 5-level page tables support"
1486 select DYNAMIC_MEMORY_LAYOUT
1487 select SPARSEMEM_VMEMMAP
1490 5-level paging enables access to larger address space:
1491 up to 128 PiB of virtual address space and 4 PiB of
1492 physical address space.
1494 It will be supported by future Intel CPUs.
1496 A kernel with the option enabled can be booted on machines that
1497 support 4- or 5-level paging.
1499 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1504 config X86_DIRECT_GBPAGES
1508 Certain kernel features effectively disable kernel
1509 linear 1 GB mappings (even if the CPU otherwise
1510 supports them), so don't confuse the user by printing
1511 that we have them enabled.
1513 config X86_CPA_STATISTICS
1514 bool "Enable statistic for Change Page Attribute"
1517 Expose statistics about the Change Page Attribute mechanism, which
1518 helps to determine the effectiveness of preserving large and huge
1519 page mappings when mapping protections are changed.
1521 config X86_MEM_ENCRYPT
1522 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1523 select DYNAMIC_PHYSICAL_MASK
1526 config AMD_MEM_ENCRYPT
1527 bool "AMD Secure Memory Encryption (SME) support"
1528 depends on X86_64 && CPU_SUP_AMD
1530 select DMA_COHERENT_POOL
1531 select ARCH_USE_MEMREMAP_PROT
1532 select INSTRUCTION_DECODER
1533 select ARCH_HAS_CC_PLATFORM
1534 select X86_MEM_ENCRYPT
1535 select UNACCEPTED_MEMORY
1537 Say yes to enable support for the encryption of system memory.
1538 This requires an AMD processor that supports Secure Memory
1541 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1542 bool "Activate AMD Secure Memory Encryption (SME) by default"
1543 depends on AMD_MEM_ENCRYPT
1545 Say yes to have system memory encrypted by default if running on
1546 an AMD processor that supports Secure Memory Encryption (SME).
1548 If set to Y, then the encryption of system memory can be
1549 deactivated with the mem_encrypt=off command line option.
1551 If set to N, then the encryption of system memory can be
1552 activated with the mem_encrypt=on command line option.
1554 # Common NUMA Features
1556 bool "NUMA Memory Allocation and Scheduler Support"
1558 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1559 default y if X86_BIGSMP
1560 select USE_PERCPU_NUMA_NODE_ID
1561 select OF_NUMA if OF
1563 Enable NUMA (Non-Uniform Memory Access) support.
1565 The kernel will try to allocate memory used by a CPU on the
1566 local memory controller of the CPU and add some more
1567 NUMA awareness to the kernel.
1569 For 64-bit this is recommended if the system is Intel Core i7
1570 (or later), AMD Opteron, or EM64T NUMA.
1572 For 32-bit this is only needed if you boot a 32-bit
1573 kernel on a 64-bit NUMA platform.
1575 Otherwise, you should say N.
1579 prompt "Old style AMD Opteron NUMA detection"
1580 depends on X86_64 && NUMA && PCI
1582 Enable AMD NUMA node topology detection. You should say Y here if
1583 you have a multi processor AMD system. This uses an old method to
1584 read the NUMA configuration directly from the builtin Northbridge
1585 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1586 which also takes priority if both are compiled in.
1588 config X86_64_ACPI_NUMA
1590 prompt "ACPI NUMA detection"
1591 depends on X86_64 && NUMA && ACPI && PCI
1594 Enable ACPI SRAT based node topology detection.
1597 bool "NUMA emulation"
1600 Enable NUMA emulation. A flat machine will be split
1601 into virtual nodes when booted with "numa=fake=N", where N is the
1602 number of nodes. This is only useful for debugging.
1605 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1607 default "10" if MAXSMP
1608 default "6" if X86_64
1612 Specify the maximum number of NUMA Nodes available on the target
1613 system. Increases memory reserved to accommodate various tables.
1615 config ARCH_FLATMEM_ENABLE
1617 depends on X86_32 && !NUMA
1619 config ARCH_SPARSEMEM_ENABLE
1621 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1622 select SPARSEMEM_STATIC if X86_32
1623 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1625 config ARCH_SPARSEMEM_DEFAULT
1626 def_bool X86_64 || (NUMA && X86_32)
1628 config ARCH_SELECT_MEMORY_MODEL
1630 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1632 config ARCH_MEMORY_PROBE
1633 bool "Enable sysfs memory/probe interface"
1634 depends on MEMORY_HOTPLUG
1636 This option enables a sysfs memory/probe interface for testing.
1637 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1638 If you are unsure how to answer this question, answer N.
1640 config ARCH_PROC_KCORE_TEXT
1642 depends on X86_64 && PROC_KCORE
1644 config ILLEGAL_POINTER_VALUE
1647 default 0xdead000000000000 if X86_64
1649 config X86_PMEM_LEGACY_DEVICE
1652 config X86_PMEM_LEGACY
1653 tristate "Support non-standard NVDIMMs and ADR protected memory"
1654 depends on PHYS_ADDR_T_64BIT
1656 select X86_PMEM_LEGACY_DEVICE
1657 select NUMA_KEEP_MEMINFO if NUMA
1660 Treat memory marked using the non-standard e820 type of 12 as used
1661 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1662 The kernel will offer these regions to the 'pmem' driver so
1663 they can be used for persistent storage.
1668 bool "Allocate 3rd-level pagetables from highmem"
1671 The VM uses one page table entry for each page of physical memory.
1672 For systems with a lot of RAM, this can be wasteful of precious
1673 low memory. Setting this option will put user-space page table
1674 entries in high memory.
