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
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_PAGE_TABLE_CHECK if X86_64
108 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
109 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
110 select ARCH_SUPPORTS_LTO_CLANG
111 select ARCH_SUPPORTS_LTO_CLANG_THIN
112 select ARCH_USE_BUILTIN_BSWAP
113 select ARCH_USE_MEMTEST
114 select ARCH_USE_QUEUED_RWLOCKS
115 select ARCH_USE_QUEUED_SPINLOCKS
116 select ARCH_USE_SYM_ANNOTATIONS
117 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
118 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
119 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
120 select ARCH_WANTS_NO_INSTR
121 select ARCH_WANT_HUGE_PMD_SHARE
122 select ARCH_WANT_LD_ORPHAN_WARN
123 select ARCH_WANTS_THP_SWAP if X86_64
124 select ARCH_HAS_PARANOID_L1D_FLUSH
125 select BUILDTIME_TABLE_SORT
127 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
128 select CLOCKSOURCE_WATCHDOG
129 select DCACHE_WORD_ACCESS
130 select DYNAMIC_SIGFRAME
131 select EDAC_ATOMIC_SCRUB
133 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
134 select GENERIC_CLOCKEVENTS_MIN_ADJUST
135 select GENERIC_CMOS_UPDATE
136 select GENERIC_CPU_AUTOPROBE
137 select GENERIC_CPU_VULNERABILITIES
138 select GENERIC_EARLY_IOREMAP
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_SETUP_PER_CPU_AREA
243 select HAVE_SOFTIRQ_ON_OWN_STACK
244 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
245 select HAVE_STACK_VALIDATION if X86_64
246 select HAVE_STATIC_CALL
247 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
248 select HAVE_PREEMPT_DYNAMIC
250 select HAVE_SYSCALL_TRACEPOINTS
251 select HAVE_UNSTABLE_SCHED_CLOCK
252 select HAVE_USER_RETURN_NOTIFIER
253 select HAVE_GENERIC_VDSO
254 select HOTPLUG_SMT if SMP
255 select IRQ_FORCED_THREADING
256 select NEED_PER_CPU_EMBED_FIRST_CHUNK
257 select NEED_PER_CPU_PAGE_FIRST_CHUNK
258 select NEED_SG_DMA_LENGTH
259 select PCI_DOMAINS if PCI
260 select PCI_LOCKLESS_CONFIG if PCI
263 select RTC_MC146818_LIB
266 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
267 select SYSCTL_EXCEPTION_TRACE
268 select THREAD_INFO_IN_TASK
269 select TRACE_IRQFLAGS_SUPPORT
270 select USER_STACKTRACE_SUPPORT
272 select HAVE_ARCH_KCSAN if X86_64
273 select X86_FEATURE_NAMES if PROC_FS
274 select PROC_PID_ARCH_STATUS if PROC_FS
275 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
276 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
278 config INSTRUCTION_DECODER
280 depends on KPROBES || PERF_EVENTS || UPROBES
284 default "elf32-i386" if X86_32
285 default "elf64-x86-64" if X86_64
287 config LOCKDEP_SUPPORT
290 config STACKTRACE_SUPPORT
296 config ARCH_MMAP_RND_BITS_MIN
300 config ARCH_MMAP_RND_BITS_MAX
304 config ARCH_MMAP_RND_COMPAT_BITS_MIN
307 config ARCH_MMAP_RND_COMPAT_BITS_MAX
313 config GENERIC_ISA_DMA
315 depends on ISA_DMA_API
320 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
322 config GENERIC_BUG_RELATIVE_POINTERS
325 config ARCH_MAY_HAVE_PC_FDC
327 depends on ISA_DMA_API
329 config GENERIC_CALIBRATE_DELAY
332 config ARCH_HAS_CPU_RELAX
335 config ARCH_HAS_FILTER_PGPROT
338 config ARCH_HIBERNATION_POSSIBLE
343 default 1024 if X86_64
346 config ARCH_SUSPEND_POSSIBLE
349 config ARCH_WANT_GENERAL_HUGETLB
355 config KASAN_SHADOW_OFFSET
358 default 0xdffffc0000000000
360 config HAVE_INTEL_TXT
362 depends on INTEL_IOMMU && ACPI
366 depends on X86_32 && SMP
370 depends on X86_64 && SMP
372 config ARCH_SUPPORTS_UPROBES
375 config FIX_EARLYCON_MEM
378 config DYNAMIC_PHYSICAL_MASK
381 config PGTABLE_LEVELS
383 default 5 if X86_5LEVEL
388 config CC_HAS_SANE_STACKPROTECTOR
390 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
391 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
393 We have to make sure stack protector is unconditionally disabled if
394 the compiler produces broken code or if it does not let us control
395 the segment on 32-bit kernels.
397 menu "Processor type and features"
400 bool "Symmetric multi-processing support"
402 This enables support for systems with more than one CPU. If you have
403 a system with only one CPU, say N. If you have a system with more
406 If you say N here, the kernel will run on uni- and multiprocessor
407 machines, but will use only one CPU of a multiprocessor machine. If
408 you say Y here, the kernel will run on many, but not all,
409 uniprocessor machines. On a uniprocessor machine, the kernel
410 will run faster if you say N here.
412 Note that if you say Y here and choose architecture "586" or
413 "Pentium" under "Processor family", the kernel will not work on 486
414 architectures. Similarly, multiprocessor kernels for the "PPro"
415 architecture may not work on all Pentium based boards.
417 People using multiprocessor machines who say Y here should also say
418 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
419 Management" code will be disabled if you say Y here.
421 See also <file:Documentation/x86/i386/IO-APIC.rst>,
422 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
423 <http://www.tldp.org/docs.html#howto>.
425 If you don't know what to do here, say N.
427 config X86_FEATURE_NAMES
428 bool "Processor feature human-readable names" if EMBEDDED
431 This option compiles in a table of x86 feature bits and corresponding
432 names. This is required to support /proc/cpuinfo and a few kernel
433 messages. You can disable this to save space, at the expense of
434 making those few kernel messages show numeric feature bits instead.
439 bool "Support x2apic"
440 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
442 This enables x2apic support on CPUs that have this feature.
444 This allows 32-bit apic IDs (so it can support very large systems),
445 and accesses the local apic via MSRs not via mmio.
447 If you don't know what to do here, say N.
450 bool "Enable MPS table" if ACPI
452 depends on X86_LOCAL_APIC
454 For old smp systems that do not have proper acpi support. Newer systems
455 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
459 depends on X86_GOLDFISH
462 bool "Avoid speculative indirect branches in kernel"
465 Compile kernel with the retpoline compiler options to guard against
466 kernel-to-user data leaks by avoiding speculative indirect
467 branches. Requires a compiler with -mindirect-branch=thunk-extern
468 support for full protection. The kernel may run slower.
471 def_bool $(cc-option,-mharden-sls=all)
474 bool "Mitigate Straight-Line-Speculation"
475 depends on CC_HAS_SLS && X86_64
478 Compile the kernel with straight-line-speculation options to guard
479 against straight line speculation. The kernel image might be slightly
482 config X86_CPU_RESCTRL
483 bool "x86 CPU resource control support"
484 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
486 select PROC_CPU_RESCTRL if PROC_FS
488 Enable x86 CPU resource control support.
490 Provide support for the allocation and monitoring of system resources
493 Intel calls this Intel Resource Director Technology
494 (Intel(R) RDT). More information about RDT can be found in the
495 Intel x86 Architecture Software Developer Manual.
497 AMD calls this AMD Platform Quality of Service (AMD QoS).
498 More information about AMD QoS can be found in the AMD64 Technology
499 Platform Quality of Service Extensions manual.
505 bool "Support for big SMP systems with more than 8 CPUs"
508 This option is needed for the systems that have more than 8 CPUs.
510 config X86_EXTENDED_PLATFORM
511 bool "Support for extended (non-PC) x86 platforms"
514 If you disable this option then the kernel will only support
515 standard PC platforms. (which covers the vast majority of
518 If you enable this option then you'll be able to select support
519 for the following (non-PC) 32 bit x86 platforms:
520 Goldfish (Android emulator)
523 SGI 320/540 (Visual Workstation)
524 STA2X11-based (e.g. Northville)
525 Moorestown MID devices
527 If you have one of these systems, or if you want to build a
528 generic distribution kernel, say Y here - otherwise say N.
532 config X86_EXTENDED_PLATFORM
533 bool "Support for extended (non-PC) x86 platforms"
536 If you disable this option then the kernel will only support
537 standard PC platforms. (which covers the vast majority of
540 If you enable this option then you'll be able to select support
541 for the following (non-PC) 64 bit x86 platforms:
546 If you have one of these systems, or if you want to build a
547 generic distribution kernel, say Y here - otherwise say N.
549 # This is an alphabetically sorted list of 64 bit extended platforms
550 # Please maintain the alphabetic order if and when there are additions
552 bool "Numascale NumaChip"
554 depends on X86_EXTENDED_PLATFORM
557 depends on X86_X2APIC
558 depends on PCI_MMCONFIG
560 Adds support for Numascale NumaChip large-SMP systems. Needed to
561 enable more than ~168 cores.
562 If you don't have one of these, you should say N here.
566 select HYPERVISOR_GUEST
568 depends on X86_64 && PCI
569 depends on X86_EXTENDED_PLATFORM
572 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
573 supposed to run on these EM64T-based machines. Only choose this option
574 if you have one of these machines.
