1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
65 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 || (X86_32 && HIGHMEM)
66 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
67 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
68 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
69 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
70 select ARCH_HAS_CACHE_LINE_SIZE
71 select ARCH_HAS_DEBUG_VIRTUAL
72 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
73 select ARCH_HAS_DEVMEM_IS_ALLOWED
74 select ARCH_HAS_EARLY_DEBUG if KGDB
75 select ARCH_HAS_ELF_RANDOMIZE
76 select ARCH_HAS_FAST_MULTIPLIER
77 select ARCH_HAS_FILTER_PGPROT
78 select ARCH_HAS_FORTIFY_SOURCE
79 select ARCH_HAS_GCOV_PROFILE_ALL
80 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
81 select ARCH_HAS_MEM_ENCRYPT
82 select ARCH_HAS_MEMBARRIER_SYNC_CORE
83 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
84 select ARCH_HAS_PMEM_API if X86_64
85 select ARCH_HAS_PTE_DEVMAP if X86_64
86 select ARCH_HAS_PTE_SPECIAL
87 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
88 select ARCH_HAS_COPY_MC if X86_64
89 select ARCH_HAS_SET_MEMORY
90 select ARCH_HAS_SET_DIRECT_MAP
91 select ARCH_HAS_STRICT_KERNEL_RWX
92 select ARCH_HAS_STRICT_MODULE_RWX
93 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
94 select ARCH_HAS_SYSCALL_WRAPPER
95 select ARCH_HAS_UBSAN_SANITIZE_ALL
96 select ARCH_HAS_DEBUG_WX
97 select ARCH_HAS_ZONE_DMA_SET if EXPERT
98 select ARCH_HAVE_NMI_SAFE_CMPXCHG
99 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
100 select ARCH_MIGHT_HAVE_PC_PARPORT
101 select ARCH_MIGHT_HAVE_PC_SERIO
102 select ARCH_STACKWALK
103 select ARCH_SUPPORTS_ACPI
104 select ARCH_SUPPORTS_ATOMIC_RMW
105 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
106 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
107 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
108 select ARCH_SUPPORTS_LTO_CLANG
109 select ARCH_SUPPORTS_LTO_CLANG_THIN
110 select ARCH_USE_BUILTIN_BSWAP
111 select ARCH_USE_MEMTEST
112 select ARCH_USE_QUEUED_RWLOCKS
113 select ARCH_USE_QUEUED_SPINLOCKS
114 select ARCH_USE_SYM_ANNOTATIONS
115 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
116 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
117 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
118 select ARCH_WANTS_NO_INSTR
119 select ARCH_WANT_HUGE_PMD_SHARE
120 select ARCH_WANT_LD_ORPHAN_WARN
121 select ARCH_WANTS_THP_SWAP if X86_64
122 select ARCH_HAS_PARANOID_L1D_FLUSH
123 select BUILDTIME_TABLE_SORT
125 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
126 select CLOCKSOURCE_WATCHDOG
127 select DCACHE_WORD_ACCESS
128 select EDAC_ATOMIC_SCRUB
130 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
131 select GENERIC_CLOCKEVENTS_MIN_ADJUST
132 select GENERIC_CMOS_UPDATE
133 select GENERIC_CPU_AUTOPROBE
134 select GENERIC_CPU_VULNERABILITIES
135 select GENERIC_EARLY_IOREMAP
137 select GENERIC_FIND_FIRST_BIT
139 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
140 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
141 select GENERIC_IRQ_MIGRATION if SMP
142 select GENERIC_IRQ_PROBE
143 select GENERIC_IRQ_RESERVATION_MODE
144 select GENERIC_IRQ_SHOW
145 select GENERIC_PENDING_IRQ if SMP
146 select GENERIC_PTDUMP
147 select GENERIC_SMP_IDLE_THREAD
148 select GENERIC_TIME_VSYSCALL
149 select GENERIC_GETTIMEOFDAY
150 select GENERIC_VDSO_TIME_NS
151 select GUP_GET_PTE_LOW_HIGH if X86_PAE
152 select HARDIRQS_SW_RESEND
153 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
154 select HAVE_ACPI_APEI if ACPI
155 select HAVE_ACPI_APEI_NMI if ACPI
156 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
157 select HAVE_ARCH_AUDITSYSCALL
158 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
159 select HAVE_ARCH_JUMP_LABEL
160 select HAVE_ARCH_JUMP_LABEL_RELATIVE
161 select HAVE_ARCH_KASAN if X86_64
162 select HAVE_ARCH_KASAN_VMALLOC if X86_64
163 select HAVE_ARCH_KFENCE
164 select HAVE_ARCH_KGDB
165 select HAVE_ARCH_MMAP_RND_BITS if MMU
166 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
167 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
168 select HAVE_ARCH_PREL32_RELOCATIONS
169 select HAVE_ARCH_SECCOMP_FILTER
170 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
171 select HAVE_ARCH_STACKLEAK
172 select HAVE_ARCH_TRACEHOOK
173 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
174 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
175 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
176 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
177 select HAVE_ARCH_VMAP_STACK if X86_64
178 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
179 select HAVE_ARCH_WITHIN_STACK_FRAMES
180 select HAVE_ASM_MODVERSIONS
181 select HAVE_CMPXCHG_DOUBLE
182 select HAVE_CMPXCHG_LOCAL
183 select HAVE_CONTEXT_TRACKING if X86_64
184 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
185 select HAVE_C_RECORDMCOUNT
186 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
187 select HAVE_DEBUG_KMEMLEAK
188 select HAVE_DMA_CONTIGUOUS
189 select HAVE_DYNAMIC_FTRACE
190 select HAVE_DYNAMIC_FTRACE_WITH_REGS
191 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
192 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
194 select HAVE_EFFICIENT_UNALIGNED_ACCESS
196 select HAVE_EXIT_THREAD
198 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
199 select HAVE_FTRACE_MCOUNT_RECORD
200 select HAVE_FUNCTION_GRAPH_TRACER
201 select HAVE_FUNCTION_TRACER
202 select HAVE_GCC_PLUGINS
203 select HAVE_HW_BREAKPOINT
204 select HAVE_IOREMAP_PROT
205 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
206 select HAVE_IRQ_TIME_ACCOUNTING
207 select HAVE_KERNEL_BZIP2
208 select HAVE_KERNEL_GZIP
209 select HAVE_KERNEL_LZ4
210 select HAVE_KERNEL_LZMA
211 select HAVE_KERNEL_LZO
212 select HAVE_KERNEL_XZ
213 select HAVE_KERNEL_ZSTD
215 select HAVE_KPROBES_ON_FTRACE
216 select HAVE_FUNCTION_ERROR_INJECTION
217 select HAVE_KRETPROBES
219 select HAVE_LIVEPATCH if X86_64
220 select HAVE_MIXED_BREAKPOINTS_REGS
221 select HAVE_MOD_ARCH_SPECIFIC
225 select HAVE_OPTPROBES
226 select HAVE_PCSPKR_PLATFORM
227 select HAVE_PERF_EVENTS
228 select HAVE_PERF_EVENTS_NMI
229 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
231 select HAVE_PERF_REGS
232 select HAVE_PERF_USER_STACK_DUMP
233 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
234 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
235 select HAVE_REGS_AND_STACK_ACCESS_API
236 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
237 select HAVE_FUNCTION_ARG_ACCESS_API
238 select HAVE_SOFTIRQ_ON_OWN_STACK
239 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
240 select HAVE_STACK_VALIDATION if X86_64
241 select HAVE_STATIC_CALL
242 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
243 select HAVE_PREEMPT_DYNAMIC
245 select HAVE_SYSCALL_TRACEPOINTS
246 select HAVE_UNSTABLE_SCHED_CLOCK
247 select HAVE_USER_RETURN_NOTIFIER
248 select HAVE_GENERIC_VDSO
249 select HOTPLUG_SMT if SMP
250 select IRQ_FORCED_THREADING
251 select NEED_SG_DMA_LENGTH
252 select PCI_DOMAINS if PCI
253 select PCI_LOCKLESS_CONFIG if PCI
256 select RTC_MC146818_LIB
259 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
260 select SYSCTL_EXCEPTION_TRACE
261 select THREAD_INFO_IN_TASK
262 select TRACE_IRQFLAGS_SUPPORT
263 select USER_STACKTRACE_SUPPORT
265 select HAVE_ARCH_KCSAN if X86_64
266 select X86_FEATURE_NAMES if PROC_FS
267 select PROC_PID_ARCH_STATUS if PROC_FS
268 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
270 config INSTRUCTION_DECODER
272 depends on KPROBES || PERF_EVENTS || UPROBES
276 default "elf32-i386" if X86_32
277 default "elf64-x86-64" if X86_64
279 config LOCKDEP_SUPPORT
282 config STACKTRACE_SUPPORT
288 config ARCH_MMAP_RND_BITS_MIN
292 config ARCH_MMAP_RND_BITS_MAX
296 config ARCH_MMAP_RND_COMPAT_BITS_MIN
299 config ARCH_MMAP_RND_COMPAT_BITS_MAX
305 config GENERIC_ISA_DMA
307 depends on ISA_DMA_API
312 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
314 config GENERIC_BUG_RELATIVE_POINTERS
317 config ARCH_MAY_HAVE_PC_FDC
319 depends on ISA_DMA_API
321 config GENERIC_CALIBRATE_DELAY
324 config ARCH_HAS_CPU_RELAX
327 config ARCH_HAS_FILTER_PGPROT
330 config HAVE_SETUP_PER_CPU_AREA
333 config NEED_PER_CPU_EMBED_FIRST_CHUNK
336 config NEED_PER_CPU_PAGE_FIRST_CHUNK
339 config ARCH_HIBERNATION_POSSIBLE
344 default 1024 if X86_64
347 config ARCH_SUSPEND_POSSIBLE
350 config ARCH_WANT_GENERAL_HUGETLB
356 config KASAN_SHADOW_OFFSET
359 default 0xdffffc0000000000
361 config HAVE_INTEL_TXT
363 depends on INTEL_IOMMU && ACPI
367 depends on X86_32 && SMP
371 depends on X86_64 && SMP
373 config ARCH_SUPPORTS_UPROBES
376 config FIX_EARLYCON_MEM
379 config DYNAMIC_PHYSICAL_MASK
382 config PGTABLE_LEVELS
384 default 5 if X86_5LEVEL
389 config CC_HAS_SANE_STACKPROTECTOR
391 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
392 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
394 We have to make sure stack protector is unconditionally disabled if
395 the compiler produces broken code or if it does not let us control
396 the segment on 32-bit kernels.