1676 config X86_CHECK_BIOS_CORRUPTION
1677 bool "Check for low memory corruption"
1679 Periodically check for memory corruption in low memory, which
1680 is suspected to be caused by BIOS. Even when enabled in the
1681 configuration, it is disabled at runtime. Enable it by
1682 setting "memory_corruption_check=1" on the kernel command
1683 line. By default it scans the low 64k of memory every 60
1684 seconds; see the memory_corruption_check_size and
1685 memory_corruption_check_period parameters in
1686 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1688 When enabled with the default parameters, this option has
1689 almost no overhead, as it reserves a relatively small amount
1690 of memory and scans it infrequently. It both detects corruption
1691 and prevents it from affecting the running system.
1693 It is, however, intended as a diagnostic tool; if repeatable
1694 BIOS-originated corruption always affects the same memory,
1695 you can use memmap= to prevent the kernel from using that
1698 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1699 bool "Set the default setting of memory_corruption_check"
1700 depends on X86_CHECK_BIOS_CORRUPTION
1703 Set whether the default state of memory_corruption_check is
1706 config MATH_EMULATION
1708 depends on MODIFY_LDT_SYSCALL
1709 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1711 Linux can emulate a math coprocessor (used for floating point
1712 operations) if you don't have one. 486DX and Pentium processors have
1713 a math coprocessor built in, 486SX and 386 do not, unless you added
1714 a 487DX or 387, respectively. (The messages during boot time can
1715 give you some hints here ["man dmesg"].) Everyone needs either a
1716 coprocessor or this emulation.
1718 If you don't have a math coprocessor, you need to say Y here; if you
1719 say Y here even though you have a coprocessor, the coprocessor will
1720 be used nevertheless. (This behavior can be changed with the kernel
1721 command line option "no387", which comes handy if your coprocessor
1722 is broken. Try "man bootparam" or see the documentation of your boot
1723 loader (lilo or loadlin) about how to pass options to the kernel at
1724 boot time.) This means that it is a good idea to say Y here if you
1725 intend to use this kernel on different machines.
1727 More information about the internals of the Linux math coprocessor
1728 emulation can be found in <file:arch/x86/math-emu/README>.
1730 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1731 kernel, it won't hurt.
1735 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1737 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1738 the Memory Type Range Registers (MTRRs) may be used to control
1739 processor access to memory ranges. This is most useful if you have
1740 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1741 allows bus write transfers to be combined into a larger transfer
1742 before bursting over the PCI/AGP bus. This can increase performance
1743 of image write operations 2.5 times or more. Saying Y here creates a
1744 /proc/mtrr file which may be used to manipulate your processor's
1745 MTRRs. Typically the X server should use this.
1747 This code has a reasonably generic interface so that similar
1748 control registers on other processors can be easily supported
1751 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1752 Registers (ARRs) which provide a similar functionality to MTRRs. For
1753 these, the ARRs are used to emulate the MTRRs.
1754 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1755 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1756 write-combining. All of these processors are supported by this code
1757 and it makes sense to say Y here if you have one of them.
1759 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1760 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1761 can lead to all sorts of problems, so it's good to say Y here.
1763 You can safely say Y even if your machine doesn't have MTRRs, you'll
1764 just add about 9 KB to your kernel.
1766 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1768 config MTRR_SANITIZER
1770 prompt "MTRR cleanup support"
1773 Convert MTRR layout from continuous to discrete, so X drivers can
1774 add writeback entries.
1776 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1777 The largest mtrr entry size for a continuous block can be set with
1782 config MTRR_SANITIZER_ENABLE_DEFAULT
1783 int "MTRR cleanup enable value (0-1)"
1786 depends on MTRR_SANITIZER
1788 Enable mtrr cleanup default value
1790 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1791 int "MTRR cleanup spare reg num (0-7)"
1794 depends on MTRR_SANITIZER
1796 mtrr cleanup spare entries default, it can be changed via
1797 mtrr_spare_reg_nr=N on the kernel command line.
1801 prompt "x86 PAT support" if EXPERT
1804 Use PAT attributes to setup page level cache control.
1806 PATs are the modern equivalents of MTRRs and are much more
1807 flexible than MTRRs.
1809 Say N here if you see bootup problems (boot crash, boot hang,
1810 spontaneous reboots) or a non-working video driver.
1814 config ARCH_USES_PG_UNCACHED
1820 prompt "User Mode Instruction Prevention" if EXPERT
1822 User Mode Instruction Prevention (UMIP) is a security feature in
1823 some x86 processors. If enabled, a general protection fault is
1824 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1825 executed in user mode. These instructions unnecessarily expose
1826 information about the hardware state.
1828 The vast majority of applications do not use these instructions.
1829 For the very few that do, software emulation is provided in
1830 specific cases in protected and virtual-8086 modes. Emulated
1834 # GCC >= 9 and binutils >= 2.29
1835 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1837 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1838 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1839 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1840 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1846 CET features configured (Shadow stack or IBT)
1848 config X86_KERNEL_IBT
1849 prompt "Indirect Branch Tracking"
1851 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1852 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1853 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1857 Build the kernel with support for Indirect Branch Tracking, a
1858 hardware support course-grain forward-edge Control Flow Integrity
1859 protection. It enforces that all indirect calls must land on
1860 an ENDBR instruction, as such, the compiler will instrument the
1861 code with them to make this happen.
1863 In addition to building the kernel with IBT, seal all functions that
1864 are not indirect call targets, avoiding them ever becoming one.
1866 This requires LTO like objtool runs and will slow down the build. It
1867 does significantly reduce the number of ENDBR instructions in the
1870 config X86_INTEL_MEMORY_PROTECTION_KEYS
1871 prompt "Memory Protection Keys"
1873 # Note: only available in 64-bit mode
1874 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1875 select ARCH_USES_HIGH_VMA_FLAGS
1876 select ARCH_HAS_PKEYS
1878 Memory Protection Keys provides a mechanism for enforcing
1879 page-based protections, but without requiring modification of the
1880 page tables when an application changes protection domains.