577 bool "SGI Ultraviolet"
579 depends on X86_EXTENDED_PLATFORM
582 depends on KEXEC_CORE
583 depends on X86_X2APIC
586 This option is needed in order to support SGI Ultraviolet systems.
587 If you don't have one of these, you should say N here.
589 # Following is an alphabetically sorted list of 32 bit extended platforms
590 # Please maintain the alphabetic order if and when there are additions
593 bool "Goldfish (Virtual Platform)"
594 depends on X86_EXTENDED_PLATFORM
596 Enable support for the Goldfish virtual platform used primarily
597 for Android development. Unless you are building for the Android
598 Goldfish emulator say N here.
601 bool "CE4100 TV platform"
603 depends on PCI_GODIRECT
604 depends on X86_IO_APIC
606 depends on X86_EXTENDED_PLATFORM
607 select X86_REBOOTFIXUPS
609 select OF_EARLY_FLATTREE
611 Select for the Intel CE media processor (CE4100) SOC.
612 This option compiles in support for the CE4100 SOC for settop
613 boxes and media devices.
616 bool "Intel MID platform support"
617 depends on X86_EXTENDED_PLATFORM
618 depends on X86_PLATFORM_DEVICES
620 depends on X86_64 || (PCI_GOANY && X86_32)
621 depends on X86_IO_APIC
626 Select to build a kernel capable of supporting Intel MID (Mobile
627 Internet Device) platform systems which do not have the PCI legacy
628 interfaces. If you are building for a PC class system say N here.
630 Intel MID platforms are based on an Intel processor and chipset which
631 consume less power than most of the x86 derivatives.
633 config X86_INTEL_QUARK
634 bool "Intel Quark platform support"
636 depends on X86_EXTENDED_PLATFORM
637 depends on X86_PLATFORM_DEVICES
641 depends on X86_IO_APIC
646 Select to include support for Quark X1000 SoC.
647 Say Y here if you have a Quark based system such as the Arduino
648 compatible Intel Galileo.
650 config X86_INTEL_LPSS
651 bool "Intel Low Power Subsystem Support"
652 depends on X86 && ACPI && PCI
657 Select to build support for Intel Low Power Subsystem such as
658 found on Intel Lynxpoint PCH. Selecting this option enables
659 things like clock tree (common clock framework) and pincontrol
660 which are needed by the LPSS peripheral drivers.
662 config X86_AMD_PLATFORM_DEVICE
663 bool "AMD ACPI2Platform devices support"
668 Select to interpret AMD specific ACPI device to platform device
669 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
670 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
671 implemented under PINCTRL subsystem.
674 tristate "Intel SoC IOSF Sideband support for SoC platforms"
677 This option enables sideband register access support for Intel SoC
678 platforms. On these platforms the IOSF sideband is used in lieu of
679 MSR's for some register accesses, mostly but not limited to thermal
680 and power. Drivers may query the availability of this device to
681 determine if they need the sideband in order to work on these
682 platforms. The sideband is available on the following SoC products.
683 This list is not meant to be exclusive.
688 You should say Y if you are running a kernel on one of these SoC's.
690 config IOSF_MBI_DEBUG
691 bool "Enable IOSF sideband access through debugfs"
692 depends on IOSF_MBI && DEBUG_FS
694 Select this option to expose the IOSF sideband access registers (MCR,
695 MDR, MCRX) through debugfs to write and read register information from
696 different units on the SoC. This is most useful for obtaining device
697 state information for debug and analysis. As this is a general access
698 mechanism, users of this option would have specific knowledge of the
699 device they want to access.
701 If you don't require the option or are in doubt, say N.
704 bool "RDC R-321x SoC"
706 depends on X86_EXTENDED_PLATFORM
708 select X86_REBOOTFIXUPS
710 This option is needed for RDC R-321x system-on-chip, also known
712 If you don't have one of these chips, you should say N here.
714 config X86_32_NON_STANDARD
715 bool "Support non-standard 32-bit SMP architectures"
716 depends on X86_32 && SMP
717 depends on X86_EXTENDED_PLATFORM
719 This option compiles in the bigsmp and STA2X11 default
720 subarchitectures. It is intended for a generic binary
721 kernel. If you select them all, kernel will probe it one by
722 one and will fallback to default.
724 # Alphabetically sorted list of Non standard 32 bit platforms
726 config X86_SUPPORTS_MEMORY_FAILURE
728 # MCE code calls memory_failure():
730 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
731 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
732 depends on X86_64 || !SPARSEMEM
733 select ARCH_SUPPORTS_MEMORY_FAILURE
736 bool "STA2X11 Companion Chip Support"
737 depends on X86_32_NON_STANDARD && PCI
742 This adds support for boards based on the STA2X11 IO-Hub,
743 a.k.a. "ConneXt". The chip is used in place of the standard
744 PC chipset, so all "standard" peripherals are missing. If this
745 option is selected the kernel will still be able to boot on
746 standard PC machines.
749 tristate "Eurobraille/Iris poweroff module"
752 The Iris machines from EuroBraille do not have APM or ACPI support
753 to shut themselves down properly. A special I/O sequence is
754 needed to do so, which is what this module does at
757 This is only for Iris machines from EuroBraille.
761 config SCHED_OMIT_FRAME_POINTER
763 prompt "Single-depth WCHAN output"
766 Calculate simpler /proc/<PID>/wchan values. If this option
767 is disabled then wchan values will recurse back to the
768 caller function. This provides more accurate wchan values,
769 at the expense of slightly more scheduling overhead.
771 If in doubt, say "Y".
773 menuconfig HYPERVISOR_GUEST
774 bool "Linux guest support"
776 Say Y here to enable options for running Linux under various hyper-
777 visors. This option enables basic hypervisor detection and platform
780 If you say N, all options in this submenu will be skipped and
781 disabled, and Linux guest support won't be built in.
786 bool "Enable paravirtualization code"
787 depends on HAVE_STATIC_CALL
789 This changes the kernel so it can modify itself when it is run
790 under a hypervisor, potentially improving performance significantly
791 over full virtualization. However, when run without a hypervisor
792 the kernel is theoretically slower and slightly larger.
797 config PARAVIRT_DEBUG
798 bool "paravirt-ops debugging"
799 depends on PARAVIRT && DEBUG_KERNEL
801 Enable to debug paravirt_ops internals. Specifically, BUG if
802 a paravirt_op is missing when it is called.
804 config PARAVIRT_SPINLOCKS
805 bool "Paravirtualization layer for spinlocks"
806 depends on PARAVIRT && SMP
808 Paravirtualized spinlocks allow a pvops backend to replace the
809 spinlock implementation with something virtualization-friendly
810 (for example, block the virtual CPU rather than spinning).
812 It has a minimal impact on native kernels and gives a nice performance
813 benefit on paravirtualized KVM / Xen kernels.
815 If you are unsure how to answer this question, answer Y.
817 config X86_HV_CALLBACK_VECTOR
820 source "arch/x86/xen/Kconfig"
823 bool "KVM Guest support (including kvmclock)"
825 select PARAVIRT_CLOCK
826 select ARCH_CPUIDLE_HALTPOLL
827 select X86_HV_CALLBACK_VECTOR
830 This option enables various optimizations for running under the KVM
831 hypervisor. It includes a paravirtualized clock, so that instead
832 of relying on a PIT (or probably other) emulation by the
833 underlying device model, the host provides the guest with
834 timing infrastructure such as time of day, and system time
836 config ARCH_CPUIDLE_HALTPOLL
838 prompt "Disable host haltpoll when loading haltpoll driver"
840 If virtualized under KVM, disable host haltpoll.
843 bool "Support for running PVH guests"
845 This option enables the PVH entry point for guest virtual machines
846 as specified in the x86/HVM direct boot ABI.
848 config PARAVIRT_TIME_ACCOUNTING
849 bool "Paravirtual steal time accounting"
852 Select this option to enable fine granularity task steal time
853 accounting. Time spent executing other tasks in parallel with
854 the current vCPU is discounted from the vCPU power. To account for
855 that, there can be a small performance impact.
857 If in doubt, say N here.
859 config PARAVIRT_CLOCK
862 config JAILHOUSE_GUEST
863 bool "Jailhouse non-root cell support"
864 depends on X86_64 && PCI
867 This option allows to run Linux as guest in a Jailhouse non-root
868 cell. You can leave this option disabled if you only want to start
869 Jailhouse and run Linux afterwards in the root cell.
872 bool "ACRN Guest support"
874 select X86_HV_CALLBACK_VECTOR
876 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
877 a flexible, lightweight reference open-source hypervisor, built with
878 real-time and safety-criticality in mind. It is built for embedded
879 IOT with small footprint and real-time features. More details can be
880 found in https://projectacrn.org/.
882 endif #HYPERVISOR_GUEST
884 source "arch/x86/Kconfig.cpu"
888 prompt "HPET Timer Support" if X86_32
890 Use the IA-PC HPET (High Precision Event Timer) to manage
891 time in preference to the PIT and RTC, if a HPET is
893 HPET is the next generation timer replacing legacy 8254s.
894 The HPET provides a stable time base on SMP
895 systems, unlike the TSC, but it is more expensive to access,
896 as it is off-chip. The interface used is documented
897 in the HPET spec, revision 1.
899 You can safely choose Y here. However, HPET will only be
900 activated if the platform and the BIOS support this feature.
901 Otherwise the 8254 will be used for timing services.
903 Choose N to continue using the legacy 8254 timer.
905 config HPET_EMULATE_RTC
907 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
909 # Mark as expert because too many people got it wrong.
910 # The code disables itself when not needed.
