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_USE_CMPXCHG_LOCKREF
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 ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
65 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 || (X86_32 && HIGHMEM)
66 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
67 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
68 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
69 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
70 select ARCH_HAS_CACHE_LINE_SIZE
71 select ARCH_HAS_DEBUG_VIRTUAL
72 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
73 select ARCH_HAS_DEVMEM_IS_ALLOWED
74 select ARCH_HAS_EARLY_DEBUG if KGDB
75 select ARCH_HAS_ELF_RANDOMIZE
76 select ARCH_HAS_FAST_MULTIPLIER
77 select ARCH_HAS_FILTER_PGPROT
78 select ARCH_HAS_FORTIFY_SOURCE
79 select ARCH_HAS_GCOV_PROFILE_ALL
80 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
81 select ARCH_HAS_MEM_ENCRYPT
82 select ARCH_HAS_MEMBARRIER_SYNC_CORE
83 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
84 select ARCH_HAS_PMEM_API if X86_64
85 select ARCH_HAS_PTE_DEVMAP if X86_64
86 select ARCH_HAS_PTE_SPECIAL
87 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
88 select ARCH_HAS_COPY_MC if X86_64
89 select ARCH_HAS_SET_MEMORY
90 select ARCH_HAS_SET_DIRECT_MAP
91 select ARCH_HAS_STRICT_KERNEL_RWX
92 select ARCH_HAS_STRICT_MODULE_RWX
93 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
94 select ARCH_HAS_SYSCALL_WRAPPER
95 select ARCH_HAS_UBSAN_SANITIZE_ALL
96 select ARCH_HAS_DEBUG_WX
97 select ARCH_HAS_ZONE_DMA_SET if EXPERT
98 select ARCH_HAVE_NMI_SAFE_CMPXCHG
99 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
100 select ARCH_MIGHT_HAVE_PC_PARPORT
101 select ARCH_MIGHT_HAVE_PC_SERIO
102 select ARCH_STACKWALK
103 select ARCH_SUPPORTS_ACPI
104 select ARCH_SUPPORTS_ATOMIC_RMW
105 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
106 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
107 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
108 select ARCH_SUPPORTS_LTO_CLANG
109 select ARCH_SUPPORTS_LTO_CLANG_THIN
110 select ARCH_USE_BUILTIN_BSWAP
111 select ARCH_USE_MEMTEST
112 select ARCH_USE_QUEUED_RWLOCKS
113 select ARCH_USE_QUEUED_SPINLOCKS
114 select ARCH_USE_SYM_ANNOTATIONS
115 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
116 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
117 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
118 select ARCH_WANTS_NO_INSTR
119 select ARCH_WANT_HUGE_PMD_SHARE
120 select ARCH_WANT_LD_ORPHAN_WARN
121 select ARCH_WANTS_THP_SWAP if X86_64
122 select BUILDTIME_TABLE_SORT
124 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
125 select CLOCKSOURCE_WATCHDOG
126 select DCACHE_WORD_ACCESS
127 select EDAC_ATOMIC_SCRUB
129 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
130 select GENERIC_CLOCKEVENTS_MIN_ADJUST
131 select GENERIC_CMOS_UPDATE
132 select GENERIC_CPU_AUTOPROBE
133 select GENERIC_CPU_VULNERABILITIES
134 select GENERIC_EARLY_IOREMAP
136 select GENERIC_FIND_FIRST_BIT
138 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
139 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
140 select GENERIC_IRQ_MIGRATION if SMP
141 select GENERIC_IRQ_PROBE
142 select GENERIC_IRQ_RESERVATION_MODE
143 select GENERIC_IRQ_SHOW
144 select GENERIC_PENDING_IRQ if SMP
145 select GENERIC_PTDUMP
146 select GENERIC_SMP_IDLE_THREAD
147 select GENERIC_STRNCPY_FROM_USER
148 select GENERIC_STRNLEN_USER
149 select GENERIC_TIME_VSYSCALL
150 select GENERIC_GETTIMEOFDAY
151 select GENERIC_VDSO_TIME_NS
152 select GUP_GET_PTE_LOW_HIGH if X86_PAE
153 select HARDIRQS_SW_RESEND
154 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
155 select HAVE_ACPI_APEI if ACPI
156 select HAVE_ACPI_APEI_NMI if ACPI
157 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
158 select HAVE_ARCH_AUDITSYSCALL
159 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
160 select HAVE_ARCH_JUMP_LABEL
161 select HAVE_ARCH_JUMP_LABEL_RELATIVE
162 select HAVE_ARCH_KASAN if X86_64
163 select HAVE_ARCH_KASAN_VMALLOC if X86_64
164 select HAVE_ARCH_KFENCE
165 select HAVE_ARCH_KGDB
166 select HAVE_ARCH_MMAP_RND_BITS if MMU
167 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
168 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
169 select HAVE_ARCH_PREL32_RELOCATIONS
170 select HAVE_ARCH_SECCOMP_FILTER
171 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
172 select HAVE_ARCH_STACKLEAK
173 select HAVE_ARCH_TRACEHOOK
174 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
175 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
176 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
177 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
178 select HAVE_ARCH_VMAP_STACK if X86_64
179 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
180 select HAVE_ARCH_WITHIN_STACK_FRAMES
181 select HAVE_ASM_MODVERSIONS
182 select HAVE_CMPXCHG_DOUBLE
183 select HAVE_CMPXCHG_LOCAL
184 select HAVE_CONTEXT_TRACKING if X86_64
185 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
186 select HAVE_C_RECORDMCOUNT
187 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
188 select HAVE_DEBUG_KMEMLEAK
189 select HAVE_DMA_CONTIGUOUS
190 select HAVE_DYNAMIC_FTRACE
191 select HAVE_DYNAMIC_FTRACE_WITH_REGS
192 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
193 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
195 select HAVE_EFFICIENT_UNALIGNED_ACCESS
197 select HAVE_EXIT_THREAD
199 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
200 select HAVE_FTRACE_MCOUNT_RECORD
201 select HAVE_FUNCTION_GRAPH_TRACER
202 select HAVE_FUNCTION_TRACER
203 select HAVE_GCC_PLUGINS
204 select HAVE_HW_BREAKPOINT
206 select HAVE_IOREMAP_PROT
207 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
208 select HAVE_IRQ_TIME_ACCOUNTING
209 select HAVE_KERNEL_BZIP2
210 select HAVE_KERNEL_GZIP
211 select HAVE_KERNEL_LZ4
212 select HAVE_KERNEL_LZMA
213 select HAVE_KERNEL_LZO
214 select HAVE_KERNEL_XZ
215 select HAVE_KERNEL_ZSTD
217 select HAVE_KPROBES_ON_FTRACE
218 select HAVE_FUNCTION_ERROR_INJECTION
219 select HAVE_KRETPROBES
221 select HAVE_LIVEPATCH if X86_64
222 select HAVE_MIXED_BREAKPOINTS_REGS
223 select HAVE_MOD_ARCH_SPECIFIC
227 select HAVE_OPTPROBES
228 select HAVE_PCSPKR_PLATFORM
229 select HAVE_PERF_EVENTS
230 select HAVE_PERF_EVENTS_NMI
231 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
233 select HAVE_PERF_REGS
234 select HAVE_PERF_USER_STACK_DUMP
235 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
236 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
237 select HAVE_REGS_AND_STACK_ACCESS_API
238 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
239 select HAVE_FUNCTION_ARG_ACCESS_API
240 select HAVE_SOFTIRQ_ON_OWN_STACK
241 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
242 select HAVE_STACK_VALIDATION if X86_64
243 select HAVE_STATIC_CALL
244 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
245 select HAVE_PREEMPT_DYNAMIC
247 select HAVE_SYSCALL_TRACEPOINTS
248 select HAVE_UNSTABLE_SCHED_CLOCK
249 select HAVE_USER_RETURN_NOTIFIER
250 select HAVE_GENERIC_VDSO
251 select HOTPLUG_SMT if SMP
252 select IRQ_FORCED_THREADING
253 select NEED_SG_DMA_LENGTH
254 select PCI_DOMAINS if PCI
255 select PCI_LOCKLESS_CONFIG if PCI
258 select RTC_MC146818_LIB
261 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
262 select SYSCTL_EXCEPTION_TRACE
263 select THREAD_INFO_IN_TASK
264 select USER_STACKTRACE_SUPPORT
266 select HAVE_ARCH_KCSAN if X86_64
267 select X86_FEATURE_NAMES if PROC_FS
268 select PROC_PID_ARCH_STATUS if PROC_FS
269 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
271 config INSTRUCTION_DECODER
273 depends on KPROBES || PERF_EVENTS || UPROBES
277 default "elf32-i386" if X86_32
278 default "elf64-x86-64" if X86_64
280 config LOCKDEP_SUPPORT
283 config STACKTRACE_SUPPORT
289 config ARCH_MMAP_RND_BITS_MIN
293 config ARCH_MMAP_RND_BITS_MAX
297 config ARCH_MMAP_RND_COMPAT_BITS_MIN
300 config ARCH_MMAP_RND_COMPAT_BITS_MAX
306 config GENERIC_ISA_DMA
308 depends on ISA_DMA_API
313 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
315 config GENERIC_BUG_RELATIVE_POINTERS
318 config ARCH_MAY_HAVE_PC_FDC
320 depends on ISA_DMA_API
322 config GENERIC_CALIBRATE_DELAY
325 config ARCH_HAS_CPU_RELAX
328 config ARCH_HAS_FILTER_PGPROT
331 config HAVE_SETUP_PER_CPU_AREA
334 config NEED_PER_CPU_EMBED_FIRST_CHUNK
337 config NEED_PER_CPU_PAGE_FIRST_CHUNK
340 config ARCH_HIBERNATION_POSSIBLE
343 config ARCH_SUSPEND_POSSIBLE
346 config ARCH_WANT_GENERAL_HUGETLB
352 config KASAN_SHADOW_OFFSET
355 default 0xdffffc0000000000
357 config HAVE_INTEL_TXT
359 depends on INTEL_IOMMU && ACPI
363 depends on X86_32 && SMP
367 depends on X86_64 && SMP
369 config ARCH_SUPPORTS_UPROBES
372 config FIX_EARLYCON_MEM
375 config DYNAMIC_PHYSICAL_MASK
378 config PGTABLE_LEVELS
380 default 5 if X86_5LEVEL
385 config CC_HAS_SANE_STACKPROTECTOR
387 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
388 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
390 We have to make sure stack protector is unconditionally disabled if
391 the compiler produces broken code or if it does not let us control
392 the segment on 32-bit kernels.