1882 For details, see Documentation/core-api/protection-keys.rst
1887 prompt "TSX enable mode"
1888 depends on CPU_SUP_INTEL
1889 default X86_INTEL_TSX_MODE_OFF
1891 Intel's TSX (Transactional Synchronization Extensions) feature
1892 allows to optimize locking protocols through lock elision which
1893 can lead to a noticeable performance boost.
1895 On the other hand it has been shown that TSX can be exploited
1896 to form side channel attacks (e.g. TAA) and chances are there
1897 will be more of those attacks discovered in the future.
1899 Therefore TSX is not enabled by default (aka tsx=off). An admin
1900 might override this decision by tsx=on the command line parameter.
1901 Even with TSX enabled, the kernel will attempt to enable the best
1902 possible TAA mitigation setting depending on the microcode available
1903 for the particular machine.
1905 This option allows to set the default tsx mode between tsx=on, =off
1906 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1909 Say off if not sure, auto if TSX is in use but it should be used on safe
1910 platforms or on if TSX is in use and the security aspect of tsx is not
1913 config X86_INTEL_TSX_MODE_OFF
1916 TSX is disabled if possible - equals to tsx=off command line parameter.
1918 config X86_INTEL_TSX_MODE_ON
1921 TSX is always enabled on TSX capable HW - equals the tsx=on command
1924 config X86_INTEL_TSX_MODE_AUTO
1927 TSX is enabled on TSX capable HW that is believed to be safe against
1928 side channel attacks- equals the tsx=auto command line parameter.
1932 bool "Software Guard eXtensions (SGX)"
1933 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1935 depends on CRYPTO_SHA256=y
1937 select NUMA_KEEP_MEMINFO if NUMA
1940 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1941 that can be used by applications to set aside private regions of code
1942 and data, referred to as enclaves. An enclave's private memory can
1943 only be accessed by code running within the enclave. Accesses from
1944 outside the enclave, including other enclaves, are disallowed by
1949 config X86_USER_SHADOW_STACK
1950 bool "X86 userspace shadow stack"
1953 select ARCH_USES_HIGH_VMA_FLAGS
1956 Shadow stack protection is a hardware feature that detects function
1957 return address corruption. This helps mitigate ROP attacks.
1958 Applications must be enabled to use it, and old userspace does not
1959 get protection "for free".
1961 CPUs supporting shadow stacks were first released in 2020.
1963 See Documentation/arch/x86/shstk.rst for more information.
1967 config INTEL_TDX_HOST
1968 bool "Intel Trust Domain Extensions (TDX) host support"
1969 depends on CPU_SUP_INTEL
1971 depends on KVM_INTEL
1973 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1974 host and certain physical attacks. This option enables necessary TDX
1975 support in the host kernel to run confidential VMs.
1980 bool "EFI runtime service support"
1983 select EFI_RUNTIME_WRAPPERS
1984 select ARCH_USE_MEMREMAP_PROT
1985 select EFI_RUNTIME_MAP if KEXEC_CORE
1987 This enables the kernel to use EFI runtime services that are
1988 available (such as the EFI variable services).
1990 This option is only useful on systems that have EFI firmware.
1991 In addition, you should use the latest ELILO loader available
1992 at <http://elilo.sourceforge.net> in order to take advantage
1993 of EFI runtime services. However, even with this option, the
1994 resultant kernel should continue to boot on existing non-EFI
1998 bool "EFI stub support"
2002 This kernel feature allows a bzImage to be loaded directly
2003 by EFI firmware without the use of a bootloader.
2005 See Documentation/admin-guide/efi-stub.rst for more information.
2007 config EFI_HANDOVER_PROTOCOL
2008 bool "EFI handover protocol (DEPRECATED)"
2012 Select this in order to include support for the deprecated EFI
2013 handover protocol, which defines alternative entry points into the
2014 EFI stub. This is a practice that has no basis in the UEFI
2015 specification, and requires a priori knowledge on the part of the
2016 bootloader about Linux/x86 specific ways of passing the command line
2017 and initrd, and where in memory those assets may be loaded.
2019 If in doubt, say Y. Even though the corresponding support is not
2020 present in upstream GRUB or other bootloaders, most distros build
2021 GRUB with numerous downstream patches applied, and may rely on the
2022 handover protocol as as result.
2025 bool "EFI mixed-mode support"
2026 depends on EFI_STUB && X86_64
2028 Enabling this feature allows a 64-bit kernel to be booted
2029 on a 32-bit firmware, provided that your CPU supports 64-bit
2032 Note that it is not possible to boot a mixed-mode enabled
2033 kernel via the EFI boot stub - a bootloader that supports
2034 the EFI handover protocol must be used.
2038 config EFI_FAKE_MEMMAP
2039 bool "Enable EFI fake memory map"
2042 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2043 this parameter, you can add arbitrary attribute to specific memory
2044 range by updating original (firmware provided) EFI memmap. This is
2045 useful for debugging of EFI memmap related feature, e.g., Address
2046 Range Mirroring feature.
2048 config EFI_MAX_FAKE_MEM
2049 int "maximum allowable number of ranges in efi_fake_mem boot option"
2050 depends on EFI_FAKE_MEMMAP
2054 Maximum allowable number of ranges in efi_fake_mem boot option.
2055 Ranges can be set up to this value using comma-separated list.
2056 The default value is 8.
2058 config EFI_RUNTIME_MAP
2059 bool "Export EFI runtime maps to sysfs" if EXPERT
2062 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2063 That memory map is required by the 2nd kernel to set up EFI virtual
2064 mappings after kexec, but can also be used for debugging purposes.