913 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
914 bool "Enable DMI scanning" if EXPERT
916 Enabled scanning of DMI to identify machine quirks. Say Y
917 here unless you have verified that your setup is not
918 affected by entries in the DMI blacklist. Required by PNP
922 bool "Old AMD GART IOMMU support"
926 depends on X86_64 && PCI && AMD_NB
928 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
929 GART based hardware IOMMUs.
931 The GART supports full DMA access for devices with 32-bit access
932 limitations, on systems with more than 3 GB. This is usually needed
933 for USB, sound, many IDE/SATA chipsets and some other devices.
935 Newer systems typically have a modern AMD IOMMU, supported via
936 the CONFIG_AMD_IOMMU=y config option.
938 In normal configurations this driver is only active when needed:
939 there's more than 3 GB of memory and the system contains a
940 32-bit limited device.
945 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
946 depends on X86_64 && SMP && DEBUG_KERNEL
947 select CPUMASK_OFFSTACK
949 Enable maximum number of CPUS and NUMA Nodes for this architecture.
953 # The maximum number of CPUs supported:
955 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
956 # and which can be configured interactively in the
957 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
959 # The ranges are different on 32-bit and 64-bit kernels, depending on
960 # hardware capabilities and scalability features of the kernel.
962 # ( If MAXSMP is enabled we just use the highest possible value and disable
963 # interactive configuration. )
966 config NR_CPUS_RANGE_BEGIN
968 default NR_CPUS_RANGE_END if MAXSMP
972 config NR_CPUS_RANGE_END
975 default 64 if SMP && X86_BIGSMP
976 default 8 if SMP && !X86_BIGSMP
979 config NR_CPUS_RANGE_END
982 default 8192 if SMP && CPUMASK_OFFSTACK
983 default 512 if SMP && !CPUMASK_OFFSTACK
986 config NR_CPUS_DEFAULT
989 default 32 if X86_BIGSMP
993 config NR_CPUS_DEFAULT
996 default 8192 if MAXSMP
1001 int "Maximum number of CPUs" if SMP && !MAXSMP
1002 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1003 default NR_CPUS_DEFAULT
1005 This allows you to specify the maximum number of CPUs which this
1006 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1007 supported value is 8192, otherwise the maximum value is 512. The
1008 minimum value which makes sense is 2.
1010 This is purely to save memory: each supported CPU adds about 8KB
1011 to the kernel image.
1013 config SCHED_CLUSTER
1014 bool "Cluster scheduler support"
1018 Cluster scheduler support improves the CPU scheduler's decision
1019 making when dealing with machines that have clusters of CPUs.
1020 Cluster usually means a couple of CPUs which are placed closely
1021 by sharing mid-level caches, last-level cache tags or internal
1029 prompt "Multi-core scheduler support"
1032 Multi-core scheduler support improves the CPU scheduler's decision
1033 making when dealing with multi-core CPU chips at a cost of slightly
1034 increased overhead in some places. If unsure say N here.
1036 config SCHED_MC_PRIO
1037 bool "CPU core priorities scheduler support"
1038 depends on SCHED_MC && CPU_SUP_INTEL
1039 select X86_INTEL_PSTATE
1043 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1044 core ordering determined at manufacturing time, which allows
1045 certain cores to reach higher turbo frequencies (when running
1046 single threaded workloads) than others.
1048 Enabling this kernel feature teaches the scheduler about
1049 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1050 scheduler's CPU selection logic accordingly, so that higher
1051 overall system performance can be achieved.
1053 This feature will have no effect on CPUs without this feature.
1055 If unsure say Y here.
1059 depends on !SMP && X86_LOCAL_APIC
1062 bool "Local APIC support on uniprocessors" if !PCI_MSI
1064 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1066 A local APIC (Advanced Programmable Interrupt Controller) is an
1067 integrated interrupt controller in the CPU. If you have a single-CPU
1068 system which has a processor with a local APIC, you can say Y here to
1069 enable and use it. If you say Y here even though your machine doesn't
1070 have a local APIC, then the kernel will still run with no slowdown at
1071 all. The local APIC supports CPU-generated self-interrupts (timer,
1072 performance counters), and the NMI watchdog which detects hard
1075 config X86_UP_IOAPIC
1076 bool "IO-APIC support on uniprocessors"
1077 depends on X86_UP_APIC
1079 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1080 SMP-capable replacement for PC-style interrupt controllers. Most
1081 SMP systems and many recent uniprocessor systems have one.
1083 If you have a single-CPU system with an IO-APIC, you can say Y here
1084 to use it. If you say Y here even though your machine doesn't have
1085 an IO-APIC, then the kernel will still run with no slowdown at all.
1087 config X86_LOCAL_APIC
1089 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1090 select IRQ_DOMAIN_HIERARCHY
1091 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1095 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1097 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1098 bool "Reroute for broken boot IRQs"
1099 depends on X86_IO_APIC
1101 This option enables a workaround that fixes a source of
1102 spurious interrupts. This is recommended when threaded
1103 interrupt handling is used on systems where the generation of
1104 superfluous "boot interrupts" cannot be disabled.
1106 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1107 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1108 kernel does during interrupt handling). On chipsets where this
1109 boot IRQ generation cannot be disabled, this workaround keeps
1110 the original IRQ line masked so that only the equivalent "boot
1111 IRQ" is delivered to the CPUs. The workaround also tells the
1112 kernel to set up the IRQ handler on the boot IRQ line. In this
1113 way only one interrupt is delivered to the kernel. Otherwise
1114 the spurious second interrupt may cause the kernel to bring
1115 down (vital) interrupt lines.
1117 Only affects "broken" chipsets. Interrupt sharing may be
1118 increased on these systems.
1121 bool "Machine Check / overheating reporting"
1122 select GENERIC_ALLOCATOR
1125 Machine Check support allows the processor to notify the
1126 kernel if it detects a problem (e.g. overheating, data corruption).
1127 The action the kernel takes depends on the severity of the problem,
1128 ranging from warning messages to halting the machine.
1130 config X86_MCELOG_LEGACY
1131 bool "Support for deprecated /dev/mcelog character device"
1134 Enable support for /dev/mcelog which is needed by the old mcelog
1135 userspace logging daemon. Consider switching to the new generation
1138 config X86_MCE_INTEL
1140 prompt "Intel MCE features"
1141 depends on X86_MCE && X86_LOCAL_APIC
1143 Additional support for intel specific MCE features such as
1144 the thermal monitor.
1148 prompt "AMD MCE features"
1149 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1151 Additional support for AMD specific MCE features such as
1152 the DRAM Error Threshold.
1154 config X86_ANCIENT_MCE
1155 bool "Support for old Pentium 5 / WinChip machine checks"
1156 depends on X86_32 && X86_MCE
1158 Include support for machine check handling on old Pentium 5 or WinChip
1159 systems. These typically need to be enabled explicitly on the command
1162 config X86_MCE_THRESHOLD
1163 depends on X86_MCE_AMD || X86_MCE_INTEL
1166 config X86_MCE_INJECT
1167 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1168 tristate "Machine check injector support"
1170 Provide support for injecting machine checks for testing purposes.
1171 If you don't know what a machine check is and you don't do kernel
1172 QA it is safe to say n.
1174 source "arch/x86/events/Kconfig"
1176 config X86_LEGACY_VM86
1177 bool "Legacy VM86 support"
1180 This option allows user programs to put the CPU into V8086
1181 mode, which is an 80286-era approximation of 16-bit real mode.
1183 Some very old versions of X and/or vbetool require this option
1184 for user mode setting. Similarly, DOSEMU will use it if
1185 available to accelerate real mode DOS programs. However, any
1186 recent version of DOSEMU, X, or vbetool should be fully
1187 functional even without kernel VM86 support, as they will all
1188 fall back to software emulation. Nevertheless, if you are using
1189 a 16-bit DOS program where 16-bit performance matters, vm86
1190 mode might be faster than emulation and you might want to
1193 Note that any app that works on a 64-bit kernel is unlikely to
1194 need this option, as 64-bit kernels don't, and can't, support
1195 V8086 mode. This option is also unrelated to 16-bit protected
1196 mode and is not needed to run most 16-bit programs under Wine.
1198 Enabling this option increases the complexity of the kernel
1199 and slows down exception handling a tiny bit.
1201 If unsure, say N here.
1205 default X86_LEGACY_VM86
1208 bool "Enable support for 16-bit segments" if EXPERT
1210 depends on MODIFY_LDT_SYSCALL
1212 This option is required by programs like Wine to run 16-bit
1213 protected mode legacy code on x86 processors. Disabling
1214 this option saves about 300 bytes on i386, or around 6K text
1215 plus 16K runtime memory on x86-64,
1219 depends on X86_16BIT && X86_32
1223 depends on X86_16BIT && X86_64
1225 config X86_VSYSCALL_EMULATION
1226 bool "Enable vsyscall emulation" if EXPERT
1230 This enables emulation of the legacy vsyscall page. Disabling
1231 it is roughly equivalent to booting with vsyscall=none, except
1232 that it will also disable the helpful warning if a program
1233 tries to use a vsyscall. With this option set to N, offending
1234 programs will just segfault, citing addresses of the form
1237 This option is required by many programs built before 2013, and
1238 care should be used even with newer programs if set to N.
1240 Disabling this option saves about 7K of kernel size and
1241 possibly 4K of additional runtime pagetable memory.
1243 config X86_IOPL_IOPERM
1244 bool "IOPERM and IOPL Emulation"
1247 This enables the ioperm() and iopl() syscalls which are necessary
1248 for legacy applications.
