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_CORRECT_STACKTRACE_ON_KRETPROBE
65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
71 select ARCH_HAS_CACHE_LINE_SIZE
72 select ARCH_HAS_DEBUG_VIRTUAL
73 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
74 select ARCH_HAS_DEVMEM_IS_ALLOWED
75 select ARCH_HAS_EARLY_DEBUG if KGDB
76 select ARCH_HAS_ELF_RANDOMIZE
77 select ARCH_HAS_FAST_MULTIPLIER
78 select ARCH_HAS_FILTER_PGPROT
79 select ARCH_HAS_FORTIFY_SOURCE
80 select ARCH_HAS_GCOV_PROFILE_ALL
81 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
82 select ARCH_HAS_MEM_ENCRYPT
83 select ARCH_HAS_MEMBARRIER_SYNC_CORE
84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85 select ARCH_HAS_PMEM_API if X86_64
86 select ARCH_HAS_PTE_DEVMAP if X86_64
87 select ARCH_HAS_PTE_SPECIAL
88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
89 select ARCH_HAS_COPY_MC if X86_64
90 select ARCH_HAS_SET_MEMORY
91 select ARCH_HAS_SET_DIRECT_MAP
92 select ARCH_HAS_STRICT_KERNEL_RWX
93 select ARCH_HAS_STRICT_MODULE_RWX
94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95 select ARCH_HAS_SYSCALL_WRAPPER
96 select ARCH_HAS_UBSAN_SANITIZE_ALL
97 select ARCH_HAS_DEBUG_WX
98 select ARCH_HAS_ZONE_DMA_SET if EXPERT
99 select ARCH_HAVE_NMI_SAFE_CMPXCHG
100 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
101 select ARCH_MIGHT_HAVE_PC_PARPORT
102 select ARCH_MIGHT_HAVE_PC_SERIO
103 select ARCH_STACKWALK
104 select ARCH_SUPPORTS_ACPI
105 select ARCH_SUPPORTS_ATOMIC_RMW
106 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
107 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
108 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
109 select ARCH_SUPPORTS_LTO_CLANG
110 select ARCH_SUPPORTS_LTO_CLANG_THIN
111 select ARCH_USE_BUILTIN_BSWAP
112 select ARCH_USE_MEMTEST
113 select ARCH_USE_QUEUED_RWLOCKS
114 select ARCH_USE_QUEUED_SPINLOCKS
115 select ARCH_USE_SYM_ANNOTATIONS
116 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
117 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
118 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
119 select ARCH_WANTS_NO_INSTR
120 select ARCH_WANT_HUGE_PMD_SHARE
121 select ARCH_WANT_LD_ORPHAN_WARN
122 select ARCH_WANTS_THP_SWAP if X86_64
123 select ARCH_HAS_PARANOID_L1D_FLUSH
124 select BUILDTIME_TABLE_SORT
126 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
127 select CLOCKSOURCE_WATCHDOG
128 select DCACHE_WORD_ACCESS
129 select DYNAMIC_SIGFRAME
130 select EDAC_ATOMIC_SCRUB
132 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
133 select GENERIC_CLOCKEVENTS_MIN_ADJUST
134 select GENERIC_CMOS_UPDATE
135 select GENERIC_CPU_AUTOPROBE
136 select GENERIC_CPU_VULNERABILITIES
137 select GENERIC_EARLY_IOREMAP
139 select GENERIC_FIND_FIRST_BIT
141 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
142 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
143 select GENERIC_IRQ_MIGRATION if SMP
144 select GENERIC_IRQ_PROBE
145 select GENERIC_IRQ_RESERVATION_MODE
146 select GENERIC_IRQ_SHOW
147 select GENERIC_PENDING_IRQ if SMP
148 select GENERIC_PTDUMP
149 select GENERIC_SMP_IDLE_THREAD
150 select GENERIC_TIME_VSYSCALL
151 select GENERIC_GETTIMEOFDAY
152 select GENERIC_VDSO_TIME_NS
153 select GUP_GET_PTE_LOW_HIGH if X86_PAE
154 select HARDIRQS_SW_RESEND
155 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
156 select HAVE_ACPI_APEI if ACPI
157 select HAVE_ACPI_APEI_NMI if ACPI
158 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
159 select HAVE_ARCH_AUDITSYSCALL
160 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
161 select HAVE_ARCH_JUMP_LABEL
162 select HAVE_ARCH_JUMP_LABEL_RELATIVE
163 select HAVE_ARCH_KASAN if X86_64
164 select HAVE_ARCH_KASAN_VMALLOC if X86_64
165 select HAVE_ARCH_KFENCE
166 select HAVE_ARCH_KGDB
167 select HAVE_ARCH_MMAP_RND_BITS if MMU
168 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
169 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
170 select HAVE_ARCH_PREL32_RELOCATIONS
171 select HAVE_ARCH_SECCOMP_FILTER
172 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
173 select HAVE_ARCH_STACKLEAK
174 select HAVE_ARCH_TRACEHOOK
175 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
176 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
177 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
178 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
179 select HAVE_ARCH_VMAP_STACK if X86_64
180 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
181 select HAVE_ARCH_WITHIN_STACK_FRAMES
182 select HAVE_ASM_MODVERSIONS
183 select HAVE_CMPXCHG_DOUBLE
184 select HAVE_CMPXCHG_LOCAL
185 select HAVE_CONTEXT_TRACKING if X86_64
186 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
187 select HAVE_C_RECORDMCOUNT
188 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
189 select HAVE_DEBUG_KMEMLEAK
190 select HAVE_DMA_CONTIGUOUS
191 select HAVE_DYNAMIC_FTRACE
192 select HAVE_DYNAMIC_FTRACE_WITH_REGS
193 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
194 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
195 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
196 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
198 select HAVE_EFFICIENT_UNALIGNED_ACCESS
200 select HAVE_EXIT_THREAD
202 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
203 select HAVE_FTRACE_MCOUNT_RECORD
204 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
205 select HAVE_FUNCTION_TRACER
206 select HAVE_GCC_PLUGINS
207 select HAVE_HW_BREAKPOINT
208 select HAVE_IOREMAP_PROT
209 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
210 select HAVE_IRQ_TIME_ACCOUNTING
211 select HAVE_KERNEL_BZIP2
212 select HAVE_KERNEL_GZIP
213 select HAVE_KERNEL_LZ4
214 select HAVE_KERNEL_LZMA
215 select HAVE_KERNEL_LZO
216 select HAVE_KERNEL_XZ
217 select HAVE_KERNEL_ZSTD
219 select HAVE_KPROBES_ON_FTRACE
220 select HAVE_FUNCTION_ERROR_INJECTION
221 select HAVE_KRETPROBES
223 select HAVE_LIVEPATCH if X86_64
224 select HAVE_MIXED_BREAKPOINTS_REGS
225 select HAVE_MOD_ARCH_SPECIFIC
229 select HAVE_OPTPROBES
230 select HAVE_PCSPKR_PLATFORM
231 select HAVE_PERF_EVENTS
232 select HAVE_PERF_EVENTS_NMI
233 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
235 select HAVE_PERF_REGS
236 select HAVE_PERF_USER_STACK_DUMP
237 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
238 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
239 select HAVE_REGS_AND_STACK_ACCESS_API
240 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
241 select HAVE_FUNCTION_ARG_ACCESS_API
242 select HAVE_SOFTIRQ_ON_OWN_STACK
243 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
244 select HAVE_STACK_VALIDATION if X86_64
245 select HAVE_STATIC_CALL
246 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
247 select HAVE_PREEMPT_DYNAMIC
249 select HAVE_SYSCALL_TRACEPOINTS
250 select HAVE_UNSTABLE_SCHED_CLOCK
251 select HAVE_USER_RETURN_NOTIFIER
252 select HAVE_GENERIC_VDSO
253 select HOTPLUG_SMT if SMP
254 select IRQ_FORCED_THREADING
255 select NEED_SG_DMA_LENGTH
256 select PCI_DOMAINS if PCI
257 select PCI_LOCKLESS_CONFIG if PCI
260 select RTC_MC146818_LIB
263 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
264 select SYSCTL_EXCEPTION_TRACE
265 select THREAD_INFO_IN_TASK
266 select TRACE_IRQFLAGS_SUPPORT
267 select USER_STACKTRACE_SUPPORT
269 select HAVE_ARCH_KCSAN if X86_64
270 select X86_FEATURE_NAMES if PROC_FS
271 select PROC_PID_ARCH_STATUS if PROC_FS
272 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
274 config INSTRUCTION_DECODER
276 depends on KPROBES || PERF_EVENTS || UPROBES
280 default "elf32-i386" if X86_32
281 default "elf64-x86-64" if X86_64
283 config LOCKDEP_SUPPORT
286 config STACKTRACE_SUPPORT
292 config ARCH_MMAP_RND_BITS_MIN
296 config ARCH_MMAP_RND_BITS_MAX
300 config ARCH_MMAP_RND_COMPAT_BITS_MIN
303 config ARCH_MMAP_RND_COMPAT_BITS_MAX
309 config GENERIC_ISA_DMA
311 depends on ISA_DMA_API
316 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
318 config GENERIC_BUG_RELATIVE_POINTERS
321 config ARCH_MAY_HAVE_PC_FDC
323 depends on ISA_DMA_API
325 config GENERIC_CALIBRATE_DELAY
328 config ARCH_HAS_CPU_RELAX
331 config ARCH_HAS_FILTER_PGPROT
334 config HAVE_SETUP_PER_CPU_AREA
337 config NEED_PER_CPU_EMBED_FIRST_CHUNK
340 config NEED_PER_CPU_PAGE_FIRST_CHUNK
343 config ARCH_HIBERNATION_POSSIBLE
348 default 1024 if X86_64
351 config ARCH_SUSPEND_POSSIBLE
354 config ARCH_WANT_GENERAL_HUGETLB
360 config KASAN_SHADOW_OFFSET
363 default 0xdffffc0000000000
365 config HAVE_INTEL_TXT
367 depends on INTEL_IOMMU && ACPI
371 depends on X86_32 && SMP
375 depends on X86_64 && SMP
377 config ARCH_SUPPORTS_UPROBES
380 config FIX_EARLYCON_MEM
383 config DYNAMIC_PHYSICAL_MASK
386 config PGTABLE_LEVELS
388 default 5 if X86_5LEVEL
393 config CC_HAS_SANE_STACKPROTECTOR
395 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
396 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
398 We have to make sure stack protector is unconditionally disabled if
399 the compiler produces broken code or if it does not let us control
400 the segment on 32-bit kernels.