2066 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2068 source "kernel/Kconfig.hz"
2070 config ARCH_SUPPORTS_KEXEC
2073 config ARCH_SUPPORTS_KEXEC_FILE
2076 config ARCH_SELECTS_KEXEC_FILE
2078 depends on KEXEC_FILE
2079 select HAVE_IMA_KEXEC if IMA
2081 config ARCH_SUPPORTS_KEXEC_PURGATORY
2084 config ARCH_SUPPORTS_KEXEC_SIG
2087 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2090 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2093 config ARCH_SUPPORTS_KEXEC_JUMP
2096 config ARCH_SUPPORTS_CRASH_DUMP
2097 def_bool X86_64 || (X86_32 && HIGHMEM)
2099 config ARCH_SUPPORTS_CRASH_HOTPLUG
2102 config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2105 config PHYSICAL_START
2106 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2109 This gives the physical address where the kernel is loaded.
2111 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2112 bzImage will decompress itself to above physical address and
2113 run from there. Otherwise, bzImage will run from the address where
2114 it has been loaded by the boot loader and will ignore above physical
2117 In normal kdump cases one does not have to set/change this option
2118 as now bzImage can be compiled as a completely relocatable image
2119 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2120 address. This option is mainly useful for the folks who don't want
2121 to use a bzImage for capturing the crash dump and want to use a
2122 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2123 to be specifically compiled to run from a specific memory area
2124 (normally a reserved region) and this option comes handy.
2126 So if you are using bzImage for capturing the crash dump,
2127 leave the value here unchanged to 0x1000000 and set
2128 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2129 for capturing the crash dump change this value to start of
2130 the reserved region. In other words, it can be set based on
2131 the "X" value as specified in the "crashkernel=YM@XM"
2132 command line boot parameter passed to the panic-ed
2133 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2134 for more details about crash dumps.
2136 Usage of bzImage for capturing the crash dump is recommended as
2137 one does not have to build two kernels. Same kernel can be used
2138 as production kernel and capture kernel. Above option should have
2139 gone away after relocatable bzImage support is introduced. But it
2140 is present because there are users out there who continue to use
2141 vmlinux for dump capture. This option should go away down the
2144 Don't change this unless you know what you are doing.
2147 bool "Build a relocatable kernel"
2150 This builds a kernel image that retains relocation information
2151 so it can be loaded someplace besides the default 1MB.
2152 The relocations tend to make the kernel binary about 10% larger,
2153 but are discarded at runtime.
2155 One use is for the kexec on panic case where the recovery kernel
2156 must live at a different physical address than the primary
2159 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2160 it has been loaded at and the compile time physical address
2161 (CONFIG_PHYSICAL_START) is used as the minimum location.
2163 config RANDOMIZE_BASE
2164 bool "Randomize the address of the kernel image (KASLR)"
2165 depends on RELOCATABLE
2168 In support of Kernel Address Space Layout Randomization (KASLR),
2169 this randomizes the physical address at which the kernel image
2170 is decompressed and the virtual address where the kernel
2171 image is mapped, as a security feature that deters exploit
2172 attempts relying on knowledge of the location of kernel
2175 On 64-bit, the kernel physical and virtual addresses are
2176 randomized separately. The physical address will be anywhere
2177 between 16MB and the top of physical memory (up to 64TB). The
2178 virtual address will be randomized from 16MB up to 1GB (9 bits
2179 of entropy). Note that this also reduces the memory space
2180 available to kernel modules from 1.5GB to 1GB.
2182 On 32-bit, the kernel physical and virtual addresses are
2183 randomized together. They will be randomized from 16MB up to
2184 512MB (8 bits of entropy).
2186 Entropy is generated using the RDRAND instruction if it is
2187 supported. If RDTSC is supported, its value is mixed into
2188 the entropy pool as well. If neither RDRAND nor RDTSC are
2189 supported, then entropy is read from the i8254 timer. The
2190 usable entropy is limited by the kernel being built using
2191 2GB addressing, and that PHYSICAL_ALIGN must be at a
2192 minimum of 2MB. As a result, only 10 bits of entropy are
2193 theoretically possible, but the implementations are further
2194 limited due to memory layouts.
2198 # Relocation on x86 needs some additional build support
2199 config X86_NEED_RELOCS
2201 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2203 config PHYSICAL_ALIGN
2204 hex "Alignment value to which kernel should be aligned"
2206 range 0x2000 0x1000000 if X86_32
2207 range 0x200000 0x1000000 if X86_64
2209 This value puts the alignment restrictions on physical address
2210 where kernel is loaded and run from. Kernel is compiled for an
2211 address which meets above alignment restriction.
2213 If bootloader loads the kernel at a non-aligned address and
2214 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2215 address aligned to above value and run from there.
2217 If bootloader loads the kernel at a non-aligned address and
2218 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2219 load address and decompress itself to the address it has been
2220 compiled for and run from there. The address for which kernel is
2221 compiled already meets above alignment restrictions. Hence the
2222 end result is that kernel runs from a physical address meeting
2223 above alignment restrictions.
2225 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2226 this value must be a multiple of 0x200000.
2228 Don't change this unless you know what you are doing.
2230 config DYNAMIC_MEMORY_LAYOUT
2233 This option makes base addresses of vmalloc and vmemmap as well as
2234 __PAGE_OFFSET movable during boot.
2236 config RANDOMIZE_MEMORY
2237 bool "Randomize the kernel memory sections"
2239 depends on RANDOMIZE_BASE
2240 select DYNAMIC_MEMORY_LAYOUT
2241 default RANDOMIZE_BASE
2243 Randomizes the base virtual address of kernel memory sections
2244 (physical memory mapping, vmalloc & vmemmap). This security feature
2245 makes exploits relying on predictable memory locations less reliable.