1250 Legacy IOPL support is an overbroad mechanism which allows user
1251 space aside of accessing all 65536 I/O ports also to disable
1252 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1253 capabilities and permission from potentially active security
1256 The emulation restricts the functionality of the syscall to
1257 only allowing the full range I/O port access, but prevents the
1258 ability to disable interrupts from user space which would be
1259 granted if the hardware IOPL mechanism would be used.
1262 tristate "Toshiba Laptop support"
1265 This adds a driver to safely access the System Management Mode of
1266 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1267 not work on models with a Phoenix BIOS. The System Management Mode
1268 is used to set the BIOS and power saving options on Toshiba portables.
1270 For information on utilities to make use of this driver see the
1271 Toshiba Linux utilities web site at:
1272 <http://www.buzzard.org.uk/toshiba/>.
1274 Say Y if you intend to run this kernel on a Toshiba portable.
1278 tristate "Dell i8k legacy laptop support"
1281 select SENSORS_DELL_SMM
1283 This option enables legacy /proc/i8k userspace interface in hwmon
1284 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1285 temperature and allows controlling fan speeds of Dell laptops via
1286 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1287 it reports also power and hotkey status. For fan speed control is
1288 needed userspace package i8kutils.
1290 Say Y if you intend to run this kernel on old Dell laptops or want to
1291 use userspace package i8kutils.
1294 config X86_REBOOTFIXUPS
1295 bool "Enable X86 board specific fixups for reboot"
1298 This enables chipset and/or board specific fixups to be done
1299 in order to get reboot to work correctly. This is only needed on
1300 some combinations of hardware and BIOS. The symptom, for which
1301 this config is intended, is when reboot ends with a stalled/hung
1304 Currently, the only fixup is for the Geode machines using
1305 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1307 Say Y if you want to enable the fixup. Currently, it's safe to
1308 enable this option even if you don't need it.
1312 bool "CPU microcode loading support"
1314 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1316 If you say Y here, you will be able to update the microcode on
1317 Intel and AMD processors. The Intel support is for the IA32 family,
1318 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1319 AMD support is for families 0x10 and later. You will obviously need
1320 the actual microcode binary data itself which is not shipped with
1323 The preferred method to load microcode from a detached initrd is described
1324 in Documentation/x86/microcode.rst. For that you need to enable
1325 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1326 initrd for microcode blobs.
1328 In addition, you can build the microcode into the kernel. For that you
1329 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1332 config MICROCODE_INTEL
1333 bool "Intel microcode loading support"
1334 depends on MICROCODE
1337 This options enables microcode patch loading support for Intel
1340 For the current Intel microcode data package go to
1341 <https://downloadcenter.intel.com> and search for
1342 'Linux Processor Microcode Data File'.
1344 config MICROCODE_AMD
1345 bool "AMD microcode loading support"
1346 depends on MICROCODE
1348 If you select this option, microcode patch loading support for AMD
1349 processors will be enabled.
1351 config MICROCODE_OLD_INTERFACE
1352 bool "Ancient loading interface (DEPRECATED)"
1354 depends on MICROCODE
1356 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1357 which was used by userspace tools like iucode_tool and microcode.ctl.
1358 It is inadequate because it runs too late to be able to properly
1359 load microcode on a machine and it needs special tools. Instead, you
1360 should've switched to the early loading method with the initrd or
1361 builtin microcode by now: Documentation/x86/microcode.rst
1364 tristate "/dev/cpu/*/msr - Model-specific register support"
1366 This device gives privileged processes access to the x86
1367 Model-Specific Registers (MSRs). It is a character device with
1368 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1369 MSR accesses are directed to a specific CPU on multi-processor
1373 tristate "/dev/cpu/*/cpuid - CPU information support"
1375 This device gives processes access to the x86 CPUID instruction to
1376 be executed on a specific processor. It is a character device
1377 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1381 prompt "High Memory Support"
1388 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1389 However, the address space of 32-bit x86 processors is only 4
1390 Gigabytes large. That means that, if you have a large amount of
1391 physical memory, not all of it can be "permanently mapped" by the
1392 kernel. The physical memory that's not permanently mapped is called
1395 If you are compiling a kernel which will never run on a machine with
1396 more than 1 Gigabyte total physical RAM, answer "off" here (default
1397 choice and suitable for most users). This will result in a "3GB/1GB"
1398 split: 3GB are mapped so that each process sees a 3GB virtual memory
1399 space and the remaining part of the 4GB virtual memory space is used
1400 by the kernel to permanently map as much physical memory as
1403 If the machine has between 1 and 4 Gigabytes physical RAM, then
1406 If more than 4 Gigabytes is used then answer "64GB" here. This
1407 selection turns Intel PAE (Physical Address Extension) mode on.
1408 PAE implements 3-level paging on IA32 processors. PAE is fully
1409 supported by Linux, PAE mode is implemented on all recent Intel
1410 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1411 then the kernel will not boot on CPUs that don't support PAE!
1413 The actual amount of total physical memory will either be
1414 auto detected or can be forced by using a kernel command line option
1415 such as "mem=256M". (Try "man bootparam" or see the documentation of
1416 your boot loader (lilo or loadlin) about how to pass options to the
1417 kernel at boot time.)
1419 If unsure, say "off".
1424 Select this if you have a 32-bit processor and between 1 and 4
1425 gigabytes of physical RAM.
1429 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1432 Select this if you have a 32-bit processor and more than 4
1433 gigabytes of physical RAM.
1438 prompt "Memory split" if EXPERT
1442 Select the desired split between kernel and user memory.
1444 If the address range available to the kernel is less than the
1445 physical memory installed, the remaining memory will be available
1446 as "high memory". Accessing high memory is a little more costly
1447 than low memory, as it needs to be mapped into the kernel first.
1448 Note that increasing the kernel address space limits the range
1449 available to user programs, making the address space there
1450 tighter. Selecting anything other than the default 3G/1G split
1451 will also likely make your kernel incompatible with binary-only
1454 If you are not absolutely sure what you are doing, leave this
1458 bool "3G/1G user/kernel split"
1459 config VMSPLIT_3G_OPT
1461 bool "3G/1G user/kernel split (for full 1G low memory)"
1463 bool "2G/2G user/kernel split"
1464 config VMSPLIT_2G_OPT
1466 bool "2G/2G user/kernel split (for full 2G low memory)"
1468 bool "1G/3G user/kernel split"
1473 default 0xB0000000 if VMSPLIT_3G_OPT
1474 default 0x80000000 if VMSPLIT_2G
1475 default 0x78000000 if VMSPLIT_2G_OPT
1476 default 0x40000000 if VMSPLIT_1G
1482 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1485 bool "PAE (Physical Address Extension) Support"
1486 depends on X86_32 && !HIGHMEM4G
1487 select PHYS_ADDR_T_64BIT
1490 PAE is required for NX support, and furthermore enables
1491 larger swapspace support for non-overcommit purposes. It
1492 has the cost of more pagetable lookup overhead, and also
1493 consumes more pagetable space per process.
1496 bool "Enable 5-level page tables support"
1498 select DYNAMIC_MEMORY_LAYOUT
1499 select SPARSEMEM_VMEMMAP
1502 5-level paging enables access to larger address space:
1503 upto 128 PiB of virtual address space and 4 PiB of
1504 physical address space.
1506 It will be supported by future Intel CPUs.
1508 A kernel with the option enabled can be booted on machines that
1509 support 4- or 5-level paging.
1511 See Documentation/x86/x86_64/5level-paging.rst for more
1516 config X86_DIRECT_GBPAGES
1520 Certain kernel features effectively disable kernel
1521 linear 1 GB mappings (even if the CPU otherwise
1522 supports them), so don't confuse the user by printing
1523 that we have them enabled.
1525 config X86_CPA_STATISTICS
1526 bool "Enable statistic for Change Page Attribute"
1529 Expose statistics about the Change Page Attribute mechanism, which
1530 helps to determine the effectiveness of preserving large and huge
1531 page mappings when mapping protections are changed.
1533 config X86_MEM_ENCRYPT
1534 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1535 select DYNAMIC_PHYSICAL_MASK
1536 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1539 config AMD_MEM_ENCRYPT
1540 bool "AMD Secure Memory Encryption (SME) support"
1541 depends on X86_64 && CPU_SUP_AMD
1542 select DMA_COHERENT_POOL
1543 select ARCH_USE_MEMREMAP_PROT
1544 select INSTRUCTION_DECODER
1545 select ARCH_HAS_CC_PLATFORM
1546 select X86_MEM_ENCRYPT
1548 Say yes to enable support for the encryption of system memory.
1549 This requires an AMD processor that supports Secure Memory
1552 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1553 bool "Activate AMD Secure Memory Encryption (SME) by default"
1554 depends on AMD_MEM_ENCRYPT
1556 Say yes to have system memory encrypted by default if running on
1557 an AMD processor that supports Secure Memory Encryption (SME).
1559 If set to Y, then the encryption of system memory can be
1560 deactivated with the mem_encrypt=off command line option.
1562 If set to N, then the encryption of system memory can be
1563 activated with the mem_encrypt=on command line option.
1565 # Common NUMA Features
1567 bool "NUMA Memory Allocation and Scheduler Support"
1569 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1570 default y if X86_BIGSMP
1571 select USE_PERCPU_NUMA_NODE_ID
1573 Enable NUMA (Non-Uniform Memory Access) support.
1575 The kernel will try to allocate memory used by a CPU on the
1576 local memory controller of the CPU and add some more
1577 NUMA awareness to the kernel.
1579 For 64-bit this is recommended if the system is Intel Core i7
1580 (or later), AMD Opteron, or EM64T NUMA.
