1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
71 select ARCH_HAS_CACHE_LINE_SIZE
72 select ARCH_HAS_DEBUG_VIRTUAL
73 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
74 select ARCH_HAS_DEVMEM_IS_ALLOWED
75 select ARCH_HAS_EARLY_DEBUG if KGDB
76 select ARCH_HAS_ELF_RANDOMIZE
77 select ARCH_HAS_FAST_MULTIPLIER
78 select ARCH_HAS_FILTER_PGPROT
79 select ARCH_HAS_FORTIFY_SOURCE
80 select ARCH_HAS_GCOV_PROFILE_ALL
81 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
82 select ARCH_HAS_MEM_ENCRYPT
83 select ARCH_HAS_MEMBARRIER_SYNC_CORE
84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85 select ARCH_HAS_PMEM_API if X86_64
86 select ARCH_HAS_PTE_DEVMAP if X86_64
87 select ARCH_HAS_PTE_SPECIAL
88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
89 select ARCH_HAS_COPY_MC if X86_64
90 select ARCH_HAS_SET_MEMORY
91 select ARCH_HAS_SET_DIRECT_MAP
92 select ARCH_HAS_STRICT_KERNEL_RWX
93 select ARCH_HAS_STRICT_MODULE_RWX
94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95 select ARCH_HAS_SYSCALL_WRAPPER
96 select ARCH_HAS_UBSAN_SANITIZE_ALL
97 select ARCH_HAS_DEBUG_WX
98 select ARCH_HAS_ZONE_DMA_SET if EXPERT
99 select ARCH_HAVE_NMI_SAFE_CMPXCHG
100 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
101 select ARCH_MIGHT_HAVE_PC_PARPORT
102 select ARCH_MIGHT_HAVE_PC_SERIO
103 select ARCH_STACKWALK
104 select ARCH_SUPPORTS_ACPI
105 select ARCH_SUPPORTS_ATOMIC_RMW
106 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
107 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
108 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
109 select ARCH_SUPPORTS_LTO_CLANG
110 select ARCH_SUPPORTS_LTO_CLANG_THIN
111 select ARCH_USE_BUILTIN_BSWAP
112 select ARCH_USE_MEMTEST
113 select ARCH_USE_QUEUED_RWLOCKS
114 select ARCH_USE_QUEUED_SPINLOCKS
115 select ARCH_USE_SYM_ANNOTATIONS
116 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
117 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
118 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
119 select ARCH_WANTS_NO_INSTR
120 select ARCH_WANT_HUGE_PMD_SHARE
121 select ARCH_WANT_LD_ORPHAN_WARN
122 select ARCH_WANTS_THP_SWAP if X86_64
123 select ARCH_HAS_PARANOID_L1D_FLUSH
124 select BUILDTIME_TABLE_SORT
126 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
127 select CLOCKSOURCE_WATCHDOG
128 select DCACHE_WORD_ACCESS
129 select DYNAMIC_SIGFRAME
130 select EDAC_ATOMIC_SCRUB
132 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
133 select GENERIC_CLOCKEVENTS_MIN_ADJUST
134 select GENERIC_CMOS_UPDATE
135 select GENERIC_CPU_AUTOPROBE
136 select GENERIC_CPU_VULNERABILITIES
137 select GENERIC_EARLY_IOREMAP
139 select GENERIC_FIND_FIRST_BIT
141 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
142 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
143 select GENERIC_IRQ_MIGRATION if SMP
144 select GENERIC_IRQ_PROBE
145 select GENERIC_IRQ_RESERVATION_MODE
146 select GENERIC_IRQ_SHOW
147 select GENERIC_PENDING_IRQ if SMP
148 select GENERIC_PTDUMP
149 select GENERIC_SMP_IDLE_THREAD
150 select GENERIC_TIME_VSYSCALL
151 select GENERIC_GETTIMEOFDAY
152 select GENERIC_VDSO_TIME_NS
153 select GUP_GET_PTE_LOW_HIGH if X86_PAE
154 select HARDIRQS_SW_RESEND
155 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
156 select HAVE_ACPI_APEI if ACPI
157 select HAVE_ACPI_APEI_NMI if ACPI
158 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
159 select HAVE_ARCH_AUDITSYSCALL
160 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
161 select HAVE_ARCH_JUMP_LABEL
162 select HAVE_ARCH_JUMP_LABEL_RELATIVE
163 select HAVE_ARCH_KASAN if X86_64
164 select HAVE_ARCH_KASAN_VMALLOC if X86_64
165 select HAVE_ARCH_KFENCE
166 select HAVE_ARCH_KGDB
167 select HAVE_ARCH_MMAP_RND_BITS if MMU
168 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
169 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
170 select HAVE_ARCH_PREL32_RELOCATIONS
171 select HAVE_ARCH_SECCOMP_FILTER
172 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
173 select HAVE_ARCH_STACKLEAK
174 select HAVE_ARCH_TRACEHOOK
175 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
176 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
177 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
178 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
179 select HAVE_ARCH_VMAP_STACK if X86_64
180 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
181 select HAVE_ARCH_WITHIN_STACK_FRAMES
182 select HAVE_ASM_MODVERSIONS
183 select HAVE_CMPXCHG_DOUBLE
184 select HAVE_CMPXCHG_LOCAL
185 select HAVE_CONTEXT_TRACKING if X86_64
186 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
187 select HAVE_C_RECORDMCOUNT
188 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
189 select HAVE_DEBUG_KMEMLEAK
190 select HAVE_DMA_CONTIGUOUS
191 select HAVE_DYNAMIC_FTRACE
192 select HAVE_DYNAMIC_FTRACE_WITH_REGS
193 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
194 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
195 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
196 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
198 select HAVE_EFFICIENT_UNALIGNED_ACCESS
200 select HAVE_EXIT_THREAD
202 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
203 select HAVE_FTRACE_MCOUNT_RECORD
204 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
205 select HAVE_FUNCTION_TRACER
206 select HAVE_GCC_PLUGINS
207 select HAVE_HW_BREAKPOINT
208 select HAVE_IOREMAP_PROT
209 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
210 select HAVE_IRQ_TIME_ACCOUNTING
211 select HAVE_KERNEL_BZIP2
212 select HAVE_KERNEL_GZIP
213 select HAVE_KERNEL_LZ4
214 select HAVE_KERNEL_LZMA
215 select HAVE_KERNEL_LZO
216 select HAVE_KERNEL_XZ
217 select HAVE_KERNEL_ZSTD
219 select HAVE_KPROBES_ON_FTRACE
220 select HAVE_FUNCTION_ERROR_INJECTION
221 select HAVE_KRETPROBES
223 select HAVE_LIVEPATCH if X86_64
224 select HAVE_MIXED_BREAKPOINTS_REGS
225 select HAVE_MOD_ARCH_SPECIFIC
229 select HAVE_OPTPROBES
230 select HAVE_PCSPKR_PLATFORM
231 select HAVE_PERF_EVENTS
232 select HAVE_PERF_EVENTS_NMI
233 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
235 select HAVE_PERF_REGS
236 select HAVE_PERF_USER_STACK_DUMP
237 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
238 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
239 select HAVE_REGS_AND_STACK_ACCESS_API
240 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
241 select HAVE_FUNCTION_ARG_ACCESS_API