398 menu "Processor type and features"
401 bool "Symmetric multi-processing support"
403 This enables support for systems with more than one CPU. If you have
404 a system with only one CPU, say N. If you have a system with more
407 If you say N here, the kernel will run on uni- and multiprocessor
408 machines, but will use only one CPU of a multiprocessor machine. If
409 you say Y here, the kernel will run on many, but not all,
410 uniprocessor machines. On a uniprocessor machine, the kernel
411 will run faster if you say N here.
413 Note that if you say Y here and choose architecture "586" or
414 "Pentium" under "Processor family", the kernel will not work on 486
415 architectures. Similarly, multiprocessor kernels for the "PPro"
416 architecture may not work on all Pentium based boards.
418 People using multiprocessor machines who say Y here should also say
419 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
420 Management" code will be disabled if you say Y here.
422 See also <file:Documentation/x86/i386/IO-APIC.rst>,
423 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
424 <http://www.tldp.org/docs.html#howto>.
426 If you don't know what to do here, say N.
428 config X86_FEATURE_NAMES
429 bool "Processor feature human-readable names" if EMBEDDED
432 This option compiles in a table of x86 feature bits and corresponding
433 names. This is required to support /proc/cpuinfo and a few kernel
434 messages. You can disable this to save space, at the expense of
435 making those few kernel messages show numeric feature bits instead.
440 bool "Support x2apic"
441 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
443 This enables x2apic support on CPUs that have this feature.
445 This allows 32-bit apic IDs (so it can support very large systems),
446 and accesses the local apic via MSRs not via mmio.
448 If you don't know what to do here, say N.
451 bool "Enable MPS table" if ACPI
453 depends on X86_LOCAL_APIC
455 For old smp systems that do not have proper acpi support. Newer systems
456 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
460 depends on X86_GOLDFISH
463 bool "Avoid speculative indirect branches in kernel"
466 Compile kernel with the retpoline compiler options to guard against
467 kernel-to-user data leaks by avoiding speculative indirect
468 branches. Requires a compiler with -mindirect-branch=thunk-extern
469 support for full protection. The kernel may run slower.
472 def_bool $(cc-option,-mharden-sls=all)
474 config CC_HAS_RETURN_THUNK
475 def_bool $(cc-option,-mfunction-return=thunk-extern)
478 bool "Mitigate Straight-Line-Speculation"
479 depends on CC_HAS_SLS && X86_64
482 Compile the kernel with straight-line-speculation options to guard
483 against straight line speculation. The kernel image might be slightly
486 config X86_CPU_RESCTRL
487 bool "x86 CPU resource control support"
488 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
490 select PROC_CPU_RESCTRL if PROC_FS
492 Enable x86 CPU resource control support.
494 Provide support for the allocation and monitoring of system resources
497 Intel calls this Intel Resource Director Technology
498 (Intel(R) RDT). More information about RDT can be found in the
499 Intel x86 Architecture Software Developer Manual.
501 AMD calls this AMD Platform Quality of Service (AMD QoS).
502 More information about AMD QoS can be found in the AMD64 Technology
503 Platform Quality of Service Extensions manual.
509 bool "Support for big SMP systems with more than 8 CPUs"
512 This option is needed for the systems that have more than 8 CPUs.
514 config X86_EXTENDED_PLATFORM
515 bool "Support for extended (non-PC) x86 platforms"
518 If you disable this option then the kernel will only support
519 standard PC platforms. (which covers the vast majority of
522 If you enable this option then you'll be able to select support
523 for the following (non-PC) 32 bit x86 platforms:
524 Goldfish (Android emulator)
527 SGI 320/540 (Visual Workstation)
528 STA2X11-based (e.g. Northville)
529 Moorestown MID devices
531 If you have one of these systems, or if you want to build a
532 generic distribution kernel, say Y here - otherwise say N.
536 config X86_EXTENDED_PLATFORM
537 bool "Support for extended (non-PC) x86 platforms"
540 If you disable this option then the kernel will only support
541 standard PC platforms. (which covers the vast majority of
544 If you enable this option then you'll be able to select support
545 for the following (non-PC) 64 bit x86 platforms:
550 If you have one of these systems, or if you want to build a
551 generic distribution kernel, say Y here - otherwise say N.
553 # This is an alphabetically sorted list of 64 bit extended platforms
554 # Please maintain the alphabetic order if and when there are additions
556 bool "Numascale NumaChip"
558 depends on X86_EXTENDED_PLATFORM
561 depends on X86_X2APIC
562 depends on PCI_MMCONFIG
564 Adds support for Numascale NumaChip large-SMP systems. Needed to
565 enable more than ~168 cores.
566 If you don't have one of these, you should say N here.
570 select HYPERVISOR_GUEST
572 depends on X86_64 && PCI
573 depends on X86_EXTENDED_PLATFORM
576 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
577 supposed to run on these EM64T-based machines. Only choose this option
578 if you have one of these machines.
581 bool "SGI Ultraviolet"
583 depends on X86_EXTENDED_PLATFORM
586 depends on KEXEC_CORE
587 depends on X86_X2APIC
590 This option is needed in order to support SGI Ultraviolet systems.
591 If you don't have one of these, you should say N here.
593 # Following is an alphabetically sorted list of 32 bit extended platforms
594 # Please maintain the alphabetic order if and when there are additions
597 bool "Goldfish (Virtual Platform)"
598 depends on X86_EXTENDED_PLATFORM
600 Enable support for the Goldfish virtual platform used primarily
601 for Android development. Unless you are building for the Android
602 Goldfish emulator say N here.
605 bool "CE4100 TV platform"
607 depends on PCI_GODIRECT
608 depends on X86_IO_APIC
610 depends on X86_EXTENDED_PLATFORM
611 select X86_REBOOTFIXUPS
613 select OF_EARLY_FLATTREE
615 Select for the Intel CE media processor (CE4100) SOC.
616 This option compiles in support for the CE4100 SOC for settop
617 boxes and media devices.
620 bool "Intel MID platform support"
621 depends on X86_EXTENDED_PLATFORM
622 depends on X86_PLATFORM_DEVICES
624 depends on X86_64 || (PCI_GOANY && X86_32)
625 depends on X86_IO_APIC
630 select MFD_INTEL_MSIC
632 Select to build a kernel capable of supporting Intel MID (Mobile
633 Internet Device) platform systems which do not have the PCI legacy
634 interfaces. If you are building for a PC class system say N here.
636 Intel MID platforms are based on an Intel processor and chipset which
637 consume less power than most of the x86 derivatives.
639 config X86_INTEL_QUARK
640 bool "Intel Quark platform support"
642 depends on X86_EXTENDED_PLATFORM
643 depends on X86_PLATFORM_DEVICES
647 depends on X86_IO_APIC
652 Select to include support for Quark X1000 SoC.
653 Say Y here if you have a Quark based system such as the Arduino
654 compatible Intel Galileo.
656 config X86_INTEL_LPSS
657 bool "Intel Low Power Subsystem Support"
658 depends on X86 && ACPI && PCI
663 Select to build support for Intel Low Power Subsystem such as
664 found on Intel Lynxpoint PCH. Selecting this option enables
665 things like clock tree (common clock framework) and pincontrol
666 which are needed by the LPSS peripheral drivers.
668 config X86_AMD_PLATFORM_DEVICE
669 bool "AMD ACPI2Platform devices support"
674 Select to interpret AMD specific ACPI device to platform device
675 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
676 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
677 implemented under PINCTRL subsystem.
680 tristate "Intel SoC IOSF Sideband support for SoC platforms"
683 This option enables sideband register access support for Intel SoC
684 platforms. On these platforms the IOSF sideband is used in lieu of
685 MSR's for some register accesses, mostly but not limited to thermal
686 and power. Drivers may query the availability of this device to
687 determine if they need the sideband in order to work on these
688 platforms. The sideband is available on the following SoC products.
689 This list is not meant to be exclusive.
694 You should say Y if you are running a kernel on one of these SoC's.
696 config IOSF_MBI_DEBUG
697 bool "Enable IOSF sideband access through debugfs"
698 depends on IOSF_MBI && DEBUG_FS
700 Select this option to expose the IOSF sideband access registers (MCR,
701 MDR, MCRX) through debugfs to write and read register information from
702 different units on the SoC. This is most useful for obtaining device
703 state information for debug and analysis. As this is a general access
704 mechanism, users of this option would have specific knowledge of the
705 device they want to access.
707 If you don't require the option or are in doubt, say N.
710 bool "RDC R-321x SoC"
712 depends on X86_EXTENDED_PLATFORM
714 select X86_REBOOTFIXUPS
716 This option is needed for RDC R-321x system-on-chip, also known
718 If you don't have one of these chips, you should say N here.
720 config X86_32_NON_STANDARD
721 bool "Support non-standard 32-bit SMP architectures"
722 depends on X86_32 && SMP
723 depends on X86_EXTENDED_PLATFORM
725 This option compiles in the bigsmp and STA2X11 default
726 subarchitectures. It is intended for a generic binary
727 kernel. If you select them all, kernel will probe it one by
728 one and will fallback to default.
730 # Alphabetically sorted list of Non standard 32 bit platforms
732 config X86_SUPPORTS_MEMORY_FAILURE
734 # MCE code calls memory_failure():
736 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
737 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
738 depends on X86_64 || !SPARSEMEM
739 select ARCH_SUPPORTS_MEMORY_FAILURE
742 bool "STA2X11 Companion Chip Support"
743 depends on X86_32_NON_STANDARD && PCI
748 This adds support for boards based on the STA2X11 IO-Hub,
749 a.k.a. "ConneXt". The chip is used in place of the standard
750 PC chipset, so all "standard" peripherals are missing. If this
751 option is selected the kernel will still be able to boot on
752 standard PC machines.