394 menu "Processor type and features"
397 bool "Symmetric multi-processing support"
399 This enables support for systems with more than one CPU. If you have
400 a system with only one CPU, say N. If you have a system with more
403 If you say N here, the kernel will run on uni- and multiprocessor
404 machines, but will use only one CPU of a multiprocessor machine. If
405 you say Y here, the kernel will run on many, but not all,
406 uniprocessor machines. On a uniprocessor machine, the kernel
407 will run faster if you say N here.
409 Note that if you say Y here and choose architecture "586" or
410 "Pentium" under "Processor family", the kernel will not work on 486
411 architectures. Similarly, multiprocessor kernels for the "PPro"
412 architecture may not work on all Pentium based boards.
414 People using multiprocessor machines who say Y here should also say
415 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
416 Management" code will be disabled if you say Y here.
418 See also <file:Documentation/x86/i386/IO-APIC.rst>,
419 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
420 <http://www.tldp.org/docs.html#howto>.
422 If you don't know what to do here, say N.
424 config X86_FEATURE_NAMES
425 bool "Processor feature human-readable names" if EMBEDDED
428 This option compiles in a table of x86 feature bits and corresponding
429 names. This is required to support /proc/cpuinfo and a few kernel
430 messages. You can disable this to save space, at the expense of
431 making those few kernel messages show numeric feature bits instead.
436 bool "Support x2apic"
437 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
439 This enables x2apic support on CPUs that have this feature.
441 This allows 32-bit apic IDs (so it can support very large systems),
442 and accesses the local apic via MSRs not via mmio.
444 If you don't know what to do here, say N.
447 bool "Enable MPS table" if ACPI
449 depends on X86_LOCAL_APIC
451 For old smp systems that do not have proper acpi support. Newer systems
452 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
456 depends on X86_GOLDFISH
459 bool "Avoid speculative indirect branches in kernel"
462 Compile kernel with the retpoline compiler options to guard against
463 kernel-to-user data leaks by avoiding speculative indirect
464 branches. Requires a compiler with -mindirect-branch=thunk-extern
465 support for full protection. The kernel may run slower.
467 config X86_CPU_RESCTRL
468 bool "x86 CPU resource control support"
469 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
471 select PROC_CPU_RESCTRL if PROC_FS
473 Enable x86 CPU resource control support.
475 Provide support for the allocation and monitoring of system resources
478 Intel calls this Intel Resource Director Technology
479 (Intel(R) RDT). More information about RDT can be found in the
480 Intel x86 Architecture Software Developer Manual.
482 AMD calls this AMD Platform Quality of Service (AMD QoS).
483 More information about AMD QoS can be found in the AMD64 Technology
484 Platform Quality of Service Extensions manual.
490 bool "Support for big SMP systems with more than 8 CPUs"
493 This option is needed for the systems that have more than 8 CPUs.
495 config X86_EXTENDED_PLATFORM
496 bool "Support for extended (non-PC) x86 platforms"
499 If you disable this option then the kernel will only support
500 standard PC platforms. (which covers the vast majority of
503 If you enable this option then you'll be able to select support
504 for the following (non-PC) 32 bit x86 platforms:
505 Goldfish (Android emulator)
508 SGI 320/540 (Visual Workstation)
509 STA2X11-based (e.g. Northville)
510 Moorestown MID devices
512 If you have one of these systems, or if you want to build a
513 generic distribution kernel, say Y here - otherwise say N.
517 config X86_EXTENDED_PLATFORM
518 bool "Support for extended (non-PC) x86 platforms"
521 If you disable this option then the kernel will only support
522 standard PC platforms. (which covers the vast majority of
525 If you enable this option then you'll be able to select support
526 for the following (non-PC) 64 bit x86 platforms:
531 If you have one of these systems, or if you want to build a
532 generic distribution kernel, say Y here - otherwise say N.
534 # This is an alphabetically sorted list of 64 bit extended platforms
535 # Please maintain the alphabetic order if and when there are additions
537 bool "Numascale NumaChip"
539 depends on X86_EXTENDED_PLATFORM
542 depends on X86_X2APIC
543 depends on PCI_MMCONFIG
545 Adds support for Numascale NumaChip large-SMP systems. Needed to
546 enable more than ~168 cores.
547 If you don't have one of these, you should say N here.
551 select HYPERVISOR_GUEST
553 depends on X86_64 && PCI
554 depends on X86_EXTENDED_PLATFORM
557 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
558 supposed to run on these EM64T-based machines. Only choose this option
559 if you have one of these machines.
562 bool "SGI Ultraviolet"
564 depends on X86_EXTENDED_PLATFORM
567 depends on KEXEC_CORE
568 depends on X86_X2APIC
571 This option is needed in order to support SGI Ultraviolet systems.
572 If you don't have one of these, you should say N here.
574 # Following is an alphabetically sorted list of 32 bit extended platforms
575 # Please maintain the alphabetic order if and when there are additions
578 bool "Goldfish (Virtual Platform)"
579 depends on X86_EXTENDED_PLATFORM
581 Enable support for the Goldfish virtual platform used primarily
582 for Android development. Unless you are building for the Android
583 Goldfish emulator say N here.
586 bool "CE4100 TV platform"
588 depends on PCI_GODIRECT
589 depends on X86_IO_APIC
591 depends on X86_EXTENDED_PLATFORM
592 select X86_REBOOTFIXUPS
594 select OF_EARLY_FLATTREE
596 Select for the Intel CE media processor (CE4100) SOC.
597 This option compiles in support for the CE4100 SOC for settop
598 boxes and media devices.
601 bool "Intel MID platform support"
602 depends on X86_EXTENDED_PLATFORM
603 depends on X86_PLATFORM_DEVICES
605 depends on X86_64 || (PCI_GOANY && X86_32)
606 depends on X86_IO_APIC
611 select MFD_INTEL_MSIC
613 Select to build a kernel capable of supporting Intel MID (Mobile
614 Internet Device) platform systems which do not have the PCI legacy
615 interfaces. If you are building for a PC class system say N here.
617 Intel MID platforms are based on an Intel processor and chipset which
618 consume less power than most of the x86 derivatives.
620 config X86_INTEL_QUARK
621 bool "Intel Quark platform support"
623 depends on X86_EXTENDED_PLATFORM
624 depends on X86_PLATFORM_DEVICES
628 depends on X86_IO_APIC
633 Select to include support for Quark X1000 SoC.
634 Say Y here if you have a Quark based system such as the Arduino
635 compatible Intel Galileo.
637 config X86_INTEL_LPSS
638 bool "Intel Low Power Subsystem Support"
639 depends on X86 && ACPI && PCI
644 Select to build support for Intel Low Power Subsystem such as
645 found on Intel Lynxpoint PCH. Selecting this option enables
646 things like clock tree (common clock framework) and pincontrol
647 which are needed by the LPSS peripheral drivers.
649 config X86_AMD_PLATFORM_DEVICE
650 bool "AMD ACPI2Platform devices support"
655 Select to interpret AMD specific ACPI device to platform device
656 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
657 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
658 implemented under PINCTRL subsystem.
661 tristate "Intel SoC IOSF Sideband support for SoC platforms"
664 This option enables sideband register access support for Intel SoC
665 platforms. On these platforms the IOSF sideband is used in lieu of
666 MSR's for some register accesses, mostly but not limited to thermal
667 and power. Drivers may query the availability of this device to
668 determine if they need the sideband in order to work on these
669 platforms. The sideband is available on the following SoC products.
670 This list is not meant to be exclusive.
675 You should say Y if you are running a kernel on one of these SoC's.
677 config IOSF_MBI_DEBUG
678 bool "Enable IOSF sideband access through debugfs"
679 depends on IOSF_MBI && DEBUG_FS
681 Select this option to expose the IOSF sideband access registers (MCR,
682 MDR, MCRX) through debugfs to write and read register information from
683 different units on the SoC. This is most useful for obtaining device
684 state information for debug and analysis. As this is a general access
685 mechanism, users of this option would have specific knowledge of the
686 device they want to access.
688 If you don't require the option or are in doubt, say N.
691 bool "RDC R-321x SoC"
693 depends on X86_EXTENDED_PLATFORM
695 select X86_REBOOTFIXUPS
697 This option is needed for RDC R-321x system-on-chip, also known
699 If you don't have one of these chips, you should say N here.
701 config X86_32_NON_STANDARD
702 bool "Support non-standard 32-bit SMP architectures"
703 depends on X86_32 && SMP
704 depends on X86_EXTENDED_PLATFORM
706 This option compiles in the bigsmp and STA2X11 default
707 subarchitectures. It is intended for a generic binary
708 kernel. If you select them all, kernel will probe it one by
709 one and will fallback to default.
711 # Alphabetically sorted list of Non standard 32 bit platforms
713 config X86_SUPPORTS_MEMORY_FAILURE
715 # MCE code calls memory_failure():
717 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
718 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
719 depends on X86_64 || !SPARSEMEM
720 select ARCH_SUPPORTS_MEMORY_FAILURE
723 bool "STA2X11 Companion Chip Support"
724 depends on X86_32_NON_STANDARD && PCI
729 This adds support for boards based on the STA2X11 IO-Hub,
730 a.k.a. "ConneXt". The chip is used in place of the standard
731 PC chipset, so all "standard" peripherals are missing. If this
732 option is selected the kernel will still be able to boot on
733 standard PC machines.
736 tristate "Eurobraille/Iris poweroff module"
739 The Iris machines from EuroBraille do not have APM or ACPI support
740 to shut themselves down properly. A special I/O sequence is
741 needed to do so, which is what this module does at
744 This is only for Iris machines from EuroBraille.
748 config SCHED_OMIT_FRAME_POINTER
750 prompt "Single-depth WCHAN output"
753 Calculate simpler /proc/<PID>/wchan values. If this option
754 is disabled then wchan values will recurse back to the
755 caller function. This provides more accurate wchan values,
756 at the expense of slightly more scheduling overhead.