242 select HAVE_SOFTIRQ_ON_OWN_STACK
243 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
244 select HAVE_STACK_VALIDATION if X86_64
245 select HAVE_STATIC_CALL
246 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
247 select HAVE_PREEMPT_DYNAMIC
249 select HAVE_SYSCALL_TRACEPOINTS
250 select HAVE_UNSTABLE_SCHED_CLOCK
251 select HAVE_USER_RETURN_NOTIFIER
252 select HAVE_GENERIC_VDSO
253 select HOTPLUG_SMT if SMP
254 select IRQ_FORCED_THREADING
255 select NEED_SG_DMA_LENGTH
256 select PCI_DOMAINS if PCI
257 select PCI_LOCKLESS_CONFIG if PCI
260 select RTC_MC146818_LIB
263 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
264 select SYSCTL_EXCEPTION_TRACE
265 select THREAD_INFO_IN_TASK
266 select TRACE_IRQFLAGS_SUPPORT
267 select USER_STACKTRACE_SUPPORT
269 select HAVE_ARCH_KCSAN if X86_64
270 select X86_FEATURE_NAMES if PROC_FS
271 select PROC_PID_ARCH_STATUS if PROC_FS
272 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
273 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
275 config INSTRUCTION_DECODER
277 depends on KPROBES || PERF_EVENTS || UPROBES
281 default "elf32-i386" if X86_32
282 default "elf64-x86-64" if X86_64
284 config LOCKDEP_SUPPORT
287 config STACKTRACE_SUPPORT
293 config ARCH_MMAP_RND_BITS_MIN
297 config ARCH_MMAP_RND_BITS_MAX
301 config ARCH_MMAP_RND_COMPAT_BITS_MIN
304 config ARCH_MMAP_RND_COMPAT_BITS_MAX
310 config GENERIC_ISA_DMA
312 depends on ISA_DMA_API
317 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
319 config GENERIC_BUG_RELATIVE_POINTERS
322 config ARCH_MAY_HAVE_PC_FDC
324 depends on ISA_DMA_API
326 config GENERIC_CALIBRATE_DELAY
329 config ARCH_HAS_CPU_RELAX
332 config ARCH_HAS_FILTER_PGPROT
335 config HAVE_SETUP_PER_CPU_AREA
338 config NEED_PER_CPU_EMBED_FIRST_CHUNK
341 config NEED_PER_CPU_PAGE_FIRST_CHUNK
344 config ARCH_HIBERNATION_POSSIBLE
349 default 1024 if X86_64
352 config ARCH_SUSPEND_POSSIBLE
355 config ARCH_WANT_GENERAL_HUGETLB
361 config KASAN_SHADOW_OFFSET
364 default 0xdffffc0000000000
366 config HAVE_INTEL_TXT
368 depends on INTEL_IOMMU && ACPI
372 depends on X86_32 && SMP
376 depends on X86_64 && SMP
378 config ARCH_SUPPORTS_UPROBES
381 config FIX_EARLYCON_MEM
384 config DYNAMIC_PHYSICAL_MASK
387 config PGTABLE_LEVELS
389 default 5 if X86_5LEVEL
394 config CC_HAS_SANE_STACKPROTECTOR
396 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
397 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
399 We have to make sure stack protector is unconditionally disabled if
400 the compiler produces broken code or if it does not let us control
401 the segment on 32-bit kernels.
403 menu "Processor type and features"
406 bool "Symmetric multi-processing support"
408 This enables support for systems with more than one CPU. If you have
409 a system with only one CPU, say N. If you have a system with more
412 If you say N here, the kernel will run on uni- and multiprocessor
413 machines, but will use only one CPU of a multiprocessor machine. If
414 you say Y here, the kernel will run on many, but not all,
415 uniprocessor machines. On a uniprocessor machine, the kernel
416 will run faster if you say N here.
418 Note that if you say Y here and choose architecture "586" or
419 "Pentium" under "Processor family", the kernel will not work on 486
420 architectures. Similarly, multiprocessor kernels for the "PPro"
421 architecture may not work on all Pentium based boards.
423 People using multiprocessor machines who say Y here should also say
424 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
425 Management" code will be disabled if you say Y here.
427 See also <file:Documentation/x86/i386/IO-APIC.rst>,
428 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
429 <http://www.tldp.org/docs.html#howto>.
431 If you don't know what to do here, say N.
433 config X86_FEATURE_NAMES
434 bool "Processor feature human-readable names" if EMBEDDED
437 This option compiles in a table of x86 feature bits and corresponding
438 names. This is required to support /proc/cpuinfo and a few kernel
439 messages. You can disable this to save space, at the expense of
440 making those few kernel messages show numeric feature bits instead.
445 bool "Support x2apic"
446 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
448 This enables x2apic support on CPUs that have this feature.
450 This allows 32-bit apic IDs (so it can support very large systems),
451 and accesses the local apic via MSRs not via mmio.
453 If you don't know what to do here, say N.
456 bool "Enable MPS table" if ACPI
458 depends on X86_LOCAL_APIC
460 For old smp systems that do not have proper acpi support. Newer systems
461 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
465 depends on X86_GOLDFISH
468 bool "Avoid speculative indirect branches in kernel"
471 Compile kernel with the retpoline compiler options to guard against
472 kernel-to-user data leaks by avoiding speculative indirect
473 branches. Requires a compiler with -mindirect-branch=thunk-extern
474 support for full protection. The kernel may run slower.
476 config X86_CPU_RESCTRL
477 bool "x86 CPU resource control support"
478 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
480 select PROC_CPU_RESCTRL if PROC_FS
482 Enable x86 CPU resource control support.
484 Provide support for the allocation and monitoring of system resources
487 Intel calls this Intel Resource Director Technology
488 (Intel(R) RDT). More information about RDT can be found in the
489 Intel x86 Architecture Software Developer Manual.
491 AMD calls this AMD Platform Quality of Service (AMD QoS).
492 More information about AMD QoS can be found in the AMD64 Technology
493 Platform Quality of Service Extensions manual.
499 bool "Support for big SMP systems with more than 8 CPUs"
502 This option is needed for the systems that have more than 8 CPUs.
504 config X86_EXTENDED_PLATFORM
505 bool "Support for extended (non-PC) x86 platforms"
508 If you disable this option then the kernel will only support
509 standard PC platforms. (which covers the vast majority of
512 If you enable this option then you'll be able to select support
513 for the following (non-PC) 32 bit x86 platforms:
514 Goldfish (Android emulator)
517 SGI 320/540 (Visual Workstation)
518 STA2X11-based (e.g. Northville)
519 Moorestown MID devices
521 If you have one of these systems, or if you want to build a
522 generic distribution kernel, say Y here - otherwise say N.