1582 For 32-bit this is only needed if you boot a 32-bit
1583 kernel on a 64-bit NUMA platform.
1585 Otherwise, you should say N.
1589 prompt "Old style AMD Opteron NUMA detection"
1590 depends on X86_64 && NUMA && PCI
1592 Enable AMD NUMA node topology detection. You should say Y here if
1593 you have a multi processor AMD system. This uses an old method to
1594 read the NUMA configuration directly from the builtin Northbridge
1595 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1596 which also takes priority if both are compiled in.
1598 config X86_64_ACPI_NUMA
1600 prompt "ACPI NUMA detection"
1601 depends on X86_64 && NUMA && ACPI && PCI
1604 Enable ACPI SRAT based node topology detection.
1607 bool "NUMA emulation"
1610 Enable NUMA emulation. A flat machine will be split
1611 into virtual nodes when booted with "numa=fake=N", where N is the
1612 number of nodes. This is only useful for debugging.
1615 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1617 default "10" if MAXSMP
1618 default "6" if X86_64
1622 Specify the maximum number of NUMA Nodes available on the target
1623 system. Increases memory reserved to accommodate various tables.
1625 config ARCH_FLATMEM_ENABLE
1627 depends on X86_32 && !NUMA
1629 config ARCH_SPARSEMEM_ENABLE
1631 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1632 select SPARSEMEM_STATIC if X86_32
1633 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1635 config ARCH_SPARSEMEM_DEFAULT
1636 def_bool X86_64 || (NUMA && X86_32)
1638 config ARCH_SELECT_MEMORY_MODEL
1640 depends on ARCH_SPARSEMEM_ENABLE
1642 config ARCH_MEMORY_PROBE
1643 bool "Enable sysfs memory/probe interface"
1644 depends on MEMORY_HOTPLUG
1646 This option enables a sysfs memory/probe interface for testing.
1647 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1648 If you are unsure how to answer this question, answer N.
1650 config ARCH_PROC_KCORE_TEXT
1652 depends on X86_64 && PROC_KCORE
1654 config ILLEGAL_POINTER_VALUE
1657 default 0xdead000000000000 if X86_64
1659 config X86_PMEM_LEGACY_DEVICE
1662 config X86_PMEM_LEGACY
1663 tristate "Support non-standard NVDIMMs and ADR protected memory"
1664 depends on PHYS_ADDR_T_64BIT
1666 select X86_PMEM_LEGACY_DEVICE
1667 select NUMA_KEEP_MEMINFO if NUMA
1670 Treat memory marked using the non-standard e820 type of 12 as used
1671 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1672 The kernel will offer these regions to the 'pmem' driver so
1673 they can be used for persistent storage.
1678 bool "Allocate 3rd-level pagetables from highmem"
1681 The VM uses one page table entry for each page of physical memory.
1682 For systems with a lot of RAM, this can be wasteful of precious
1683 low memory. Setting this option will put user-space page table
1684 entries in high memory.
1686 config X86_CHECK_BIOS_CORRUPTION
1687 bool "Check for low memory corruption"
1689 Periodically check for memory corruption in low memory, which
1690 is suspected to be caused by BIOS. Even when enabled in the
1691 configuration, it is disabled at runtime. Enable it by
1692 setting "memory_corruption_check=1" on the kernel command
1693 line. By default it scans the low 64k of memory every 60
1694 seconds; see the memory_corruption_check_size and
1695 memory_corruption_check_period parameters in
1696 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1698 When enabled with the default parameters, this option has
1699 almost no overhead, as it reserves a relatively small amount
1700 of memory and scans it infrequently. It both detects corruption
1701 and prevents it from affecting the running system.
1703 It is, however, intended as a diagnostic tool; if repeatable
1704 BIOS-originated corruption always affects the same memory,
1705 you can use memmap= to prevent the kernel from using that
1708 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1709 bool "Set the default setting of memory_corruption_check"
1710 depends on X86_CHECK_BIOS_CORRUPTION
1713 Set whether the default state of memory_corruption_check is
1716 config MATH_EMULATION
1718 depends on MODIFY_LDT_SYSCALL
1719 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1721 Linux can emulate a math coprocessor (used for floating point
1722 operations) if you don't have one. 486DX and Pentium processors have
1723 a math coprocessor built in, 486SX and 386 do not, unless you added
1724 a 487DX or 387, respectively. (The messages during boot time can
1725 give you some hints here ["man dmesg"].) Everyone needs either a
1726 coprocessor or this emulation.
1728 If you don't have a math coprocessor, you need to say Y here; if you
1729 say Y here even though you have a coprocessor, the coprocessor will
1730 be used nevertheless. (This behavior can be changed with the kernel
1731 command line option "no387", which comes handy if your coprocessor
1732 is broken. Try "man bootparam" or see the documentation of your boot
1733 loader (lilo or loadlin) about how to pass options to the kernel at
1734 boot time.) This means that it is a good idea to say Y here if you
1735 intend to use this kernel on different machines.
1737 More information about the internals of the Linux math coprocessor
1738 emulation can be found in <file:arch/x86/math-emu/README>.
1740 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1741 kernel, it won't hurt.
1745 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1747 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1748 the Memory Type Range Registers (MTRRs) may be used to control
1749 processor access to memory ranges. This is most useful if you have
1750 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1751 allows bus write transfers to be combined into a larger transfer
1752 before bursting over the PCI/AGP bus. This can increase performance
1753 of image write operations 2.5 times or more. Saying Y here creates a
1754 /proc/mtrr file which may be used to manipulate your processor's
1755 MTRRs. Typically the X server should use this.
1757 This code has a reasonably generic interface so that similar
1758 control registers on other processors can be easily supported
1761 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1762 Registers (ARRs) which provide a similar functionality to MTRRs. For
1763 these, the ARRs are used to emulate the MTRRs.
1764 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1765 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1766 write-combining. All of these processors are supported by this code
1767 and it makes sense to say Y here if you have one of them.
1769 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1770 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1771 can lead to all sorts of problems, so it's good to say Y here.
1773 You can safely say Y even if your machine doesn't have MTRRs, you'll
1774 just add about 9 KB to your kernel.
1776 See <file:Documentation/x86/mtrr.rst> for more information.
1778 config MTRR_SANITIZER
1780 prompt "MTRR cleanup support"
1783 Convert MTRR layout from continuous to discrete, so X drivers can
1784 add writeback entries.
1786 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1787 The largest mtrr entry size for a continuous block can be set with
1792 config MTRR_SANITIZER_ENABLE_DEFAULT
1793 int "MTRR cleanup enable value (0-1)"
1796 depends on MTRR_SANITIZER
1798 Enable mtrr cleanup default value
1800 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1801 int "MTRR cleanup spare reg num (0-7)"
1804 depends on MTRR_SANITIZER
1806 mtrr cleanup spare entries default, it can be changed via
1807 mtrr_spare_reg_nr=N on the kernel command line.
1811 prompt "x86 PAT support" if EXPERT
1814 Use PAT attributes to setup page level cache control.
1816 PATs are the modern equivalents of MTRRs and are much more
1817 flexible than MTRRs.
1819 Say N here if you see bootup problems (boot crash, boot hang,
1820 spontaneous reboots) or a non-working video driver.
1824 config ARCH_USES_PG_UNCACHED
1830 prompt "x86 architectural random number generator" if EXPERT
1832 Enable the x86 architectural RDRAND instruction
1833 (Intel Bull Mountain technology) to generate random numbers.
1834 If supported, this is a high bandwidth, cryptographically
1835 secure hardware random number generator.
1839 prompt "Supervisor Mode Access Prevention" if EXPERT
1841 Supervisor Mode Access Prevention (SMAP) is a security
1842 feature in newer Intel processors. There is a small
1843 performance cost if this enabled and turned on; there is
1844 also a small increase in the kernel size if this is enabled.
1850 prompt "User Mode Instruction Prevention" if EXPERT
1852 User Mode Instruction Prevention (UMIP) is a security feature in
1853 some x86 processors. If enabled, a general protection fault is
1854 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1855 executed in user mode. These instructions unnecessarily expose
1856 information about the hardware state.
1858 The vast majority of applications do not use these instructions.
1859 For the very few that do, software emulation is provided in
1860 specific cases in protected and virtual-8086 modes. Emulated
1863 config X86_INTEL_MEMORY_PROTECTION_KEYS
1864 prompt "Memory Protection Keys"
1866 # Note: only available in 64-bit mode
1867 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1868 select ARCH_USES_HIGH_VMA_FLAGS
1869 select ARCH_HAS_PKEYS
1871 Memory Protection Keys provides a mechanism for enforcing
1872 page-based protections, but without requiring modification of the
1873 page tables when an application changes protection domains.
1875 For details, see Documentation/core-api/protection-keys.rst
1880 prompt "TSX enable mode"
1881 depends on CPU_SUP_INTEL
1882 default X86_INTEL_TSX_MODE_OFF
1884 Intel's TSX (Transactional Synchronization Extensions) feature
1885 allows to optimize locking protocols through lock elision which
1886 can lead to a noticeable performance boost.
1888 On the other hand it has been shown that TSX can be exploited
1889 to form side channel attacks (e.g. TAA) and chances are there
1890 will be more of those attacks discovered in the future.
1892 Therefore TSX is not enabled by default (aka tsx=off). An admin
1893 might override this decision by tsx=on the command line parameter.