402 menu "Processor type and features"
405 bool "Symmetric multi-processing support"
407 This enables support for systems with more than one CPU. If you have
408 a system with only one CPU, say N. If you have a system with more
411 If you say N here, the kernel will run on uni- and multiprocessor
412 machines, but will use only one CPU of a multiprocessor machine. If
413 you say Y here, the kernel will run on many, but not all,
414 uniprocessor machines. On a uniprocessor machine, the kernel
415 will run faster if you say N here.
417 Note that if you say Y here and choose architecture "586" or
418 "Pentium" under "Processor family", the kernel will not work on 486
419 architectures. Similarly, multiprocessor kernels for the "PPro"
420 architecture may not work on all Pentium based boards.
422 People using multiprocessor machines who say Y here should also say
423 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
424 Management" code will be disabled if you say Y here.
426 See also <file:Documentation/x86/i386/IO-APIC.rst>,
427 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
428 <http://www.tldp.org/docs.html#howto>.
430 If you don't know what to do here, say N.
432 config X86_FEATURE_NAMES
433 bool "Processor feature human-readable names" if EMBEDDED
436 This option compiles in a table of x86 feature bits and corresponding
437 names. This is required to support /proc/cpuinfo and a few kernel
438 messages. You can disable this to save space, at the expense of
439 making those few kernel messages show numeric feature bits instead.
444 bool "Support x2apic"
445 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
447 This enables x2apic support on CPUs that have this feature.
449 This allows 32-bit apic IDs (so it can support very large systems),
450 and accesses the local apic via MSRs not via mmio.
452 If you don't know what to do here, say N.
455 bool "Enable MPS table" if ACPI
457 depends on X86_LOCAL_APIC
459 For old smp systems that do not have proper acpi support. Newer systems
460 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
464 depends on X86_GOLDFISH
467 bool "Avoid speculative indirect branches in kernel"
470 Compile kernel with the retpoline compiler options to guard against
471 kernel-to-user data leaks by avoiding speculative indirect
472 branches. Requires a compiler with -mindirect-branch=thunk-extern
473 support for full protection. The kernel may run slower.
475 config X86_CPU_RESCTRL
476 bool "x86 CPU resource control support"
477 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
479 select PROC_CPU_RESCTRL if PROC_FS
481 Enable x86 CPU resource control support.
483 Provide support for the allocation and monitoring of system resources
486 Intel calls this Intel Resource Director Technology
487 (Intel(R) RDT). More information about RDT can be found in the
488 Intel x86 Architecture Software Developer Manual.
490 AMD calls this AMD Platform Quality of Service (AMD QoS).
491 More information about AMD QoS can be found in the AMD64 Technology
492 Platform Quality of Service Extensions manual.
498 bool "Support for big SMP systems with more than 8 CPUs"
501 This option is needed for the systems that have more than 8 CPUs.
503 config X86_EXTENDED_PLATFORM
504 bool "Support for extended (non-PC) x86 platforms"
507 If you disable this option then the kernel will only support
508 standard PC platforms. (which covers the vast majority of
511 If you enable this option then you'll be able to select support
512 for the following (non-PC) 32 bit x86 platforms:
513 Goldfish (Android emulator)
516 SGI 320/540 (Visual Workstation)
517 STA2X11-based (e.g. Northville)
518 Moorestown MID devices
520 If you have one of these systems, or if you want to build a
521 generic distribution kernel, say Y here - otherwise say N.
525 config X86_EXTENDED_PLATFORM
526 bool "Support for extended (non-PC) x86 platforms"
529 If you disable this option then the kernel will only support
530 standard PC platforms. (which covers the vast majority of
533 If you enable this option then you'll be able to select support
534 for the following (non-PC) 64 bit x86 platforms:
539 If you have one of these systems, or if you want to build a
540 generic distribution kernel, say Y here - otherwise say N.
542 # This is an alphabetically sorted list of 64 bit extended platforms
543 # Please maintain the alphabetic order if and when there are additions
545 bool "Numascale NumaChip"
547 depends on X86_EXTENDED_PLATFORM
550 depends on X86_X2APIC
551 depends on PCI_MMCONFIG
553 Adds support for Numascale NumaChip large-SMP systems. Needed to
554 enable more than ~168 cores.
555 If you don't have one of these, you should say N here.
559 select HYPERVISOR_GUEST
561 depends on X86_64 && PCI
562 depends on X86_EXTENDED_PLATFORM
565 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
566 supposed to run on these EM64T-based machines. Only choose this option
567 if you have one of these machines.
570 bool "SGI Ultraviolet"
572 depends on X86_EXTENDED_PLATFORM
575 depends on KEXEC_CORE
576 depends on X86_X2APIC
579 This option is needed in order to support SGI Ultraviolet systems.
580 If you don't have one of these, you should say N here.
582 # Following is an alphabetically sorted list of 32 bit extended platforms
583 # Please maintain the alphabetic order if and when there are additions
586 bool "Goldfish (Virtual Platform)"
587 depends on X86_EXTENDED_PLATFORM
589 Enable support for the Goldfish virtual platform used primarily
590 for Android development. Unless you are building for the Android
591 Goldfish emulator say N here.
594 bool "CE4100 TV platform"
596 depends on PCI_GODIRECT
597 depends on X86_IO_APIC
599 depends on X86_EXTENDED_PLATFORM
600 select X86_REBOOTFIXUPS
602 select OF_EARLY_FLATTREE
604 Select for the Intel CE media processor (CE4100) SOC.
605 This option compiles in support for the CE4100 SOC for settop
606 boxes and media devices.
609 bool "Intel MID platform support"
610 depends on X86_EXTENDED_PLATFORM
611 depends on X86_PLATFORM_DEVICES
613 depends on X86_64 || (PCI_GOANY && X86_32)
614 depends on X86_IO_APIC
619 Select to build a kernel capable of supporting Intel MID (Mobile
620 Internet Device) platform systems which do not have the PCI legacy
621 interfaces. If you are building for a PC class system say N here.
623 Intel MID platforms are based on an Intel processor and chipset which
624 consume less power than most of the x86 derivatives.
626 config X86_INTEL_QUARK
627 bool "Intel Quark platform support"
629 depends on X86_EXTENDED_PLATFORM
630 depends on X86_PLATFORM_DEVICES
634 depends on X86_IO_APIC
639 Select to include support for Quark X1000 SoC.
640 Say Y here if you have a Quark based system such as the Arduino
641 compatible Intel Galileo.
643 config X86_INTEL_LPSS
644 bool "Intel Low Power Subsystem Support"
645 depends on X86 && ACPI && PCI
650 Select to build support for Intel Low Power Subsystem such as
651 found on Intel Lynxpoint PCH. Selecting this option enables
652 things like clock tree (common clock framework) and pincontrol
653 which are needed by the LPSS peripheral drivers.
655 config X86_AMD_PLATFORM_DEVICE
656 bool "AMD ACPI2Platform devices support"
661 Select to interpret AMD specific ACPI device to platform device
662 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
663 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
664 implemented under PINCTRL subsystem.
667 tristate "Intel SoC IOSF Sideband support for SoC platforms"
670 This option enables sideband register access support for Intel SoC
671 platforms. On these platforms the IOSF sideband is used in lieu of
672 MSR's for some register accesses, mostly but not limited to thermal
673 and power. Drivers may query the availability of this device to
674 determine if they need the sideband in order to work on these
675 platforms. The sideband is available on the following SoC products.
676 This list is not meant to be exclusive.
681 You should say Y if you are running a kernel on one of these SoC's.
683 config IOSF_MBI_DEBUG
684 bool "Enable IOSF sideband access through debugfs"
685 depends on IOSF_MBI && DEBUG_FS
687 Select this option to expose the IOSF sideband access registers (MCR,
688 MDR, MCRX) through debugfs to write and read register information from
689 different units on the SoC. This is most useful for obtaining device
690 state information for debug and analysis. As this is a general access
691 mechanism, users of this option would have specific knowledge of the
692 device they want to access.
694 If you don't require the option or are in doubt, say N.
697 bool "RDC R-321x SoC"
699 depends on X86_EXTENDED_PLATFORM
701 select X86_REBOOTFIXUPS
703 This option is needed for RDC R-321x system-on-chip, also known
705 If you don't have one of these chips, you should say N here.
707 config X86_32_NON_STANDARD
708 bool "Support non-standard 32-bit SMP architectures"
709 depends on X86_32 && SMP
710 depends on X86_EXTENDED_PLATFORM
712 This option compiles in the bigsmp and STA2X11 default
713 subarchitectures. It is intended for a generic binary
714 kernel. If you select them all, kernel will probe it one by
715 one and will fallback to default.
717 # Alphabetically sorted list of Non standard 32 bit platforms
719 config X86_SUPPORTS_MEMORY_FAILURE
721 # MCE code calls memory_failure():
723 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
724 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
725 depends on X86_64 || !SPARSEMEM
726 select ARCH_SUPPORTS_MEMORY_FAILURE
729 bool "STA2X11 Companion Chip Support"
730 depends on X86_32_NON_STANDARD && PCI
735 This adds support for boards based on the STA2X11 IO-Hub,
736 a.k.a. "ConneXt". The chip is used in place of the standard
737 PC chipset, so all "standard" peripherals are missing. If this
738 option is selected the kernel will still be able to boot on
739 standard PC machines.
742 tristate "Eurobraille/Iris poweroff module"
745 The Iris machines from EuroBraille do not have APM or ACPI support
746 to shut themselves down properly. A special I/O sequence is
747 needed to do so, which is what this module does at
750 This is only for Iris machines from EuroBraille.
754 config SCHED_OMIT_FRAME_POINTER
756 prompt "Single-depth WCHAN output"
759 Calculate simpler /proc/<PID>/wchan values. If this option
760 is disabled then wchan values will recurse back to the
761 caller function. This provides more accurate wchan values,
762 at the expense of slightly more scheduling overhead.