755 tristate "Eurobraille/Iris poweroff module"
758 The Iris machines from EuroBraille do not have APM or ACPI support
759 to shut themselves down properly. A special I/O sequence is
760 needed to do so, which is what this module does at
763 This is only for Iris machines from EuroBraille.
767 config SCHED_OMIT_FRAME_POINTER
769 prompt "Single-depth WCHAN output"
772 Calculate simpler /proc/<PID>/wchan values. If this option
773 is disabled then wchan values will recurse back to the
774 caller function. This provides more accurate wchan values,
775 at the expense of slightly more scheduling overhead.
777 If in doubt, say "Y".
779 menuconfig HYPERVISOR_GUEST
780 bool "Linux guest support"
782 Say Y here to enable options for running Linux under various hyper-
783 visors. This option enables basic hypervisor detection and platform
786 If you say N, all options in this submenu will be skipped and
787 disabled, and Linux guest support won't be built in.
792 bool "Enable paravirtualization code"
793 depends on HAVE_STATIC_CALL
795 This changes the kernel so it can modify itself when it is run
796 under a hypervisor, potentially improving performance significantly
797 over full virtualization. However, when run without a hypervisor
798 the kernel is theoretically slower and slightly larger.
803 config PARAVIRT_DEBUG
804 bool "paravirt-ops debugging"
805 depends on PARAVIRT && DEBUG_KERNEL
807 Enable to debug paravirt_ops internals. Specifically, BUG if
808 a paravirt_op is missing when it is called.
810 config PARAVIRT_SPINLOCKS
811 bool "Paravirtualization layer for spinlocks"
812 depends on PARAVIRT && SMP
814 Paravirtualized spinlocks allow a pvops backend to replace the
815 spinlock implementation with something virtualization-friendly
816 (for example, block the virtual CPU rather than spinning).
818 It has a minimal impact on native kernels and gives a nice performance
819 benefit on paravirtualized KVM / Xen kernels.
821 If you are unsure how to answer this question, answer Y.
823 config X86_HV_CALLBACK_VECTOR
826 source "arch/x86/xen/Kconfig"
829 bool "KVM Guest support (including kvmclock)"
831 select PARAVIRT_CLOCK
832 select ARCH_CPUIDLE_HALTPOLL
833 select X86_HV_CALLBACK_VECTOR
836 This option enables various optimizations for running under the KVM
837 hypervisor. It includes a paravirtualized clock, so that instead
838 of relying on a PIT (or probably other) emulation by the
839 underlying device model, the host provides the guest with
840 timing infrastructure such as time of day, and system time
842 config ARCH_CPUIDLE_HALTPOLL
844 prompt "Disable host haltpoll when loading haltpoll driver"
846 If virtualized under KVM, disable host haltpoll.
849 bool "Support for running PVH guests"
851 This option enables the PVH entry point for guest virtual machines
852 as specified in the x86/HVM direct boot ABI.
854 config PARAVIRT_TIME_ACCOUNTING
855 bool "Paravirtual steal time accounting"
858 Select this option to enable fine granularity task steal time
859 accounting. Time spent executing other tasks in parallel with
860 the current vCPU is discounted from the vCPU power. To account for
861 that, there can be a small performance impact.
863 If in doubt, say N here.
865 config PARAVIRT_CLOCK
868 config JAILHOUSE_GUEST
869 bool "Jailhouse non-root cell support"
870 depends on X86_64 && PCI
873 This option allows to run Linux as guest in a Jailhouse non-root
874 cell. You can leave this option disabled if you only want to start
875 Jailhouse and run Linux afterwards in the root cell.
878 bool "ACRN Guest support"
880 select X86_HV_CALLBACK_VECTOR
882 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
883 a flexible, lightweight reference open-source hypervisor, built with
884 real-time and safety-criticality in mind. It is built for embedded
885 IOT with small footprint and real-time features. More details can be
886 found in https://projectacrn.org/.
888 endif #HYPERVISOR_GUEST
890 source "arch/x86/Kconfig.cpu"
894 prompt "HPET Timer Support" if X86_32
896 Use the IA-PC HPET (High Precision Event Timer) to manage
897 time in preference to the PIT and RTC, if a HPET is
899 HPET is the next generation timer replacing legacy 8254s.
900 The HPET provides a stable time base on SMP
901 systems, unlike the TSC, but it is more expensive to access,
902 as it is off-chip. The interface used is documented
903 in the HPET spec, revision 1.
905 You can safely choose Y here. However, HPET will only be
906 activated if the platform and the BIOS support this feature.
907 Otherwise the 8254 will be used for timing services.
909 Choose N to continue using the legacy 8254 timer.
911 config HPET_EMULATE_RTC
913 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
915 # Mark as expert because too many people got it wrong.
916 # The code disables itself when not needed.
919 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
920 bool "Enable DMI scanning" if EXPERT
922 Enabled scanning of DMI to identify machine quirks. Say Y
923 here unless you have verified that your setup is not
924 affected by entries in the DMI blacklist. Required by PNP
928 bool "Old AMD GART IOMMU support"
932 depends on X86_64 && PCI && AMD_NB
934 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
935 GART based hardware IOMMUs.
937 The GART supports full DMA access for devices with 32-bit access
938 limitations, on systems with more than 3 GB. This is usually needed
939 for USB, sound, many IDE/SATA chipsets and some other devices.
941 Newer systems typically have a modern AMD IOMMU, supported via
942 the CONFIG_AMD_IOMMU=y config option.
944 In normal configurations this driver is only active when needed:
945 there's more than 3 GB of memory and the system contains a
946 32-bit limited device.
951 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
952 depends on X86_64 && SMP && DEBUG_KERNEL
953 select CPUMASK_OFFSTACK
955 Enable maximum number of CPUS and NUMA Nodes for this architecture.
959 # The maximum number of CPUs supported:
961 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
962 # and which can be configured interactively in the
963 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
965 # The ranges are different on 32-bit and 64-bit kernels, depending on
966 # hardware capabilities and scalability features of the kernel.
968 # ( If MAXSMP is enabled we just use the highest possible value and disable
969 # interactive configuration. )
972 config NR_CPUS_RANGE_BEGIN
974 default NR_CPUS_RANGE_END if MAXSMP
978 config NR_CPUS_RANGE_END
981 default 64 if SMP && X86_BIGSMP
982 default 8 if SMP && !X86_BIGSMP
985 config NR_CPUS_RANGE_END
988 default 8192 if SMP && CPUMASK_OFFSTACK
989 default 512 if SMP && !CPUMASK_OFFSTACK
992 config NR_CPUS_DEFAULT
995 default 32 if X86_BIGSMP
999 config NR_CPUS_DEFAULT
1002 default 8192 if MAXSMP
1007 int "Maximum number of CPUs" if SMP && !MAXSMP
1008 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1009 default NR_CPUS_DEFAULT
1011 This allows you to specify the maximum number of CPUs which this
1012 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1013 supported value is 8192, otherwise the maximum value is 512. The
1014 minimum value which makes sense is 2.
1016 This is purely to save memory: each supported CPU adds about 8KB
1017 to the kernel image.
1024 prompt "Multi-core scheduler support"
1027 Multi-core scheduler support improves the CPU scheduler's decision
1028 making when dealing with multi-core CPU chips at a cost of slightly
1029 increased overhead in some places. If unsure say N here.
1031 config SCHED_MC_PRIO
1032 bool "CPU core priorities scheduler support"
1033 depends on SCHED_MC && CPU_SUP_INTEL
1034 select X86_INTEL_PSTATE
1038 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1039 core ordering determined at manufacturing time, which allows
1040 certain cores to reach higher turbo frequencies (when running
1041 single threaded workloads) than others.
1043 Enabling this kernel feature teaches the scheduler about
1044 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1045 scheduler's CPU selection logic accordingly, so that higher
1046 overall system performance can be achieved.
1048 This feature will have no effect on CPUs without this feature.
1050 If unsure say Y here.
1054 depends on !SMP && X86_LOCAL_APIC
1057 bool "Local APIC support on uniprocessors" if !PCI_MSI
1059 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1061 A local APIC (Advanced Programmable Interrupt Controller) is an
1062 integrated interrupt controller in the CPU. If you have a single-CPU
1063 system which has a processor with a local APIC, you can say Y here to
1064 enable and use it. If you say Y here even though your machine doesn't
1065 have a local APIC, then the kernel will still run with no slowdown at
1066 all. The local APIC supports CPU-generated self-interrupts (timer,
1067 performance counters), and the NMI watchdog which detects hard
1070 config X86_UP_IOAPIC
1071 bool "IO-APIC support on uniprocessors"
1072 depends on X86_UP_APIC
1074 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1075 SMP-capable replacement for PC-style interrupt controllers. Most
1076 SMP systems and many recent uniprocessor systems have one.
1078 If you have a single-CPU system with an IO-APIC, you can say Y here
1079 to use it. If you say Y here even though your machine doesn't have
1080 an IO-APIC, then the kernel will still run with no slowdown at all.
1082 config X86_LOCAL_APIC
1084 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1085 select IRQ_DOMAIN_HIERARCHY
1086 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1090 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1092 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1093 bool "Reroute for broken boot IRQs"
1094 depends on X86_IO_APIC
1096 This option enables a workaround that fixes a source of
1097 spurious interrupts. This is recommended when threaded
1098 interrupt handling is used on systems where the generation of
1099 superfluous "boot interrupts" cannot be disabled.
1101 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1102 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1103 kernel does during interrupt handling). On chipsets where this
1104 boot IRQ generation cannot be disabled, this workaround keeps
1105 the original IRQ line masked so that only the equivalent "boot
1106 IRQ" is delivered to the CPUs. The workaround also tells the
1107 kernel to set up the IRQ handler on the boot IRQ line. In this
1108 way only one interrupt is delivered to the kernel. Otherwise
1109 the spurious second interrupt may cause the kernel to bring
1110 down (vital) interrupt lines.
1112 Only affects "broken" chipsets. Interrupt sharing may be
1113 increased on these systems.
1116 bool "Machine Check / overheating reporting"
1117 select GENERIC_ALLOCATOR
1120 Machine Check support allows the processor to notify the
1121 kernel if it detects a problem (e.g. overheating, data corruption).