2247 The order of allocations remains unchanged. Entropy is generated in
2248 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2249 configuration have in average 30,000 different possible virtual
2250 addresses for each memory section.
2254 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2255 hex "Physical memory mapping padding" if EXPERT
2256 depends on RANDOMIZE_MEMORY
2257 default "0xa" if MEMORY_HOTPLUG
2259 range 0x1 0x40 if MEMORY_HOTPLUG
2262 Define the padding in terabytes added to the existing physical
2263 memory size during kernel memory randomization. It is useful
2264 for memory hotplug support but reduces the entropy available for
2265 address randomization.
2267 If unsure, leave at the default value.
2269 config ADDRESS_MASKING
2270 bool "Linear Address Masking support"
2273 Linear Address Masking (LAM) modifies the checking that is applied
2274 to 64-bit linear addresses, allowing software to use of the
2275 untranslated address bits for metadata.
2277 The capability can be used for efficient address sanitizers (ASAN)
2278 implementation and for optimizations in JITs.
2286 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2287 depends on COMPAT_32
2289 Certain buggy versions of glibc will crash if they are
2290 presented with a 32-bit vDSO that is not mapped at the address
2291 indicated in its segment table.
2293 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2294 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2295 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2296 the only released version with the bug, but OpenSUSE 9
2297 contains a buggy "glibc 2.3.2".
2299 The symptom of the bug is that everything crashes on startup, saying:
2300 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2302 Saying Y here changes the default value of the vdso32 boot
2303 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2304 This works around the glibc bug but hurts performance.
2306 If unsure, say N: if you are compiling your own kernel, you
2307 are unlikely to be using a buggy version of glibc.
2310 prompt "vsyscall table for legacy applications"
2312 default LEGACY_VSYSCALL_XONLY
2314 Legacy user code that does not know how to find the vDSO expects
2315 to be able to issue three syscalls by calling fixed addresses in
2316 kernel space. Since this location is not randomized with ASLR,
2317 it can be used to assist security vulnerability exploitation.
2319 This setting can be changed at boot time via the kernel command
2320 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2321 is deprecated and can only be enabled using the kernel command
2324 On a system with recent enough glibc (2.14 or newer) and no
2325 static binaries, you can say None without a performance penalty
2326 to improve security.
2328 If unsure, select "Emulate execution only".
2330 config LEGACY_VSYSCALL_XONLY
2331 bool "Emulate execution only"
2333 The kernel traps and emulates calls into the fixed vsyscall
2334 address mapping and does not allow reads. This
2335 configuration is recommended when userspace might use the
2336 legacy vsyscall area but support for legacy binary
2337 instrumentation of legacy code is not needed. It mitigates
2338 certain uses of the vsyscall area as an ASLR-bypassing
2341 config LEGACY_VSYSCALL_NONE
2344 There will be no vsyscall mapping at all. This will
2345 eliminate any risk of ASLR bypass due to the vsyscall
2346 fixed address mapping. Attempts to use the vsyscalls
2347 will be reported to dmesg, so that either old or
2348 malicious userspace programs can be identified.
2353 bool "Built-in kernel command line"
2355 Allow for specifying boot arguments to the kernel at
2356 build time. On some systems (e.g. embedded ones), it is
2357 necessary or convenient to provide some or all of the
2358 kernel boot arguments with the kernel itself (that is,
2359 to not rely on the boot loader to provide them.)
2361 To compile command line arguments into the kernel,
2362 set this option to 'Y', then fill in the
2363 boot arguments in CONFIG_CMDLINE.
2365 Systems with fully functional boot loaders (i.e. non-embedded)
2366 should leave this option set to 'N'.
2369 string "Built-in kernel command string"
2370 depends on CMDLINE_BOOL
2373 Enter arguments here that should be compiled into the kernel
2374 image and used at boot time. If the boot loader provides a
2375 command line at boot time, it is appended to this string to
2376 form the full kernel command line, when the system boots.
2378 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2379 change this behavior.
2381 In most cases, the command line (whether built-in or provided
2382 by the boot loader) should specify the device for the root
2385 config CMDLINE_OVERRIDE
2386 bool "Built-in command line overrides boot loader arguments"
2387 depends on CMDLINE_BOOL && CMDLINE != ""
2389 Set this option to 'Y' to have the kernel ignore the boot loader
2390 command line, and use ONLY the built-in command line.
2392 This is used to work around broken boot loaders. This should
2393 be set to 'N' under normal conditions.
2395 config MODIFY_LDT_SYSCALL
2396 bool "Enable the LDT (local descriptor table)" if EXPERT
2399 Linux can allow user programs to install a per-process x86
2400 Local Descriptor Table (LDT) using the modify_ldt(2) system
2401 call. This is required to run 16-bit or segmented code such as
2402 DOSEMU or some Wine programs. It is also used by some very old
2403 threading libraries.
2405 Enabling this feature adds a small amount of overhead to
2406 context switches and increases the low-level kernel attack
2407 surface. Disabling it removes the modify_ldt(2) system call.
2409 Saying 'N' here may make sense for embedded or server kernels.
2411 config STRICT_SIGALTSTACK_SIZE
2412 bool "Enforce strict size checking for sigaltstack"
2413 depends on DYNAMIC_SIGFRAME
2415 For historical reasons MINSIGSTKSZ is a constant which became
2416 already too small with AVX512 support. Add a mechanism to
2417 enforce strict checking of the sigaltstack size against the
2418 real size of the FPU frame. This option enables the check
2419 by default. It can also be controlled via the kernel command
2420 line option 'strict_sas_size' independent of this config
2421 switch. Enabling it might break existing applications which
2422 allocate a too small sigaltstack but 'work' because they
2423 never get a signal delivered.