758 If in doubt, say "Y".
760 menuconfig HYPERVISOR_GUEST
761 bool "Linux guest support"
763 Say Y here to enable options for running Linux under various hyper-
764 visors. This option enables basic hypervisor detection and platform
767 If you say N, all options in this submenu will be skipped and
768 disabled, and Linux guest support won't be built in.
773 bool "Enable paravirtualization code"
774 depends on HAVE_STATIC_CALL
776 This changes the kernel so it can modify itself when it is run
777 under a hypervisor, potentially improving performance significantly
778 over full virtualization. However, when run without a hypervisor
779 the kernel is theoretically slower and slightly larger.
784 config PARAVIRT_DEBUG
785 bool "paravirt-ops debugging"
786 depends on PARAVIRT && DEBUG_KERNEL
788 Enable to debug paravirt_ops internals. Specifically, BUG if
789 a paravirt_op is missing when it is called.
791 config PARAVIRT_SPINLOCKS
792 bool "Paravirtualization layer for spinlocks"
793 depends on PARAVIRT && SMP
795 Paravirtualized spinlocks allow a pvops backend to replace the
796 spinlock implementation with something virtualization-friendly
797 (for example, block the virtual CPU rather than spinning).
799 It has a minimal impact on native kernels and gives a nice performance
800 benefit on paravirtualized KVM / Xen kernels.
802 If you are unsure how to answer this question, answer Y.
804 config X86_HV_CALLBACK_VECTOR
807 source "arch/x86/xen/Kconfig"
810 bool "KVM Guest support (including kvmclock)"
812 select PARAVIRT_CLOCK
813 select ARCH_CPUIDLE_HALTPOLL
814 select X86_HV_CALLBACK_VECTOR
817 This option enables various optimizations for running under the KVM
818 hypervisor. It includes a paravirtualized clock, so that instead
819 of relying on a PIT (or probably other) emulation by the
820 underlying device model, the host provides the guest with
821 timing infrastructure such as time of day, and system time
823 config ARCH_CPUIDLE_HALTPOLL
825 prompt "Disable host haltpoll when loading haltpoll driver"
827 If virtualized under KVM, disable host haltpoll.
830 bool "Support for running PVH guests"
832 This option enables the PVH entry point for guest virtual machines
833 as specified in the x86/HVM direct boot ABI.
835 config PARAVIRT_TIME_ACCOUNTING
836 bool "Paravirtual steal time accounting"
839 Select this option to enable fine granularity task steal time
840 accounting. Time spent executing other tasks in parallel with
841 the current vCPU is discounted from the vCPU power. To account for
842 that, there can be a small performance impact.
844 If in doubt, say N here.
846 config PARAVIRT_CLOCK
849 config JAILHOUSE_GUEST
850 bool "Jailhouse non-root cell support"
851 depends on X86_64 && PCI
854 This option allows to run Linux as guest in a Jailhouse non-root
855 cell. You can leave this option disabled if you only want to start
856 Jailhouse and run Linux afterwards in the root cell.
859 bool "ACRN Guest support"
861 select X86_HV_CALLBACK_VECTOR
863 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
864 a flexible, lightweight reference open-source hypervisor, built with
865 real-time and safety-criticality in mind. It is built for embedded
866 IOT with small footprint and real-time features. More details can be
867 found in https://projectacrn.org/.
869 endif #HYPERVISOR_GUEST
871 source "arch/x86/Kconfig.cpu"
875 prompt "HPET Timer Support" if X86_32
877 Use the IA-PC HPET (High Precision Event Timer) to manage
878 time in preference to the PIT and RTC, if a HPET is
880 HPET is the next generation timer replacing legacy 8254s.
881 The HPET provides a stable time base on SMP
882 systems, unlike the TSC, but it is more expensive to access,
883 as it is off-chip. The interface used is documented
884 in the HPET spec, revision 1.
886 You can safely choose Y here. However, HPET will only be
887 activated if the platform and the BIOS support this feature.
888 Otherwise the 8254 will be used for timing services.
890 Choose N to continue using the legacy 8254 timer.
892 config HPET_EMULATE_RTC
894 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
896 # Mark as expert because too many people got it wrong.
897 # The code disables itself when not needed.
900 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
901 bool "Enable DMI scanning" if EXPERT
903 Enabled scanning of DMI to identify machine quirks. Say Y
904 here unless you have verified that your setup is not
905 affected by entries in the DMI blacklist. Required by PNP
909 bool "Old AMD GART IOMMU support"
913 depends on X86_64 && PCI && AMD_NB
915 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
916 GART based hardware IOMMUs.
918 The GART supports full DMA access for devices with 32-bit access
919 limitations, on systems with more than 3 GB. This is usually needed
920 for USB, sound, many IDE/SATA chipsets and some other devices.
922 Newer systems typically have a modern AMD IOMMU, supported via
923 the CONFIG_AMD_IOMMU=y config option.
925 In normal configurations this driver is only active when needed:
926 there's more than 3 GB of memory and the system contains a
927 32-bit limited device.
932 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
933 depends on X86_64 && SMP && DEBUG_KERNEL
934 select CPUMASK_OFFSTACK
936 Enable maximum number of CPUS and NUMA Nodes for this architecture.
940 # The maximum number of CPUs supported:
942 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
943 # and which can be configured interactively in the
944 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
946 # The ranges are different on 32-bit and 64-bit kernels, depending on
947 # hardware capabilities and scalability features of the kernel.
949 # ( If MAXSMP is enabled we just use the highest possible value and disable
950 # interactive configuration. )
953 config NR_CPUS_RANGE_BEGIN
955 default NR_CPUS_RANGE_END if MAXSMP
959 config NR_CPUS_RANGE_END
962 default 64 if SMP && X86_BIGSMP
963 default 8 if SMP && !X86_BIGSMP
966 config NR_CPUS_RANGE_END
969 default 8192 if SMP && CPUMASK_OFFSTACK
970 default 512 if SMP && !CPUMASK_OFFSTACK
973 config NR_CPUS_DEFAULT
976 default 32 if X86_BIGSMP
980 config NR_CPUS_DEFAULT
983 default 8192 if MAXSMP
988 int "Maximum number of CPUs" if SMP && !MAXSMP
989 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
990 default NR_CPUS_DEFAULT
992 This allows you to specify the maximum number of CPUs which this
993 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
994 supported value is 8192, otherwise the maximum value is 512. The
995 minimum value which makes sense is 2.
997 This is purely to save memory: each supported CPU adds about 8KB
1005 prompt "Multi-core scheduler support"
1008 Multi-core scheduler support improves the CPU scheduler's decision
1009 making when dealing with multi-core CPU chips at a cost of slightly
1010 increased overhead in some places. If unsure say N here.
1012 config SCHED_MC_PRIO
1013 bool "CPU core priorities scheduler support"
1014 depends on SCHED_MC && CPU_SUP_INTEL
1015 select X86_INTEL_PSTATE
1019 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1020 core ordering determined at manufacturing time, which allows
1021 certain cores to reach higher turbo frequencies (when running
1022 single threaded workloads) than others.
1024 Enabling this kernel feature teaches the scheduler about
1025 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1026 scheduler's CPU selection logic accordingly, so that higher
1027 overall system performance can be achieved.
1029 This feature will have no effect on CPUs without this feature.
1031 If unsure say Y here.
1035 depends on !SMP && X86_LOCAL_APIC
1038 bool "Local APIC support on uniprocessors" if !PCI_MSI
1040 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1042 A local APIC (Advanced Programmable Interrupt Controller) is an
1043 integrated interrupt controller in the CPU. If you have a single-CPU
1044 system which has a processor with a local APIC, you can say Y here to
1045 enable and use it. If you say Y here even though your machine doesn't
1046 have a local APIC, then the kernel will still run with no slowdown at
1047 all. The local APIC supports CPU-generated self-interrupts (timer,
1048 performance counters), and the NMI watchdog which detects hard
1051 config X86_UP_IOAPIC
1052 bool "IO-APIC support on uniprocessors"
1053 depends on X86_UP_APIC
1055 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1056 SMP-capable replacement for PC-style interrupt controllers. Most
1057 SMP systems and many recent uniprocessor systems have one.
1059 If you have a single-CPU system with an IO-APIC, you can say Y here
1060 to use it. If you say Y here even though your machine doesn't have
1061 an IO-APIC, then the kernel will still run with no slowdown at all.
1063 config X86_LOCAL_APIC
1065 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1066 select IRQ_DOMAIN_HIERARCHY
1067 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1071 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1073 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1074 bool "Reroute for broken boot IRQs"
1075 depends on X86_IO_APIC
1077 This option enables a workaround that fixes a source of
1078 spurious interrupts. This is recommended when threaded
1079 interrupt handling is used on systems where the generation of
1080 superfluous "boot interrupts" cannot be disabled.
1082 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1083 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1084 kernel does during interrupt handling). On chipsets where this
1085 boot IRQ generation cannot be disabled, this workaround keeps
1086 the original IRQ line masked so that only the equivalent "boot
1087 IRQ" is delivered to the CPUs. The workaround also tells the
1088 kernel to set up the IRQ handler on the boot IRQ line. In this
1089 way only one interrupt is delivered to the kernel. Otherwise
1090 the spurious second interrupt may cause the kernel to bring
1091 down (vital) interrupt lines.
1093 Only affects "broken" chipsets. Interrupt sharing may be
1094 increased on these systems.
1097 bool "Machine Check / overheating reporting"
1098 select GENERIC_ALLOCATOR
1101 Machine Check support allows the processor to notify the
1102 kernel if it detects a problem (e.g. overheating, data corruption).
1103 The action the kernel takes depends on the severity of the problem,
1104 ranging from warning messages to halting the machine.
1106 config X86_MCELOG_LEGACY
1107 bool "Support for deprecated /dev/mcelog character device"
1110 Enable support for /dev/mcelog which is needed by the old mcelog
1111 userspace logging daemon. Consider switching to the new generation
1114 config X86_MCE_INTEL
1116 prompt "Intel MCE features"
1117 depends on X86_MCE && X86_LOCAL_APIC
1119 Additional support for intel specific MCE features such as
1120 the thermal monitor.