764 If in doubt, say "Y".
766 menuconfig HYPERVISOR_GUEST
767 bool "Linux guest support"
769 Say Y here to enable options for running Linux under various hyper-
770 visors. This option enables basic hypervisor detection and platform
773 If you say N, all options in this submenu will be skipped and
774 disabled, and Linux guest support won't be built in.
779 bool "Enable paravirtualization code"
780 depends on HAVE_STATIC_CALL
782 This changes the kernel so it can modify itself when it is run
783 under a hypervisor, potentially improving performance significantly
784 over full virtualization. However, when run without a hypervisor
785 the kernel is theoretically slower and slightly larger.
790 config PARAVIRT_DEBUG
791 bool "paravirt-ops debugging"
792 depends on PARAVIRT && DEBUG_KERNEL
794 Enable to debug paravirt_ops internals. Specifically, BUG if
795 a paravirt_op is missing when it is called.
797 config PARAVIRT_SPINLOCKS
798 bool "Paravirtualization layer for spinlocks"
799 depends on PARAVIRT && SMP
801 Paravirtualized spinlocks allow a pvops backend to replace the
802 spinlock implementation with something virtualization-friendly
803 (for example, block the virtual CPU rather than spinning).
805 It has a minimal impact on native kernels and gives a nice performance
806 benefit on paravirtualized KVM / Xen kernels.
808 If you are unsure how to answer this question, answer Y.
810 config X86_HV_CALLBACK_VECTOR
813 source "arch/x86/xen/Kconfig"
816 bool "KVM Guest support (including kvmclock)"
818 select PARAVIRT_CLOCK
819 select ARCH_CPUIDLE_HALTPOLL
820 select X86_HV_CALLBACK_VECTOR
823 This option enables various optimizations for running under the KVM
824 hypervisor. It includes a paravirtualized clock, so that instead
825 of relying on a PIT (or probably other) emulation by the
826 underlying device model, the host provides the guest with
827 timing infrastructure such as time of day, and system time
829 config ARCH_CPUIDLE_HALTPOLL
831 prompt "Disable host haltpoll when loading haltpoll driver"
833 If virtualized under KVM, disable host haltpoll.
836 bool "Support for running PVH guests"
838 This option enables the PVH entry point for guest virtual machines
839 as specified in the x86/HVM direct boot ABI.
841 config PARAVIRT_TIME_ACCOUNTING
842 bool "Paravirtual steal time accounting"
845 Select this option to enable fine granularity task steal time
846 accounting. Time spent executing other tasks in parallel with
847 the current vCPU is discounted from the vCPU power. To account for
848 that, there can be a small performance impact.
850 If in doubt, say N here.
852 config PARAVIRT_CLOCK
855 config JAILHOUSE_GUEST
856 bool "Jailhouse non-root cell support"
857 depends on X86_64 && PCI
860 This option allows to run Linux as guest in a Jailhouse non-root
861 cell. You can leave this option disabled if you only want to start
862 Jailhouse and run Linux afterwards in the root cell.
865 bool "ACRN Guest support"
867 select X86_HV_CALLBACK_VECTOR
869 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
870 a flexible, lightweight reference open-source hypervisor, built with
871 real-time and safety-criticality in mind. It is built for embedded
872 IOT with small footprint and real-time features. More details can be
873 found in https://projectacrn.org/.
875 endif #HYPERVISOR_GUEST
877 source "arch/x86/Kconfig.cpu"
881 prompt "HPET Timer Support" if X86_32
883 Use the IA-PC HPET (High Precision Event Timer) to manage
884 time in preference to the PIT and RTC, if a HPET is
886 HPET is the next generation timer replacing legacy 8254s.
887 The HPET provides a stable time base on SMP
888 systems, unlike the TSC, but it is more expensive to access,
889 as it is off-chip. The interface used is documented
890 in the HPET spec, revision 1.
892 You can safely choose Y here. However, HPET will only be
893 activated if the platform and the BIOS support this feature.
894 Otherwise the 8254 will be used for timing services.
896 Choose N to continue using the legacy 8254 timer.
898 config HPET_EMULATE_RTC
900 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
902 # Mark as expert because too many people got it wrong.
903 # The code disables itself when not needed.
906 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
907 bool "Enable DMI scanning" if EXPERT
909 Enabled scanning of DMI to identify machine quirks. Say Y
910 here unless you have verified that your setup is not
911 affected by entries in the DMI blacklist. Required by PNP
915 bool "Old AMD GART IOMMU support"
919 depends on X86_64 && PCI && AMD_NB
921 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
922 GART based hardware IOMMUs.
924 The GART supports full DMA access for devices with 32-bit access
925 limitations, on systems with more than 3 GB. This is usually needed
926 for USB, sound, many IDE/SATA chipsets and some other devices.
928 Newer systems typically have a modern AMD IOMMU, supported via
929 the CONFIG_AMD_IOMMU=y config option.
931 In normal configurations this driver is only active when needed:
932 there's more than 3 GB of memory and the system contains a
933 32-bit limited device.
938 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
939 depends on X86_64 && SMP && DEBUG_KERNEL
940 select CPUMASK_OFFSTACK
942 Enable maximum number of CPUS and NUMA Nodes for this architecture.
946 # The maximum number of CPUs supported:
948 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
949 # and which can be configured interactively in the
950 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
952 # The ranges are different on 32-bit and 64-bit kernels, depending on
953 # hardware capabilities and scalability features of the kernel.
955 # ( If MAXSMP is enabled we just use the highest possible value and disable
956 # interactive configuration. )
959 config NR_CPUS_RANGE_BEGIN
961 default NR_CPUS_RANGE_END if MAXSMP
965 config NR_CPUS_RANGE_END
968 default 64 if SMP && X86_BIGSMP
969 default 8 if SMP && !X86_BIGSMP
972 config NR_CPUS_RANGE_END
975 default 8192 if SMP && CPUMASK_OFFSTACK
976 default 512 if SMP && !CPUMASK_OFFSTACK
979 config NR_CPUS_DEFAULT
982 default 32 if X86_BIGSMP
986 config NR_CPUS_DEFAULT
989 default 8192 if MAXSMP
994 int "Maximum number of CPUs" if SMP && !MAXSMP
995 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
996 default NR_CPUS_DEFAULT
998 This allows you to specify the maximum number of CPUs which this
999 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1000 supported value is 8192, otherwise the maximum value is 512. The
1001 minimum value which makes sense is 2.
1003 This is purely to save memory: each supported CPU adds about 8KB
1004 to the kernel image.
1006 config SCHED_CLUSTER
1007 bool "Cluster scheduler support"
1011 Cluster scheduler support improves the CPU scheduler's decision
1012 making when dealing with machines that have clusters of CPUs.
1013 Cluster usually means a couple of CPUs which are placed closely
1014 by sharing mid-level caches, last-level cache tags or internal
1022 prompt "Multi-core scheduler support"
1025 Multi-core scheduler support improves the CPU scheduler's decision
1026 making when dealing with multi-core CPU chips at a cost of slightly
1027 increased overhead in some places. If unsure say N here.
1029 config SCHED_MC_PRIO
1030 bool "CPU core priorities scheduler support"
1031 depends on SCHED_MC && CPU_SUP_INTEL
1032 select X86_INTEL_PSTATE
1036 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1037 core ordering determined at manufacturing time, which allows
1038 certain cores to reach higher turbo frequencies (when running
1039 single threaded workloads) than others.
1041 Enabling this kernel feature teaches the scheduler about
1042 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1043 scheduler's CPU selection logic accordingly, so that higher
1044 overall system performance can be achieved.
1046 This feature will have no effect on CPUs without this feature.
1048 If unsure say Y here.
1052 depends on !SMP && X86_LOCAL_APIC
1055 bool "Local APIC support on uniprocessors" if !PCI_MSI
1057 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1059 A local APIC (Advanced Programmable Interrupt Controller) is an
1060 integrated interrupt controller in the CPU. If you have a single-CPU
1061 system which has a processor with a local APIC, you can say Y here to
1062 enable and use it. If you say Y here even though your machine doesn't
1063 have a local APIC, then the kernel will still run with no slowdown at
1064 all. The local APIC supports CPU-generated self-interrupts (timer,
1065 performance counters), and the NMI watchdog which detects hard
1068 config X86_UP_IOAPIC
1069 bool "IO-APIC support on uniprocessors"
1070 depends on X86_UP_APIC
1072 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1073 SMP-capable replacement for PC-style interrupt controllers. Most
1074 SMP systems and many recent uniprocessor systems have one.
1076 If you have a single-CPU system with an IO-APIC, you can say Y here
1077 to use it. If you say Y here even though your machine doesn't have
1078 an IO-APIC, then the kernel will still run with no slowdown at all.
1080 config X86_LOCAL_APIC
1082 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1083 select IRQ_DOMAIN_HIERARCHY
1084 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1088 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1090 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1091 bool "Reroute for broken boot IRQs"
1092 depends on X86_IO_APIC
1094 This option enables a workaround that fixes a source of
1095 spurious interrupts. This is recommended when threaded
1096 interrupt handling is used on systems where the generation of
1097 superfluous "boot interrupts" cannot be disabled.
1099 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1100 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1101 kernel does during interrupt handling). On chipsets where this
1102 boot IRQ generation cannot be disabled, this workaround keeps
1103 the original IRQ line masked so that only the equivalent "boot
1104 IRQ" is delivered to the CPUs. The workaround also tells the
1105 kernel to set up the IRQ handler on the boot IRQ line. In this
1106 way only one interrupt is delivered to the kernel. Otherwise
1107 the spurious second interrupt may cause the kernel to bring
1108 down (vital) interrupt lines.
1110 Only affects "broken" chipsets. Interrupt sharing may be
1111 increased on these systems.
1114 bool "Machine Check / overheating reporting"
1115 select GENERIC_ALLOCATOR
1118 Machine Check support allows the processor to notify the
1119 kernel if it detects a problem (e.g. overheating, data corruption).