1894 Even with TSX enabled, the kernel will attempt to enable the best
1895 possible TAA mitigation setting depending on the microcode available
1896 for the particular machine.
1898 This option allows to set the default tsx mode between tsx=on, =off
1899 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1902 Say off if not sure, auto if TSX is in use but it should be used on safe
1903 platforms or on if TSX is in use and the security aspect of tsx is not
1906 config X86_INTEL_TSX_MODE_OFF
1909 TSX is disabled if possible - equals to tsx=off command line parameter.
1911 config X86_INTEL_TSX_MODE_ON
1914 TSX is always enabled on TSX capable HW - equals the tsx=on command
1917 config X86_INTEL_TSX_MODE_AUTO
1920 TSX is enabled on TSX capable HW that is believed to be safe against
1921 side channel attacks- equals the tsx=auto command line parameter.
1925 bool "Software Guard eXtensions (SGX)"
1926 depends on X86_64 && CPU_SUP_INTEL
1928 depends on CRYPTO_SHA256=y
1931 select NUMA_KEEP_MEMINFO if NUMA
1934 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1935 that can be used by applications to set aside private regions of code
1936 and data, referred to as enclaves. An enclave's private memory can
1937 only be accessed by code running within the enclave. Accesses from
1938 outside the enclave, including other enclaves, are disallowed by
1944 bool "EFI runtime service support"
1947 select EFI_RUNTIME_WRAPPERS
1948 select ARCH_USE_MEMREMAP_PROT
1950 This enables the kernel to use EFI runtime services that are
1951 available (such as the EFI variable services).
1953 This option is only useful on systems that have EFI firmware.
1954 In addition, you should use the latest ELILO loader available
1955 at <http://elilo.sourceforge.net> in order to take advantage
1956 of EFI runtime services. However, even with this option, the
1957 resultant kernel should continue to boot on existing non-EFI
1961 bool "EFI stub support"
1963 depends on $(cc-option,-mabi=ms) || X86_32
1966 This kernel feature allows a bzImage to be loaded directly
1967 by EFI firmware without the use of a bootloader.
1969 See Documentation/admin-guide/efi-stub.rst for more information.
1972 bool "EFI mixed-mode support"
1973 depends on EFI_STUB && X86_64
1975 Enabling this feature allows a 64-bit kernel to be booted
1976 on a 32-bit firmware, provided that your CPU supports 64-bit
1979 Note that it is not possible to boot a mixed-mode enabled
1980 kernel via the EFI boot stub - a bootloader that supports
1981 the EFI handover protocol must be used.
1985 source "kernel/Kconfig.hz"
1988 bool "kexec system call"
1991 kexec is a system call that implements the ability to shutdown your
1992 current kernel, and to start another kernel. It is like a reboot
1993 but it is independent of the system firmware. And like a reboot
1994 you can start any kernel with it, not just Linux.
1996 The name comes from the similarity to the exec system call.
1998 It is an ongoing process to be certain the hardware in a machine
1999 is properly shutdown, so do not be surprised if this code does not
2000 initially work for you. As of this writing the exact hardware
2001 interface is strongly in flux, so no good recommendation can be
2005 bool "kexec file based system call"
2010 depends on CRYPTO_SHA256=y
2012 This is new version of kexec system call. This system call is
2013 file based and takes file descriptors as system call argument
2014 for kernel and initramfs as opposed to list of segments as
2015 accepted by previous system call.
2017 config ARCH_HAS_KEXEC_PURGATORY
2021 bool "Verify kernel signature during kexec_file_load() syscall"
2022 depends on KEXEC_FILE
2025 This option makes the kexec_file_load() syscall check for a valid
2026 signature of the kernel image. The image can still be loaded without
2027 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2028 there's a signature that we can check, then it must be valid.
2030 In addition to this option, you need to enable signature
2031 verification for the corresponding kernel image type being
2032 loaded in order for this to work.
2034 config KEXEC_SIG_FORCE
2035 bool "Require a valid signature in kexec_file_load() syscall"
2036 depends on KEXEC_SIG
2038 This option makes kernel signature verification mandatory for
2039 the kexec_file_load() syscall.
2041 config KEXEC_BZIMAGE_VERIFY_SIG
2042 bool "Enable bzImage signature verification support"
2043 depends on KEXEC_SIG
2044 depends on SIGNED_PE_FILE_VERIFICATION
2045 select SYSTEM_TRUSTED_KEYRING
2047 Enable bzImage signature verification support.
2050 bool "kernel crash dumps"
2051 depends on X86_64 || (X86_32 && HIGHMEM)
2053 Generate crash dump after being started by kexec.
2054 This should be normally only set in special crash dump kernels
2055 which are loaded in the main kernel with kexec-tools into
2056 a specially reserved region and then later executed after
2057 a crash by kdump/kexec. The crash dump kernel must be compiled
2058 to a memory address not used by the main kernel or BIOS using
2059 PHYSICAL_START, or it must be built as a relocatable image
2060 (CONFIG_RELOCATABLE=y).
2061 For more details see Documentation/admin-guide/kdump/kdump.rst
2065 depends on KEXEC && HIBERNATION
2067 Jump between original kernel and kexeced kernel and invoke
2068 code in physical address mode via KEXEC
2070 config PHYSICAL_START
2071 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2074 This gives the physical address where the kernel is loaded.
2076 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2077 bzImage will decompress itself to above physical address and
2078 run from there. Otherwise, bzImage will run from the address where
2079 it has been loaded by the boot loader and will ignore above physical
2082 In normal kdump cases one does not have to set/change this option
2083 as now bzImage can be compiled as a completely relocatable image
2084 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2085 address. This option is mainly useful for the folks who don't want
2086 to use a bzImage for capturing the crash dump and want to use a
2087 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2088 to be specifically compiled to run from a specific memory area
2089 (normally a reserved region) and this option comes handy.
2091 So if you are using bzImage for capturing the crash dump,
2092 leave the value here unchanged to 0x1000000 and set
2093 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2094 for capturing the crash dump change this value to start of
2095 the reserved region. In other words, it can be set based on
2096 the "X" value as specified in the "crashkernel=YM@XM"
2097 command line boot parameter passed to the panic-ed
2098 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2099 for more details about crash dumps.
2101 Usage of bzImage for capturing the crash dump is recommended as
2102 one does not have to build two kernels. Same kernel can be used
2103 as production kernel and capture kernel. Above option should have
2104 gone away after relocatable bzImage support is introduced. But it
2105 is present because there are users out there who continue to use
2106 vmlinux for dump capture. This option should go away down the
2109 Don't change this unless you know what you are doing.
2112 bool "Build a relocatable kernel"
2115 This builds a kernel image that retains relocation information
2116 so it can be loaded someplace besides the default 1MB.
2117 The relocations tend to make the kernel binary about 10% larger,
2118 but are discarded at runtime.
2120 One use is for the kexec on panic case where the recovery kernel
2121 must live at a different physical address than the primary
2124 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2125 it has been loaded at and the compile time physical address
2126 (CONFIG_PHYSICAL_START) is used as the minimum location.
2128 config RANDOMIZE_BASE
2129 bool "Randomize the address of the kernel image (KASLR)"
2130 depends on RELOCATABLE
2133 In support of Kernel Address Space Layout Randomization (KASLR),
2134 this randomizes the physical address at which the kernel image
2135 is decompressed and the virtual address where the kernel
2136 image is mapped, as a security feature that deters exploit
2137 attempts relying on knowledge of the location of kernel
2140 On 64-bit, the kernel physical and virtual addresses are
2141 randomized separately. The physical address will be anywhere
2142 between 16MB and the top of physical memory (up to 64TB). The
2143 virtual address will be randomized from 16MB up to 1GB (9 bits
2144 of entropy). Note that this also reduces the memory space
2145 available to kernel modules from 1.5GB to 1GB.
2147 On 32-bit, the kernel physical and virtual addresses are
2148 randomized together. They will be randomized from 16MB up to
2149 512MB (8 bits of entropy).
2151 Entropy is generated using the RDRAND instruction if it is
2152 supported. If RDTSC is supported, its value is mixed into
2153 the entropy pool as well. If neither RDRAND nor RDTSC are
2154 supported, then entropy is read from the i8254 timer. The
2155 usable entropy is limited by the kernel being built using
2156 2GB addressing, and that PHYSICAL_ALIGN must be at a
2157 minimum of 2MB. As a result, only 10 bits of entropy are
2158 theoretically possible, but the implementations are further
2159 limited due to memory layouts.
2163 # Relocation on x86 needs some additional build support
2164 config X86_NEED_RELOCS
2166 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2168 config PHYSICAL_ALIGN
2169 hex "Alignment value to which kernel should be aligned"
2171 range 0x2000 0x1000000 if X86_32
2172 range 0x200000 0x1000000 if X86_64
2174 This value puts the alignment restrictions on physical address
2175 where kernel is loaded and run from. Kernel is compiled for an
2176 address which meets above alignment restriction.
2178 If bootloader loads the kernel at a non-aligned address and
2179 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2180 address aligned to above value and run from there.
2182 If bootloader loads the kernel at a non-aligned address and
2183 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2184 load address and decompress itself to the address it has been
2185 compiled for and run from there. The address for which kernel is
2186 compiled already meets above alignment restrictions. Hence the
2187 end result is that kernel runs from a physical address meeting
2188 above alignment restrictions.
2190 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2191 this value must be a multiple of 0x200000.
2193 Don't change this unless you know what you are doing.
2195 config DYNAMIC_MEMORY_LAYOUT
2198 This option makes base addresses of vmalloc and vmemmap as well as
2199 __PAGE_OFFSET movable during boot.