1122 The action the kernel takes depends on the severity of the problem,
1123 ranging from warning messages to halting the machine.
1125 config X86_MCELOG_LEGACY
1126 bool "Support for deprecated /dev/mcelog character device"
1129 Enable support for /dev/mcelog which is needed by the old mcelog
1130 userspace logging daemon. Consider switching to the new generation
1133 config X86_MCE_INTEL
1135 prompt "Intel MCE features"
1136 depends on X86_MCE && X86_LOCAL_APIC
1138 Additional support for intel specific MCE features such as
1139 the thermal monitor.
1143 prompt "AMD MCE features"
1144 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1146 Additional support for AMD specific MCE features such as
1147 the DRAM Error Threshold.
1149 config X86_ANCIENT_MCE
1150 bool "Support for old Pentium 5 / WinChip machine checks"
1151 depends on X86_32 && X86_MCE
1153 Include support for machine check handling on old Pentium 5 or WinChip
1154 systems. These typically need to be enabled explicitly on the command
1157 config X86_MCE_THRESHOLD
1158 depends on X86_MCE_AMD || X86_MCE_INTEL
1161 config X86_MCE_INJECT
1162 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1163 tristate "Machine check injector support"
1165 Provide support for injecting machine checks for testing purposes.
1166 If you don't know what a machine check is and you don't do kernel
1167 QA it is safe to say n.
1169 source "arch/x86/events/Kconfig"
1171 config X86_LEGACY_VM86
1172 bool "Legacy VM86 support"
1175 This option allows user programs to put the CPU into V8086
1176 mode, which is an 80286-era approximation of 16-bit real mode.
1178 Some very old versions of X and/or vbetool require this option
1179 for user mode setting. Similarly, DOSEMU will use it if
1180 available to accelerate real mode DOS programs. However, any
1181 recent version of DOSEMU, X, or vbetool should be fully
1182 functional even without kernel VM86 support, as they will all
1183 fall back to software emulation. Nevertheless, if you are using
1184 a 16-bit DOS program where 16-bit performance matters, vm86
1185 mode might be faster than emulation and you might want to
1188 Note that any app that works on a 64-bit kernel is unlikely to
1189 need this option, as 64-bit kernels don't, and can't, support
1190 V8086 mode. This option is also unrelated to 16-bit protected
1191 mode and is not needed to run most 16-bit programs under Wine.
1193 Enabling this option increases the complexity of the kernel
1194 and slows down exception handling a tiny bit.
1196 If unsure, say N here.
1200 default X86_LEGACY_VM86
1203 bool "Enable support for 16-bit segments" if EXPERT
1205 depends on MODIFY_LDT_SYSCALL
1207 This option is required by programs like Wine to run 16-bit
1208 protected mode legacy code on x86 processors. Disabling
1209 this option saves about 300 bytes on i386, or around 6K text
1210 plus 16K runtime memory on x86-64,
1214 depends on X86_16BIT && X86_32
1218 depends on X86_16BIT && X86_64
1220 config X86_VSYSCALL_EMULATION
1221 bool "Enable vsyscall emulation" if EXPERT
1225 This enables emulation of the legacy vsyscall page. Disabling
1226 it is roughly equivalent to booting with vsyscall=none, except
1227 that it will also disable the helpful warning if a program
1228 tries to use a vsyscall. With this option set to N, offending
1229 programs will just segfault, citing addresses of the form
1232 This option is required by many programs built before 2013, and
1233 care should be used even with newer programs if set to N.
1235 Disabling this option saves about 7K of kernel size and
1236 possibly 4K of additional runtime pagetable memory.
1238 config X86_IOPL_IOPERM
1239 bool "IOPERM and IOPL Emulation"
1242 This enables the ioperm() and iopl() syscalls which are necessary
1243 for legacy applications.
1245 Legacy IOPL support is an overbroad mechanism which allows user
1246 space aside of accessing all 65536 I/O ports also to disable
1247 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1248 capabilities and permission from potentially active security
1251 The emulation restricts the functionality of the syscall to
1252 only allowing the full range I/O port access, but prevents the
1253 ability to disable interrupts from user space which would be
1254 granted if the hardware IOPL mechanism would be used.
1257 tristate "Toshiba Laptop support"
1260 This adds a driver to safely access the System Management Mode of
1261 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1262 not work on models with a Phoenix BIOS. The System Management Mode
1263 is used to set the BIOS and power saving options on Toshiba portables.
1265 For information on utilities to make use of this driver see the
1266 Toshiba Linux utilities web site at:
1267 <http://www.buzzard.org.uk/toshiba/>.
1269 Say Y if you intend to run this kernel on a Toshiba portable.
1273 tristate "Dell i8k legacy laptop support"
1276 select SENSORS_DELL_SMM
1278 This option enables legacy /proc/i8k userspace interface in hwmon
1279 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1280 temperature and allows controlling fan speeds of Dell laptops via
1281 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1282 it reports also power and hotkey status. For fan speed control is
1283 needed userspace package i8kutils.
1285 Say Y if you intend to run this kernel on old Dell laptops or want to
1286 use userspace package i8kutils.
1289 config X86_REBOOTFIXUPS
1290 bool "Enable X86 board specific fixups for reboot"
1293 This enables chipset and/or board specific fixups to be done
1294 in order to get reboot to work correctly. This is only needed on
1295 some combinations of hardware and BIOS. The symptom, for which
1296 this config is intended, is when reboot ends with a stalled/hung
1299 Currently, the only fixup is for the Geode machines using
1300 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1302 Say Y if you want to enable the fixup. Currently, it's safe to
1303 enable this option even if you don't need it.
1307 bool "CPU microcode loading support"
1309 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1311 If you say Y here, you will be able to update the microcode on
1312 Intel and AMD processors. The Intel support is for the IA32 family,
1313 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1314 AMD support is for families 0x10 and later. You will obviously need
1315 the actual microcode binary data itself which is not shipped with
1318 The preferred method to load microcode from a detached initrd is described
1319 in Documentation/x86/microcode.rst. For that you need to enable
1320 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1321 initrd for microcode blobs.
1323 In addition, you can build the microcode into the kernel. For that you
1324 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1327 config MICROCODE_INTEL
1328 bool "Intel microcode loading support"
1329 depends on CPU_SUP_INTEL && MICROCODE
1332 This options enables microcode patch loading support for Intel
1335 For the current Intel microcode data package go to
1336 <https://downloadcenter.intel.com> and search for
1337 'Linux Processor Microcode Data File'.
1339 config MICROCODE_AMD
1340 bool "AMD microcode loading support"
1341 depends on CPU_SUP_AMD && MICROCODE
1343 If you select this option, microcode patch loading support for AMD
1344 processors will be enabled.
1346 config MICROCODE_OLD_INTERFACE
1347 bool "Ancient loading interface (DEPRECATED)"
1349 depends on MICROCODE
1351 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1352 which was used by userspace tools like iucode_tool and microcode.ctl.
1353 It is inadequate because it runs too late to be able to properly
1354 load microcode on a machine and it needs special tools. Instead, you
1355 should've switched to the early loading method with the initrd or
1356 builtin microcode by now: Documentation/x86/microcode.rst
1359 tristate "/dev/cpu/*/msr - Model-specific register support"
1361 This device gives privileged processes access to the x86
1362 Model-Specific Registers (MSRs). It is a character device with
1363 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1364 MSR accesses are directed to a specific CPU on multi-processor
1368 tristate "/dev/cpu/*/cpuid - CPU information support"
1370 This device gives processes access to the x86 CPUID instruction to
1371 be executed on a specific processor. It is a character device
1372 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1376 prompt "High Memory Support"
1383 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1384 However, the address space of 32-bit x86 processors is only 4
1385 Gigabytes large. That means that, if you have a large amount of
1386 physical memory, not all of it can be "permanently mapped" by the
1387 kernel. The physical memory that's not permanently mapped is called
1390 If you are compiling a kernel which will never run on a machine with
1391 more than 1 Gigabyte total physical RAM, answer "off" here (default
1392 choice and suitable for most users). This will result in a "3GB/1GB"
1393 split: 3GB are mapped so that each process sees a 3GB virtual memory
1394 space and the remaining part of the 4GB virtual memory space is used
1395 by the kernel to permanently map as much physical memory as
1398 If the machine has between 1 and 4 Gigabytes physical RAM, then
1401 If more than 4 Gigabytes is used then answer "64GB" here. This
1402 selection turns Intel PAE (Physical Address Extension) mode on.
1403 PAE implements 3-level paging on IA32 processors. PAE is fully
1404 supported by Linux, PAE mode is implemented on all recent Intel
1405 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1406 then the kernel will not boot on CPUs that don't support PAE!
1408 The actual amount of total physical memory will either be
1409 auto detected or can be forced by using a kernel command line option
1410 such as "mem=256M". (Try "man bootparam" or see the documentation of
1411 your boot loader (lilo or loadlin) about how to pass options to the
1412 kernel at boot time.)
1414 If unsure, say "off".
1419 Select this if you have a 32-bit processor and between 1 and 4
1420 gigabytes of physical RAM.
1424 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1427 Select this if you have a 32-bit processor and more than 4
1428 gigabytes of physical RAM.
1433 prompt "Memory split" if EXPERT
1437 Select the desired split between kernel and user memory.
1439 If the address range available to the kernel is less than the
1440 physical memory installed, the remaining memory will be available
1441 as "high memory". Accessing high memory is a little more costly
1442 than low memory, as it needs to be mapped into the kernel first.
1443 Note that increasing the kernel address space limits the range
1444 available to user programs, making the address space there
1445 tighter. Selecting anything other than the default 3G/1G split
1446 will also likely make your kernel incompatible with binary-only
1449 If you are not absolutely sure what you are doing, leave this
1453 bool "3G/1G user/kernel split"
1454 config VMSPLIT_3G_OPT
1456 bool "3G/1G user/kernel split (for full 1G low memory)"
1458 bool "2G/2G user/kernel split"
1459 config VMSPLIT_2G_OPT
1461 bool "2G/2G user/kernel split (for full 2G low memory)"
1463 bool "1G/3G user/kernel split"
1468 default 0xB0000000 if VMSPLIT_3G_OPT
1469 default 0x80000000 if VMSPLIT_2G
1470 default 0x78000000 if VMSPLIT_2G_OPT
1471 default 0x40000000 if VMSPLIT_1G
1477 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1480 bool "PAE (Physical Address Extension) Support"
1481 depends on X86_32 && !HIGHMEM4G
1482 select PHYS_ADDR_T_64BIT
1485 PAE is required for NX support, and furthermore enables
1486 larger swapspace support for non-overcommit purposes. It
1487 has the cost of more pagetable lookup overhead, and also
1488 consumes more pagetable space per process.