1120 The action the kernel takes depends on the severity of the problem,
1121 ranging from warning messages to halting the machine.
1123 config X86_MCELOG_LEGACY
1124 bool "Support for deprecated /dev/mcelog character device"
1127 Enable support for /dev/mcelog which is needed by the old mcelog
1128 userspace logging daemon. Consider switching to the new generation
1131 config X86_MCE_INTEL
1133 prompt "Intel MCE features"
1134 depends on X86_MCE && X86_LOCAL_APIC
1136 Additional support for intel specific MCE features such as
1137 the thermal monitor.
1141 prompt "AMD MCE features"
1142 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1144 Additional support for AMD specific MCE features such as
1145 the DRAM Error Threshold.
1147 config X86_ANCIENT_MCE
1148 bool "Support for old Pentium 5 / WinChip machine checks"
1149 depends on X86_32 && X86_MCE
1151 Include support for machine check handling on old Pentium 5 or WinChip
1152 systems. These typically need to be enabled explicitly on the command
1155 config X86_MCE_THRESHOLD
1156 depends on X86_MCE_AMD || X86_MCE_INTEL
1159 config X86_MCE_INJECT
1160 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1161 tristate "Machine check injector support"
1163 Provide support for injecting machine checks for testing purposes.
1164 If you don't know what a machine check is and you don't do kernel
1165 QA it is safe to say n.
1167 source "arch/x86/events/Kconfig"
1169 config X86_LEGACY_VM86
1170 bool "Legacy VM86 support"
1173 This option allows user programs to put the CPU into V8086
1174 mode, which is an 80286-era approximation of 16-bit real mode.
1176 Some very old versions of X and/or vbetool require this option
1177 for user mode setting. Similarly, DOSEMU will use it if
1178 available to accelerate real mode DOS programs. However, any
1179 recent version of DOSEMU, X, or vbetool should be fully
1180 functional even without kernel VM86 support, as they will all
1181 fall back to software emulation. Nevertheless, if you are using
1182 a 16-bit DOS program where 16-bit performance matters, vm86
1183 mode might be faster than emulation and you might want to
1186 Note that any app that works on a 64-bit kernel is unlikely to
1187 need this option, as 64-bit kernels don't, and can't, support
1188 V8086 mode. This option is also unrelated to 16-bit protected
1189 mode and is not needed to run most 16-bit programs under Wine.
1191 Enabling this option increases the complexity of the kernel
1192 and slows down exception handling a tiny bit.
1194 If unsure, say N here.
1198 default X86_LEGACY_VM86
1201 bool "Enable support for 16-bit segments" if EXPERT
1203 depends on MODIFY_LDT_SYSCALL
1205 This option is required by programs like Wine to run 16-bit
1206 protected mode legacy code on x86 processors. Disabling
1207 this option saves about 300 bytes on i386, or around 6K text
1208 plus 16K runtime memory on x86-64,
1212 depends on X86_16BIT && X86_32
1216 depends on X86_16BIT && X86_64
1218 config X86_VSYSCALL_EMULATION
1219 bool "Enable vsyscall emulation" if EXPERT
1223 This enables emulation of the legacy vsyscall page. Disabling
1224 it is roughly equivalent to booting with vsyscall=none, except
1225 that it will also disable the helpful warning if a program
1226 tries to use a vsyscall. With this option set to N, offending
1227 programs will just segfault, citing addresses of the form
1230 This option is required by many programs built before 2013, and
1231 care should be used even with newer programs if set to N.
1233 Disabling this option saves about 7K of kernel size and
1234 possibly 4K of additional runtime pagetable memory.
1236 config X86_IOPL_IOPERM
1237 bool "IOPERM and IOPL Emulation"
1240 This enables the ioperm() and iopl() syscalls which are necessary
1241 for legacy applications.
1243 Legacy IOPL support is an overbroad mechanism which allows user
1244 space aside of accessing all 65536 I/O ports also to disable
1245 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1246 capabilities and permission from potentially active security
1249 The emulation restricts the functionality of the syscall to
1250 only allowing the full range I/O port access, but prevents the
1251 ability to disable interrupts from user space which would be
1252 granted if the hardware IOPL mechanism would be used.
1255 tristate "Toshiba Laptop support"
1258 This adds a driver to safely access the System Management Mode of
1259 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1260 not work on models with a Phoenix BIOS. The System Management Mode
1261 is used to set the BIOS and power saving options on Toshiba portables.
1263 For information on utilities to make use of this driver see the
1264 Toshiba Linux utilities web site at:
1265 <http://www.buzzard.org.uk/toshiba/>.
1267 Say Y if you intend to run this kernel on a Toshiba portable.
1271 tristate "Dell i8k legacy laptop support"
1274 select SENSORS_DELL_SMM
1276 This option enables legacy /proc/i8k userspace interface in hwmon
1277 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1278 temperature and allows controlling fan speeds of Dell laptops via
1279 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1280 it reports also power and hotkey status. For fan speed control is
1281 needed userspace package i8kutils.
1283 Say Y if you intend to run this kernel on old Dell laptops or want to
1284 use userspace package i8kutils.
1287 config X86_REBOOTFIXUPS
1288 bool "Enable X86 board specific fixups for reboot"
1291 This enables chipset and/or board specific fixups to be done
1292 in order to get reboot to work correctly. This is only needed on
1293 some combinations of hardware and BIOS. The symptom, for which
1294 this config is intended, is when reboot ends with a stalled/hung
1297 Currently, the only fixup is for the Geode machines using
1298 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1300 Say Y if you want to enable the fixup. Currently, it's safe to
1301 enable this option even if you don't need it.
1305 bool "CPU microcode loading support"
1307 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1309 If you say Y here, you will be able to update the microcode on
1310 Intel and AMD processors. The Intel support is for the IA32 family,
1311 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1312 AMD support is for families 0x10 and later. You will obviously need
1313 the actual microcode binary data itself which is not shipped with
1316 The preferred method to load microcode from a detached initrd is described
1317 in Documentation/x86/microcode.rst. For that you need to enable
1318 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1319 initrd for microcode blobs.
1321 In addition, you can build the microcode into the kernel. For that you
1322 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1325 config MICROCODE_INTEL
1326 bool "Intel microcode loading support"
1327 depends on MICROCODE
1330 This options enables microcode patch loading support for Intel
1333 For the current Intel microcode data package go to
1334 <https://downloadcenter.intel.com> and search for
1335 'Linux Processor Microcode Data File'.
1337 config MICROCODE_AMD
1338 bool "AMD microcode loading support"
1339 depends on MICROCODE
1341 If you select this option, microcode patch loading support for AMD
1342 processors will be enabled.
1344 config MICROCODE_OLD_INTERFACE
1345 bool "Ancient loading interface (DEPRECATED)"
1347 depends on MICROCODE
1349 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1350 which was used by userspace tools like iucode_tool and microcode.ctl.
1351 It is inadequate because it runs too late to be able to properly
1352 load microcode on a machine and it needs special tools. Instead, you
1353 should've switched to the early loading method with the initrd or
1354 builtin microcode by now: Documentation/x86/microcode.rst
1357 tristate "/dev/cpu/*/msr - Model-specific register support"
1359 This device gives privileged processes access to the x86
1360 Model-Specific Registers (MSRs). It is a character device with
1361 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1362 MSR accesses are directed to a specific CPU on multi-processor
1366 tristate "/dev/cpu/*/cpuid - CPU information support"
1368 This device gives processes access to the x86 CPUID instruction to
1369 be executed on a specific processor. It is a character device
1370 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1374 prompt "High Memory Support"
1381 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1382 However, the address space of 32-bit x86 processors is only 4
1383 Gigabytes large. That means that, if you have a large amount of
1384 physical memory, not all of it can be "permanently mapped" by the
1385 kernel. The physical memory that's not permanently mapped is called
1388 If you are compiling a kernel which will never run on a machine with
1389 more than 1 Gigabyte total physical RAM, answer "off" here (default
1390 choice and suitable for most users). This will result in a "3GB/1GB"
1391 split: 3GB are mapped so that each process sees a 3GB virtual memory
1392 space and the remaining part of the 4GB virtual memory space is used
1393 by the kernel to permanently map as much physical memory as
1396 If the machine has between 1 and 4 Gigabytes physical RAM, then
1399 If more than 4 Gigabytes is used then answer "64GB" here. This
1400 selection turns Intel PAE (Physical Address Extension) mode on.
1401 PAE implements 3-level paging on IA32 processors. PAE is fully
1402 supported by Linux, PAE mode is implemented on all recent Intel
1403 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1404 then the kernel will not boot on CPUs that don't support PAE!
1406 The actual amount of total physical memory will either be
1407 auto detected or can be forced by using a kernel command line option
1408 such as "mem=256M". (Try "man bootparam" or see the documentation of
1409 your boot loader (lilo or loadlin) about how to pass options to the
1410 kernel at boot time.)
1412 If unsure, say "off".
1417 Select this if you have a 32-bit processor and between 1 and 4
1418 gigabytes of physical RAM.
1422 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1425 Select this if you have a 32-bit processor and more than 4
1426 gigabytes of physical RAM.
1431 prompt "Memory split" if EXPERT
1435 Select the desired split between kernel and user memory.
1437 If the address range available to the kernel is less than the
1438 physical memory installed, the remaining memory will be available
1439 as "high memory". Accessing high memory is a little more costly
1440 than low memory, as it needs to be mapped into the kernel first.
1441 Note that increasing the kernel address space limits the range
1442 available to user programs, making the address space there
1443 tighter. Selecting anything other than the default 3G/1G split
1444 will also likely make your kernel incompatible with binary-only
1447 If you are not absolutely sure what you are doing, leave this
1451 bool "3G/1G user/kernel split"
1452 config VMSPLIT_3G_OPT
1454 bool "3G/1G user/kernel split (for full 1G low memory)"
1456 bool "2G/2G user/kernel split"
1457 config VMSPLIT_2G_OPT
1459 bool "2G/2G user/kernel split (for full 2G low memory)"
1461 bool "1G/3G user/kernel split"
1466 default 0xB0000000 if VMSPLIT_3G_OPT
1467 default 0x80000000 if VMSPLIT_2G
1468 default 0x78000000 if VMSPLIT_2G_OPT
1469 default 0x40000000 if VMSPLIT_1G
1475 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1478 bool "PAE (Physical Address Extension) Support"
1479 depends on X86_32 && !HIGHMEM4G
1480 select PHYS_ADDR_T_64BIT
1483 PAE is required for NX support, and furthermore enables
1484 larger swapspace support for non-overcommit purposes. It
1485 has the cost of more pagetable lookup overhead, and also
1486 consumes more pagetable space per process.