526 config X86_EXTENDED_PLATFORM
527 bool "Support for extended (non-PC) x86 platforms"
530 If you disable this option then the kernel will only support
531 standard PC platforms. (which covers the vast majority of
534 If you enable this option then you'll be able to select support
535 for the following (non-PC) 64 bit x86 platforms:
540 If you have one of these systems, or if you want to build a
541 generic distribution kernel, say Y here - otherwise say N.
543 # This is an alphabetically sorted list of 64 bit extended platforms
544 # Please maintain the alphabetic order if and when there are additions
546 bool "Numascale NumaChip"
548 depends on X86_EXTENDED_PLATFORM
551 depends on X86_X2APIC
552 depends on PCI_MMCONFIG
554 Adds support for Numascale NumaChip large-SMP systems. Needed to
555 enable more than ~168 cores.
556 If you don't have one of these, you should say N here.
560 select HYPERVISOR_GUEST
562 depends on X86_64 && PCI
563 depends on X86_EXTENDED_PLATFORM
566 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
567 supposed to run on these EM64T-based machines. Only choose this option
568 if you have one of these machines.
571 bool "SGI Ultraviolet"
573 depends on X86_EXTENDED_PLATFORM
576 depends on KEXEC_CORE
577 depends on X86_X2APIC
580 This option is needed in order to support SGI Ultraviolet systems.
581 If you don't have one of these, you should say N here.
583 # Following is an alphabetically sorted list of 32 bit extended platforms
584 # Please maintain the alphabetic order if and when there are additions
587 bool "Goldfish (Virtual Platform)"
588 depends on X86_EXTENDED_PLATFORM
590 Enable support for the Goldfish virtual platform used primarily
591 for Android development. Unless you are building for the Android
592 Goldfish emulator say N here.
595 bool "CE4100 TV platform"
597 depends on PCI_GODIRECT
598 depends on X86_IO_APIC
600 depends on X86_EXTENDED_PLATFORM
601 select X86_REBOOTFIXUPS
603 select OF_EARLY_FLATTREE
605 Select for the Intel CE media processor (CE4100) SOC.
606 This option compiles in support for the CE4100 SOC for settop
607 boxes and media devices.
610 bool "Intel MID platform support"
611 depends on X86_EXTENDED_PLATFORM
612 depends on X86_PLATFORM_DEVICES
614 depends on X86_64 || (PCI_GOANY && X86_32)
615 depends on X86_IO_APIC
620 Select to build a kernel capable of supporting Intel MID (Mobile
621 Internet Device) platform systems which do not have the PCI legacy
622 interfaces. If you are building for a PC class system say N here.
624 Intel MID platforms are based on an Intel processor and chipset which
625 consume less power than most of the x86 derivatives.
627 config X86_INTEL_QUARK
628 bool "Intel Quark platform support"
630 depends on X86_EXTENDED_PLATFORM
631 depends on X86_PLATFORM_DEVICES
635 depends on X86_IO_APIC
640 Select to include support for Quark X1000 SoC.
641 Say Y here if you have a Quark based system such as the Arduino
642 compatible Intel Galileo.
644 config X86_INTEL_LPSS
645 bool "Intel Low Power Subsystem Support"
646 depends on X86 && ACPI && PCI
651 Select to build support for Intel Low Power Subsystem such as
652 found on Intel Lynxpoint PCH. Selecting this option enables
653 things like clock tree (common clock framework) and pincontrol
654 which are needed by the LPSS peripheral drivers.
656 config X86_AMD_PLATFORM_DEVICE
657 bool "AMD ACPI2Platform devices support"
662 Select to interpret AMD specific ACPI device to platform device
663 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
664 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
665 implemented under PINCTRL subsystem.
668 tristate "Intel SoC IOSF Sideband support for SoC platforms"
671 This option enables sideband register access support for Intel SoC
672 platforms. On these platforms the IOSF sideband is used in lieu of
673 MSR's for some register accesses, mostly but not limited to thermal
674 and power. Drivers may query the availability of this device to
675 determine if they need the sideband in order to work on these
676 platforms. The sideband is available on the following SoC products.
677 This list is not meant to be exclusive.
682 You should say Y if you are running a kernel on one of these SoC's.
684 config IOSF_MBI_DEBUG
685 bool "Enable IOSF sideband access through debugfs"
686 depends on IOSF_MBI && DEBUG_FS
688 Select this option to expose the IOSF sideband access registers (MCR,
689 MDR, MCRX) through debugfs to write and read register information from
690 different units on the SoC. This is most useful for obtaining device
691 state information for debug and analysis. As this is a general access
692 mechanism, users of this option would have specific knowledge of the
693 device they want to access.
695 If you don't require the option or are in doubt, say N.
698 bool "RDC R-321x SoC"
700 depends on X86_EXTENDED_PLATFORM
702 select X86_REBOOTFIXUPS
704 This option is needed for RDC R-321x system-on-chip, also known
706 If you don't have one of these chips, you should say N here.
708 config X86_32_NON_STANDARD
709 bool "Support non-standard 32-bit SMP architectures"
710 depends on X86_32 && SMP
711 depends on X86_EXTENDED_PLATFORM
713 This option compiles in the bigsmp and STA2X11 default
714 subarchitectures. It is intended for a generic binary
715 kernel. If you select them all, kernel will probe it one by
716 one and will fallback to default.
718 # Alphabetically sorted list of Non standard 32 bit platforms
720 config X86_SUPPORTS_MEMORY_FAILURE
722 # MCE code calls memory_failure():
724 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
725 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
726 depends on X86_64 || !SPARSEMEM
727 select ARCH_SUPPORTS_MEMORY_FAILURE
730 bool "STA2X11 Companion Chip Support"
731 depends on X86_32_NON_STANDARD && PCI
736 This adds support for boards based on the STA2X11 IO-Hub,
737 a.k.a. "ConneXt". The chip is used in place of the standard
738 PC chipset, so all "standard" peripherals are missing. If this
739 option is selected the kernel will still be able to boot on
740 standard PC machines.
743 tristate "Eurobraille/Iris poweroff module"
746 The Iris machines from EuroBraille do not have APM or ACPI support
747 to shut themselves down properly. A special I/O sequence is
748 needed to do so, which is what this module does at
751 This is only for Iris machines from EuroBraille.
755 config SCHED_OMIT_FRAME_POINTER
757 prompt "Single-depth WCHAN output"
760 Calculate simpler /proc/<PID>/wchan values. If this option
761 is disabled then wchan values will recurse back to the
762 caller function. This provides more accurate wchan values,
763 at the expense of slightly more scheduling overhead.
765 If in doubt, say "Y".
767 menuconfig HYPERVISOR_GUEST
768 bool "Linux guest support"
770 Say Y here to enable options for running Linux under various hyper-
771 visors. This option enables basic hypervisor detection and platform
774 If you say N, all options in this submenu will be skipped and
775 disabled, and Linux guest support won't be built in.