1491 bool "Enable 5-level page tables support"
1493 select DYNAMIC_MEMORY_LAYOUT
1494 select SPARSEMEM_VMEMMAP
1497 5-level paging enables access to larger address space:
1498 upto 128 PiB of virtual address space and 4 PiB of
1499 physical address space.
1501 It will be supported by future Intel CPUs.
1503 A kernel with the option enabled can be booted on machines that
1504 support 4- or 5-level paging.
1506 See Documentation/x86/x86_64/5level-paging.rst for more
1511 config X86_DIRECT_GBPAGES
1515 Certain kernel features effectively disable kernel
1516 linear 1 GB mappings (even if the CPU otherwise
1517 supports them), so don't confuse the user by printing
1518 that we have them enabled.
1520 config X86_CPA_STATISTICS
1521 bool "Enable statistic for Change Page Attribute"
1524 Expose statistics about the Change Page Attribute mechanism, which
1525 helps to determine the effectiveness of preserving large and huge
1526 page mappings when mapping protections are changed.
1528 config AMD_MEM_ENCRYPT
1529 bool "AMD Secure Memory Encryption (SME) support"
1530 depends on X86_64 && CPU_SUP_AMD
1531 select DMA_COHERENT_POOL
1532 select DYNAMIC_PHYSICAL_MASK
1533 select ARCH_USE_MEMREMAP_PROT
1534 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1535 select INSTRUCTION_DECODER
1536 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1537 select ARCH_HAS_CC_PLATFORM
1539 Say yes to enable support for the encryption of system memory.
1540 This requires an AMD processor that supports Secure Memory
1543 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1544 bool "Activate AMD Secure Memory Encryption (SME) by default"
1545 depends on AMD_MEM_ENCRYPT
1547 Say yes to have system memory encrypted by default if running on
1548 an AMD processor that supports Secure Memory Encryption (SME).
1550 If set to Y, then the encryption of system memory can be
1551 deactivated with the mem_encrypt=off command line option.
1553 If set to N, then the encryption of system memory can be
1554 activated with the mem_encrypt=on command line option.
1556 # Common NUMA Features
1558 bool "NUMA Memory Allocation and Scheduler Support"
1560 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1561 default y if X86_BIGSMP
1563 Enable NUMA (Non-Uniform Memory Access) support.
1565 The kernel will try to allocate memory used by a CPU on the
1566 local memory controller of the CPU and add some more
1567 NUMA awareness to the kernel.
1569 For 64-bit this is recommended if the system is Intel Core i7
1570 (or later), AMD Opteron, or EM64T NUMA.
1572 For 32-bit this is only needed if you boot a 32-bit
1573 kernel on a 64-bit NUMA platform.
1575 Otherwise, you should say N.
1579 prompt "Old style AMD Opteron NUMA detection"
1580 depends on X86_64 && NUMA && PCI
1582 Enable AMD NUMA node topology detection. You should say Y here if
1583 you have a multi processor AMD system. This uses an old method to
1584 read the NUMA configuration directly from the builtin Northbridge
1585 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1586 which also takes priority if both are compiled in.
1588 config X86_64_ACPI_NUMA
1590 prompt "ACPI NUMA detection"
1591 depends on X86_64 && NUMA && ACPI && PCI
1594 Enable ACPI SRAT based node topology detection.
1597 bool "NUMA emulation"
1600 Enable NUMA emulation. A flat machine will be split
1601 into virtual nodes when booted with "numa=fake=N", where N is the
1602 number of nodes. This is only useful for debugging.
1605 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1607 default "10" if MAXSMP
1608 default "6" if X86_64
1612 Specify the maximum number of NUMA Nodes available on the target
1613 system. Increases memory reserved to accommodate various tables.
1615 config ARCH_FLATMEM_ENABLE
1617 depends on X86_32 && !NUMA
1619 config ARCH_SPARSEMEM_ENABLE
1621 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1622 select SPARSEMEM_STATIC if X86_32
1623 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1625 config ARCH_SPARSEMEM_DEFAULT
1626 def_bool X86_64 || (NUMA && X86_32)
1628 config ARCH_SELECT_MEMORY_MODEL
1630 depends on ARCH_SPARSEMEM_ENABLE
1632 config ARCH_MEMORY_PROBE
1633 bool "Enable sysfs memory/probe interface"
1634 depends on X86_64 && MEMORY_HOTPLUG
1636 This option enables a sysfs memory/probe interface for testing.
1637 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1638 If you are unsure how to answer this question, answer N.
1640 config ARCH_PROC_KCORE_TEXT
1642 depends on X86_64 && PROC_KCORE
1644 config ILLEGAL_POINTER_VALUE
1647 default 0xdead000000000000 if X86_64
1649 config X86_PMEM_LEGACY_DEVICE
1652 config X86_PMEM_LEGACY
1653 tristate "Support non-standard NVDIMMs and ADR protected memory"
1654 depends on PHYS_ADDR_T_64BIT
1656 select X86_PMEM_LEGACY_DEVICE
1657 select NUMA_KEEP_MEMINFO if NUMA
1660 Treat memory marked using the non-standard e820 type of 12 as used
1661 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1662 The kernel will offer these regions to the 'pmem' driver so
1663 they can be used for persistent storage.
1668 bool "Allocate 3rd-level pagetables from highmem"
1671 The VM uses one page table entry for each page of physical memory.
1672 For systems with a lot of RAM, this can be wasteful of precious
1673 low memory. Setting this option will put user-space page table
1674 entries in high memory.
1676 config X86_CHECK_BIOS_CORRUPTION
1677 bool "Check for low memory corruption"
1679 Periodically check for memory corruption in low memory, which
1680 is suspected to be caused by BIOS. Even when enabled in the
1681 configuration, it is disabled at runtime. Enable it by
1682 setting "memory_corruption_check=1" on the kernel command
1683 line. By default it scans the low 64k of memory every 60
1684 seconds; see the memory_corruption_check_size and
1685 memory_corruption_check_period parameters in
1686 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1688 When enabled with the default parameters, this option has
1689 almost no overhead, as it reserves a relatively small amount
1690 of memory and scans it infrequently. It both detects corruption
1691 and prevents it from affecting the running system.
1693 It is, however, intended as a diagnostic tool; if repeatable
1694 BIOS-originated corruption always affects the same memory,
1695 you can use memmap= to prevent the kernel from using that
1698 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1699 bool "Set the default setting of memory_corruption_check"
1700 depends on X86_CHECK_BIOS_CORRUPTION
1703 Set whether the default state of memory_corruption_check is
1706 config MATH_EMULATION
1708 depends on MODIFY_LDT_SYSCALL
1709 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1711 Linux can emulate a math coprocessor (used for floating point
1712 operations) if you don't have one. 486DX and Pentium processors have
1713 a math coprocessor built in, 486SX and 386 do not, unless you added
1714 a 487DX or 387, respectively. (The messages during boot time can
1715 give you some hints here ["man dmesg"].) Everyone needs either a
1716 coprocessor or this emulation.
1718 If you don't have a math coprocessor, you need to say Y here; if you
1719 say Y here even though you have a coprocessor, the coprocessor will
1720 be used nevertheless. (This behavior can be changed with the kernel
1721 command line option "no387", which comes handy if your coprocessor
1722 is broken. Try "man bootparam" or see the documentation of your boot
1723 loader (lilo or loadlin) about how to pass options to the kernel at
1724 boot time.) This means that it is a good idea to say Y here if you
1725 intend to use this kernel on different machines.
1727 More information about the internals of the Linux math coprocessor
1728 emulation can be found in <file:arch/x86/math-emu/README>.
1730 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1731 kernel, it won't hurt.
1735 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1737 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1738 the Memory Type Range Registers (MTRRs) may be used to control
1739 processor access to memory ranges. This is most useful if you have
1740 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1741 allows bus write transfers to be combined into a larger transfer
1742 before bursting over the PCI/AGP bus. This can increase performance
1743 of image write operations 2.5 times or more. Saying Y here creates a
1744 /proc/mtrr file which may be used to manipulate your processor's
1745 MTRRs. Typically the X server should use this.
1747 This code has a reasonably generic interface so that similar
1748 control registers on other processors can be easily supported
1751 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1752 Registers (ARRs) which provide a similar functionality to MTRRs. For
1753 these, the ARRs are used to emulate the MTRRs.
1754 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1755 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1756 write-combining. All of these processors are supported by this code
1757 and it makes sense to say Y here if you have one of them.
1759 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1760 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1761 can lead to all sorts of problems, so it's good to say Y here.
1763 You can safely say Y even if your machine doesn't have MTRRs, you'll
1764 just add about 9 KB to your kernel.
1766 See <file:Documentation/x86/mtrr.rst> for more information.
1768 config MTRR_SANITIZER
1770 prompt "MTRR cleanup support"
1773 Convert MTRR layout from continuous to discrete, so X drivers can
1774 add writeback entries.
1776 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1777 The largest mtrr entry size for a continuous block can be set with
1782 config MTRR_SANITIZER_ENABLE_DEFAULT
1783 int "MTRR cleanup enable value (0-1)"
1786 depends on MTRR_SANITIZER
1788 Enable mtrr cleanup default value
1790 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1791 int "MTRR cleanup spare reg num (0-7)"
1794 depends on MTRR_SANITIZER
1796 mtrr cleanup spare entries default, it can be changed via
1797 mtrr_spare_reg_nr=N on the kernel command line.
1801 prompt "x86 PAT support" if EXPERT
1804 Use PAT attributes to setup page level cache control.
1806 PATs are the modern equivalents of MTRRs and are much more
1807 flexible than MTRRs.