1489 bool "Enable 5-level page tables support"
1491 select DYNAMIC_MEMORY_LAYOUT
1492 select SPARSEMEM_VMEMMAP
1495 5-level paging enables access to larger address space:
1496 upto 128 PiB of virtual address space and 4 PiB of
1497 physical address space.
1499 It will be supported by future Intel CPUs.
1501 A kernel with the option enabled can be booted on machines that
1502 support 4- or 5-level paging.
1504 See Documentation/x86/x86_64/5level-paging.rst for more
1509 config X86_DIRECT_GBPAGES
1513 Certain kernel features effectively disable kernel
1514 linear 1 GB mappings (even if the CPU otherwise
1515 supports them), so don't confuse the user by printing
1516 that we have them enabled.
1518 config X86_CPA_STATISTICS
1519 bool "Enable statistic for Change Page Attribute"
1522 Expose statistics about the Change Page Attribute mechanism, which
1523 helps to determine the effectiveness of preserving large and huge
1524 page mappings when mapping protections are changed.
1526 config AMD_MEM_ENCRYPT
1527 bool "AMD Secure Memory Encryption (SME) support"
1528 depends on X86_64 && CPU_SUP_AMD
1529 select DMA_COHERENT_POOL
1530 select DYNAMIC_PHYSICAL_MASK
1531 select ARCH_USE_MEMREMAP_PROT
1532 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1533 select INSTRUCTION_DECODER
1534 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1535 select ARCH_HAS_CC_PLATFORM
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
1561 Enable NUMA (Non-Uniform Memory Access) support.
1563 The kernel will try to allocate memory used by a CPU on the
1564 local memory controller of the CPU and add some more
1565 NUMA awareness to the kernel.
1567 For 64-bit this is recommended if the system is Intel Core i7
1568 (or later), AMD Opteron, or EM64T NUMA.
1570 For 32-bit this is only needed if you boot a 32-bit
1571 kernel on a 64-bit NUMA platform.
1573 Otherwise, you should say N.
1577 prompt "Old style AMD Opteron NUMA detection"
1578 depends on X86_64 && NUMA && PCI
1580 Enable AMD NUMA node topology detection. You should say Y here if
1581 you have a multi processor AMD system. This uses an old method to
1582 read the NUMA configuration directly from the builtin Northbridge
1583 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1584 which also takes priority if both are compiled in.
1586 config X86_64_ACPI_NUMA
1588 prompt "ACPI NUMA detection"
1589 depends on X86_64 && NUMA && ACPI && PCI
1592 Enable ACPI SRAT based node topology detection.
1595 bool "NUMA emulation"
1598 Enable NUMA emulation. A flat machine will be split
1599 into virtual nodes when booted with "numa=fake=N", where N is the
1600 number of nodes. This is only useful for debugging.
1603 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1605 default "10" if MAXSMP
1606 default "6" if X86_64
1610 Specify the maximum number of NUMA Nodes available on the target
1611 system. Increases memory reserved to accommodate various tables.
1613 config ARCH_FLATMEM_ENABLE
1615 depends on X86_32 && !NUMA
1617 config ARCH_SPARSEMEM_ENABLE
1619 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1620 select SPARSEMEM_STATIC if X86_32
1621 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1623 config ARCH_SPARSEMEM_DEFAULT
1624 def_bool X86_64 || (NUMA && X86_32)
1626 config ARCH_SELECT_MEMORY_MODEL
1628 depends on ARCH_SPARSEMEM_ENABLE
1630 config ARCH_MEMORY_PROBE
1631 bool "Enable sysfs memory/probe interface"
1632 depends on MEMORY_HOTPLUG
1634 This option enables a sysfs memory/probe interface for testing.
1635 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1636 If you are unsure how to answer this question, answer N.
1638 config ARCH_PROC_KCORE_TEXT
1640 depends on X86_64 && PROC_KCORE
1642 config ILLEGAL_POINTER_VALUE
1645 default 0xdead000000000000 if X86_64
1647 config X86_PMEM_LEGACY_DEVICE
1650 config X86_PMEM_LEGACY
1651 tristate "Support non-standard NVDIMMs and ADR protected memory"
1652 depends on PHYS_ADDR_T_64BIT
1654 select X86_PMEM_LEGACY_DEVICE
1655 select NUMA_KEEP_MEMINFO if NUMA
1658 Treat memory marked using the non-standard e820 type of 12 as used
1659 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1660 The kernel will offer these regions to the 'pmem' driver so
1661 they can be used for persistent storage.
1666 bool "Allocate 3rd-level pagetables from highmem"
1669 The VM uses one page table entry for each page of physical memory.
1670 For systems with a lot of RAM, this can be wasteful of precious
1671 low memory. Setting this option will put user-space page table
1672 entries in high memory.
1674 config X86_CHECK_BIOS_CORRUPTION
1675 bool "Check for low memory corruption"
1677 Periodically check for memory corruption in low memory, which
1678 is suspected to be caused by BIOS. Even when enabled in the
1679 configuration, it is disabled at runtime. Enable it by
1680 setting "memory_corruption_check=1" on the kernel command
1681 line. By default it scans the low 64k of memory every 60
1682 seconds; see the memory_corruption_check_size and
1683 memory_corruption_check_period parameters in
1684 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1686 When enabled with the default parameters, this option has
1687 almost no overhead, as it reserves a relatively small amount
1688 of memory and scans it infrequently. It both detects corruption
1689 and prevents it from affecting the running system.
1691 It is, however, intended as a diagnostic tool; if repeatable
1692 BIOS-originated corruption always affects the same memory,
1693 you can use memmap= to prevent the kernel from using that
1696 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1697 bool "Set the default setting of memory_corruption_check"
1698 depends on X86_CHECK_BIOS_CORRUPTION
1701 Set whether the default state of memory_corruption_check is
1704 config MATH_EMULATION
1706 depends on MODIFY_LDT_SYSCALL
1707 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1709 Linux can emulate a math coprocessor (used for floating point
1710 operations) if you don't have one. 486DX and Pentium processors have
1711 a math coprocessor built in, 486SX and 386 do not, unless you added
1712 a 487DX or 387, respectively. (The messages during boot time can
1713 give you some hints here ["man dmesg"].) Everyone needs either a
1714 coprocessor or this emulation.
1716 If you don't have a math coprocessor, you need to say Y here; if you
1717 say Y here even though you have a coprocessor, the coprocessor will
1718 be used nevertheless. (This behavior can be changed with the kernel
1719 command line option "no387", which comes handy if your coprocessor
1720 is broken. Try "man bootparam" or see the documentation of your boot
1721 loader (lilo or loadlin) about how to pass options to the kernel at
1722 boot time.) This means that it is a good idea to say Y here if you
1723 intend to use this kernel on different machines.
1725 More information about the internals of the Linux math coprocessor
1726 emulation can be found in <file:arch/x86/math-emu/README>.
1728 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1729 kernel, it won't hurt.
1733 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1735 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1736 the Memory Type Range Registers (MTRRs) may be used to control
1737 processor access to memory ranges. This is most useful if you have
1738 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1739 allows bus write transfers to be combined into a larger transfer
1740 before bursting over the PCI/AGP bus. This can increase performance
1741 of image write operations 2.5 times or more. Saying Y here creates a
1742 /proc/mtrr file which may be used to manipulate your processor's
1743 MTRRs. Typically the X server should use this.
1745 This code has a reasonably generic interface so that similar
1746 control registers on other processors can be easily supported
1749 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1750 Registers (ARRs) which provide a similar functionality to MTRRs. For
1751 these, the ARRs are used to emulate the MTRRs.
1752 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1753 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1754 write-combining. All of these processors are supported by this code
1755 and it makes sense to say Y here if you have one of them.
1757 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1758 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1759 can lead to all sorts of problems, so it's good to say Y here.
1761 You can safely say Y even if your machine doesn't have MTRRs, you'll
1762 just add about 9 KB to your kernel.
1764 See <file:Documentation/x86/mtrr.rst> for more information.
1766 config MTRR_SANITIZER
1768 prompt "MTRR cleanup support"
1771 Convert MTRR layout from continuous to discrete, so X drivers can
1772 add writeback entries.
1774 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1775 The largest mtrr entry size for a continuous block can be set with
1780 config MTRR_SANITIZER_ENABLE_DEFAULT
1781 int "MTRR cleanup enable value (0-1)"
1784 depends on MTRR_SANITIZER
1786 Enable mtrr cleanup default value
1788 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1789 int "MTRR cleanup spare reg num (0-7)"
1792 depends on MTRR_SANITIZER
1794 mtrr cleanup spare entries default, it can be changed via
1795 mtrr_spare_reg_nr=N on the kernel command line.
1799 prompt "x86 PAT support" if EXPERT
1802 Use PAT attributes to setup page level cache control.
1804 PATs are the modern equivalents of MTRRs and are much more
1805 flexible than MTRRs.
1807 Say N here if you see bootup problems (boot crash, boot hang,
1808 spontaneous reboots) or a non-working video driver.
1812 config ARCH_USES_PG_UNCACHED
1818 prompt "x86 architectural random number generator" if EXPERT
1820 Enable the x86 architectural RDRAND instruction
1821 (Intel Bull Mountain technology) to generate random numbers.
1822 If supported, this is a high bandwidth, cryptographically
1823 secure hardware random number generator.
1827 prompt "Supervisor Mode Access Prevention" if EXPERT
1829 Supervisor Mode Access Prevention (SMAP) is a security
1830 feature in newer Intel processors. There is a small
1831 performance cost if this enabled and turned on; there is
1832 also a small increase in the kernel size if this is enabled.