780 bool "Enable paravirtualization code"
781 depends on HAVE_STATIC_CALL
783 This changes the kernel so it can modify itself when it is run
784 under a hypervisor, potentially improving performance significantly
785 over full virtualization. However, when run without a hypervisor
786 the kernel is theoretically slower and slightly larger.
791 config PARAVIRT_DEBUG
792 bool "paravirt-ops debugging"
793 depends on PARAVIRT && DEBUG_KERNEL
795 Enable to debug paravirt_ops internals. Specifically, BUG if
796 a paravirt_op is missing when it is called.
798 config PARAVIRT_SPINLOCKS
799 bool "Paravirtualization layer for spinlocks"
800 depends on PARAVIRT && SMP
802 Paravirtualized spinlocks allow a pvops backend to replace the
803 spinlock implementation with something virtualization-friendly
804 (for example, block the virtual CPU rather than spinning).
806 It has a minimal impact on native kernels and gives a nice performance
807 benefit on paravirtualized KVM / Xen kernels.
809 If you are unsure how to answer this question, answer Y.
811 config X86_HV_CALLBACK_VECTOR
814 source "arch/x86/xen/Kconfig"
817 bool "KVM Guest support (including kvmclock)"
819 select PARAVIRT_CLOCK
820 select ARCH_CPUIDLE_HALTPOLL
821 select X86_HV_CALLBACK_VECTOR
824 This option enables various optimizations for running under the KVM
825 hypervisor. It includes a paravirtualized clock, so that instead
826 of relying on a PIT (or probably other) emulation by the
827 underlying device model, the host provides the guest with
828 timing infrastructure such as time of day, and system time
830 config ARCH_CPUIDLE_HALTPOLL
832 prompt "Disable host haltpoll when loading haltpoll driver"
834 If virtualized under KVM, disable host haltpoll.
837 bool "Support for running PVH guests"
839 This option enables the PVH entry point for guest virtual machines
840 as specified in the x86/HVM direct boot ABI.
842 config PARAVIRT_TIME_ACCOUNTING
843 bool "Paravirtual steal time accounting"
846 Select this option to enable fine granularity task steal time
847 accounting. Time spent executing other tasks in parallel with
848 the current vCPU is discounted from the vCPU power. To account for
849 that, there can be a small performance impact.
851 If in doubt, say N here.
853 config PARAVIRT_CLOCK
856 config JAILHOUSE_GUEST
857 bool "Jailhouse non-root cell support"
858 depends on X86_64 && PCI
861 This option allows to run Linux as guest in a Jailhouse non-root
862 cell. You can leave this option disabled if you only want to start
863 Jailhouse and run Linux afterwards in the root cell.
866 bool "ACRN Guest support"
868 select X86_HV_CALLBACK_VECTOR
870 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
871 a flexible, lightweight reference open-source hypervisor, built with
872 real-time and safety-criticality in mind. It is built for embedded
873 IOT with small footprint and real-time features. More details can be
874 found in https://projectacrn.org/.
876 endif #HYPERVISOR_GUEST
878 source "arch/x86/Kconfig.cpu"
882 prompt "HPET Timer Support" if X86_32
884 Use the IA-PC HPET (High Precision Event Timer) to manage
885 time in preference to the PIT and RTC, if a HPET is
887 HPET is the next generation timer replacing legacy 8254s.
888 The HPET provides a stable time base on SMP
889 systems, unlike the TSC, but it is more expensive to access,
890 as it is off-chip. The interface used is documented
891 in the HPET spec, revision 1.
893 You can safely choose Y here. However, HPET will only be
894 activated if the platform and the BIOS support this feature.
895 Otherwise the 8254 will be used for timing services.
897 Choose N to continue using the legacy 8254 timer.
899 config HPET_EMULATE_RTC
901 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
903 # Mark as expert because too many people got it wrong.
904 # The code disables itself when not needed.
907 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
908 bool "Enable DMI scanning" if EXPERT
910 Enabled scanning of DMI to identify machine quirks. Say Y
911 here unless you have verified that your setup is not
912 affected by entries in the DMI blacklist. Required by PNP
916 bool "Old AMD GART IOMMU support"
920 depends on X86_64 && PCI && AMD_NB
922 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
923 GART based hardware IOMMUs.
925 The GART supports full DMA access for devices with 32-bit access
926 limitations, on systems with more than 3 GB. This is usually needed
927 for USB, sound, many IDE/SATA chipsets and some other devices.
929 Newer systems typically have a modern AMD IOMMU, supported via
930 the CONFIG_AMD_IOMMU=y config option.
932 In normal configurations this driver is only active when needed:
933 there's more than 3 GB of memory and the system contains a
934 32-bit limited device.
939 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
940 depends on X86_64 && SMP && DEBUG_KERNEL
941 select CPUMASK_OFFSTACK
943 Enable maximum number of CPUS and NUMA Nodes for this architecture.
947 # The maximum number of CPUs supported:
949 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
950 # and which can be configured interactively in the
951 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
953 # The ranges are different on 32-bit and 64-bit kernels, depending on
954 # hardware capabilities and scalability features of the kernel.
956 # ( If MAXSMP is enabled we just use the highest possible value and disable
957 # interactive configuration. )
960 config NR_CPUS_RANGE_BEGIN
962 default NR_CPUS_RANGE_END if MAXSMP
966 config NR_CPUS_RANGE_END
969 default 64 if SMP && X86_BIGSMP
970 default 8 if SMP && !X86_BIGSMP
973 config NR_CPUS_RANGE_END
976 default 8192 if SMP && CPUMASK_OFFSTACK
977 default 512 if SMP && !CPUMASK_OFFSTACK
980 config NR_CPUS_DEFAULT
983 default 32 if X86_BIGSMP
987 config NR_CPUS_DEFAULT
990 default 8192 if MAXSMP
995 int "Maximum number of CPUs" if SMP && !MAXSMP
996 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
997 default NR_CPUS_DEFAULT
999 This allows you to specify the maximum number of CPUs which this
1000 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1001 supported value is 8192, otherwise the maximum value is 512. The
1002 minimum value which makes sense is 2.
1004 This is purely to save memory: each supported CPU adds about 8KB
1005 to the kernel image.
1007 config SCHED_CLUSTER
1008 bool "Cluster scheduler support"
1012 Cluster scheduler support improves the CPU scheduler's decision
1013 making when dealing with machines that have clusters of CPUs.
1014 Cluster usually means a couple of CPUs which are placed closely
1015 by sharing mid-level caches, last-level cache tags or internal
1023 prompt "Multi-core scheduler support"
1026 Multi-core scheduler support improves the CPU scheduler's decision
1027 making when dealing with multi-core CPU chips at a cost of slightly
1028 increased overhead in some places. If unsure say N here.