1124 prompt "AMD MCE features"
1125 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1127 Additional support for AMD specific MCE features such as
1128 the DRAM Error Threshold.
1130 config X86_ANCIENT_MCE
1131 bool "Support for old Pentium 5 / WinChip machine checks"
1132 depends on X86_32 && X86_MCE
1134 Include support for machine check handling on old Pentium 5 or WinChip
1135 systems. These typically need to be enabled explicitly on the command
1138 config X86_MCE_THRESHOLD
1139 depends on X86_MCE_AMD || X86_MCE_INTEL
1142 config X86_MCE_INJECT
1143 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1144 tristate "Machine check injector support"
1146 Provide support for injecting machine checks for testing purposes.
1147 If you don't know what a machine check is and you don't do kernel
1148 QA it is safe to say n.
1150 source "arch/x86/events/Kconfig"
1152 config X86_LEGACY_VM86
1153 bool "Legacy VM86 support"
1156 This option allows user programs to put the CPU into V8086
1157 mode, which is an 80286-era approximation of 16-bit real mode.
1159 Some very old versions of X and/or vbetool require this option
1160 for user mode setting. Similarly, DOSEMU will use it if
1161 available to accelerate real mode DOS programs. However, any
1162 recent version of DOSEMU, X, or vbetool should be fully
1163 functional even without kernel VM86 support, as they will all
1164 fall back to software emulation. Nevertheless, if you are using
1165 a 16-bit DOS program where 16-bit performance matters, vm86
1166 mode might be faster than emulation and you might want to
1169 Note that any app that works on a 64-bit kernel is unlikely to
1170 need this option, as 64-bit kernels don't, and can't, support
1171 V8086 mode. This option is also unrelated to 16-bit protected
1172 mode and is not needed to run most 16-bit programs under Wine.
1174 Enabling this option increases the complexity of the kernel
1175 and slows down exception handling a tiny bit.
1177 If unsure, say N here.
1181 default X86_LEGACY_VM86
1184 bool "Enable support for 16-bit segments" if EXPERT
1186 depends on MODIFY_LDT_SYSCALL
1188 This option is required by programs like Wine to run 16-bit
1189 protected mode legacy code on x86 processors. Disabling
1190 this option saves about 300 bytes on i386, or around 6K text
1191 plus 16K runtime memory on x86-64,
1195 depends on X86_16BIT && X86_32
1199 depends on X86_16BIT && X86_64
1201 config X86_VSYSCALL_EMULATION
1202 bool "Enable vsyscall emulation" if EXPERT
1206 This enables emulation of the legacy vsyscall page. Disabling
1207 it is roughly equivalent to booting with vsyscall=none, except
1208 that it will also disable the helpful warning if a program
1209 tries to use a vsyscall. With this option set to N, offending
1210 programs will just segfault, citing addresses of the form
1213 This option is required by many programs built before 2013, and
1214 care should be used even with newer programs if set to N.
1216 Disabling this option saves about 7K of kernel size and
1217 possibly 4K of additional runtime pagetable memory.
1219 config X86_IOPL_IOPERM
1220 bool "IOPERM and IOPL Emulation"
1223 This enables the ioperm() and iopl() syscalls which are necessary
1224 for legacy applications.
1226 Legacy IOPL support is an overbroad mechanism which allows user
1227 space aside of accessing all 65536 I/O ports also to disable
1228 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1229 capabilities and permission from potentially active security
1232 The emulation restricts the functionality of the syscall to
1233 only allowing the full range I/O port access, but prevents the
1234 ability to disable interrupts from user space which would be
1235 granted if the hardware IOPL mechanism would be used.
1238 tristate "Toshiba Laptop support"
1241 This adds a driver to safely access the System Management Mode of
1242 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1243 not work on models with a Phoenix BIOS. The System Management Mode
1244 is used to set the BIOS and power saving options on Toshiba portables.
1246 For information on utilities to make use of this driver see the
1247 Toshiba Linux utilities web site at:
1248 <http://www.buzzard.org.uk/toshiba/>.
1250 Say Y if you intend to run this kernel on a Toshiba portable.
1254 tristate "Dell i8k legacy laptop support"
1256 select SENSORS_DELL_SMM
1258 This option enables legacy /proc/i8k userspace interface in hwmon
1259 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1260 temperature and allows controlling fan speeds of Dell laptops via
1261 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1262 it reports also power and hotkey status. For fan speed control is
1263 needed userspace package i8kutils.
1265 Say Y if you intend to run this kernel on old Dell laptops or want to
1266 use userspace package i8kutils.
1269 config X86_REBOOTFIXUPS
1270 bool "Enable X86 board specific fixups for reboot"
1273 This enables chipset and/or board specific fixups to be done
1274 in order to get reboot to work correctly. This is only needed on
1275 some combinations of hardware and BIOS. The symptom, for which
1276 this config is intended, is when reboot ends with a stalled/hung
1279 Currently, the only fixup is for the Geode machines using
1280 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1282 Say Y if you want to enable the fixup. Currently, it's safe to
1283 enable this option even if you don't need it.
1287 bool "CPU microcode loading support"
1289 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1291 If you say Y here, you will be able to update the microcode on
1292 Intel and AMD processors. The Intel support is for the IA32 family,
1293 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1294 AMD support is for families 0x10 and later. You will obviously need
1295 the actual microcode binary data itself which is not shipped with
1298 The preferred method to load microcode from a detached initrd is described
1299 in Documentation/x86/microcode.rst. For that you need to enable
1300 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1301 initrd for microcode blobs.
1303 In addition, you can build the microcode into the kernel. For that you
1304 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1307 config MICROCODE_INTEL
1308 bool "Intel microcode loading support"
1309 depends on MICROCODE
1312 This options enables microcode patch loading support for Intel
1315 For the current Intel microcode data package go to
1316 <https://downloadcenter.intel.com> and search for
1317 'Linux Processor Microcode Data File'.
1319 config MICROCODE_AMD
1320 bool "AMD microcode loading support"
1321 depends on MICROCODE
1323 If you select this option, microcode patch loading support for AMD
1324 processors will be enabled.
1326 config MICROCODE_OLD_INTERFACE
1327 bool "Ancient loading interface (DEPRECATED)"
1329 depends on MICROCODE
1331 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1332 which was used by userspace tools like iucode_tool and microcode.ctl.
1333 It is inadequate because it runs too late to be able to properly
1334 load microcode on a machine and it needs special tools. Instead, you
1335 should've switched to the early loading method with the initrd or
1336 builtin microcode by now: Documentation/x86/microcode.rst
1339 tristate "/dev/cpu/*/msr - Model-specific register support"
1341 This device gives privileged processes access to the x86
1342 Model-Specific Registers (MSRs). It is a character device with
1343 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1344 MSR accesses are directed to a specific CPU on multi-processor
1348 tristate "/dev/cpu/*/cpuid - CPU information support"
1350 This device gives processes access to the x86 CPUID instruction to
1351 be executed on a specific processor. It is a character device
1352 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1356 prompt "High Memory Support"
1363 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1364 However, the address space of 32-bit x86 processors is only 4
1365 Gigabytes large. That means that, if you have a large amount of
1366 physical memory, not all of it can be "permanently mapped" by the
1367 kernel. The physical memory that's not permanently mapped is called
1370 If you are compiling a kernel which will never run on a machine with
1371 more than 1 Gigabyte total physical RAM, answer "off" here (default
1372 choice and suitable for most users). This will result in a "3GB/1GB"
1373 split: 3GB are mapped so that each process sees a 3GB virtual memory
1374 space and the remaining part of the 4GB virtual memory space is used
1375 by the kernel to permanently map as much physical memory as
1378 If the machine has between 1 and 4 Gigabytes physical RAM, then
1381 If more than 4 Gigabytes is used then answer "64GB" here. This
1382 selection turns Intel PAE (Physical Address Extension) mode on.
1383 PAE implements 3-level paging on IA32 processors. PAE is fully
1384 supported by Linux, PAE mode is implemented on all recent Intel
1385 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1386 then the kernel will not boot on CPUs that don't support PAE!
1388 The actual amount of total physical memory will either be
1389 auto detected or can be forced by using a kernel command line option
1390 such as "mem=256M". (Try "man bootparam" or see the documentation of
1391 your boot loader (lilo or loadlin) about how to pass options to the
1392 kernel at boot time.)
1394 If unsure, say "off".
1399 Select this if you have a 32-bit processor and between 1 and 4
1400 gigabytes of physical RAM.
1404 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1407 Select this if you have a 32-bit processor and more than 4
1408 gigabytes of physical RAM.
1413 prompt "Memory split" if EXPERT
1417 Select the desired split between kernel and user memory.
1419 If the address range available to the kernel is less than the
1420 physical memory installed, the remaining memory will be available
1421 as "high memory". Accessing high memory is a little more costly
1422 than low memory, as it needs to be mapped into the kernel first.
1423 Note that increasing the kernel address space limits the range
1424 available to user programs, making the address space there
1425 tighter. Selecting anything other than the default 3G/1G split
1426 will also likely make your kernel incompatible with binary-only
1429 If you are not absolutely sure what you are doing, leave this
1433 bool "3G/1G user/kernel split"
1434 config VMSPLIT_3G_OPT
1436 bool "3G/1G user/kernel split (for full 1G low memory)"
1438 bool "2G/2G user/kernel split"
1439 config VMSPLIT_2G_OPT
1441 bool "2G/2G user/kernel split (for full 2G low memory)"
1443 bool "1G/3G user/kernel split"
1448 default 0xB0000000 if VMSPLIT_3G_OPT
1449 default 0x80000000 if VMSPLIT_2G
1450 default 0x78000000 if VMSPLIT_2G_OPT
1451 default 0x40000000 if VMSPLIT_1G
1457 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1460 bool "PAE (Physical Address Extension) Support"
1461 depends on X86_32 && !HIGHMEM4G
1462 select PHYS_ADDR_T_64BIT
1465 PAE is required for NX support, and furthermore enables
1466 larger swapspace support for non-overcommit purposes. It
1467 has the cost of more pagetable lookup overhead, and also
1468 consumes more pagetable space per process.