1838 prompt "User Mode Instruction Prevention" if EXPERT
1840 User Mode Instruction Prevention (UMIP) is a security feature in
1841 some x86 processors. If enabled, a general protection fault is
1842 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1843 executed in user mode. These instructions unnecessarily expose
1844 information about the hardware state.
1846 The vast majority of applications do not use these instructions.
1847 For the very few that do, software emulation is provided in
1848 specific cases in protected and virtual-8086 modes. Emulated
1851 config X86_INTEL_MEMORY_PROTECTION_KEYS
1852 prompt "Memory Protection Keys"
1854 # Note: only available in 64-bit mode
1855 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1856 select ARCH_USES_HIGH_VMA_FLAGS
1857 select ARCH_HAS_PKEYS
1859 Memory Protection Keys provides a mechanism for enforcing
1860 page-based protections, but without requiring modification of the
1861 page tables when an application changes protection domains.
1863 For details, see Documentation/core-api/protection-keys.rst
1868 prompt "TSX enable mode"
1869 depends on CPU_SUP_INTEL
1870 default X86_INTEL_TSX_MODE_OFF
1872 Intel's TSX (Transactional Synchronization Extensions) feature
1873 allows to optimize locking protocols through lock elision which
1874 can lead to a noticeable performance boost.
1876 On the other hand it has been shown that TSX can be exploited
1877 to form side channel attacks (e.g. TAA) and chances are there
1878 will be more of those attacks discovered in the future.
1880 Therefore TSX is not enabled by default (aka tsx=off). An admin
1881 might override this decision by tsx=on the command line parameter.
1882 Even with TSX enabled, the kernel will attempt to enable the best
1883 possible TAA mitigation setting depending on the microcode available
1884 for the particular machine.
1886 This option allows to set the default tsx mode between tsx=on, =off
1887 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1890 Say off if not sure, auto if TSX is in use but it should be used on safe
1891 platforms or on if TSX is in use and the security aspect of tsx is not
1894 config X86_INTEL_TSX_MODE_OFF
1897 TSX is disabled if possible - equals to tsx=off command line parameter.
1899 config X86_INTEL_TSX_MODE_ON
1902 TSX is always enabled on TSX capable HW - equals the tsx=on command
1905 config X86_INTEL_TSX_MODE_AUTO
1908 TSX is enabled on TSX capable HW that is believed to be safe against
1909 side channel attacks- equals the tsx=auto command line parameter.
1913 bool "Software Guard eXtensions (SGX)"
1914 depends on X86_64 && CPU_SUP_INTEL
1916 depends on CRYPTO_SHA256=y
1919 select NUMA_KEEP_MEMINFO if NUMA
1921 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1922 that can be used by applications to set aside private regions of code
1923 and data, referred to as enclaves. An enclave's private memory can
1924 only be accessed by code running within the enclave. Accesses from
1925 outside the enclave, including other enclaves, are disallowed by
1931 bool "EFI runtime service support"
1934 select EFI_RUNTIME_WRAPPERS
1935 select ARCH_USE_MEMREMAP_PROT
1937 This enables the kernel to use EFI runtime services that are
1938 available (such as the EFI variable services).
1940 This option is only useful on systems that have EFI firmware.
1941 In addition, you should use the latest ELILO loader available
1942 at <http://elilo.sourceforge.net> in order to take advantage
1943 of EFI runtime services. However, even with this option, the
1944 resultant kernel should continue to boot on existing non-EFI
1948 bool "EFI stub support"
1949 depends on EFI && !X86_USE_3DNOW
1950 depends on $(cc-option,-mabi=ms) || X86_32
1953 This kernel feature allows a bzImage to be loaded directly
1954 by EFI firmware without the use of a bootloader.
1956 See Documentation/admin-guide/efi-stub.rst for more information.
1959 bool "EFI mixed-mode support"
1960 depends on EFI_STUB && X86_64
1962 Enabling this feature allows a 64-bit kernel to be booted
1963 on a 32-bit firmware, provided that your CPU supports 64-bit
1966 Note that it is not possible to boot a mixed-mode enabled
1967 kernel via the EFI boot stub - a bootloader that supports
1968 the EFI handover protocol must be used.
1972 source "kernel/Kconfig.hz"
1975 bool "kexec system call"
1978 kexec is a system call that implements the ability to shutdown your
1979 current kernel, and to start another kernel. It is like a reboot
1980 but it is independent of the system firmware. And like a reboot
1981 you can start any kernel with it, not just Linux.
1983 The name comes from the similarity to the exec system call.
1985 It is an ongoing process to be certain the hardware in a machine
1986 is properly shutdown, so do not be surprised if this code does not
1987 initially work for you. As of this writing the exact hardware
1988 interface is strongly in flux, so no good recommendation can be
1992 bool "kexec file based system call"
1997 depends on CRYPTO_SHA256=y
1999 This is new version of kexec system call. This system call is
2000 file based and takes file descriptors as system call argument
2001 for kernel and initramfs as opposed to list of segments as
2002 accepted by previous system call.
2004 config ARCH_HAS_KEXEC_PURGATORY
2008 bool "Verify kernel signature during kexec_file_load() syscall"
2009 depends on KEXEC_FILE
2012 This option makes the kexec_file_load() syscall check for a valid
2013 signature of the kernel image. The image can still be loaded without
2014 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2015 there's a signature that we can check, then it must be valid.
2017 In addition to this option, you need to enable signature
2018 verification for the corresponding kernel image type being
2019 loaded in order for this to work.
2021 config KEXEC_SIG_FORCE
2022 bool "Require a valid signature in kexec_file_load() syscall"
2023 depends on KEXEC_SIG
2025 This option makes kernel signature verification mandatory for
2026 the kexec_file_load() syscall.
2028 config KEXEC_BZIMAGE_VERIFY_SIG
2029 bool "Enable bzImage signature verification support"
2030 depends on KEXEC_SIG
2031 depends on SIGNED_PE_FILE_VERIFICATION
2032 select SYSTEM_TRUSTED_KEYRING
2034 Enable bzImage signature verification support.
2037 bool "kernel crash dumps"
2038 depends on X86_64 || (X86_32 && HIGHMEM)
2040 Generate crash dump after being started by kexec.
2041 This should be normally only set in special crash dump kernels
2042 which are loaded in the main kernel with kexec-tools into
2043 a specially reserved region and then later executed after
2044 a crash by kdump/kexec. The crash dump kernel must be compiled
2045 to a memory address not used by the main kernel or BIOS using
2046 PHYSICAL_START, or it must be built as a relocatable image
2047 (CONFIG_RELOCATABLE=y).
2048 For more details see Documentation/admin-guide/kdump/kdump.rst
2052 depends on KEXEC && HIBERNATION
2054 Jump between original kernel and kexeced kernel and invoke
2055 code in physical address mode via KEXEC
2057 config PHYSICAL_START
2058 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2061 This gives the physical address where the kernel is loaded.
2063 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2064 bzImage will decompress itself to above physical address and
2065 run from there. Otherwise, bzImage will run from the address where
2066 it has been loaded by the boot loader and will ignore above physical
2069 In normal kdump cases one does not have to set/change this option
2070 as now bzImage can be compiled as a completely relocatable image
2071 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2072 address. This option is mainly useful for the folks who don't want
2073 to use a bzImage for capturing the crash dump and want to use a
2074 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2075 to be specifically compiled to run from a specific memory area
2076 (normally a reserved region) and this option comes handy.
2078 So if you are using bzImage for capturing the crash dump,
2079 leave the value here unchanged to 0x1000000 and set
2080 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2081 for capturing the crash dump change this value to start of
2082 the reserved region. In other words, it can be set based on
2083 the "X" value as specified in the "crashkernel=YM@XM"
2084 command line boot parameter passed to the panic-ed
2085 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2086 for more details about crash dumps.
2088 Usage of bzImage for capturing the crash dump is recommended as
2089 one does not have to build two kernels. Same kernel can be used
2090 as production kernel and capture kernel. Above option should have
2091 gone away after relocatable bzImage support is introduced. But it
2092 is present because there are users out there who continue to use
2093 vmlinux for dump capture. This option should go away down the
2096 Don't change this unless you know what you are doing.
2099 bool "Build a relocatable kernel"
2102 This builds a kernel image that retains relocation information
2103 so it can be loaded someplace besides the default 1MB.
2104 The relocations tend to make the kernel binary about 10% larger,
2105 but are discarded at runtime.
2107 One use is for the kexec on panic case where the recovery kernel
2108 must live at a different physical address than the primary
2111 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2112 it has been loaded at and the compile time physical address
2113 (CONFIG_PHYSICAL_START) is used as the minimum location.
2115 config RANDOMIZE_BASE
2116 bool "Randomize the address of the kernel image (KASLR)"
2117 depends on RELOCATABLE
2120 In support of Kernel Address Space Layout Randomization (KASLR),
2121 this randomizes the physical address at which the kernel image
2122 is decompressed and the virtual address where the kernel
2123 image is mapped, as a security feature that deters exploit
2124 attempts relying on knowledge of the location of kernel
2127 On 64-bit, the kernel physical and virtual addresses are
2128 randomized separately. The physical address will be anywhere
2129 between 16MB and the top of physical memory (up to 64TB). The
2130 virtual address will be randomized from 16MB up to 1GB (9 bits
2131 of entropy). Note that this also reduces the memory space
2132 available to kernel modules from 1.5GB to 1GB.
2134 On 32-bit, the kernel physical and virtual addresses are
2135 randomized together. They will be randomized from 16MB up to
2136 512MB (8 bits of entropy).
2138 Entropy is generated using the RDRAND instruction if it is
2139 supported. If RDTSC is supported, its value is mixed into
2140 the entropy pool as well. If neither RDRAND nor RDTSC are
2141 supported, then entropy is read from the i8254 timer. The
2142 usable entropy is limited by the kernel being built using
2143 2GB addressing, and that PHYSICAL_ALIGN must be at a
2144 minimum of 2MB. As a result, only 10 bits of entropy are
2145 theoretically possible, but the implementations are further
2146 limited due to memory layouts.