1030 config SCHED_MC_PRIO
1031 bool "CPU core priorities scheduler support"
1032 depends on SCHED_MC && CPU_SUP_INTEL
1033 select X86_INTEL_PSTATE
1037 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1038 core ordering determined at manufacturing time, which allows
1039 certain cores to reach higher turbo frequencies (when running
1040 single threaded workloads) than others.
1042 Enabling this kernel feature teaches the scheduler about
1043 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1044 scheduler's CPU selection logic accordingly, so that higher
1045 overall system performance can be achieved.
1047 This feature will have no effect on CPUs without this feature.
1049 If unsure say Y here.
1053 depends on !SMP && X86_LOCAL_APIC
1056 bool "Local APIC support on uniprocessors" if !PCI_MSI
1058 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1060 A local APIC (Advanced Programmable Interrupt Controller) is an
1061 integrated interrupt controller in the CPU. If you have a single-CPU
1062 system which has a processor with a local APIC, you can say Y here to
1063 enable and use it. If you say Y here even though your machine doesn't
1064 have a local APIC, then the kernel will still run with no slowdown at
1065 all. The local APIC supports CPU-generated self-interrupts (timer,
1066 performance counters), and the NMI watchdog which detects hard
1069 config X86_UP_IOAPIC
1070 bool "IO-APIC support on uniprocessors"
1071 depends on X86_UP_APIC
1073 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1074 SMP-capable replacement for PC-style interrupt controllers. Most
1075 SMP systems and many recent uniprocessor systems have one.
1077 If you have a single-CPU system with an IO-APIC, you can say Y here
1078 to use it. If you say Y here even though your machine doesn't have
1079 an IO-APIC, then the kernel will still run with no slowdown at all.
1081 config X86_LOCAL_APIC
1083 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1084 select IRQ_DOMAIN_HIERARCHY
1085 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1089 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1091 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1092 bool "Reroute for broken boot IRQs"
1093 depends on X86_IO_APIC
1095 This option enables a workaround that fixes a source of
1096 spurious interrupts. This is recommended when threaded
1097 interrupt handling is used on systems where the generation of
1098 superfluous "boot interrupts" cannot be disabled.
1100 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1101 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1102 kernel does during interrupt handling). On chipsets where this
1103 boot IRQ generation cannot be disabled, this workaround keeps
1104 the original IRQ line masked so that only the equivalent "boot
1105 IRQ" is delivered to the CPUs. The workaround also tells the
1106 kernel to set up the IRQ handler on the boot IRQ line. In this
1107 way only one interrupt is delivered to the kernel. Otherwise
1108 the spurious second interrupt may cause the kernel to bring
1109 down (vital) interrupt lines.
1111 Only affects "broken" chipsets. Interrupt sharing may be
1112 increased on these systems.
1115 bool "Machine Check / overheating reporting"
1116 select GENERIC_ALLOCATOR
1119 Machine Check support allows the processor to notify the
1120 kernel if it detects a problem (e.g. overheating, data corruption).
1121 The action the kernel takes depends on the severity of the problem,
1122 ranging from warning messages to halting the machine.
1124 config X86_MCELOG_LEGACY
1125 bool "Support for deprecated /dev/mcelog character device"
1128 Enable support for /dev/mcelog which is needed by the old mcelog
1129 userspace logging daemon. Consider switching to the new generation
1132 config X86_MCE_INTEL
1134 prompt "Intel MCE features"
1135 depends on X86_MCE && X86_LOCAL_APIC
1137 Additional support for intel specific MCE features such as
1138 the thermal monitor.
1142 prompt "AMD MCE features"
1143 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1145 Additional support for AMD specific MCE features such as
1146 the DRAM Error Threshold.
1148 config X86_ANCIENT_MCE
1149 bool "Support for old Pentium 5 / WinChip machine checks"
1150 depends on X86_32 && X86_MCE
1152 Include support for machine check handling on old Pentium 5 or WinChip
1153 systems. These typically need to be enabled explicitly on the command
1156 config X86_MCE_THRESHOLD
1157 depends on X86_MCE_AMD || X86_MCE_INTEL
1160 config X86_MCE_INJECT
1161 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1162 tristate "Machine check injector support"
1164 Provide support for injecting machine checks for testing purposes.
1165 If you don't know what a machine check is and you don't do kernel
1166 QA it is safe to say n.
1168 source "arch/x86/events/Kconfig"
1170 config X86_LEGACY_VM86
1171 bool "Legacy VM86 support"
1174 This option allows user programs to put the CPU into V8086
1175 mode, which is an 80286-era approximation of 16-bit real mode.
1177 Some very old versions of X and/or vbetool require this option
1178 for user mode setting. Similarly, DOSEMU will use it if
1179 available to accelerate real mode DOS programs. However, any
1180 recent version of DOSEMU, X, or vbetool should be fully
1181 functional even without kernel VM86 support, as they will all
1182 fall back to software emulation. Nevertheless, if you are using
1183 a 16-bit DOS program where 16-bit performance matters, vm86
1184 mode might be faster than emulation and you might want to
1187 Note that any app that works on a 64-bit kernel is unlikely to
1188 need this option, as 64-bit kernels don't, and can't, support
1189 V8086 mode. This option is also unrelated to 16-bit protected
1190 mode and is not needed to run most 16-bit programs under Wine.
1192 Enabling this option increases the complexity of the kernel
1193 and slows down exception handling a tiny bit.
1195 If unsure, say N here.
1199 default X86_LEGACY_VM86
1202 bool "Enable support for 16-bit segments" if EXPERT
1204 depends on MODIFY_LDT_SYSCALL
1206 This option is required by programs like Wine to run 16-bit
1207 protected mode legacy code on x86 processors. Disabling
1208 this option saves about 300 bytes on i386, or around 6K text
1209 plus 16K runtime memory on x86-64,
1213 depends on X86_16BIT && X86_32
1217 depends on X86_16BIT && X86_64
1219 config X86_VSYSCALL_EMULATION
1220 bool "Enable vsyscall emulation" if EXPERT
1224 This enables emulation of the legacy vsyscall page. Disabling
1225 it is roughly equivalent to booting with vsyscall=none, except
1226 that it will also disable the helpful warning if a program
1227 tries to use a vsyscall. With this option set to N, offending
1228 programs will just segfault, citing addresses of the form
1231 This option is required by many programs built before 2013, and
1232 care should be used even with newer programs if set to N.
1234 Disabling this option saves about 7K of kernel size and
1235 possibly 4K of additional runtime pagetable memory.
1237 config X86_IOPL_IOPERM
1238 bool "IOPERM and IOPL Emulation"
1241 This enables the ioperm() and iopl() syscalls which are necessary
1242 for legacy applications.
1244 Legacy IOPL support is an overbroad mechanism which allows user
1245 space aside of accessing all 65536 I/O ports also to disable
1246 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1247 capabilities and permission from potentially active security
1250 The emulation restricts the functionality of the syscall to
1251 only allowing the full range I/O port access, but prevents the
1252 ability to disable interrupts from user space which would be
1253 granted if the hardware IOPL mechanism would be used.