2425 Say 'N' unless you want to really enforce this check.
2427 source "kernel/livepatch/Kconfig"
2432 def_bool $(cc-option,-mharden-sls=all)
2434 config CC_HAS_RETURN_THUNK
2435 def_bool $(cc-option,-mfunction-return=thunk-extern)
2437 config CC_HAS_ENTRY_PADDING
2438 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2440 config FUNCTION_PADDING_CFI
2442 default 59 if FUNCTION_ALIGNMENT_64B
2443 default 27 if FUNCTION_ALIGNMENT_32B
2444 default 11 if FUNCTION_ALIGNMENT_16B
2445 default 3 if FUNCTION_ALIGNMENT_8B
2448 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2449 # except Kconfig can't do arithmetic :/
2450 config FUNCTION_PADDING_BYTES
2452 default FUNCTION_PADDING_CFI if CFI_CLANG
2453 default FUNCTION_ALIGNMENT
2457 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2458 select FUNCTION_ALIGNMENT_16B
2462 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2465 config HAVE_CALL_THUNKS
2467 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2473 config PREFIX_SYMBOLS
2475 depends on CALL_PADDING && !CFI_CLANG
2477 menuconfig SPECULATION_MITIGATIONS
2478 bool "Mitigations for speculative execution vulnerabilities"
2481 Say Y here to enable options which enable mitigations for
2482 speculative execution hardware vulnerabilities.
2484 If you say N, all mitigations will be disabled. You really
2485 should know what you are doing to say so.
2487 if SPECULATION_MITIGATIONS
2489 config PAGE_TABLE_ISOLATION
2490 bool "Remove the kernel mapping in user mode"
2492 depends on (X86_64 || X86_PAE)
2494 This feature reduces the number of hardware side channels by
2495 ensuring that the majority of kernel addresses are not mapped
2498 See Documentation/arch/x86/pti.rst for more details.
2501 bool "Avoid speculative indirect branches in kernel"
2502 select OBJTOOL if HAVE_OBJTOOL
2505 Compile kernel with the retpoline compiler options to guard against
2506 kernel-to-user data leaks by avoiding speculative indirect
2507 branches. Requires a compiler with -mindirect-branch=thunk-extern
2508 support for full protection. The kernel may run slower.
2511 bool "Enable return-thunks"
2512 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2513 select OBJTOOL if HAVE_OBJTOOL
2516 Compile the kernel with the return-thunks compiler option to guard
2517 against kernel-to-user data leaks by avoiding return speculation.
2518 Requires a compiler with -mfunction-return=thunk-extern
2519 support for full protection. The kernel may run slower.
2521 config CPU_UNRET_ENTRY
2522 bool "Enable UNRET on kernel entry"
2523 depends on CPU_SUP_AMD && RETHUNK && X86_64
2526 Compile the kernel with support for the retbleed=unret mitigation.
2528 config CALL_DEPTH_TRACKING
2529 bool "Mitigate RSB underflow with call depth tracking"
2530 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2531 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2535 Compile the kernel with call depth tracking to mitigate the Intel
2536 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2537 mitigation is off by default and needs to be enabled on the
2538 kernel command line via the retbleed=stuff option. For
2539 non-affected systems the overhead of this option is marginal as
2540 the call depth tracking is using run-time generated call thunks
2541 in a compiler generated padding area and call patching. This
2542 increases text size by ~5%. For non affected systems this space
2543 is unused. On affected SKL systems this results in a significant
2544 performance gain over the IBRS mitigation.
2546 config CALL_THUNKS_DEBUG
2547 bool "Enable call thunks and call depth tracking debugging"
2548 depends on CALL_DEPTH_TRACKING
2549 select FUNCTION_ALIGNMENT_32B
2552 Enable call/ret counters for imbalance detection and build in
2553 a noisy dmesg about callthunks generation and call patching for
2554 trouble shooting. The debug prints need to be enabled on the
2555 kernel command line with 'debug-callthunks'.
2556 Only enable this when you are debugging call thunks as this
2557 creates a noticeable runtime overhead. If unsure say N.
2559 config CPU_IBPB_ENTRY
2560 bool "Enable IBPB on kernel entry"
2561 depends on CPU_SUP_AMD && X86_64
2564 Compile the kernel with support for the retbleed=ibpb mitigation.
2566 config CPU_IBRS_ENTRY
2567 bool "Enable IBRS on kernel entry"
2568 depends on CPU_SUP_INTEL && X86_64
2571 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2572 This mitigates both spectre_v2 and retbleed at great cost to
2576 bool "Mitigate speculative RAS overflow on AMD"
2577 depends on CPU_SUP_AMD && X86_64 && RETHUNK
2580 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2583 bool "Mitigate Straight-Line-Speculation"
2584 depends on CC_HAS_SLS && X86_64
2585 select OBJTOOL if HAVE_OBJTOOL
2588 Compile the kernel with straight-line-speculation options to guard
2589 against straight line speculation. The kernel image might be slightly
2592 config GDS_FORCE_MITIGATION
2593 bool "Force GDS Mitigation"
2594 depends on CPU_SUP_INTEL
2597 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2598 unprivileged speculative access to data which was previously stored in
2601 This option is equivalent to setting gather_data_sampling=force on the
2602 command line. The microcode mitigation is used if present, otherwise
2603 AVX is disabled as a mitigation. On affected systems that are missing
2604 the microcode any userspace code that unconditionally uses AVX will
2605 break with this option set.