1809 Say N here if you see bootup problems (boot crash, boot hang,
1810 spontaneous reboots) or a non-working video driver.
1814 config ARCH_USES_PG_UNCACHED
1820 prompt "x86 architectural random number generator" if EXPERT
1822 Enable the x86 architectural RDRAND instruction
1823 (Intel Bull Mountain technology) to generate random numbers.
1824 If supported, this is a high bandwidth, cryptographically
1825 secure hardware random number generator.
1829 prompt "Supervisor Mode Access Prevention" if EXPERT
1831 Supervisor Mode Access Prevention (SMAP) is a security
1832 feature in newer Intel processors. There is a small
1833 performance cost if this enabled and turned on; there is
1834 also a small increase in the kernel size if this is enabled.
1840 prompt "User Mode Instruction Prevention" if EXPERT
1842 User Mode Instruction Prevention (UMIP) is a security feature in
1843 some x86 processors. If enabled, a general protection fault is
1844 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1845 executed in user mode. These instructions unnecessarily expose
1846 information about the hardware state.
1848 The vast majority of applications do not use these instructions.
1849 For the very few that do, software emulation is provided in
1850 specific cases in protected and virtual-8086 modes. Emulated
1853 config X86_INTEL_MEMORY_PROTECTION_KEYS
1854 prompt "Memory Protection Keys"
1856 # Note: only available in 64-bit mode
1857 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1858 select ARCH_USES_HIGH_VMA_FLAGS
1859 select ARCH_HAS_PKEYS
1861 Memory Protection Keys provides a mechanism for enforcing
1862 page-based protections, but without requiring modification of the
1863 page tables when an application changes protection domains.
1865 For details, see Documentation/core-api/protection-keys.rst
1870 prompt "TSX enable mode"
1871 depends on CPU_SUP_INTEL
1872 default X86_INTEL_TSX_MODE_OFF
1874 Intel's TSX (Transactional Synchronization Extensions) feature
1875 allows to optimize locking protocols through lock elision which
1876 can lead to a noticeable performance boost.
1878 On the other hand it has been shown that TSX can be exploited
1879 to form side channel attacks (e.g. TAA) and chances are there
1880 will be more of those attacks discovered in the future.
1882 Therefore TSX is not enabled by default (aka tsx=off). An admin
1883 might override this decision by tsx=on the command line parameter.
1884 Even with TSX enabled, the kernel will attempt to enable the best
1885 possible TAA mitigation setting depending on the microcode available
1886 for the particular machine.
1888 This option allows to set the default tsx mode between tsx=on, =off
1889 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1892 Say off if not sure, auto if TSX is in use but it should be used on safe
1893 platforms or on if TSX is in use and the security aspect of tsx is not
1896 config X86_INTEL_TSX_MODE_OFF
1899 TSX is disabled if possible - equals to tsx=off command line parameter.
1901 config X86_INTEL_TSX_MODE_ON
1904 TSX is always enabled on TSX capable HW - equals the tsx=on command
1907 config X86_INTEL_TSX_MODE_AUTO
1910 TSX is enabled on TSX capable HW that is believed to be safe against
1911 side channel attacks- equals the tsx=auto command line parameter.
1915 bool "Software Guard eXtensions (SGX)"
1916 depends on X86_64 && CPU_SUP_INTEL
1918 depends on CRYPTO_SHA256=y
1921 select NUMA_KEEP_MEMINFO if NUMA
1923 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1924 that can be used by applications to set aside private regions of code
1925 and data, referred to as enclaves. An enclave's private memory can
1926 only be accessed by code running within the enclave. Accesses from
1927 outside the enclave, including other enclaves, are disallowed by
1933 bool "EFI runtime service support"
1936 select EFI_RUNTIME_WRAPPERS
1937 select ARCH_USE_MEMREMAP_PROT
1939 This enables the kernel to use EFI runtime services that are
1940 available (such as the EFI variable services).
1942 This option is only useful on systems that have EFI firmware.
1943 In addition, you should use the latest ELILO loader available
1944 at <http://elilo.sourceforge.net> in order to take advantage
1945 of EFI runtime services. However, even with this option, the
1946 resultant kernel should continue to boot on existing non-EFI
1950 bool "EFI stub support"
1951 depends on EFI && !X86_USE_3DNOW
1952 depends on $(cc-option,-mabi=ms) || X86_32
1955 This kernel feature allows a bzImage to be loaded directly
1956 by EFI firmware without the use of a bootloader.
1958 See Documentation/admin-guide/efi-stub.rst for more information.
1961 bool "EFI mixed-mode support"
1962 depends on EFI_STUB && X86_64
1964 Enabling this feature allows a 64-bit kernel to be booted
1965 on a 32-bit firmware, provided that your CPU supports 64-bit
1968 Note that it is not possible to boot a mixed-mode enabled
1969 kernel via the EFI boot stub - a bootloader that supports
1970 the EFI handover protocol must be used.
1974 source "kernel/Kconfig.hz"
1977 bool "kexec system call"
1980 kexec is a system call that implements the ability to shutdown your
1981 current kernel, and to start another kernel. It is like a reboot
1982 but it is independent of the system firmware. And like a reboot
1983 you can start any kernel with it, not just Linux.
1985 The name comes from the similarity to the exec system call.
1987 It is an ongoing process to be certain the hardware in a machine
1988 is properly shutdown, so do not be surprised if this code does not
1989 initially work for you. As of this writing the exact hardware
1990 interface is strongly in flux, so no good recommendation can be
1994 bool "kexec file based system call"
1999 depends on CRYPTO_SHA256=y
2001 This is new version of kexec system call. This system call is
2002 file based and takes file descriptors as system call argument
2003 for kernel and initramfs as opposed to list of segments as
2004 accepted by previous system call.
2006 config ARCH_HAS_KEXEC_PURGATORY
2010 bool "Verify kernel signature during kexec_file_load() syscall"
2011 depends on KEXEC_FILE
2014 This option makes the kexec_file_load() syscall check for a valid
2015 signature of the kernel image. The image can still be loaded without
2016 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2017 there's a signature that we can check, then it must be valid.
2019 In addition to this option, you need to enable signature
2020 verification for the corresponding kernel image type being
2021 loaded in order for this to work.
2023 config KEXEC_SIG_FORCE
2024 bool "Require a valid signature in kexec_file_load() syscall"
2025 depends on KEXEC_SIG
2027 This option makes kernel signature verification mandatory for
2028 the kexec_file_load() syscall.
2030 config KEXEC_BZIMAGE_VERIFY_SIG
2031 bool "Enable bzImage signature verification support"
2032 depends on KEXEC_SIG
2033 depends on SIGNED_PE_FILE_VERIFICATION
2034 select SYSTEM_TRUSTED_KEYRING
2036 Enable bzImage signature verification support.
2039 bool "kernel crash dumps"
2040 depends on X86_64 || (X86_32 && HIGHMEM)
2042 Generate crash dump after being started by kexec.
2043 This should be normally only set in special crash dump kernels
2044 which are loaded in the main kernel with kexec-tools into
2045 a specially reserved region and then later executed after
2046 a crash by kdump/kexec. The crash dump kernel must be compiled
2047 to a memory address not used by the main kernel or BIOS using
2048 PHYSICAL_START, or it must be built as a relocatable image
2049 (CONFIG_RELOCATABLE=y).
2050 For more details see Documentation/admin-guide/kdump/kdump.rst
2054 depends on KEXEC && HIBERNATION
2056 Jump between original kernel and kexeced kernel and invoke
2057 code in physical address mode via KEXEC
2059 config PHYSICAL_START
2060 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2063 This gives the physical address where the kernel is loaded.
2065 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2066 bzImage will decompress itself to above physical address and
2067 run from there. Otherwise, bzImage will run from the address where
2068 it has been loaded by the boot loader and will ignore above physical
2071 In normal kdump cases one does not have to set/change this option
2072 as now bzImage can be compiled as a completely relocatable image
2073 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2074 address. This option is mainly useful for the folks who don't want
2075 to use a bzImage for capturing the crash dump and want to use a
2076 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2077 to be specifically compiled to run from a specific memory area
2078 (normally a reserved region) and this option comes handy.
2080 So if you are using bzImage for capturing the crash dump,
2081 leave the value here unchanged to 0x1000000 and set
2082 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2083 for capturing the crash dump change this value to start of
2084 the reserved region. In other words, it can be set based on
2085 the "X" value as specified in the "crashkernel=YM@XM"
2086 command line boot parameter passed to the panic-ed
2087 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2088 for more details about crash dumps.
2090 Usage of bzImage for capturing the crash dump is recommended as
2091 one does not have to build two kernels. Same kernel can be used
2092 as production kernel and capture kernel. Above option should have
2093 gone away after relocatable bzImage support is introduced. But it
2094 is present because there are users out there who continue to use
2095 vmlinux for dump capture. This option should go away down the
2098 Don't change this unless you know what you are doing.
2101 bool "Build a relocatable kernel"
2104 This builds a kernel image that retains relocation information
2105 so it can be loaded someplace besides the default 1MB.
2106 The relocations tend to make the kernel binary about 10% larger,
2107 but are discarded at runtime.
2109 One use is for the kexec on panic case where the recovery kernel
2110 must live at a different physical address than the primary
2113 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2114 it has been loaded at and the compile time physical address
2115 (CONFIG_PHYSICAL_START) is used as the minimum location.
2117 config RANDOMIZE_BASE
2118 bool "Randomize the address of the kernel image (KASLR)"
2119 depends on RELOCATABLE
2122 In support of Kernel Address Space Layout Randomization (KASLR),
2123 this randomizes the physical address at which the kernel image
2124 is decompressed and the virtual address where the kernel
2125 image is mapped, as a security feature that deters exploit
2126 attempts relying on knowledge of the location of kernel
2129 On 64-bit, the kernel physical and virtual addresses are
2130 randomized separately. The physical address will be anywhere
2131 between 16MB and the top of physical memory (up to 64TB). The
2132 virtual address will be randomized from 16MB up to 1GB (9 bits
2133 of entropy). Note that this also reduces the memory space
2134 available to kernel modules from 1.5GB to 1GB.