1256 tristate "Toshiba Laptop support"
1259 This adds a driver to safely access the System Management Mode of
1260 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1261 not work on models with a Phoenix BIOS. The System Management Mode
1262 is used to set the BIOS and power saving options on Toshiba portables.
1264 For information on utilities to make use of this driver see the
1265 Toshiba Linux utilities web site at:
1266 <http://www.buzzard.org.uk/toshiba/>.
1268 Say Y if you intend to run this kernel on a Toshiba portable.
1272 tristate "Dell i8k legacy laptop support"
1275 select SENSORS_DELL_SMM
1277 This option enables legacy /proc/i8k userspace interface in hwmon
1278 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1279 temperature and allows controlling fan speeds of Dell laptops via
1280 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1281 it reports also power and hotkey status. For fan speed control is
1282 needed userspace package i8kutils.
1284 Say Y if you intend to run this kernel on old Dell laptops or want to
1285 use userspace package i8kutils.
1288 config X86_REBOOTFIXUPS
1289 bool "Enable X86 board specific fixups for reboot"
1292 This enables chipset and/or board specific fixups to be done
1293 in order to get reboot to work correctly. This is only needed on
1294 some combinations of hardware and BIOS. The symptom, for which
1295 this config is intended, is when reboot ends with a stalled/hung
1298 Currently, the only fixup is for the Geode machines using
1299 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1301 Say Y if you want to enable the fixup. Currently, it's safe to
1302 enable this option even if you don't need it.
1306 bool "CPU microcode loading support"
1308 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1310 If you say Y here, you will be able to update the microcode on
1311 Intel and AMD processors. The Intel support is for the IA32 family,
1312 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1313 AMD support is for families 0x10 and later. You will obviously need
1314 the actual microcode binary data itself which is not shipped with
1317 The preferred method to load microcode from a detached initrd is described
1318 in Documentation/x86/microcode.rst. For that you need to enable
1319 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1320 initrd for microcode blobs.
1322 In addition, you can build the microcode into the kernel. For that you
1323 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1326 config MICROCODE_INTEL
1327 bool "Intel microcode loading support"
1328 depends on MICROCODE
1331 This options enables microcode patch loading support for Intel
1334 For the current Intel microcode data package go to
1335 <https://downloadcenter.intel.com> and search for
1336 'Linux Processor Microcode Data File'.
1338 config MICROCODE_AMD
1339 bool "AMD microcode loading support"
1340 depends on MICROCODE
1342 If you select this option, microcode patch loading support for AMD
1343 processors will be enabled.
1345 config MICROCODE_OLD_INTERFACE
1346 bool "Ancient loading interface (DEPRECATED)"
1348 depends on MICROCODE
1350 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1351 which was used by userspace tools like iucode_tool and microcode.ctl.
1352 It is inadequate because it runs too late to be able to properly
1353 load microcode on a machine and it needs special tools. Instead, you
1354 should've switched to the early loading method with the initrd or
1355 builtin microcode by now: Documentation/x86/microcode.rst
1358 tristate "/dev/cpu/*/msr - Model-specific register support"
1360 This device gives privileged processes access to the x86
1361 Model-Specific Registers (MSRs). It is a character device with
1362 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1363 MSR accesses are directed to a specific CPU on multi-processor
1367 tristate "/dev/cpu/*/cpuid - CPU information support"
1369 This device gives processes access to the x86 CPUID instruction to
1370 be executed on a specific processor. It is a character device
1371 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1375 prompt "High Memory Support"
1382 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1383 However, the address space of 32-bit x86 processors is only 4
1384 Gigabytes large. That means that, if you have a large amount of
1385 physical memory, not all of it can be "permanently mapped" by the
1386 kernel. The physical memory that's not permanently mapped is called
1389 If you are compiling a kernel which will never run on a machine with
1390 more than 1 Gigabyte total physical RAM, answer "off" here (default
1391 choice and suitable for most users). This will result in a "3GB/1GB"
1392 split: 3GB are mapped so that each process sees a 3GB virtual memory
1393 space and the remaining part of the 4GB virtual memory space is used
1394 by the kernel to permanently map as much physical memory as
1397 If the machine has between 1 and 4 Gigabytes physical RAM, then
1400 If more than 4 Gigabytes is used then answer "64GB" here. This
1401 selection turns Intel PAE (Physical Address Extension) mode on.
1402 PAE implements 3-level paging on IA32 processors. PAE is fully
1403 supported by Linux, PAE mode is implemented on all recent Intel
1404 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1405 then the kernel will not boot on CPUs that don't support PAE!
1407 The actual amount of total physical memory will either be
1408 auto detected or can be forced by using a kernel command line option
1409 such as "mem=256M". (Try "man bootparam" or see the documentation of
1410 your boot loader (lilo or loadlin) about how to pass options to the
1411 kernel at boot time.)
1413 If unsure, say "off".
1418 Select this if you have a 32-bit processor and between 1 and 4
1419 gigabytes of physical RAM.
1423 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1426 Select this if you have a 32-bit processor and more than 4
1427 gigabytes of physical RAM.
1432 prompt "Memory split" if EXPERT
1436 Select the desired split between kernel and user memory.
1438 If the address range available to the kernel is less than the
1439 physical memory installed, the remaining memory will be available
1440 as "high memory". Accessing high memory is a little more costly
1441 than low memory, as it needs to be mapped into the kernel first.
1442 Note that increasing the kernel address space limits the range
1443 available to user programs, making the address space there
1444 tighter. Selecting anything other than the default 3G/1G split
1445 will also likely make your kernel incompatible with binary-only
1448 If you are not absolutely sure what you are doing, leave this
1452 bool "3G/1G user/kernel split"
1453 config VMSPLIT_3G_OPT
1455 bool "3G/1G user/kernel split (for full 1G low memory)"
1457 bool "2G/2G user/kernel split"
1458 config VMSPLIT_2G_OPT
1460 bool "2G/2G user/kernel split (for full 2G low memory)"
1462 bool "1G/3G user/kernel split"
1467 default 0xB0000000 if VMSPLIT_3G_OPT
1468 default 0x80000000 if VMSPLIT_2G
1469 default 0x78000000 if VMSPLIT_2G_OPT
1470 default 0x40000000 if VMSPLIT_1G
1476 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1479 bool "PAE (Physical Address Extension) Support"
1480 depends on X86_32 && !HIGHMEM4G
1481 select PHYS_ADDR_T_64BIT
1484 PAE is required for NX support, and furthermore enables
1485 larger swapspace support for non-overcommit purposes. It
1486 has the cost of more pagetable lookup overhead, and also
1487 consumes more pagetable space per process.
1490 bool "Enable 5-level page tables support"
1492 select DYNAMIC_MEMORY_LAYOUT
1493 select SPARSEMEM_VMEMMAP
1496 5-level paging enables access to larger address space:
1497 upto 128 PiB of virtual address space and 4 PiB of
1498 physical address space.