2201 config RANDOMIZE_MEMORY
2202 bool "Randomize the kernel memory sections"
2204 depends on RANDOMIZE_BASE
2205 select DYNAMIC_MEMORY_LAYOUT
2206 default RANDOMIZE_BASE
2208 Randomizes the base virtual address of kernel memory sections
2209 (physical memory mapping, vmalloc & vmemmap). This security feature
2210 makes exploits relying on predictable memory locations less reliable.
2212 The order of allocations remains unchanged. Entropy is generated in
2213 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2214 configuration have in average 30,000 different possible virtual
2215 addresses for each memory section.
2219 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2220 hex "Physical memory mapping padding" if EXPERT
2221 depends on RANDOMIZE_MEMORY
2222 default "0xa" if MEMORY_HOTPLUG
2224 range 0x1 0x40 if MEMORY_HOTPLUG
2227 Define the padding in terabytes added to the existing physical
2228 memory size during kernel memory randomization. It is useful
2229 for memory hotplug support but reduces the entropy available for
2230 address randomization.
2232 If unsure, leave at the default value.
2238 config BOOTPARAM_HOTPLUG_CPU0
2239 bool "Set default setting of cpu0_hotpluggable"
2240 depends on HOTPLUG_CPU
2242 Set whether default state of cpu0_hotpluggable is on or off.
2244 Say Y here to enable CPU0 hotplug by default. If this switch
2245 is turned on, there is no need to give cpu0_hotplug kernel
2246 parameter and the CPU0 hotplug feature is enabled by default.
2248 Please note: there are two known CPU0 dependencies if you want
2249 to enable the CPU0 hotplug feature either by this switch or by
2250 cpu0_hotplug kernel parameter.
2252 First, resume from hibernate or suspend always starts from CPU0.
2253 So hibernate and suspend are prevented if CPU0 is offline.
2255 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2256 offline if any interrupt can not migrate out of CPU0. There may
2257 be other CPU0 dependencies.
2259 Please make sure the dependencies are under your control before
2260 you enable this feature.
2262 Say N if you don't want to enable CPU0 hotplug feature by default.
2263 You still can enable the CPU0 hotplug feature at boot by kernel
2264 parameter cpu0_hotplug.
2266 config DEBUG_HOTPLUG_CPU0
2268 prompt "Debug CPU0 hotplug"
2269 depends on HOTPLUG_CPU
2271 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2272 soon as possible and boots up userspace with CPU0 offlined. User
2273 can online CPU0 back after boot time.
2275 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2276 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2277 compilation or giving cpu0_hotplug kernel parameter at boot.
2283 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2284 depends on COMPAT_32
2286 Certain buggy versions of glibc will crash if they are
2287 presented with a 32-bit vDSO that is not mapped at the address
2288 indicated in its segment table.
2290 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2291 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2292 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2293 the only released version with the bug, but OpenSUSE 9
2294 contains a buggy "glibc 2.3.2".
2296 The symptom of the bug is that everything crashes on startup, saying:
2297 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2299 Saying Y here changes the default value of the vdso32 boot
2300 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2301 This works around the glibc bug but hurts performance.
2303 If unsure, say N: if you are compiling your own kernel, you
2304 are unlikely to be using a buggy version of glibc.
2307 prompt "vsyscall table for legacy applications"
2309 default LEGACY_VSYSCALL_XONLY
2311 Legacy user code that does not know how to find the vDSO expects
2312 to be able to issue three syscalls by calling fixed addresses in
2313 kernel space. Since this location is not randomized with ASLR,
2314 it can be used to assist security vulnerability exploitation.
2316 This setting can be changed at boot time via the kernel command
2317 line parameter vsyscall=[emulate|xonly|none].
2319 On a system with recent enough glibc (2.14 or newer) and no
2320 static binaries, you can say None without a performance penalty
2321 to improve security.
2323 If unsure, select "Emulate execution only".
2325 config LEGACY_VSYSCALL_EMULATE
2326 bool "Full emulation"
2328 The kernel traps and emulates calls into the fixed vsyscall
2329 address mapping. This makes the mapping non-executable, but
2330 it still contains readable known contents, which could be
2331 used in certain rare security vulnerability exploits. This
2332 configuration is recommended when using legacy userspace
2333 that still uses vsyscalls along with legacy binary
2334 instrumentation tools that require code to be readable.
2336 An example of this type of legacy userspace is running
2337 Pin on an old binary that still uses vsyscalls.
2339 config LEGACY_VSYSCALL_XONLY
2340 bool "Emulate execution only"
2342 The kernel traps and emulates calls into the fixed vsyscall
2343 address mapping and does not allow reads. This
2344 configuration is recommended when userspace might use the
2345 legacy vsyscall area but support for legacy binary
2346 instrumentation of legacy code is not needed. It mitigates
2347 certain uses of the vsyscall area as an ASLR-bypassing
2350 config LEGACY_VSYSCALL_NONE
2353 There will be no vsyscall mapping at all. This will
2354 eliminate any risk of ASLR bypass due to the vsyscall
2355 fixed address mapping. Attempts to use the vsyscalls
2356 will be reported to dmesg, so that either old or
2357 malicious userspace programs can be identified.
2362 bool "Built-in kernel command line"
2364 Allow for specifying boot arguments to the kernel at
2365 build time. On some systems (e.g. embedded ones), it is
2366 necessary or convenient to provide some or all of the
2367 kernel boot arguments with the kernel itself (that is,
2368 to not rely on the boot loader to provide them.)
2370 To compile command line arguments into the kernel,
2371 set this option to 'Y', then fill in the
2372 boot arguments in CONFIG_CMDLINE.
2374 Systems with fully functional boot loaders (i.e. non-embedded)
2375 should leave this option set to 'N'.
2378 string "Built-in kernel command string"
2379 depends on CMDLINE_BOOL
2382 Enter arguments here that should be compiled into the kernel
2383 image and used at boot time. If the boot loader provides a
2384 command line at boot time, it is appended to this string to
2385 form the full kernel command line, when the system boots.
2387 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2388 change this behavior.
2390 In most cases, the command line (whether built-in or provided
2391 by the boot loader) should specify the device for the root
2394 config CMDLINE_OVERRIDE
2395 bool "Built-in command line overrides boot loader arguments"
2396 depends on CMDLINE_BOOL && CMDLINE != ""
2398 Set this option to 'Y' to have the kernel ignore the boot loader
2399 command line, and use ONLY the built-in command line.
2401 This is used to work around broken boot loaders. This should
2402 be set to 'N' under normal conditions.
2404 config MODIFY_LDT_SYSCALL
2405 bool "Enable the LDT (local descriptor table)" if EXPERT
2408 Linux can allow user programs to install a per-process x86
2409 Local Descriptor Table (LDT) using the modify_ldt(2) system
2410 call. This is required to run 16-bit or segmented code such as
2411 DOSEMU or some Wine programs. It is also used by some very old
2412 threading libraries.
2414 Enabling this feature adds a small amount of overhead to
2415 context switches and increases the low-level kernel attack
2416 surface. Disabling it removes the modify_ldt(2) system call.
2418 Saying 'N' here may make sense for embedded or server kernels.
2420 config STRICT_SIGALTSTACK_SIZE
2421 bool "Enforce strict size checking for sigaltstack"
2422 depends on DYNAMIC_SIGFRAME
2424 For historical reasons MINSIGSTKSZ is a constant which became
2425 already too small with AVX512 support. Add a mechanism to
2426 enforce strict checking of the sigaltstack size against the
2427 real size of the FPU frame. This option enables the check
2428 by default. It can also be controlled via the kernel command
2429 line option 'strict_sas_size' independent of this config
2430 switch. Enabling it might break existing applications which
2431 allocate a too small sigaltstack but 'work' because they
2432 never get a signal delivered.
2434 Say 'N' unless you want to really enforce this check.
2436 source "kernel/livepatch/Kconfig"
2440 config ARCH_HAS_ADD_PAGES
2442 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2444 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2447 menu "Power management and ACPI options"
2449 config ARCH_HIBERNATION_HEADER
2451 depends on HIBERNATION
2453 source "kernel/power/Kconfig"
2455 source "drivers/acpi/Kconfig"
2462 tristate "APM (Advanced Power Management) BIOS support"
2463 depends on X86_32 && PM_SLEEP
2465 APM is a BIOS specification for saving power using several different
2466 techniques. This is mostly useful for battery powered laptops with
2467 APM compliant BIOSes. If you say Y here, the system time will be
2468 reset after a RESUME operation, the /proc/apm device will provide
2469 battery status information, and user-space programs will receive
2470 notification of APM "events" (e.g. battery status change).
2472 If you select "Y" here, you can disable actual use of the APM
2473 BIOS by passing the "apm=off" option to the kernel at boot time.
2475 Note that the APM support is almost completely disabled for
2476 machines with more than one CPU.
2478 In order to use APM, you will need supporting software. For location
2479 and more information, read <file:Documentation/power/apm-acpi.rst>
2480 and the Battery Powered Linux mini-HOWTO, available from
2481 <http://www.tldp.org/docs.html#howto>.
2483 This driver does not spin down disk drives (see the hdparm(8)
2484 manpage ("man 8 hdparm") for that), and it doesn't turn off
2485 VESA-compliant "green" monitors.
2487 This driver does not support the TI 4000M TravelMate and the ACER
2488 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2489 desktop machines also don't have compliant BIOSes, and this driver
2490 may cause those machines to panic during the boot phase.