2150 # Relocation on x86 needs some additional build support
2151 config X86_NEED_RELOCS
2153 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2155 config PHYSICAL_ALIGN
2156 hex "Alignment value to which kernel should be aligned"
2158 range 0x2000 0x1000000 if X86_32
2159 range 0x200000 0x1000000 if X86_64
2161 This value puts the alignment restrictions on physical address
2162 where kernel is loaded and run from. Kernel is compiled for an
2163 address which meets above alignment restriction.
2165 If bootloader loads the kernel at a non-aligned address and
2166 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2167 address aligned to above value and run from there.
2169 If bootloader loads the kernel at a non-aligned address and
2170 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2171 load address and decompress itself to the address it has been
2172 compiled for and run from there. The address for which kernel is
2173 compiled already meets above alignment restrictions. Hence the
2174 end result is that kernel runs from a physical address meeting
2175 above alignment restrictions.
2177 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2178 this value must be a multiple of 0x200000.
2180 Don't change this unless you know what you are doing.
2182 config DYNAMIC_MEMORY_LAYOUT
2185 This option makes base addresses of vmalloc and vmemmap as well as
2186 __PAGE_OFFSET movable during boot.
2188 config RANDOMIZE_MEMORY
2189 bool "Randomize the kernel memory sections"
2191 depends on RANDOMIZE_BASE
2192 select DYNAMIC_MEMORY_LAYOUT
2193 default RANDOMIZE_BASE
2195 Randomizes the base virtual address of kernel memory sections
2196 (physical memory mapping, vmalloc & vmemmap). This security feature
2197 makes exploits relying on predictable memory locations less reliable.
2199 The order of allocations remains unchanged. Entropy is generated in
2200 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2201 configuration have in average 30,000 different possible virtual
2202 addresses for each memory section.
2206 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2207 hex "Physical memory mapping padding" if EXPERT
2208 depends on RANDOMIZE_MEMORY
2209 default "0xa" if MEMORY_HOTPLUG
2211 range 0x1 0x40 if MEMORY_HOTPLUG
2214 Define the padding in terabytes added to the existing physical
2215 memory size during kernel memory randomization. It is useful
2216 for memory hotplug support but reduces the entropy available for
2217 address randomization.
2219 If unsure, leave at the default value.
2225 config BOOTPARAM_HOTPLUG_CPU0
2226 bool "Set default setting of cpu0_hotpluggable"
2227 depends on HOTPLUG_CPU
2229 Set whether default state of cpu0_hotpluggable is on or off.
2231 Say Y here to enable CPU0 hotplug by default. If this switch
2232 is turned on, there is no need to give cpu0_hotplug kernel
2233 parameter and the CPU0 hotplug feature is enabled by default.
2235 Please note: there are two known CPU0 dependencies if you want
2236 to enable the CPU0 hotplug feature either by this switch or by
2237 cpu0_hotplug kernel parameter.
2239 First, resume from hibernate or suspend always starts from CPU0.
2240 So hibernate and suspend are prevented if CPU0 is offline.
2242 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2243 offline if any interrupt can not migrate out of CPU0. There may
2244 be other CPU0 dependencies.
2246 Please make sure the dependencies are under your control before
2247 you enable this feature.
2249 Say N if you don't want to enable CPU0 hotplug feature by default.
2250 You still can enable the CPU0 hotplug feature at boot by kernel
2251 parameter cpu0_hotplug.
2253 config DEBUG_HOTPLUG_CPU0
2255 prompt "Debug CPU0 hotplug"
2256 depends on HOTPLUG_CPU
2258 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2259 soon as possible and boots up userspace with CPU0 offlined. User
2260 can online CPU0 back after boot time.
2262 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2263 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2264 compilation or giving cpu0_hotplug kernel parameter at boot.
2270 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2271 depends on COMPAT_32
2273 Certain buggy versions of glibc will crash if they are
2274 presented with a 32-bit vDSO that is not mapped at the address
2275 indicated in its segment table.
2277 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2278 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2279 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2280 the only released version with the bug, but OpenSUSE 9
2281 contains a buggy "glibc 2.3.2".
2283 The symptom of the bug is that everything crashes on startup, saying:
2284 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2286 Saying Y here changes the default value of the vdso32 boot
2287 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2288 This works around the glibc bug but hurts performance.
2290 If unsure, say N: if you are compiling your own kernel, you
2291 are unlikely to be using a buggy version of glibc.
2294 prompt "vsyscall table for legacy applications"
2296 default LEGACY_VSYSCALL_XONLY
2298 Legacy user code that does not know how to find the vDSO expects
2299 to be able to issue three syscalls by calling fixed addresses in
2300 kernel space. Since this location is not randomized with ASLR,
2301 it can be used to assist security vulnerability exploitation.
2303 This setting can be changed at boot time via the kernel command
2304 line parameter vsyscall=[emulate|xonly|none].
2306 On a system with recent enough glibc (2.14 or newer) and no
2307 static binaries, you can say None without a performance penalty
2308 to improve security.
2310 If unsure, select "Emulate execution only".
2312 config LEGACY_VSYSCALL_EMULATE
2313 bool "Full emulation"
2315 The kernel traps and emulates calls into the fixed vsyscall
2316 address mapping. This makes the mapping non-executable, but
2317 it still contains readable known contents, which could be
2318 used in certain rare security vulnerability exploits. This
2319 configuration is recommended when using legacy userspace
2320 that still uses vsyscalls along with legacy binary
2321 instrumentation tools that require code to be readable.
2323 An example of this type of legacy userspace is running
2324 Pin on an old binary that still uses vsyscalls.
2326 config LEGACY_VSYSCALL_XONLY
2327 bool "Emulate execution only"
2329 The kernel traps and emulates calls into the fixed vsyscall
2330 address mapping and does not allow reads. This
2331 configuration is recommended when userspace might use the
2332 legacy vsyscall area but support for legacy binary
2333 instrumentation of legacy code is not needed. It mitigates
2334 certain uses of the vsyscall area as an ASLR-bypassing
2337 config LEGACY_VSYSCALL_NONE
2340 There will be no vsyscall mapping at all. This will
2341 eliminate any risk of ASLR bypass due to the vsyscall
2342 fixed address mapping. Attempts to use the vsyscalls
2343 will be reported to dmesg, so that either old or
2344 malicious userspace programs can be identified.
2349 bool "Built-in kernel command line"
2351 Allow for specifying boot arguments to the kernel at
2352 build time. On some systems (e.g. embedded ones), it is
2353 necessary or convenient to provide some or all of the
2354 kernel boot arguments with the kernel itself (that is,
2355 to not rely on the boot loader to provide them.)
2357 To compile command line arguments into the kernel,
2358 set this option to 'Y', then fill in the
2359 boot arguments in CONFIG_CMDLINE.
2361 Systems with fully functional boot loaders (i.e. non-embedded)
2362 should leave this option set to 'N'.
2365 string "Built-in kernel command string"
2366 depends on CMDLINE_BOOL
2369 Enter arguments here that should be compiled into the kernel
2370 image and used at boot time. If the boot loader provides a
2371 command line at boot time, it is appended to this string to
2372 form the full kernel command line, when the system boots.
2374 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2375 change this behavior.
2377 In most cases, the command line (whether built-in or provided
2378 by the boot loader) should specify the device for the root
2381 config CMDLINE_OVERRIDE
2382 bool "Built-in command line overrides boot loader arguments"
2383 depends on CMDLINE_BOOL && CMDLINE != ""
2385 Set this option to 'Y' to have the kernel ignore the boot loader
2386 command line, and use ONLY the built-in command line.
2388 This is used to work around broken boot loaders. This should
2389 be set to 'N' under normal conditions.
2391 config MODIFY_LDT_SYSCALL
2392 bool "Enable the LDT (local descriptor table)" if EXPERT
2395 Linux can allow user programs to install a per-process x86
2396 Local Descriptor Table (LDT) using the modify_ldt(2) system
2397 call. This is required to run 16-bit or segmented code such as
2398 DOSEMU or some Wine programs. It is also used by some very old
2399 threading libraries.
2401 Enabling this feature adds a small amount of overhead to
2402 context switches and increases the low-level kernel attack
2403 surface. Disabling it removes the modify_ldt(2) system call.
2405 Saying 'N' here may make sense for embedded or server kernels.
2407 config STRICT_SIGALTSTACK_SIZE
2408 bool "Enforce strict size checking for sigaltstack"
2409 depends on DYNAMIC_SIGFRAME
2411 For historical reasons MINSIGSTKSZ is a constant which became
2412 already too small with AVX512 support. Add a mechanism to
2413 enforce strict checking of the sigaltstack size against the
2414 real size of the FPU frame. This option enables the check
2415 by default. It can also be controlled via the kernel command
2416 line option 'strict_sas_size' independent of this config
2417 switch. Enabling it might break existing applications which
2418 allocate a too small sigaltstack but 'work' because they
2419 never get a signal delivered.
2421 Say 'N' unless you want to really enforce this check.
2423 source "kernel/livepatch/Kconfig"
2427 config ARCH_HAS_ADD_PAGES
2429 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2431 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2434 config USE_PERCPU_NUMA_NODE_ID
2438 menu "Power management and ACPI options"
2440 config ARCH_HIBERNATION_HEADER
2442 depends on HIBERNATION
2444 source "kernel/power/Kconfig"
2446 source "drivers/acpi/Kconfig"
2453 tristate "APM (Advanced Power Management) BIOS support"
2454 depends on X86_32 && PM_SLEEP
2456 APM is a BIOS specification for saving power using several different
2457 techniques. This is mostly useful for battery powered laptops with
2458 APM compliant BIOSes. If you say Y here, the system time will be
2459 reset after a RESUME operation, the /proc/apm device will provide
2460 battery status information, and user-space programs will receive
2461 notification of APM "events" (e.g. battery status change).
2463 If you select "Y" here, you can disable actual use of the APM
2464 BIOS by passing the "apm=off" option to the kernel at boot time.
2466 Note that the APM support is almost completely disabled for
2467 machines with more than one CPU.