1500 It will be supported by future Intel CPUs.
1502 A kernel with the option enabled can be booted on machines that
1503 support 4- or 5-level paging.
1505 See Documentation/x86/x86_64/5level-paging.rst for more
1510 config X86_DIRECT_GBPAGES
1514 Certain kernel features effectively disable kernel
1515 linear 1 GB mappings (even if the CPU otherwise
1516 supports them), so don't confuse the user by printing
1517 that we have them enabled.
1519 config X86_CPA_STATISTICS
1520 bool "Enable statistic for Change Page Attribute"
1523 Expose statistics about the Change Page Attribute mechanism, which
1524 helps to determine the effectiveness of preserving large and huge
1525 page mappings when mapping protections are changed.
1527 config X86_MEM_ENCRYPT
1528 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1529 select DYNAMIC_PHYSICAL_MASK
1530 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1533 config AMD_MEM_ENCRYPT
1534 bool "AMD Secure Memory Encryption (SME) support"
1535 depends on X86_64 && CPU_SUP_AMD
1536 select DMA_COHERENT_POOL
1537 select ARCH_USE_MEMREMAP_PROT
1538 select INSTRUCTION_DECODER
1539 select ARCH_HAS_CC_PLATFORM
1540 select X86_MEM_ENCRYPT
1542 Say yes to enable support for the encryption of system memory.
1543 This requires an AMD processor that supports Secure Memory
1546 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1547 bool "Activate AMD Secure Memory Encryption (SME) by default"
1548 depends on AMD_MEM_ENCRYPT
1550 Say yes to have system memory encrypted by default if running on
1551 an AMD processor that supports Secure Memory Encryption (SME).
1553 If set to Y, then the encryption of system memory can be
1554 deactivated with the mem_encrypt=off command line option.
1556 If set to N, then the encryption of system memory can be
1557 activated with the mem_encrypt=on command line option.
1559 # Common NUMA Features
1561 bool "NUMA Memory Allocation and Scheduler Support"
1563 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1564 default y if X86_BIGSMP
1566 Enable NUMA (Non-Uniform Memory Access) support.
1568 The kernel will try to allocate memory used by a CPU on the
1569 local memory controller of the CPU and add some more
1570 NUMA awareness to the kernel.
1572 For 64-bit this is recommended if the system is Intel Core i7
1573 (or later), AMD Opteron, or EM64T NUMA.
1575 For 32-bit this is only needed if you boot a 32-bit
1576 kernel on a 64-bit NUMA platform.
1578 Otherwise, you should say N.
1582 prompt "Old style AMD Opteron NUMA detection"
1583 depends on X86_64 && NUMA && PCI
1585 Enable AMD NUMA node topology detection. You should say Y here if
1586 you have a multi processor AMD system. This uses an old method to
1587 read the NUMA configuration directly from the builtin Northbridge
1588 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1589 which also takes priority if both are compiled in.
1591 config X86_64_ACPI_NUMA
1593 prompt "ACPI NUMA detection"
1594 depends on X86_64 && NUMA && ACPI && PCI
1597 Enable ACPI SRAT based node topology detection.
1600 bool "NUMA emulation"
1603 Enable NUMA emulation. A flat machine will be split
1604 into virtual nodes when booted with "numa=fake=N", where N is the
1605 number of nodes. This is only useful for debugging.
1608 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1610 default "10" if MAXSMP
1611 default "6" if X86_64
1615 Specify the maximum number of NUMA Nodes available on the target
1616 system. Increases memory reserved to accommodate various tables.
1618 config ARCH_FLATMEM_ENABLE
1620 depends on X86_32 && !NUMA
1622 config ARCH_SPARSEMEM_ENABLE
1624 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1625 select SPARSEMEM_STATIC if X86_32
1626 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1628 config ARCH_SPARSEMEM_DEFAULT
1629 def_bool X86_64 || (NUMA && X86_32)
1631 config ARCH_SELECT_MEMORY_MODEL
1633 depends on ARCH_SPARSEMEM_ENABLE
1635 config ARCH_MEMORY_PROBE
1636 bool "Enable sysfs memory/probe interface"
1637 depends on MEMORY_HOTPLUG
1639 This option enables a sysfs memory/probe interface for testing.
1640 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1641 If you are unsure how to answer this question, answer N.
1643 config ARCH_PROC_KCORE_TEXT
1645 depends on X86_64 && PROC_KCORE
1647 config ILLEGAL_POINTER_VALUE
1650 default 0xdead000000000000 if X86_64
1652 config X86_PMEM_LEGACY_DEVICE
1655 config X86_PMEM_LEGACY
1656 tristate "Support non-standard NVDIMMs and ADR protected memory"
1657 depends on PHYS_ADDR_T_64BIT
1659 select X86_PMEM_LEGACY_DEVICE
1660 select NUMA_KEEP_MEMINFO if NUMA
1663 Treat memory marked using the non-standard e820 type of 12 as used
1664 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1665 The kernel will offer these regions to the 'pmem' driver so
1666 they can be used for persistent storage.
1671 bool "Allocate 3rd-level pagetables from highmem"
1674 The VM uses one page table entry for each page of physical memory.
1675 For systems with a lot of RAM, this can be wasteful of precious
1676 low memory. Setting this option will put user-space page table
1677 entries in high memory.
1679 config X86_CHECK_BIOS_CORRUPTION
1680 bool "Check for low memory corruption"
1682 Periodically check for memory corruption in low memory, which
1683 is suspected to be caused by BIOS. Even when enabled in the
1684 configuration, it is disabled at runtime. Enable it by
1685 setting "memory_corruption_check=1" on the kernel command
1686 line. By default it scans the low 64k of memory every 60
1687 seconds; see the memory_corruption_check_size and
1688 memory_corruption_check_period parameters in
1689 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1691 When enabled with the default parameters, this option has
1692 almost no overhead, as it reserves a relatively small amount
1693 of memory and scans it infrequently. It both detects corruption
1694 and prevents it from affecting the running system.
1696 It is, however, intended as a diagnostic tool; if repeatable
1697 BIOS-originated corruption always affects the same memory,
1698 you can use memmap= to prevent the kernel from using that
1701 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1702 bool "Set the default setting of memory_corruption_check"
1703 depends on X86_CHECK_BIOS_CORRUPTION
1706 Set whether the default state of memory_corruption_check is
1709 config MATH_EMULATION
1711 depends on MODIFY_LDT_SYSCALL
1712 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1714 Linux can emulate a math coprocessor (used for floating point
1715 operations) if you don't have one. 486DX and Pentium processors have
1716 a math coprocessor built in, 486SX and 386 do not, unless you added
1717 a 487DX or 387, respectively. (The messages during boot time can
1718 give you some hints here ["man dmesg"].) Everyone needs either a
1719 coprocessor or this emulation.