2492 Generally, if you don't have a battery in your machine, there isn't
2493 much point in using this driver and you should say N. If you get
2494 random kernel OOPSes or reboots that don't seem to be related to
2495 anything, try disabling/enabling this option (or disabling/enabling
2498 Some other things you should try when experiencing seemingly random,
2501 1) make sure that you have enough swap space and that it is
2503 2) pass the "no-hlt" option to the kernel
2504 3) switch on floating point emulation in the kernel and pass
2505 the "no387" option to the kernel
2506 4) pass the "floppy=nodma" option to the kernel
2507 5) pass the "mem=4M" option to the kernel (thereby disabling
2508 all but the first 4 MB of RAM)
2509 6) make sure that the CPU is not over clocked.
2510 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2511 8) disable the cache from your BIOS settings
2512 9) install a fan for the video card or exchange video RAM
2513 10) install a better fan for the CPU
2514 11) exchange RAM chips
2515 12) exchange the motherboard.
2517 To compile this driver as a module, choose M here: the
2518 module will be called apm.
2522 config APM_IGNORE_USER_SUSPEND
2523 bool "Ignore USER SUSPEND"
2525 This option will ignore USER SUSPEND requests. On machines with a
2526 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2527 series notebooks, it is necessary to say Y because of a BIOS bug.
2529 config APM_DO_ENABLE
2530 bool "Enable PM at boot time"
2532 Enable APM features at boot time. From page 36 of the APM BIOS
2533 specification: "When disabled, the APM BIOS does not automatically
2534 power manage devices, enter the Standby State, enter the Suspend
2535 State, or take power saving steps in response to CPU Idle calls."
2536 This driver will make CPU Idle calls when Linux is idle (unless this
2537 feature is turned off -- see "Do CPU IDLE calls", below). This
2538 should always save battery power, but more complicated APM features
2539 will be dependent on your BIOS implementation. You may need to turn
2540 this option off if your computer hangs at boot time when using APM
2541 support, or if it beeps continuously instead of suspending. Turn
2542 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2543 T400CDT. This is off by default since most machines do fine without
2548 bool "Make CPU Idle calls when idle"
2550 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2551 On some machines, this can activate improved power savings, such as
2552 a slowed CPU clock rate, when the machine is idle. These idle calls
2553 are made after the idle loop has run for some length of time (e.g.,
2554 333 mS). On some machines, this will cause a hang at boot time or
2555 whenever the CPU becomes idle. (On machines with more than one CPU,
2556 this option does nothing.)
2558 config APM_DISPLAY_BLANK
2559 bool "Enable console blanking using APM"
2561 Enable console blanking using the APM. Some laptops can use this to
2562 turn off the LCD backlight when the screen blanker of the Linux
2563 virtual console blanks the screen. Note that this is only used by
2564 the virtual console screen blanker, and won't turn off the backlight
2565 when using the X Window system. This also doesn't have anything to
2566 do with your VESA-compliant power-saving monitor. Further, this
2567 option doesn't work for all laptops -- it might not turn off your
2568 backlight at all, or it might print a lot of errors to the console,
2569 especially if you are using gpm.
2571 config APM_ALLOW_INTS
2572 bool "Allow interrupts during APM BIOS calls"
2574 Normally we disable external interrupts while we are making calls to
2575 the APM BIOS as a measure to lessen the effects of a badly behaving
2576 BIOS implementation. The BIOS should reenable interrupts if it
2577 needs to. Unfortunately, some BIOSes do not -- especially those in
2578 many of the newer IBM Thinkpads. If you experience hangs when you
2579 suspend, try setting this to Y. Otherwise, say N.
2583 source "drivers/cpufreq/Kconfig"
2585 source "drivers/cpuidle/Kconfig"
2587 source "drivers/idle/Kconfig"
2592 menu "Bus options (PCI etc.)"
2595 prompt "PCI access mode"
2596 depends on X86_32 && PCI
2599 On PCI systems, the BIOS can be used to detect the PCI devices and
2600 determine their configuration. However, some old PCI motherboards
2601 have BIOS bugs and may crash if this is done. Also, some embedded
2602 PCI-based systems don't have any BIOS at all. Linux can also try to
2603 detect the PCI hardware directly without using the BIOS.
2605 With this option, you can specify how Linux should detect the
2606 PCI devices. If you choose "BIOS", the BIOS will be used,
2607 if you choose "Direct", the BIOS won't be used, and if you
2608 choose "MMConfig", then PCI Express MMCONFIG will be used.
2609 If you choose "Any", the kernel will try MMCONFIG, then the
2610 direct access method and falls back to the BIOS if that doesn't
2611 work. If unsure, go with the default, which is "Any".
2616 config PCI_GOMMCONFIG
2633 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2635 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2638 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2641 bool "Support mmconfig PCI config space access" if X86_64
2643 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2644 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2648 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2652 depends on PCI && XEN
2654 config MMCONF_FAM10H
2656 depends on X86_64 && PCI_MMCONFIG && ACPI
2658 config PCI_CNB20LE_QUIRK
2659 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2662 Read the PCI windows out of the CNB20LE host bridge. This allows
2663 PCI hotplug to work on systems with the CNB20LE chipset which do
2666 There's no public spec for this chipset, and this functionality
2667 is known to be incomplete.
2669 You should say N unless you know you need this.
2672 bool "ISA bus support on modern systems" if EXPERT
2674 Expose ISA bus device drivers and options available for selection and
2675 configuration. Enable this option if your target machine has an ISA
2676 bus. ISA is an older system, displaced by PCI and newer bus
2677 architectures -- if your target machine is modern, it probably does
2678 not have an ISA bus.
2682 # x86_64 have no ISA slots, but can have ISA-style DMA.
2684 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2687 Enables ISA-style DMA support for devices requiring such controllers.
2695 Find out whether you have ISA slots on your motherboard. ISA is the
2696 name of a bus system, i.e. the way the CPU talks to the other stuff
2697 inside your box. Other bus systems are PCI, EISA, MicroChannel
2698 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2699 newer boards don't support it. If you have ISA, say Y, otherwise N.
2702 tristate "NatSemi SCx200 support"
2704 This provides basic support for National Semiconductor's
2705 (now AMD's) Geode processors. The driver probes for the
2706 PCI-IDs of several on-chip devices, so its a good dependency
2707 for other scx200_* drivers.
2709 If compiled as a module, the driver is named scx200.
2711 config SCx200HR_TIMER
2712 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2716 This driver provides a clocksource built upon the on-chip
2717 27MHz high-resolution timer. Its also a workaround for
2718 NSC Geode SC-1100's buggy TSC, which loses time when the
2719 processor goes idle (as is done by the scheduler). The
2720 other workaround is idle=poll boot option.
2723 bool "One Laptop Per Child support"
2731 Add support for detecting the unique features of the OLPC
2735 bool "OLPC XO-1 Power Management"
2736 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2738 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2741 bool "OLPC XO-1 Real Time Clock"
2742 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2744 Add support for the XO-1 real time clock, which can be used as a
2745 programmable wakeup source.
2748 bool "OLPC XO-1 SCI extras"
2749 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2753 Add support for SCI-based features of the OLPC XO-1 laptop:
2754 - EC-driven system wakeups
2758 - AC adapter status updates
2759 - Battery status updates
2761 config OLPC_XO15_SCI
2762 bool "OLPC XO-1.5 SCI extras"
2763 depends on OLPC && ACPI
2766 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2767 - EC-driven system wakeups
2768 - AC adapter status updates
2769 - Battery status updates
2772 bool "PCEngines ALIX System Support (LED setup)"
2775 This option enables system support for the PCEngines ALIX.
2776 At present this just sets up LEDs for GPIO control on
2777 ALIX2/3/6 boards. However, other system specific setup should
2780 Note: You must still enable the drivers for GPIO and LED support
2781 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2783 Note: You have to set alix.force=1 for boards with Award BIOS.
2786 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2789 This option enables system support for the Soekris Engineering net5501.
2792 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2796 This option enables system support for the Traverse Technologies GEOS.
2799 bool "Technologic Systems TS-5500 platform support"
2801 select CHECK_SIGNATURE
2805 This option enables system support for the Technologic Systems TS-5500.
2811 depends on CPU_SUP_AMD && PCI
2816 menu "Binary Emulations"
2818 config IA32_EMULATION
2819 bool "IA32 Emulation"
2821 select ARCH_WANT_OLD_COMPAT_IPC
2823 select COMPAT_OLD_SIGACTION
2825 Include code to run legacy 32-bit programs under a
2826 64-bit kernel. You should likely turn this on, unless you're
2827 100% sure that you don't have any 32-bit programs left.
2830 tristate "IA32 a.out support"
2831 depends on IA32_EMULATION
2834 Support old a.out binaries in the 32bit emulation.
2837 bool "x32 ABI for 64-bit mode"
2840 Include code to run binaries for the x32 native 32-bit ABI
2841 for 64-bit processors. An x32 process gets access to the
2842 full 64-bit register file and wide data path while leaving
2843 pointers at 32 bits for smaller memory footprint.
2845 You will need a recent binutils (2.22 or later) with
2846 elf32_x86_64 support enabled to compile a kernel with this
2851 depends on IA32_EMULATION || X86_32
2853 select OLD_SIGSUSPEND3
2857 depends on IA32_EMULATION || X86_X32
2860 config COMPAT_FOR_U64_ALIGNMENT
2863 config SYSVIPC_COMPAT
2871 config HAVE_ATOMIC_IOMAP
2875 source "arch/x86/kvm/Kconfig"
2877 source "arch/x86/Kconfig.assembler"