2136 On 32-bit, the kernel physical and virtual addresses are
2137 randomized together. They will be randomized from 16MB up to
2138 512MB (8 bits of entropy).
2140 Entropy is generated using the RDRAND instruction if it is
2141 supported. If RDTSC is supported, its value is mixed into
2142 the entropy pool as well. If neither RDRAND nor RDTSC are
2143 supported, then entropy is read from the i8254 timer. The
2144 usable entropy is limited by the kernel being built using
2145 2GB addressing, and that PHYSICAL_ALIGN must be at a
2146 minimum of 2MB. As a result, only 10 bits of entropy are
2147 theoretically possible, but the implementations are further
2148 limited due to memory layouts.
2152 # Relocation on x86 needs some additional build support
2153 config X86_NEED_RELOCS
2155 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2157 config PHYSICAL_ALIGN
2158 hex "Alignment value to which kernel should be aligned"
2160 range 0x2000 0x1000000 if X86_32
2161 range 0x200000 0x1000000 if X86_64
2163 This value puts the alignment restrictions on physical address
2164 where kernel is loaded and run from. Kernel is compiled for an
2165 address which meets above alignment restriction.
2167 If bootloader loads the kernel at a non-aligned address and
2168 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2169 address aligned to above value and run from there.
2171 If bootloader loads the kernel at a non-aligned address and
2172 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2173 load address and decompress itself to the address it has been
2174 compiled for and run from there. The address for which kernel is
2175 compiled already meets above alignment restrictions. Hence the
2176 end result is that kernel runs from a physical address meeting
2177 above alignment restrictions.
2179 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2180 this value must be a multiple of 0x200000.
2182 Don't change this unless you know what you are doing.
2184 config DYNAMIC_MEMORY_LAYOUT
2187 This option makes base addresses of vmalloc and vmemmap as well as
2188 __PAGE_OFFSET movable during boot.
2190 config RANDOMIZE_MEMORY
2191 bool "Randomize the kernel memory sections"
2193 depends on RANDOMIZE_BASE
2194 select DYNAMIC_MEMORY_LAYOUT
2195 default RANDOMIZE_BASE
2197 Randomizes the base virtual address of kernel memory sections
2198 (physical memory mapping, vmalloc & vmemmap). This security feature
2199 makes exploits relying on predictable memory locations less reliable.
2201 The order of allocations remains unchanged. Entropy is generated in
2202 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2203 configuration have in average 30,000 different possible virtual
2204 addresses for each memory section.
2208 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2209 hex "Physical memory mapping padding" if EXPERT
2210 depends on RANDOMIZE_MEMORY
2211 default "0xa" if MEMORY_HOTPLUG
2213 range 0x1 0x40 if MEMORY_HOTPLUG
2216 Define the padding in terabytes added to the existing physical
2217 memory size during kernel memory randomization. It is useful
2218 for memory hotplug support but reduces the entropy available for
2219 address randomization.
2221 If unsure, leave at the default value.
2227 config BOOTPARAM_HOTPLUG_CPU0
2228 bool "Set default setting of cpu0_hotpluggable"
2229 depends on HOTPLUG_CPU
2231 Set whether default state of cpu0_hotpluggable is on or off.
2233 Say Y here to enable CPU0 hotplug by default. If this switch
2234 is turned on, there is no need to give cpu0_hotplug kernel
2235 parameter and the CPU0 hotplug feature is enabled by default.
2237 Please note: there are two known CPU0 dependencies if you want
2238 to enable the CPU0 hotplug feature either by this switch or by
2239 cpu0_hotplug kernel parameter.
2241 First, resume from hibernate or suspend always starts from CPU0.
2242 So hibernate and suspend are prevented if CPU0 is offline.
2244 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2245 offline if any interrupt can not migrate out of CPU0. There may
2246 be other CPU0 dependencies.
2248 Please make sure the dependencies are under your control before
2249 you enable this feature.
2251 Say N if you don't want to enable CPU0 hotplug feature by default.
2252 You still can enable the CPU0 hotplug feature at boot by kernel
2253 parameter cpu0_hotplug.
2255 config DEBUG_HOTPLUG_CPU0
2257 prompt "Debug CPU0 hotplug"
2258 depends on HOTPLUG_CPU
2260 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2261 soon as possible and boots up userspace with CPU0 offlined. User
2262 can online CPU0 back after boot time.
2264 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2265 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2266 compilation or giving cpu0_hotplug kernel parameter at boot.
2272 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2273 depends on COMPAT_32
2275 Certain buggy versions of glibc will crash if they are
2276 presented with a 32-bit vDSO that is not mapped at the address
2277 indicated in its segment table.
2279 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2280 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2281 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2282 the only released version with the bug, but OpenSUSE 9
2283 contains a buggy "glibc 2.3.2".
2285 The symptom of the bug is that everything crashes on startup, saying:
2286 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2288 Saying Y here changes the default value of the vdso32 boot
2289 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2290 This works around the glibc bug but hurts performance.
2292 If unsure, say N: if you are compiling your own kernel, you
2293 are unlikely to be using a buggy version of glibc.
2296 prompt "vsyscall table for legacy applications"
2298 default LEGACY_VSYSCALL_XONLY
2300 Legacy user code that does not know how to find the vDSO expects
2301 to be able to issue three syscalls by calling fixed addresses in
2302 kernel space. Since this location is not randomized with ASLR,
2303 it can be used to assist security vulnerability exploitation.
2305 This setting can be changed at boot time via the kernel command
2306 line parameter vsyscall=[emulate|xonly|none].
2308 On a system with recent enough glibc (2.14 or newer) and no
2309 static binaries, you can say None without a performance penalty
2310 to improve security.
2312 If unsure, select "Emulate execution only".
2314 config LEGACY_VSYSCALL_EMULATE
2315 bool "Full emulation"
2317 The kernel traps and emulates calls into the fixed vsyscall
2318 address mapping. This makes the mapping non-executable, but
2319 it still contains readable known contents, which could be
2320 used in certain rare security vulnerability exploits. This
2321 configuration is recommended when using legacy userspace
2322 that still uses vsyscalls along with legacy binary
2323 instrumentation tools that require code to be readable.
2325 An example of this type of legacy userspace is running
2326 Pin on an old binary that still uses vsyscalls.
2328 config LEGACY_VSYSCALL_XONLY
2329 bool "Emulate execution only"
2331 The kernel traps and emulates calls into the fixed vsyscall
2332 address mapping and does not allow reads. This
2333 configuration is recommended when userspace might use the
2334 legacy vsyscall area but support for legacy binary
2335 instrumentation of legacy code is not needed. It mitigates
2336 certain uses of the vsyscall area as an ASLR-bypassing
2339 config LEGACY_VSYSCALL_NONE
2342 There will be no vsyscall mapping at all. This will
2343 eliminate any risk of ASLR bypass due to the vsyscall
2344 fixed address mapping. Attempts to use the vsyscalls
2345 will be reported to dmesg, so that either old or
2346 malicious userspace programs can be identified.
2351 bool "Built-in kernel command line"
2353 Allow for specifying boot arguments to the kernel at
2354 build time. On some systems (e.g. embedded ones), it is
2355 necessary or convenient to provide some or all of the
2356 kernel boot arguments with the kernel itself (that is,
2357 to not rely on the boot loader to provide them.)
2359 To compile command line arguments into the kernel,
2360 set this option to 'Y', then fill in the
2361 boot arguments in CONFIG_CMDLINE.
2363 Systems with fully functional boot loaders (i.e. non-embedded)
2364 should leave this option set to 'N'.
2367 string "Built-in kernel command string"
2368 depends on CMDLINE_BOOL
2371 Enter arguments here that should be compiled into the kernel
2372 image and used at boot time. If the boot loader provides a
2373 command line at boot time, it is appended to this string to
2374 form the full kernel command line, when the system boots.
2376 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2377 change this behavior.
2379 In most cases, the command line (whether built-in or provided
2380 by the boot loader) should specify the device for the root
2383 config CMDLINE_OVERRIDE
2384 bool "Built-in command line overrides boot loader arguments"
2385 depends on CMDLINE_BOOL && CMDLINE != ""
2387 Set this option to 'Y' to have the kernel ignore the boot loader
2388 command line, and use ONLY the built-in command line.
2390 This is used to work around broken boot loaders. This should
2391 be set to 'N' under normal conditions.
2393 config MODIFY_LDT_SYSCALL
2394 bool "Enable the LDT (local descriptor table)" if EXPERT
2397 Linux can allow user programs to install a per-process x86
2398 Local Descriptor Table (LDT) using the modify_ldt(2) system
2399 call. This is required to run 16-bit or segmented code such as
2400 DOSEMU or some Wine programs. It is also used by some very old
2401 threading libraries.
2403 Enabling this feature adds a small amount of overhead to
2404 context switches and increases the low-level kernel attack
2405 surface. Disabling it removes the modify_ldt(2) system call.
2407 Saying 'N' here may make sense for embedded or server kernels.
2409 source "kernel/livepatch/Kconfig"
2413 config ARCH_HAS_ADD_PAGES
2415 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2417 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2420 config USE_PERCPU_NUMA_NODE_ID
2424 menu "Power management and ACPI options"
2426 config ARCH_HIBERNATION_HEADER
2428 depends on HIBERNATION
2430 source "kernel/power/Kconfig"
2432 source "drivers/acpi/Kconfig"
2439 tristate "APM (Advanced Power Management) BIOS support"
2440 depends on X86_32 && PM_SLEEP
2442 APM is a BIOS specification for saving power using several different
2443 techniques. This is mostly useful for battery powered laptops with
2444 APM compliant BIOSes. If you say Y here, the system time will be
2445 reset after a RESUME operation, the /proc/apm device will provide
2446 battery status information, and user-space programs will receive
2447 notification of APM "events" (e.g. battery status change).
2449 If you select "Y" here, you can disable actual use of the APM
2450 BIOS by passing the "apm=off" option to the kernel at boot time.
2452 Note that the APM support is almost completely disabled for
2453 machines with more than one CPU.
2455 In order to use APM, you will need supporting software. For location
2456 and more information, read <file:Documentation/power/apm-acpi.rst>
2457 and the Battery Powered Linux mini-HOWTO, available from
2458 <http://www.tldp.org/docs.html#howto>.