1471 bool "Enable 5-level page tables support"
1473 select DYNAMIC_MEMORY_LAYOUT
1474 select SPARSEMEM_VMEMMAP
1477 5-level paging enables access to larger address space:
1478 upto 128 PiB of virtual address space and 4 PiB of
1479 physical address space.
1481 It will be supported by future Intel CPUs.
1483 A kernel with the option enabled can be booted on machines that
1484 support 4- or 5-level paging.
1486 See Documentation/x86/x86_64/5level-paging.rst for more
1491 config X86_DIRECT_GBPAGES
1495 Certain kernel features effectively disable kernel
1496 linear 1 GB mappings (even if the CPU otherwise
1497 supports them), so don't confuse the user by printing
1498 that we have them enabled.
1500 config X86_CPA_STATISTICS
1501 bool "Enable statistic for Change Page Attribute"
1504 Expose statistics about the Change Page Attribute mechanism, which
1505 helps to determine the effectiveness of preserving large and huge
1506 page mappings when mapping protections are changed.
1508 config AMD_MEM_ENCRYPT
1509 bool "AMD Secure Memory Encryption (SME) support"
1510 depends on X86_64 && CPU_SUP_AMD
1511 select DMA_COHERENT_POOL
1512 select DYNAMIC_PHYSICAL_MASK
1513 select ARCH_USE_MEMREMAP_PROT
1514 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1515 select INSTRUCTION_DECODER
1516 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1518 Say yes to enable support for the encryption of system memory.
1519 This requires an AMD processor that supports Secure Memory
1522 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1523 bool "Activate AMD Secure Memory Encryption (SME) by default"
1525 depends on AMD_MEM_ENCRYPT
1527 Say yes to have system memory encrypted by default if running on
1528 an AMD processor that supports Secure Memory Encryption (SME).
1530 If set to Y, then the encryption of system memory can be
1531 deactivated with the mem_encrypt=off command line option.
1533 If set to N, then the encryption of system memory can be
1534 activated with the mem_encrypt=on command line option.
1536 # Common NUMA Features
1538 bool "NUMA Memory Allocation and Scheduler Support"
1540 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1541 default y if X86_BIGSMP
1543 Enable NUMA (Non-Uniform Memory Access) support.
1545 The kernel will try to allocate memory used by a CPU on the
1546 local memory controller of the CPU and add some more
1547 NUMA awareness to the kernel.
1549 For 64-bit this is recommended if the system is Intel Core i7
1550 (or later), AMD Opteron, or EM64T NUMA.
1552 For 32-bit this is only needed if you boot a 32-bit
1553 kernel on a 64-bit NUMA platform.
1555 Otherwise, you should say N.
1559 prompt "Old style AMD Opteron NUMA detection"
1560 depends on X86_64 && NUMA && PCI
1562 Enable AMD NUMA node topology detection. You should say Y here if
1563 you have a multi processor AMD system. This uses an old method to
1564 read the NUMA configuration directly from the builtin Northbridge
1565 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1566 which also takes priority if both are compiled in.
1568 config X86_64_ACPI_NUMA
1570 prompt "ACPI NUMA detection"
1571 depends on X86_64 && NUMA && ACPI && PCI
1574 Enable ACPI SRAT based node topology detection.
1577 bool "NUMA emulation"
1580 Enable NUMA emulation. A flat machine will be split
1581 into virtual nodes when booted with "numa=fake=N", where N is the
1582 number of nodes. This is only useful for debugging.
1585 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1587 default "10" if MAXSMP
1588 default "6" if X86_64
1592 Specify the maximum number of NUMA Nodes available on the target
1593 system. Increases memory reserved to accommodate various tables.
1595 config ARCH_FLATMEM_ENABLE
1597 depends on X86_32 && !NUMA
1599 config ARCH_SPARSEMEM_ENABLE
1601 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1602 select SPARSEMEM_STATIC if X86_32
1603 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1605 config ARCH_SPARSEMEM_DEFAULT
1606 def_bool X86_64 || (NUMA && X86_32)
1608 config ARCH_SELECT_MEMORY_MODEL
1610 depends on ARCH_SPARSEMEM_ENABLE
1612 config ARCH_MEMORY_PROBE
1613 bool "Enable sysfs memory/probe interface"
1614 depends on X86_64 && MEMORY_HOTPLUG
1616 This option enables a sysfs memory/probe interface for testing.
1617 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1618 If you are unsure how to answer this question, answer N.
1620 config ARCH_PROC_KCORE_TEXT
1622 depends on X86_64 && PROC_KCORE
1624 config ILLEGAL_POINTER_VALUE
1627 default 0xdead000000000000 if X86_64
1629 config X86_PMEM_LEGACY_DEVICE
1632 config X86_PMEM_LEGACY
1633 tristate "Support non-standard NVDIMMs and ADR protected memory"
1634 depends on PHYS_ADDR_T_64BIT
1636 select X86_PMEM_LEGACY_DEVICE
1637 select NUMA_KEEP_MEMINFO if NUMA
1640 Treat memory marked using the non-standard e820 type of 12 as used
1641 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1642 The kernel will offer these regions to the 'pmem' driver so
1643 they can be used for persistent storage.
1648 bool "Allocate 3rd-level pagetables from highmem"
1651 The VM uses one page table entry for each page of physical memory.
1652 For systems with a lot of RAM, this can be wasteful of precious
1653 low memory. Setting this option will put user-space page table
1654 entries in high memory.
1656 config X86_CHECK_BIOS_CORRUPTION
1657 bool "Check for low memory corruption"
1659 Periodically check for memory corruption in low memory, which
1660 is suspected to be caused by BIOS. Even when enabled in the
1661 configuration, it is disabled at runtime. Enable it by
1662 setting "memory_corruption_check=1" on the kernel command
1663 line. By default it scans the low 64k of memory every 60
1664 seconds; see the memory_corruption_check_size and
1665 memory_corruption_check_period parameters in
1666 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1668 When enabled with the default parameters, this option has
1669 almost no overhead, as it reserves a relatively small amount
1670 of memory and scans it infrequently. It both detects corruption
1671 and prevents it from affecting the running system.
1673 It is, however, intended as a diagnostic tool; if repeatable
1674 BIOS-originated corruption always affects the same memory,
1675 you can use memmap= to prevent the kernel from using that
1678 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1679 bool "Set the default setting of memory_corruption_check"
1680 depends on X86_CHECK_BIOS_CORRUPTION
1683 Set whether the default state of memory_corruption_check is
1686 config MATH_EMULATION
1688 depends on MODIFY_LDT_SYSCALL
1689 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1691 Linux can emulate a math coprocessor (used for floating point
1692 operations) if you don't have one. 486DX and Pentium processors have
1693 a math coprocessor built in, 486SX and 386 do not, unless you added
1694 a 487DX or 387, respectively. (The messages during boot time can
1695 give you some hints here ["man dmesg"].) Everyone needs either a
1696 coprocessor or this emulation.
1698 If you don't have a math coprocessor, you need to say Y here; if you
1699 say Y here even though you have a coprocessor, the coprocessor will
1700 be used nevertheless. (This behavior can be changed with the kernel
1701 command line option "no387", which comes handy if your coprocessor
1702 is broken. Try "man bootparam" or see the documentation of your boot
1703 loader (lilo or loadlin) about how to pass options to the kernel at
1704 boot time.) This means that it is a good idea to say Y here if you
1705 intend to use this kernel on different machines.
1707 More information about the internals of the Linux math coprocessor
1708 emulation can be found in <file:arch/x86/math-emu/README>.
1710 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1711 kernel, it won't hurt.
1715 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1717 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1718 the Memory Type Range Registers (MTRRs) may be used to control
1719 processor access to memory ranges. This is most useful if you have
1720 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1721 allows bus write transfers to be combined into a larger transfer
1722 before bursting over the PCI/AGP bus. This can increase performance
1723 of image write operations 2.5 times or more. Saying Y here creates a
1724 /proc/mtrr file which may be used to manipulate your processor's
1725 MTRRs. Typically the X server should use this.
1727 This code has a reasonably generic interface so that similar
1728 control registers on other processors can be easily supported
1731 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1732 Registers (ARRs) which provide a similar functionality to MTRRs. For
1733 these, the ARRs are used to emulate the MTRRs.
1734 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1735 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1736 write-combining. All of these processors are supported by this code
1737 and it makes sense to say Y here if you have one of them.
1739 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1740 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1741 can lead to all sorts of problems, so it's good to say Y here.
1743 You can safely say Y even if your machine doesn't have MTRRs, you'll
1744 just add about 9 KB to your kernel.
1746 See <file:Documentation/x86/mtrr.rst> for more information.
1748 config MTRR_SANITIZER
1750 prompt "MTRR cleanup support"
1753 Convert MTRR layout from continuous to discrete, so X drivers can
1754 add writeback entries.
1756 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1757 The largest mtrr entry size for a continuous block can be set with
1762 config MTRR_SANITIZER_ENABLE_DEFAULT
1763 int "MTRR cleanup enable value (0-1)"
1766 depends on MTRR_SANITIZER
1768 Enable mtrr cleanup default value
1770 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1771 int "MTRR cleanup spare reg num (0-7)"
1774 depends on MTRR_SANITIZER
1776 mtrr cleanup spare entries default, it can be changed via
1777 mtrr_spare_reg_nr=N on the kernel command line.
1781 prompt "x86 PAT support" if EXPERT
1784 Use PAT attributes to setup page level cache control.
1786 PATs are the modern equivalents of MTRRs and are much more
1787 flexible than MTRRs.
1789 Say N here if you see bootup problems (boot crash, boot hang,
1790 spontaneous reboots) or a non-working video driver.
1794 config ARCH_USES_PG_UNCACHED
1800 prompt "x86 architectural random number generator" if EXPERT
1802 Enable the x86 architectural RDRAND instruction
1803 (Intel Bull Mountain technology) to generate random numbers.
1804 If supported, this is a high bandwidth, cryptographically
1805 secure hardware random number generator.