2607 Setting this option on systems not vulnerable to GDS has no effect.
2613 config ARCH_HAS_ADD_PAGES
2615 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2617 menu "Power management and ACPI options"
2619 config ARCH_HIBERNATION_HEADER
2621 depends on HIBERNATION
2623 source "kernel/power/Kconfig"
2625 source "drivers/acpi/Kconfig"
2632 tristate "APM (Advanced Power Management) BIOS support"
2633 depends on X86_32 && PM_SLEEP
2635 APM is a BIOS specification for saving power using several different
2636 techniques. This is mostly useful for battery powered laptops with
2637 APM compliant BIOSes. If you say Y here, the system time will be
2638 reset after a RESUME operation, the /proc/apm device will provide
2639 battery status information, and user-space programs will receive
2640 notification of APM "events" (e.g. battery status change).
2642 If you select "Y" here, you can disable actual use of the APM
2643 BIOS by passing the "apm=off" option to the kernel at boot time.
2645 Note that the APM support is almost completely disabled for
2646 machines with more than one CPU.
2648 In order to use APM, you will need supporting software. For location
2649 and more information, read <file:Documentation/power/apm-acpi.rst>
2650 and the Battery Powered Linux mini-HOWTO, available from
2651 <http://www.tldp.org/docs.html#howto>.
2653 This driver does not spin down disk drives (see the hdparm(8)
2654 manpage ("man 8 hdparm") for that), and it doesn't turn off
2655 VESA-compliant "green" monitors.
2657 This driver does not support the TI 4000M TravelMate and the ACER
2658 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2659 desktop machines also don't have compliant BIOSes, and this driver
2660 may cause those machines to panic during the boot phase.
2662 Generally, if you don't have a battery in your machine, there isn't
2663 much point in using this driver and you should say N. If you get
2664 random kernel OOPSes or reboots that don't seem to be related to
2665 anything, try disabling/enabling this option (or disabling/enabling
2668 Some other things you should try when experiencing seemingly random,
2671 1) make sure that you have enough swap space and that it is
2673 2) pass the "idle=poll" option to the kernel
2674 3) switch on floating point emulation in the kernel and pass
2675 the "no387" option to the kernel
2676 4) pass the "floppy=nodma" option to the kernel
2677 5) pass the "mem=4M" option to the kernel (thereby disabling
2678 all but the first 4 MB of RAM)
2679 6) make sure that the CPU is not over clocked.
2680 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2681 8) disable the cache from your BIOS settings
2682 9) install a fan for the video card or exchange video RAM
2683 10) install a better fan for the CPU
2684 11) exchange RAM chips
2685 12) exchange the motherboard.
2687 To compile this driver as a module, choose M here: the
2688 module will be called apm.
2692 config APM_IGNORE_USER_SUSPEND
2693 bool "Ignore USER SUSPEND"
2695 This option will ignore USER SUSPEND requests. On machines with a
2696 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2697 series notebooks, it is necessary to say Y because of a BIOS bug.
2699 config APM_DO_ENABLE
2700 bool "Enable PM at boot time"
2702 Enable APM features at boot time. From page 36 of the APM BIOS
2703 specification: "When disabled, the APM BIOS does not automatically
2704 power manage devices, enter the Standby State, enter the Suspend
2705 State, or take power saving steps in response to CPU Idle calls."
2706 This driver will make CPU Idle calls when Linux is idle (unless this
2707 feature is turned off -- see "Do CPU IDLE calls", below). This
2708 should always save battery power, but more complicated APM features
2709 will be dependent on your BIOS implementation. You may need to turn
2710 this option off if your computer hangs at boot time when using APM
2711 support, or if it beeps continuously instead of suspending. Turn
2712 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2713 T400CDT. This is off by default since most machines do fine without
2718 bool "Make CPU Idle calls when idle"
2720 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2721 On some machines, this can activate improved power savings, such as
2722 a slowed CPU clock rate, when the machine is idle. These idle calls
2723 are made after the idle loop has run for some length of time (e.g.,
2724 333 mS). On some machines, this will cause a hang at boot time or
2725 whenever the CPU becomes idle. (On machines with more than one CPU,
2726 this option does nothing.)
2728 config APM_DISPLAY_BLANK
2729 bool "Enable console blanking using APM"
2731 Enable console blanking using the APM. Some laptops can use this to
2732 turn off the LCD backlight when the screen blanker of the Linux
2733 virtual console blanks the screen. Note that this is only used by
2734 the virtual console screen blanker, and won't turn off the backlight
2735 when using the X Window system. This also doesn't have anything to
2736 do with your VESA-compliant power-saving monitor. Further, this
2737 option doesn't work for all laptops -- it might not turn off your
2738 backlight at all, or it might print a lot of errors to the console,
2739 especially if you are using gpm.
2741 config APM_ALLOW_INTS
2742 bool "Allow interrupts during APM BIOS calls"
2744 Normally we disable external interrupts while we are making calls to
2745 the APM BIOS as a measure to lessen the effects of a badly behaving
2746 BIOS implementation. The BIOS should reenable interrupts if it
2747 needs to. Unfortunately, some BIOSes do not -- especially those in
2748 many of the newer IBM Thinkpads. If you experience hangs when you
2749 suspend, try setting this to Y. Otherwise, say N.
2753 source "drivers/cpufreq/Kconfig"
2755 source "drivers/cpuidle/Kconfig"
2757 source "drivers/idle/Kconfig"
2761 menu "Bus options (PCI etc.)"
2764 prompt "PCI access mode"
2765 depends on X86_32 && PCI
2768 On PCI systems, the BIOS can be used to detect the PCI devices and
2769 determine their configuration. However, some old PCI motherboards
2770 have BIOS bugs and may crash if this is done. Also, some embedded
2771 PCI-based systems don't have any BIOS at all. Linux can also try to
2772 detect the PCI hardware directly without using the BIOS.