2460 This driver does not spin down disk drives (see the hdparm(8)
2461 manpage ("man 8 hdparm") for that), and it doesn't turn off
2462 VESA-compliant "green" monitors.
2464 This driver does not support the TI 4000M TravelMate and the ACER
2465 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2466 desktop machines also don't have compliant BIOSes, and this driver
2467 may cause those machines to panic during the boot phase.
2469 Generally, if you don't have a battery in your machine, there isn't
2470 much point in using this driver and you should say N. If you get
2471 random kernel OOPSes or reboots that don't seem to be related to
2472 anything, try disabling/enabling this option (or disabling/enabling
2475 Some other things you should try when experiencing seemingly random,
2478 1) make sure that you have enough swap space and that it is
2480 2) pass the "no-hlt" option to the kernel
2481 3) switch on floating point emulation in the kernel and pass
2482 the "no387" option to the kernel
2483 4) pass the "floppy=nodma" option to the kernel
2484 5) pass the "mem=4M" option to the kernel (thereby disabling
2485 all but the first 4 MB of RAM)
2486 6) make sure that the CPU is not over clocked.
2487 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2488 8) disable the cache from your BIOS settings
2489 9) install a fan for the video card or exchange video RAM
2490 10) install a better fan for the CPU
2491 11) exchange RAM chips
2492 12) exchange the motherboard.
2494 To compile this driver as a module, choose M here: the
2495 module will be called apm.
2499 config APM_IGNORE_USER_SUSPEND
2500 bool "Ignore USER SUSPEND"
2502 This option will ignore USER SUSPEND requests. On machines with a
2503 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2504 series notebooks, it is necessary to say Y because of a BIOS bug.
2506 config APM_DO_ENABLE
2507 bool "Enable PM at boot time"
2509 Enable APM features at boot time. From page 36 of the APM BIOS
2510 specification: "When disabled, the APM BIOS does not automatically
2511 power manage devices, enter the Standby State, enter the Suspend
2512 State, or take power saving steps in response to CPU Idle calls."
2513 This driver will make CPU Idle calls when Linux is idle (unless this
2514 feature is turned off -- see "Do CPU IDLE calls", below). This
2515 should always save battery power, but more complicated APM features
2516 will be dependent on your BIOS implementation. You may need to turn
2517 this option off if your computer hangs at boot time when using APM
2518 support, or if it beeps continuously instead of suspending. Turn
2519 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2520 T400CDT. This is off by default since most machines do fine without
2525 bool "Make CPU Idle calls when idle"
2527 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2528 On some machines, this can activate improved power savings, such as
2529 a slowed CPU clock rate, when the machine is idle. These idle calls
2530 are made after the idle loop has run for some length of time (e.g.,
2531 333 mS). On some machines, this will cause a hang at boot time or
2532 whenever the CPU becomes idle. (On machines with more than one CPU,
2533 this option does nothing.)
2535 config APM_DISPLAY_BLANK
2536 bool "Enable console blanking using APM"
2538 Enable console blanking using the APM. Some laptops can use this to
2539 turn off the LCD backlight when the screen blanker of the Linux
2540 virtual console blanks the screen. Note that this is only used by
2541 the virtual console screen blanker, and won't turn off the backlight
2542 when using the X Window system. This also doesn't have anything to
2543 do with your VESA-compliant power-saving monitor. Further, this
2544 option doesn't work for all laptops -- it might not turn off your
2545 backlight at all, or it might print a lot of errors to the console,
2546 especially if you are using gpm.
2548 config APM_ALLOW_INTS
2549 bool "Allow interrupts during APM BIOS calls"
2551 Normally we disable external interrupts while we are making calls to
2552 the APM BIOS as a measure to lessen the effects of a badly behaving
2553 BIOS implementation. The BIOS should reenable interrupts if it
2554 needs to. Unfortunately, some BIOSes do not -- especially those in
2555 many of the newer IBM Thinkpads. If you experience hangs when you
2556 suspend, try setting this to Y. Otherwise, say N.
2560 source "drivers/cpufreq/Kconfig"
2562 source "drivers/cpuidle/Kconfig"
2564 source "drivers/idle/Kconfig"
2569 menu "Bus options (PCI etc.)"
2572 prompt "PCI access mode"
2573 depends on X86_32 && PCI
2576 On PCI systems, the BIOS can be used to detect the PCI devices and
2577 determine their configuration. However, some old PCI motherboards
2578 have BIOS bugs and may crash if this is done. Also, some embedded
2579 PCI-based systems don't have any BIOS at all. Linux can also try to
2580 detect the PCI hardware directly without using the BIOS.
2582 With this option, you can specify how Linux should detect the
2583 PCI devices. If you choose "BIOS", the BIOS will be used,
2584 if you choose "Direct", the BIOS won't be used, and if you
2585 choose "MMConfig", then PCI Express MMCONFIG will be used.
2586 If you choose "Any", the kernel will try MMCONFIG, then the
2587 direct access method and falls back to the BIOS if that doesn't
2588 work. If unsure, go with the default, which is "Any".
2593 config PCI_GOMMCONFIG
2610 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2612 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2615 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2618 bool "Support mmconfig PCI config space access" if X86_64
2620 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2621 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2625 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2629 depends on PCI && XEN
2631 config MMCONF_FAM10H
2633 depends on X86_64 && PCI_MMCONFIG && ACPI
2635 config PCI_CNB20LE_QUIRK
2636 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2639 Read the PCI windows out of the CNB20LE host bridge. This allows
2640 PCI hotplug to work on systems with the CNB20LE chipset which do
2643 There's no public spec for this chipset, and this functionality
2644 is known to be incomplete.
2646 You should say N unless you know you need this.
2649 bool "ISA bus support on modern systems" if EXPERT
2651 Expose ISA bus device drivers and options available for selection and
2652 configuration. Enable this option if your target machine has an ISA
2653 bus. ISA is an older system, displaced by PCI and newer bus
2654 architectures -- if your target machine is modern, it probably does
2655 not have an ISA bus.
2659 # x86_64 have no ISA slots, but can have ISA-style DMA.
2661 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2664 Enables ISA-style DMA support for devices requiring such controllers.
2672 Find out whether you have ISA slots on your motherboard. ISA is the
2673 name of a bus system, i.e. the way the CPU talks to the other stuff
2674 inside your box. Other bus systems are PCI, EISA, MicroChannel
2675 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2676 newer boards don't support it. If you have ISA, say Y, otherwise N.
2679 tristate "NatSemi SCx200 support"
2681 This provides basic support for National Semiconductor's
2682 (now AMD's) Geode processors. The driver probes for the
2683 PCI-IDs of several on-chip devices, so its a good dependency
2684 for other scx200_* drivers.
2686 If compiled as a module, the driver is named scx200.
2688 config SCx200HR_TIMER
2689 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2693 This driver provides a clocksource built upon the on-chip
2694 27MHz high-resolution timer. Its also a workaround for
2695 NSC Geode SC-1100's buggy TSC, which loses time when the
2696 processor goes idle (as is done by the scheduler). The
2697 other workaround is idle=poll boot option.
2700 bool "One Laptop Per Child support"
2708 Add support for detecting the unique features of the OLPC
2712 bool "OLPC XO-1 Power Management"
2713 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2715 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2718 bool "OLPC XO-1 Real Time Clock"
2719 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2721 Add support for the XO-1 real time clock, which can be used as a
2722 programmable wakeup source.
2725 bool "OLPC XO-1 SCI extras"
2726 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2730 Add support for SCI-based features of the OLPC XO-1 laptop:
2731 - EC-driven system wakeups
2735 - AC adapter status updates
2736 - Battery status updates
2738 config OLPC_XO15_SCI
2739 bool "OLPC XO-1.5 SCI extras"
2740 depends on OLPC && ACPI
2743 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2744 - EC-driven system wakeups
2745 - AC adapter status updates
2746 - Battery status updates
2749 bool "PCEngines ALIX System Support (LED setup)"
2752 This option enables system support for the PCEngines ALIX.
2753 At present this just sets up LEDs for GPIO control on
2754 ALIX2/3/6 boards. However, other system specific setup should
2757 Note: You must still enable the drivers for GPIO and LED support
2758 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2760 Note: You have to set alix.force=1 for boards with Award BIOS.
2763 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2766 This option enables system support for the Soekris Engineering net5501.
2769 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2773 This option enables system support for the Traverse Technologies GEOS.
2776 bool "Technologic Systems TS-5500 platform support"
2778 select CHECK_SIGNATURE
2782 This option enables system support for the Technologic Systems TS-5500.
2788 depends on CPU_SUP_AMD && PCI
2793 menu "Binary Emulations"
2795 config IA32_EMULATION
2796 bool "IA32 Emulation"
2798 select ARCH_WANT_OLD_COMPAT_IPC
2800 select COMPAT_OLD_SIGACTION
2802 Include code to run legacy 32-bit programs under a
2803 64-bit kernel. You should likely turn this on, unless you're
2804 100% sure that you don't have any 32-bit programs left.
2807 tristate "IA32 a.out support"
2808 depends on IA32_EMULATION
2811 Support old a.out binaries in the 32bit emulation.
2814 bool "x32 ABI for 64-bit mode"
2816 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2817 # compressed debug sections to x86_x32 properly:
2818 # https://github.com/ClangBuiltLinux/linux/issues/514
2819 # https://github.com/ClangBuiltLinux/linux/issues/1141
2820 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2822 Include code to run binaries for the x32 native 32-bit ABI
2823 for 64-bit processors. An x32 process gets access to the
2824 full 64-bit register file and wide data path while leaving
2825 pointers at 32 bits for smaller memory footprint.
2827 You will need a recent binutils (2.22 or later) with
2828 elf32_x86_64 support enabled to compile a kernel with this
2833 depends on IA32_EMULATION || X86_32
2835 select OLD_SIGSUSPEND3
2839 depends on IA32_EMULATION || X86_X32
2842 config COMPAT_FOR_U64_ALIGNMENT
2845 config SYSVIPC_COMPAT
2853 config HAVE_ATOMIC_IOMAP
2857 source "arch/x86/kvm/Kconfig"
2859 source "arch/x86/Kconfig.assembler"