1809 prompt "Supervisor Mode Access Prevention" if EXPERT
1811 Supervisor Mode Access Prevention (SMAP) is a security
1812 feature in newer Intel processors. There is a small
1813 performance cost if this enabled and turned on; there is
1814 also a small increase in the kernel size if this is enabled.
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
1833 config X86_INTEL_MEMORY_PROTECTION_KEYS
1834 prompt "Memory Protection Keys"
1836 # Note: only available in 64-bit mode
1837 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1838 select ARCH_USES_HIGH_VMA_FLAGS
1839 select ARCH_HAS_PKEYS
1841 Memory Protection Keys provides a mechanism for enforcing
1842 page-based protections, but without requiring modification of the
1843 page tables when an application changes protection domains.
1845 For details, see Documentation/core-api/protection-keys.rst
1850 prompt "TSX enable mode"
1851 depends on CPU_SUP_INTEL
1852 default X86_INTEL_TSX_MODE_OFF
1854 Intel's TSX (Transactional Synchronization Extensions) feature
1855 allows to optimize locking protocols through lock elision which
1856 can lead to a noticeable performance boost.
1858 On the other hand it has been shown that TSX can be exploited
1859 to form side channel attacks (e.g. TAA) and chances are there
1860 will be more of those attacks discovered in the future.
1862 Therefore TSX is not enabled by default (aka tsx=off). An admin
1863 might override this decision by tsx=on the command line parameter.
1864 Even with TSX enabled, the kernel will attempt to enable the best
1865 possible TAA mitigation setting depending on the microcode available
1866 for the particular machine.
1868 This option allows to set the default tsx mode between tsx=on, =off
1869 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1872 Say off if not sure, auto if TSX is in use but it should be used on safe
1873 platforms or on if TSX is in use and the security aspect of tsx is not
1876 config X86_INTEL_TSX_MODE_OFF
1879 TSX is disabled if possible - equals to tsx=off command line parameter.
1881 config X86_INTEL_TSX_MODE_ON
1884 TSX is always enabled on TSX capable HW - equals the tsx=on command
1887 config X86_INTEL_TSX_MODE_AUTO
1890 TSX is enabled on TSX capable HW that is believed to be safe against
1891 side channel attacks- equals the tsx=auto command line parameter.
1895 bool "Software Guard eXtensions (SGX)"
1896 depends on X86_64 && CPU_SUP_INTEL
1898 depends on CRYPTO_SHA256=y
1901 select NUMA_KEEP_MEMINFO if NUMA
1903 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1904 that can be used by applications to set aside private regions of code
1905 and data, referred to as enclaves. An enclave's private memory can
1906 only be accessed by code running within the enclave. Accesses from
1907 outside the enclave, including other enclaves, are disallowed by
1913 bool "EFI runtime service support"
1916 select EFI_RUNTIME_WRAPPERS
1918 This enables the kernel to use EFI runtime services that are
1919 available (such as the EFI variable services).
1921 This option is only useful on systems that have EFI firmware.
1922 In addition, you should use the latest ELILO loader available
1923 at <http://elilo.sourceforge.net> in order to take advantage
1924 of EFI runtime services. However, even with this option, the
1925 resultant kernel should continue to boot on existing non-EFI
1929 bool "EFI stub support"
1930 depends on EFI && !X86_USE_3DNOW
1931 depends on $(cc-option,-mabi=ms) || X86_32
1934 This kernel feature allows a bzImage to be loaded directly
1935 by EFI firmware without the use of a bootloader.
1937 See Documentation/admin-guide/efi-stub.rst for more information.
1940 bool "EFI mixed-mode support"
1941 depends on EFI_STUB && X86_64
1943 Enabling this feature allows a 64-bit kernel to be booted
1944 on a 32-bit firmware, provided that your CPU supports 64-bit
1947 Note that it is not possible to boot a mixed-mode enabled
1948 kernel via the EFI boot stub - a bootloader that supports
1949 the EFI handover protocol must be used.
1953 source "kernel/Kconfig.hz"
1956 bool "kexec system call"
1959 kexec is a system call that implements the ability to shutdown your
1960 current kernel, and to start another kernel. It is like a reboot
1961 but it is independent of the system firmware. And like a reboot
1962 you can start any kernel with it, not just Linux.
1964 The name comes from the similarity to the exec system call.
1966 It is an ongoing process to be certain the hardware in a machine
1967 is properly shutdown, so do not be surprised if this code does not
1968 initially work for you. As of this writing the exact hardware
1969 interface is strongly in flux, so no good recommendation can be
1973 bool "kexec file based system call"
1978 depends on CRYPTO_SHA256=y
1980 This is new version of kexec system call. This system call is
1981 file based and takes file descriptors as system call argument
1982 for kernel and initramfs as opposed to list of segments as
1983 accepted by previous system call.
1985 config ARCH_HAS_KEXEC_PURGATORY
1989 bool "Verify kernel signature during kexec_file_load() syscall"
1990 depends on KEXEC_FILE
1993 This option makes the kexec_file_load() syscall check for a valid
1994 signature of the kernel image. The image can still be loaded without
1995 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
1996 there's a signature that we can check, then it must be valid.
1998 In addition to this option, you need to enable signature
1999 verification for the corresponding kernel image type being
2000 loaded in order for this to work.
2002 config KEXEC_SIG_FORCE
2003 bool "Require a valid signature in kexec_file_load() syscall"
2004 depends on KEXEC_SIG
2006 This option makes kernel signature verification mandatory for
2007 the kexec_file_load() syscall.
2009 config KEXEC_BZIMAGE_VERIFY_SIG
2010 bool "Enable bzImage signature verification support"
2011 depends on KEXEC_SIG
2012 depends on SIGNED_PE_FILE_VERIFICATION
2013 select SYSTEM_TRUSTED_KEYRING
2015 Enable bzImage signature verification support.
2018 bool "kernel crash dumps"
2019 depends on X86_64 || (X86_32 && HIGHMEM)
2021 Generate crash dump after being started by kexec.
2022 This should be normally only set in special crash dump kernels
2023 which are loaded in the main kernel with kexec-tools into
2024 a specially reserved region and then later executed after
2025 a crash by kdump/kexec. The crash dump kernel must be compiled
2026 to a memory address not used by the main kernel or BIOS using
2027 PHYSICAL_START, or it must be built as a relocatable image
2028 (CONFIG_RELOCATABLE=y).
2029 For more details see Documentation/admin-guide/kdump/kdump.rst
2033 depends on KEXEC && HIBERNATION
2035 Jump between original kernel and kexeced kernel and invoke
2036 code in physical address mode via KEXEC
2038 config PHYSICAL_START
2039 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2042 This gives the physical address where the kernel is loaded.
2044 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2045 bzImage will decompress itself to above physical address and
2046 run from there. Otherwise, bzImage will run from the address where
2047 it has been loaded by the boot loader and will ignore above physical
2050 In normal kdump cases one does not have to set/change this option
2051 as now bzImage can be compiled as a completely relocatable image
2052 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2053 address. This option is mainly useful for the folks who don't want
2054 to use a bzImage for capturing the crash dump and want to use a
2055 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2056 to be specifically compiled to run from a specific memory area
2057 (normally a reserved region) and this option comes handy.
2059 So if you are using bzImage for capturing the crash dump,
2060 leave the value here unchanged to 0x1000000 and set
2061 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2062 for capturing the crash dump change this value to start of
2063 the reserved region. In other words, it can be set based on
2064 the "X" value as specified in the "crashkernel=YM@XM"
2065 command line boot parameter passed to the panic-ed
2066 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2067 for more details about crash dumps.
2069 Usage of bzImage for capturing the crash dump is recommended as
2070 one does not have to build two kernels. Same kernel can be used
2071 as production kernel and capture kernel. Above option should have
2072 gone away after relocatable bzImage support is introduced. But it
2073 is present because there are users out there who continue to use
2074 vmlinux for dump capture. This option should go away down the
2077 Don't change this unless you know what you are doing.
2080 bool "Build a relocatable kernel"
2083 This builds a kernel image that retains relocation information
2084 so it can be loaded someplace besides the default 1MB.
2085 The relocations tend to make the kernel binary about 10% larger,
2086 but are discarded at runtime.
2088 One use is for the kexec on panic case where the recovery kernel
2089 must live at a different physical address than the primary
2092 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2093 it has been loaded at and the compile time physical address
2094 (CONFIG_PHYSICAL_START) is used as the minimum location.
2096 config RANDOMIZE_BASE
2097 bool "Randomize the address of the kernel image (KASLR)"
2098 depends on RELOCATABLE
2101 In support of Kernel Address Space Layout Randomization (KASLR),
2102 this randomizes the physical address at which the kernel image
2103 is decompressed and the virtual address where the kernel
2104 image is mapped, as a security feature that deters exploit
2105 attempts relying on knowledge of the location of kernel
2108 On 64-bit, the kernel physical and virtual addresses are
2109 randomized separately. The physical address will be anywhere
2110 between 16MB and the top of physical memory (up to 64TB). The
2111 virtual address will be randomized from 16MB up to 1GB (9 bits
2112 of entropy). Note that this also reduces the memory space
2113 available to kernel modules from 1.5GB to 1GB.
2115 On 32-bit, the kernel physical and virtual addresses are
2116 randomized together. They will be randomized from 16MB up to
2117 512MB (8 bits of entropy).
2119 Entropy is generated using the RDRAND instruction if it is
2120 supported. If RDTSC is supported, its value is mixed into
2121 the entropy pool as well. If neither RDRAND nor RDTSC are
2122 supported, then entropy is read from the i8254 timer. The
2123 usable entropy is limited by the kernel being built using
2124 2GB addressing, and that PHYSICAL_ALIGN must be at a
2125 minimum of 2MB. As a result, only 10 bits of entropy are
2126 theoretically possible, but the implementations are further
2127 limited due to memory layouts.
2131 # Relocation on x86 needs some additional build support
2132 config X86_NEED_RELOCS
2134 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2136 config PHYSICAL_ALIGN
2137 hex "Alignment value to which kernel should be aligned"
2139 range 0x2000 0x1000000 if X86_32
2140 range 0x200000 0x1000000 if X86_64
2142 This value puts the alignment restrictions on physical address
2143 where kernel is loaded and run from. Kernel is compiled for an
2144 address which meets above alignment restriction.