2469 In order to use APM, you will need supporting software. For location
2470 and more information, read <file:Documentation/power/apm-acpi.rst>
2471 and the Battery Powered Linux mini-HOWTO, available from
2472 <http://www.tldp.org/docs.html#howto>.
2474 This driver does not spin down disk drives (see the hdparm(8)
2475 manpage ("man 8 hdparm") for that), and it doesn't turn off
2476 VESA-compliant "green" monitors.
2478 This driver does not support the TI 4000M TravelMate and the ACER
2479 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2480 desktop machines also don't have compliant BIOSes, and this driver
2481 may cause those machines to panic during the boot phase.
2483 Generally, if you don't have a battery in your machine, there isn't
2484 much point in using this driver and you should say N. If you get
2485 random kernel OOPSes or reboots that don't seem to be related to
2486 anything, try disabling/enabling this option (or disabling/enabling
2489 Some other things you should try when experiencing seemingly random,
2492 1) make sure that you have enough swap space and that it is
2494 2) pass the "no-hlt" option to the kernel
2495 3) switch on floating point emulation in the kernel and pass
2496 the "no387" option to the kernel
2497 4) pass the "floppy=nodma" option to the kernel
2498 5) pass the "mem=4M" option to the kernel (thereby disabling
2499 all but the first 4 MB of RAM)
2500 6) make sure that the CPU is not over clocked.
2501 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2502 8) disable the cache from your BIOS settings
2503 9) install a fan for the video card or exchange video RAM
2504 10) install a better fan for the CPU
2505 11) exchange RAM chips
2506 12) exchange the motherboard.
2508 To compile this driver as a module, choose M here: the
2509 module will be called apm.
2513 config APM_IGNORE_USER_SUSPEND
2514 bool "Ignore USER SUSPEND"
2516 This option will ignore USER SUSPEND requests. On machines with a
2517 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2518 series notebooks, it is necessary to say Y because of a BIOS bug.
2520 config APM_DO_ENABLE
2521 bool "Enable PM at boot time"
2523 Enable APM features at boot time. From page 36 of the APM BIOS
2524 specification: "When disabled, the APM BIOS does not automatically
2525 power manage devices, enter the Standby State, enter the Suspend
2526 State, or take power saving steps in response to CPU Idle calls."
2527 This driver will make CPU Idle calls when Linux is idle (unless this
2528 feature is turned off -- see "Do CPU IDLE calls", below). This
2529 should always save battery power, but more complicated APM features
2530 will be dependent on your BIOS implementation. You may need to turn
2531 this option off if your computer hangs at boot time when using APM
2532 support, or if it beeps continuously instead of suspending. Turn
2533 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2534 T400CDT. This is off by default since most machines do fine without
2539 bool "Make CPU Idle calls when idle"
2541 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2542 On some machines, this can activate improved power savings, such as
2543 a slowed CPU clock rate, when the machine is idle. These idle calls
2544 are made after the idle loop has run for some length of time (e.g.,
2545 333 mS). On some machines, this will cause a hang at boot time or
2546 whenever the CPU becomes idle. (On machines with more than one CPU,
2547 this option does nothing.)
2549 config APM_DISPLAY_BLANK
2550 bool "Enable console blanking using APM"
2552 Enable console blanking using the APM. Some laptops can use this to
2553 turn off the LCD backlight when the screen blanker of the Linux
2554 virtual console blanks the screen. Note that this is only used by
2555 the virtual console screen blanker, and won't turn off the backlight
2556 when using the X Window system. This also doesn't have anything to
2557 do with your VESA-compliant power-saving monitor. Further, this
2558 option doesn't work for all laptops -- it might not turn off your
2559 backlight at all, or it might print a lot of errors to the console,
2560 especially if you are using gpm.
2562 config APM_ALLOW_INTS
2563 bool "Allow interrupts during APM BIOS calls"
2565 Normally we disable external interrupts while we are making calls to
2566 the APM BIOS as a measure to lessen the effects of a badly behaving
2567 BIOS implementation. The BIOS should reenable interrupts if it
2568 needs to. Unfortunately, some BIOSes do not -- especially those in
2569 many of the newer IBM Thinkpads. If you experience hangs when you
2570 suspend, try setting this to Y. Otherwise, say N.
2574 source "drivers/cpufreq/Kconfig"
2576 source "drivers/cpuidle/Kconfig"
2578 source "drivers/idle/Kconfig"
2583 menu "Bus options (PCI etc.)"
2586 prompt "PCI access mode"
2587 depends on X86_32 && PCI
2590 On PCI systems, the BIOS can be used to detect the PCI devices and
2591 determine their configuration. However, some old PCI motherboards
2592 have BIOS bugs and may crash if this is done. Also, some embedded
2593 PCI-based systems don't have any BIOS at all. Linux can also try to
2594 detect the PCI hardware directly without using the BIOS.
2596 With this option, you can specify how Linux should detect the
2597 PCI devices. If you choose "BIOS", the BIOS will be used,
2598 if you choose "Direct", the BIOS won't be used, and if you
2599 choose "MMConfig", then PCI Express MMCONFIG will be used.
2600 If you choose "Any", the kernel will try MMCONFIG, then the
2601 direct access method and falls back to the BIOS if that doesn't
2602 work. If unsure, go with the default, which is "Any".
2607 config PCI_GOMMCONFIG
2624 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2626 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2629 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2632 bool "Support mmconfig PCI config space access" if X86_64
2634 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2635 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2639 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2643 depends on PCI && XEN
2645 config MMCONF_FAM10H
2647 depends on X86_64 && PCI_MMCONFIG && ACPI
2649 config PCI_CNB20LE_QUIRK
2650 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2653 Read the PCI windows out of the CNB20LE host bridge. This allows
2654 PCI hotplug to work on systems with the CNB20LE chipset which do
2657 There's no public spec for this chipset, and this functionality
2658 is known to be incomplete.
2660 You should say N unless you know you need this.
2663 bool "ISA bus support on modern systems" if EXPERT
2665 Expose ISA bus device drivers and options available for selection and
2666 configuration. Enable this option if your target machine has an ISA
2667 bus. ISA is an older system, displaced by PCI and newer bus
2668 architectures -- if your target machine is modern, it probably does
2669 not have an ISA bus.
2673 # x86_64 have no ISA slots, but can have ISA-style DMA.
2675 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2678 Enables ISA-style DMA support for devices requiring such controllers.
2686 Find out whether you have ISA slots on your motherboard. ISA is the
2687 name of a bus system, i.e. the way the CPU talks to the other stuff
2688 inside your box. Other bus systems are PCI, EISA, MicroChannel
2689 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2690 newer boards don't support it. If you have ISA, say Y, otherwise N.
2693 tristate "NatSemi SCx200 support"
2695 This provides basic support for National Semiconductor's
2696 (now AMD's) Geode processors. The driver probes for the
2697 PCI-IDs of several on-chip devices, so its a good dependency
2698 for other scx200_* drivers.
2700 If compiled as a module, the driver is named scx200.
2702 config SCx200HR_TIMER
2703 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2707 This driver provides a clocksource built upon the on-chip
2708 27MHz high-resolution timer. Its also a workaround for
2709 NSC Geode SC-1100's buggy TSC, which loses time when the
2710 processor goes idle (as is done by the scheduler). The
2711 other workaround is idle=poll boot option.
2714 bool "One Laptop Per Child support"
2722 Add support for detecting the unique features of the OLPC
2726 bool "OLPC XO-1 Power Management"
2727 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2729 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2732 bool "OLPC XO-1 Real Time Clock"
2733 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2735 Add support for the XO-1 real time clock, which can be used as a
2736 programmable wakeup source.
2739 bool "OLPC XO-1 SCI extras"
2740 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2744 Add support for SCI-based features of the OLPC XO-1 laptop:
2745 - EC-driven system wakeups
2749 - AC adapter status updates
2750 - Battery status updates
2752 config OLPC_XO15_SCI
2753 bool "OLPC XO-1.5 SCI extras"
2754 depends on OLPC && ACPI
2757 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2758 - EC-driven system wakeups
2759 - AC adapter status updates
2760 - Battery status updates
2763 bool "PCEngines ALIX System Support (LED setup)"
2766 This option enables system support for the PCEngines ALIX.
2767 At present this just sets up LEDs for GPIO control on
2768 ALIX2/3/6 boards. However, other system specific setup should
2771 Note: You must still enable the drivers for GPIO and LED support
2772 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2774 Note: You have to set alix.force=1 for boards with Award BIOS.
2777 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2780 This option enables system support for the Soekris Engineering net5501.
2783 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2787 This option enables system support for the Traverse Technologies GEOS.
2790 bool "Technologic Systems TS-5500 platform support"
2792 select CHECK_SIGNATURE
2796 This option enables system support for the Technologic Systems TS-5500.
2802 depends on CPU_SUP_AMD && PCI
2807 menu "Binary Emulations"
2809 config IA32_EMULATION
2810 bool "IA32 Emulation"
2812 select ARCH_WANT_OLD_COMPAT_IPC
2814 select COMPAT_OLD_SIGACTION
2816 Include code to run legacy 32-bit programs under a
2817 64-bit kernel. You should likely turn this on, unless you're
2818 100% sure that you don't have any 32-bit programs left.
2821 tristate "IA32 a.out support"
2822 depends on IA32_EMULATION
2825 Support old a.out binaries in the 32bit emulation.
2828 bool "x32 ABI for 64-bit mode"
2831 Include code to run binaries for the x32 native 32-bit ABI
2832 for 64-bit processors. An x32 process gets access to the
2833 full 64-bit register file and wide data path while leaving
2834 pointers at 32 bits for smaller memory footprint.
2836 You will need a recent binutils (2.22 or later) with
2837 elf32_x86_64 support enabled to compile a kernel with this
2842 depends on IA32_EMULATION || X86_32
2844 select OLD_SIGSUSPEND3
2848 depends on IA32_EMULATION || X86_X32
2851 config COMPAT_FOR_U64_ALIGNMENT
2854 config SYSVIPC_COMPAT
2862 config HAVE_ATOMIC_IOMAP
2866 source "arch/x86/kvm/Kconfig"
2868 source "arch/x86/Kconfig.assembler"