2774 With this option, you can specify how Linux should detect the
2775 PCI devices. If you choose "BIOS", the BIOS will be used,
2776 if you choose "Direct", the BIOS won't be used, and if you
2777 choose "MMConfig", then PCI Express MMCONFIG will be used.
2778 If you choose "Any", the kernel will try MMCONFIG, then the
2779 direct access method and falls back to the BIOS if that doesn't
2780 work. If unsure, go with the default, which is "Any".
2785 config PCI_GOMMCONFIG
2802 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2804 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2807 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2810 bool "Support mmconfig PCI config space access" if X86_64
2812 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2813 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2817 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2821 depends on PCI && XEN
2823 config MMCONF_FAM10H
2825 depends on X86_64 && PCI_MMCONFIG && ACPI
2827 config PCI_CNB20LE_QUIRK
2828 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2831 Read the PCI windows out of the CNB20LE host bridge. This allows
2832 PCI hotplug to work on systems with the CNB20LE chipset which do
2835 There's no public spec for this chipset, and this functionality
2836 is known to be incomplete.
2838 You should say N unless you know you need this.
2841 bool "ISA bus support on modern systems" if EXPERT
2843 Expose ISA bus device drivers and options available for selection and
2844 configuration. Enable this option if your target machine has an ISA
2845 bus. ISA is an older system, displaced by PCI and newer bus
2846 architectures -- if your target machine is modern, it probably does
2847 not have an ISA bus.
2851 # x86_64 have no ISA slots, but can have ISA-style DMA.
2853 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2856 Enables ISA-style DMA support for devices requiring such controllers.
2864 Find out whether you have ISA slots on your motherboard. ISA is the
2865 name of a bus system, i.e. the way the CPU talks to the other stuff
2866 inside your box. Other bus systems are PCI, EISA, MicroChannel
2867 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2868 newer boards don't support it. If you have ISA, say Y, otherwise N.
2871 tristate "NatSemi SCx200 support"
2873 This provides basic support for National Semiconductor's
2874 (now AMD's) Geode processors. The driver probes for the
2875 PCI-IDs of several on-chip devices, so its a good dependency
2876 for other scx200_* drivers.
2878 If compiled as a module, the driver is named scx200.
2880 config SCx200HR_TIMER
2881 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2885 This driver provides a clocksource built upon the on-chip
2886 27MHz high-resolution timer. Its also a workaround for
2887 NSC Geode SC-1100's buggy TSC, which loses time when the
2888 processor goes idle (as is done by the scheduler). The
2889 other workaround is idle=poll boot option.
2892 bool "One Laptop Per Child support"
2900 Add support for detecting the unique features of the OLPC
2904 bool "OLPC XO-1 Power Management"
2905 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2907 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2910 bool "OLPC XO-1 Real Time Clock"
2911 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2913 Add support for the XO-1 real time clock, which can be used as a
2914 programmable wakeup source.
2917 bool "OLPC XO-1 SCI extras"
2918 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2922 Add support for SCI-based features of the OLPC XO-1 laptop:
2923 - EC-driven system wakeups
2927 - AC adapter status updates
2928 - Battery status updates
2930 config OLPC_XO15_SCI
2931 bool "OLPC XO-1.5 SCI extras"
2932 depends on OLPC && ACPI
2935 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2936 - EC-driven system wakeups
2937 - AC adapter status updates
2938 - Battery status updates
2941 bool "PCEngines ALIX System Support (LED setup)"
2944 This option enables system support for the PCEngines ALIX.
2945 At present this just sets up LEDs for GPIO control on
2946 ALIX2/3/6 boards. However, other system specific setup should
2949 Note: You must still enable the drivers for GPIO and LED support
2950 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2952 Note: You have to set alix.force=1 for boards with Award BIOS.
2955 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2958 This option enables system support for the Soekris Engineering net5501.
2961 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2965 This option enables system support for the Traverse Technologies GEOS.
2968 bool "Technologic Systems TS-5500 platform support"
2970 select CHECK_SIGNATURE
2974 This option enables system support for the Technologic Systems TS-5500.
2980 depends on CPU_SUP_AMD && PCI
2984 menu "Binary Emulations"
2986 config IA32_EMULATION
2987 bool "IA32 Emulation"
2989 select ARCH_WANT_OLD_COMPAT_IPC
2991 select COMPAT_OLD_SIGACTION
2993 Include code to run legacy 32-bit programs under a
2994 64-bit kernel. You should likely turn this on, unless you're
2995 100% sure that you don't have any 32-bit programs left.
2997 config IA32_EMULATION_DEFAULT_DISABLED
2998 bool "IA32 emulation disabled by default"
3000 depends on IA32_EMULATION
3002 Make IA32 emulation disabled by default. This prevents loading 32-bit
3003 processes and access to 32-bit syscalls. If unsure, leave it to its
3007 bool "x32 ABI for 64-bit mode"
3009 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3010 # compressed debug sections to x86_x32 properly:
3011 # https://github.com/ClangBuiltLinux/linux/issues/514
3012 # https://github.com/ClangBuiltLinux/linux/issues/1141
3013 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3015 Include code to run binaries for the x32 native 32-bit ABI
3016 for 64-bit processors. An x32 process gets access to the
3017 full 64-bit register file and wide data path while leaving
3018 pointers at 32 bits for smaller memory footprint.
3022 depends on IA32_EMULATION || X86_32
3024 select OLD_SIGSUSPEND3
3028 depends on IA32_EMULATION || X86_X32_ABI
3030 config COMPAT_FOR_U64_ALIGNMENT
3036 config HAVE_ATOMIC_IOMAP
3040 source "arch/x86/kvm/Kconfig"
3042 source "arch/x86/Kconfig.assembler"