2146 If bootloader loads the kernel at a non-aligned address and
2147 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2148 address aligned to above value and run from there.
2150 If bootloader loads the kernel at a non-aligned address and
2151 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2152 load address and decompress itself to the address it has been
2153 compiled for and run from there. The address for which kernel is
2154 compiled already meets above alignment restrictions. Hence the
2155 end result is that kernel runs from a physical address meeting
2156 above alignment restrictions.
2158 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2159 this value must be a multiple of 0x200000.
2161 Don't change this unless you know what you are doing.
2163 config DYNAMIC_MEMORY_LAYOUT
2166 This option makes base addresses of vmalloc and vmemmap as well as
2167 __PAGE_OFFSET movable during boot.
2169 config RANDOMIZE_MEMORY
2170 bool "Randomize the kernel memory sections"
2172 depends on RANDOMIZE_BASE
2173 select DYNAMIC_MEMORY_LAYOUT
2174 default RANDOMIZE_BASE
2176 Randomizes the base virtual address of kernel memory sections
2177 (physical memory mapping, vmalloc & vmemmap). This security feature
2178 makes exploits relying on predictable memory locations less reliable.
2180 The order of allocations remains unchanged. Entropy is generated in
2181 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2182 configuration have in average 30,000 different possible virtual
2183 addresses for each memory section.
2187 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2188 hex "Physical memory mapping padding" if EXPERT
2189 depends on RANDOMIZE_MEMORY
2190 default "0xa" if MEMORY_HOTPLUG
2192 range 0x1 0x40 if MEMORY_HOTPLUG
2195 Define the padding in terabytes added to the existing physical
2196 memory size during kernel memory randomization. It is useful
2197 for memory hotplug support but reduces the entropy available for
2198 address randomization.
2200 If unsure, leave at the default value.
2206 config BOOTPARAM_HOTPLUG_CPU0
2207 bool "Set default setting of cpu0_hotpluggable"
2208 depends on HOTPLUG_CPU
2210 Set whether default state of cpu0_hotpluggable is on or off.
2212 Say Y here to enable CPU0 hotplug by default. If this switch
2213 is turned on, there is no need to give cpu0_hotplug kernel
2214 parameter and the CPU0 hotplug feature is enabled by default.
2216 Please note: there are two known CPU0 dependencies if you want
2217 to enable the CPU0 hotplug feature either by this switch or by
2218 cpu0_hotplug kernel parameter.
2220 First, resume from hibernate or suspend always starts from CPU0.
2221 So hibernate and suspend are prevented if CPU0 is offline.
2223 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2224 offline if any interrupt can not migrate out of CPU0. There may
2225 be other CPU0 dependencies.
2227 Please make sure the dependencies are under your control before
2228 you enable this feature.
2230 Say N if you don't want to enable CPU0 hotplug feature by default.
2231 You still can enable the CPU0 hotplug feature at boot by kernel
2232 parameter cpu0_hotplug.
2234 config DEBUG_HOTPLUG_CPU0
2236 prompt "Debug CPU0 hotplug"
2237 depends on HOTPLUG_CPU
2239 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2240 soon as possible and boots up userspace with CPU0 offlined. User
2241 can online CPU0 back after boot time.
2243 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2244 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2245 compilation or giving cpu0_hotplug kernel parameter at boot.
2251 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2252 depends on COMPAT_32
2254 Certain buggy versions of glibc will crash if they are
2255 presented with a 32-bit vDSO that is not mapped at the address
2256 indicated in its segment table.
2258 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2259 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2260 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2261 the only released version with the bug, but OpenSUSE 9
2262 contains a buggy "glibc 2.3.2".
2264 The symptom of the bug is that everything crashes on startup, saying:
2265 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2267 Saying Y here changes the default value of the vdso32 boot
2268 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2269 This works around the glibc bug but hurts performance.
2271 If unsure, say N: if you are compiling your own kernel, you
2272 are unlikely to be using a buggy version of glibc.
2275 prompt "vsyscall table for legacy applications"
2277 default LEGACY_VSYSCALL_XONLY
2279 Legacy user code that does not know how to find the vDSO expects
2280 to be able to issue three syscalls by calling fixed addresses in
2281 kernel space. Since this location is not randomized with ASLR,
2282 it can be used to assist security vulnerability exploitation.
2284 This setting can be changed at boot time via the kernel command
2285 line parameter vsyscall=[emulate|xonly|none].
2287 On a system with recent enough glibc (2.14 or newer) and no
2288 static binaries, you can say None without a performance penalty
2289 to improve security.
2291 If unsure, select "Emulate execution only".
2293 config LEGACY_VSYSCALL_EMULATE
2294 bool "Full emulation"
2296 The kernel traps and emulates calls into the fixed vsyscall
2297 address mapping. This makes the mapping non-executable, but
2298 it still contains readable known contents, which could be
2299 used in certain rare security vulnerability exploits. This
2300 configuration is recommended when using legacy userspace
2301 that still uses vsyscalls along with legacy binary
2302 instrumentation tools that require code to be readable.
2304 An example of this type of legacy userspace is running
2305 Pin on an old binary that still uses vsyscalls.
2307 config LEGACY_VSYSCALL_XONLY
2308 bool "Emulate execution only"
2310 The kernel traps and emulates calls into the fixed vsyscall
2311 address mapping and does not allow reads. This
2312 configuration is recommended when userspace might use the
2313 legacy vsyscall area but support for legacy binary
2314 instrumentation of legacy code is not needed. It mitigates
2315 certain uses of the vsyscall area as an ASLR-bypassing
2318 config LEGACY_VSYSCALL_NONE
2321 There will be no vsyscall mapping at all. This will
2322 eliminate any risk of ASLR bypass due to the vsyscall
2323 fixed address mapping. Attempts to use the vsyscalls
2324 will be reported to dmesg, so that either old or
2325 malicious userspace programs can be identified.
2330 bool "Built-in kernel command line"
2332 Allow for specifying boot arguments to the kernel at
2333 build time. On some systems (e.g. embedded ones), it is
2334 necessary or convenient to provide some or all of the
2335 kernel boot arguments with the kernel itself (that is,
2336 to not rely on the boot loader to provide them.)
2338 To compile command line arguments into the kernel,
2339 set this option to 'Y', then fill in the
2340 boot arguments in CONFIG_CMDLINE.
2342 Systems with fully functional boot loaders (i.e. non-embedded)
2343 should leave this option set to 'N'.
2346 string "Built-in kernel command string"
2347 depends on CMDLINE_BOOL
2350 Enter arguments here that should be compiled into the kernel
2351 image and used at boot time. If the boot loader provides a
2352 command line at boot time, it is appended to this string to
2353 form the full kernel command line, when the system boots.
2355 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2356 change this behavior.
2358 In most cases, the command line (whether built-in or provided
2359 by the boot loader) should specify the device for the root
2362 config CMDLINE_OVERRIDE
2363 bool "Built-in command line overrides boot loader arguments"
2364 depends on CMDLINE_BOOL && CMDLINE != ""
2366 Set this option to 'Y' to have the kernel ignore the boot loader
2367 command line, and use ONLY the built-in command line.
2369 This is used to work around broken boot loaders. This should
2370 be set to 'N' under normal conditions.
2372 config MODIFY_LDT_SYSCALL
2373 bool "Enable the LDT (local descriptor table)" if EXPERT
2376 Linux can allow user programs to install a per-process x86
2377 Local Descriptor Table (LDT) using the modify_ldt(2) system
2378 call. This is required to run 16-bit or segmented code such as
2379 DOSEMU or some Wine programs. It is also used by some very old
2380 threading libraries.
2382 Enabling this feature adds a small amount of overhead to
2383 context switches and increases the low-level kernel attack
2384 surface. Disabling it removes the modify_ldt(2) system call.
2386 Saying 'N' here may make sense for embedded or server kernels.
2388 source "kernel/livepatch/Kconfig"
2392 config ARCH_HAS_ADD_PAGES
2394 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2396 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2399 config USE_PERCPU_NUMA_NODE_ID
2403 menu "Power management and ACPI options"
2405 config ARCH_HIBERNATION_HEADER
2407 depends on HIBERNATION
2409 source "kernel/power/Kconfig"
2411 source "drivers/acpi/Kconfig"
2418 tristate "APM (Advanced Power Management) BIOS support"
2419 depends on X86_32 && PM_SLEEP
2421 APM is a BIOS specification for saving power using several different
2422 techniques. This is mostly useful for battery powered laptops with
2423 APM compliant BIOSes. If you say Y here, the system time will be
2424 reset after a RESUME operation, the /proc/apm device will provide
2425 battery status information, and user-space programs will receive
2426 notification of APM "events" (e.g. battery status change).
2428 If you select "Y" here, you can disable actual use of the APM
2429 BIOS by passing the "apm=off" option to the kernel at boot time.
2431 Note that the APM support is almost completely disabled for
2432 machines with more than one CPU.
2434 In order to use APM, you will need supporting software. For location
2435 and more information, read <file:Documentation/power/apm-acpi.rst>
2436 and the Battery Powered Linux mini-HOWTO, available from
2437 <http://www.tldp.org/docs.html#howto>.
2439 This driver does not spin down disk drives (see the hdparm(8)
2440 manpage ("man 8 hdparm") for that), and it doesn't turn off
2441 VESA-compliant "green" monitors.
2443 This driver does not support the TI 4000M TravelMate and the ACER
2444 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2445 desktop machines also don't have compliant BIOSes, and this driver
2446 may cause those machines to panic during the boot phase.
2448 Generally, if you don't have a battery in your machine, there isn't
2449 much point in using this driver and you should say N. If you get
2450 random kernel OOPSes or reboots that don't seem to be related to
2451 anything, try disabling/enabling this option (or disabling/enabling
2454 Some other things you should try when experiencing seemingly random,
2457 1) make sure that you have enough swap space and that it is
2459 2) pass the "no-hlt" option to the kernel
2460 3) switch on floating point emulation in the kernel and pass
2461 the "no387" option to the kernel
2462 4) pass the "floppy=nodma" option to the kernel
2463 5) pass the "mem=4M" option to the kernel (thereby disabling
2464 all but the first 4 MB of RAM)
2465 6) make sure that the CPU is not over clocked.
2466 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2467 8) disable the cache from your BIOS settings
2468 9) install a fan for the video card or exchange video RAM
2469 10) install a better fan for the CPU
2470 11) exchange RAM chips
2471 12) exchange the motherboard.
2473 To compile this driver as a module, choose M here: the
2474 module will be called apm.
2478 config APM_IGNORE_USER_SUSPEND
2479 bool "Ignore USER SUSPEND"
2481 This option will ignore USER SUSPEND requests. On machines with a
2482 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2483 series notebooks, it is necessary to say Y because of a BIOS bug.
2485 config APM_DO_ENABLE
2486 bool "Enable PM at boot time"
2488 Enable APM features at boot time. From page 36 of the APM BIOS
2489 specification: "When disabled, the APM BIOS does not automatically
2490 power manage devices, enter the Standby State, enter the Suspend
2491 State, or take power saving steps in response to CPU Idle calls."
2492 This driver will make CPU Idle calls when Linux is idle (unless this
2493 feature is turned off -- see "Do CPU IDLE calls", below). This
2494 should always save battery power, but more complicated APM features
2495 will be dependent on your BIOS implementation. You may need to turn
2496 this option off if your computer hangs at boot time when using APM
2497 support, or if it beeps continuously instead of suspending. Turn
2498 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2499 T400CDT. This is off by default since most machines do fine without
2504 bool "Make CPU Idle calls when idle"
2506 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2507 On some machines, this can activate improved power savings, such as
2508 a slowed CPU clock rate, when the machine is idle. These idle calls
2509 are made after the idle loop has run for some length of time (e.g.,
2510 333 mS). On some machines, this will cause a hang at boot time or
2511 whenever the CPU becomes idle. (On machines with more than one CPU,
2512 this option does nothing.)
2514 config APM_DISPLAY_BLANK
2515 bool "Enable console blanking using APM"
2517 Enable console blanking using the APM. Some laptops can use this to
2518 turn off the LCD backlight when the screen blanker of the Linux
2519 virtual console blanks the screen. Note that this is only used by
2520 the virtual console screen blanker, and won't turn off the backlight
2521 when using the X Window system. This also doesn't have anything to
2522 do with your VESA-compliant power-saving monitor. Further, this
2523 option doesn't work for all laptops -- it might not turn off your
2524 backlight at all, or it might print a lot of errors to the console,
2525 especially if you are using gpm.
2527 config APM_ALLOW_INTS
2528 bool "Allow interrupts during APM BIOS calls"
2530 Normally we disable external interrupts while we are making calls to
2531 the APM BIOS as a measure to lessen the effects of a badly behaving
2532 BIOS implementation. The BIOS should reenable interrupts if it
2533 needs to. Unfortunately, some BIOSes do not -- especially those in
2534 many of the newer IBM Thinkpads. If you experience hangs when you
2535 suspend, try setting this to Y. Otherwise, say N.
2539 source "drivers/cpufreq/Kconfig"
2541 source "drivers/cpuidle/Kconfig"
2543 source "drivers/idle/Kconfig"
2548 menu "Bus options (PCI etc.)"
2551 prompt "PCI access mode"
2552 depends on X86_32 && PCI
2555 On PCI systems, the BIOS can be used to detect the PCI devices and
2556 determine their configuration. However, some old PCI motherboards
2557 have BIOS bugs and may crash if this is done. Also, some embedded
2558 PCI-based systems don't have any BIOS at all. Linux can also try to
2559 detect the PCI hardware directly without using the BIOS.
2561 With this option, you can specify how Linux should detect the
2562 PCI devices. If you choose "BIOS", the BIOS will be used,
2563 if you choose "Direct", the BIOS won't be used, and if you
2564 choose "MMConfig", then PCI Express MMCONFIG will be used.
2565 If you choose "Any", the kernel will try MMCONFIG, then the
2566 direct access method and falls back to the BIOS if that doesn't
2567 work. If unsure, go with the default, which is "Any".
2572 config PCI_GOMMCONFIG
2589 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2591 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2594 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2597 bool "Support mmconfig PCI config space access" if X86_64
2599 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2600 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2604 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2608 depends on PCI && XEN
2611 config MMCONF_FAM10H
2613 depends on X86_64 && PCI_MMCONFIG && ACPI
2615 config PCI_CNB20LE_QUIRK
2616 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2619 Read the PCI windows out of the CNB20LE host bridge. This allows
2620 PCI hotplug to work on systems with the CNB20LE chipset which do
2623 There's no public spec for this chipset, and this functionality
2624 is known to be incomplete.
2626 You should say N unless you know you need this.
2629 bool "ISA bus support on modern systems" if EXPERT
2631 Expose ISA bus device drivers and options available for selection and
2632 configuration. Enable this option if your target machine has an ISA
2633 bus. ISA is an older system, displaced by PCI and newer bus
2634 architectures -- if your target machine is modern, it probably does
2635 not have an ISA bus.
2639 # x86_64 have no ISA slots, but can have ISA-style DMA.
2641 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2644 Enables ISA-style DMA support for devices requiring such controllers.
2652 Find out whether you have ISA slots on your motherboard. ISA is the
2653 name of a bus system, i.e. the way the CPU talks to the other stuff
2654 inside your box. Other bus systems are PCI, EISA, MicroChannel
2655 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2656 newer boards don't support it. If you have ISA, say Y, otherwise N.
2659 tristate "NatSemi SCx200 support"
2661 This provides basic support for National Semiconductor's
2662 (now AMD's) Geode processors. The driver probes for the
2663 PCI-IDs of several on-chip devices, so its a good dependency
2664 for other scx200_* drivers.
2666 If compiled as a module, the driver is named scx200.
2668 config SCx200HR_TIMER
2669 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2673 This driver provides a clocksource built upon the on-chip
2674 27MHz high-resolution timer. Its also a workaround for
2675 NSC Geode SC-1100's buggy TSC, which loses time when the
2676 processor goes idle (as is done by the scheduler). The
2677 other workaround is idle=poll boot option.
2680 bool "One Laptop Per Child support"
2688 Add support for detecting the unique features of the OLPC
2692 bool "OLPC XO-1 Power Management"
2693 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2695 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2698 bool "OLPC XO-1 Real Time Clock"
2699 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2701 Add support for the XO-1 real time clock, which can be used as a
2702 programmable wakeup source.
2705 bool "OLPC XO-1 SCI extras"
2706 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2710 Add support for SCI-based features of the OLPC XO-1 laptop:
2711 - EC-driven system wakeups
2715 - AC adapter status updates
2716 - Battery status updates
2718 config OLPC_XO15_SCI
2719 bool "OLPC XO-1.5 SCI extras"
2720 depends on OLPC && ACPI
2723 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2724 - EC-driven system wakeups
2725 - AC adapter status updates
2726 - Battery status updates
2729 bool "PCEngines ALIX System Support (LED setup)"
2732 This option enables system support for the PCEngines ALIX.
2733 At present this just sets up LEDs for GPIO control on
2734 ALIX2/3/6 boards. However, other system specific setup should
2737 Note: You must still enable the drivers for GPIO and LED support
2738 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2740 Note: You have to set alix.force=1 for boards with Award BIOS.
2743 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2746 This option enables system support for the Soekris Engineering net5501.
2749 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2753 This option enables system support for the Traverse Technologies GEOS.
2756 bool "Technologic Systems TS-5500 platform support"
2758 select CHECK_SIGNATURE
2762 This option enables system support for the Technologic Systems TS-5500.
2768 depends on CPU_SUP_AMD && PCI
2771 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2773 Firmwares often provide initial graphics framebuffers so the BIOS,
2774 bootloader or kernel can show basic video-output during boot for
2775 user-guidance and debugging. Historically, x86 used the VESA BIOS
2776 Extensions and EFI-framebuffers for this, which are mostly limited
2778 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2779 framebuffers so the new generic system-framebuffer drivers can be
2780 used on x86. If the framebuffer is not compatible with the generic
2781 modes, it is advertised as fallback platform framebuffer so legacy
2782 drivers like efifb, vesafb and uvesafb can pick it up.
2783 If this option is not selected, all system framebuffers are always
2784 marked as fallback platform framebuffers as usual.
2786 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2787 not be able to pick up generic system framebuffers if this option
2788 is selected. You are highly encouraged to enable simplefb as
2789 replacement if you select this option. simplefb can correctly deal
2790 with generic system framebuffers. But you should still keep vesafb
2791 and others enabled as fallback if a system framebuffer is
2792 incompatible with simplefb.
2799 menu "Binary Emulations"
2801 config IA32_EMULATION
2802 bool "IA32 Emulation"
2804 select ARCH_WANT_OLD_COMPAT_IPC
2806 select COMPAT_OLD_SIGACTION
2808 Include code to run legacy 32-bit programs under a
2809 64-bit kernel. You should likely turn this on, unless you're
2810 100% sure that you don't have any 32-bit programs left.
2813 tristate "IA32 a.out support"
2814 depends on IA32_EMULATION
2817 Support old a.out binaries in the 32bit emulation.
2820 bool "x32 ABI for 64-bit mode"
2823 Include code to run binaries for the x32 native 32-bit ABI
2824 for 64-bit processors. An x32 process gets access to the
2825 full 64-bit register file and wide data path while leaving
2826 pointers at 32 bits for smaller memory footprint.
2828 You will need a recent binutils (2.22 or later) with
2829 elf32_x86_64 support enabled to compile a kernel with this
2834 depends on IA32_EMULATION || X86_32
2836 select OLD_SIGSUSPEND3
2840 depends on IA32_EMULATION || X86_X32
2843 config COMPAT_FOR_U64_ALIGNMENT
2846 config SYSVIPC_COMPAT
2854 config HAVE_ATOMIC_IOMAP
2858 source "drivers/firmware/Kconfig"
2860 source "arch/x86/kvm/Kconfig"
2862 source "arch/x86/Kconfig.assembler"