1721 If you don't have a math coprocessor, you need to say Y here; if you
1722 say Y here even though you have a coprocessor, the coprocessor will
1723 be used nevertheless. (This behavior can be changed with the kernel
1724 command line option "no387", which comes handy if your coprocessor
1725 is broken. Try "man bootparam" or see the documentation of your boot
1726 loader (lilo or loadlin) about how to pass options to the kernel at
1727 boot time.) This means that it is a good idea to say Y here if you
1728 intend to use this kernel on different machines.
1730 More information about the internals of the Linux math coprocessor
1731 emulation can be found in <file:arch/x86/math-emu/README>.
1733 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1734 kernel, it won't hurt.
1738 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1740 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1741 the Memory Type Range Registers (MTRRs) may be used to control
1742 processor access to memory ranges. This is most useful if you have
1743 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1744 allows bus write transfers to be combined into a larger transfer
1745 before bursting over the PCI/AGP bus. This can increase performance
1746 of image write operations 2.5 times or more. Saying Y here creates a
1747 /proc/mtrr file which may be used to manipulate your processor's
1748 MTRRs. Typically the X server should use this.
1750 This code has a reasonably generic interface so that similar
1751 control registers on other processors can be easily supported
1754 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1755 Registers (ARRs) which provide a similar functionality to MTRRs. For
1756 these, the ARRs are used to emulate the MTRRs.
1757 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1758 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1759 write-combining. All of these processors are supported by this code
1760 and it makes sense to say Y here if you have one of them.
1762 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1763 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1764 can lead to all sorts of problems, so it's good to say Y here.
1766 You can safely say Y even if your machine doesn't have MTRRs, you'll
1767 just add about 9 KB to your kernel.
1769 See <file:Documentation/x86/mtrr.rst> for more information.
1771 config MTRR_SANITIZER
1773 prompt "MTRR cleanup support"
1776 Convert MTRR layout from continuous to discrete, so X drivers can
1777 add writeback entries.
1779 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1780 The largest mtrr entry size for a continuous block can be set with
1785 config MTRR_SANITIZER_ENABLE_DEFAULT
1786 int "MTRR cleanup enable value (0-1)"
1789 depends on MTRR_SANITIZER
1791 Enable mtrr cleanup default value
1793 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1794 int "MTRR cleanup spare reg num (0-7)"
1797 depends on MTRR_SANITIZER
1799 mtrr cleanup spare entries default, it can be changed via
1800 mtrr_spare_reg_nr=N on the kernel command line.
1804 prompt "x86 PAT support" if EXPERT
1807 Use PAT attributes to setup page level cache control.
1809 PATs are the modern equivalents of MTRRs and are much more
1810 flexible than MTRRs.
1812 Say N here if you see bootup problems (boot crash, boot hang,
1813 spontaneous reboots) or a non-working video driver.
1817 config ARCH_USES_PG_UNCACHED
1823 prompt "x86 architectural random number generator" if EXPERT
1825 Enable the x86 architectural RDRAND instruction
1826 (Intel Bull Mountain technology) to generate random numbers.
1827 If supported, this is a high bandwidth, cryptographically
1828 secure hardware random number generator.
1832 prompt "Supervisor Mode Access Prevention" if EXPERT
1834 Supervisor Mode Access Prevention (SMAP) is a security
1835 feature in newer Intel processors. There is a small
1836 performance cost if this enabled and turned on; there is
1837 also a small increase in the kernel size if this is enabled.
1843 prompt "User Mode Instruction Prevention" if EXPERT
1845 User Mode Instruction Prevention (UMIP) is a security feature in
1846 some x86 processors. If enabled, a general protection fault is
1847 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1848 executed in user mode. These instructions unnecessarily expose
1849 information about the hardware state.
1851 The vast majority of applications do not use these instructions.
1852 For the very few that do, software emulation is provided in
1853 specific cases in protected and virtual-8086 modes. Emulated
1856 config X86_INTEL_MEMORY_PROTECTION_KEYS
1857 prompt "Memory Protection Keys"
1859 # Note: only available in 64-bit mode
1860 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1861 select ARCH_USES_HIGH_VMA_FLAGS
1862 select ARCH_HAS_PKEYS
1864 Memory Protection Keys provides a mechanism for enforcing
1865 page-based protections, but without requiring modification of the
1866 page tables when an application changes protection domains.
1868 For details, see Documentation/core-api/protection-keys.rst
1873 prompt "TSX enable mode"
1874 depends on CPU_SUP_INTEL
1875 default X86_INTEL_TSX_MODE_OFF
1877 Intel's TSX (Transactional Synchronization Extensions) feature
1878 allows to optimize locking protocols through lock elision which
1879 can lead to a noticeable performance boost.
1881 On the other hand it has been shown that TSX can be exploited
1882 to form side channel attacks (e.g. TAA) and chances are there
1883 will be more of those attacks discovered in the future.
1885 Therefore TSX is not enabled by default (aka tsx=off). An admin
1886 might override this decision by tsx=on the command line parameter.
1887 Even with TSX enabled, the kernel will attempt to enable the best
1888 possible TAA mitigation setting depending on the microcode available
1889 for the particular machine.
1891 This option allows to set the default tsx mode between tsx=on, =off
1892 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1895 Say off if not sure, auto if TSX is in use but it should be used on safe
1896 platforms or on if TSX is in use and the security aspect of tsx is not
1899 config X86_INTEL_TSX_MODE_OFF
1902 TSX is disabled if possible - equals to tsx=off command line parameter.
1904 config X86_INTEL_TSX_MODE_ON
1907 TSX is always enabled on TSX capable HW - equals the tsx=on command
1910 config X86_INTEL_TSX_MODE_AUTO
1913 TSX is enabled on TSX capable HW that is believed to be safe against
1914 side channel attacks- equals the tsx=auto command line parameter.
1918 bool "Software Guard eXtensions (SGX)"
1919 depends on X86_64 && CPU_SUP_INTEL
1921 depends on CRYPTO_SHA256=y
1924 select NUMA_KEEP_MEMINFO if NUMA
1927 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1928 that can be used by applications to set aside private regions of code
1929 and data, referred to as enclaves. An enclave's private memory can
1930 only be accessed by code running within the enclave. Accesses from
1931 outside the enclave, including other enclaves, are disallowed by
1937 bool "EFI runtime service support"
1940 select EFI_RUNTIME_WRAPPERS
1941 select ARCH_USE_MEMREMAP_PROT
1943 This enables the kernel to use EFI runtime services that are
1944 available (such as the EFI variable services).
1946 This option is only useful on systems that have EFI firmware.
1947 In addition, you should use the latest ELILO loader available
1948 at <http://elilo.sourceforge.net> in order to take advantage
1949 of EFI runtime services. However, even with this option, the
1950 resultant kernel should continue to boot on existing non-EFI
1954 bool "EFI stub support"
1955 depends on EFI && !X86_USE_3DNOW
1956 depends on $(cc-option,-mabi=ms) || X86_32
1959 This kernel feature allows a bzImage to be loaded directly
1960 by EFI firmware without the use of a bootloader.
1962 See Documentation/admin-guide/efi-stub.rst for more information.
1965 bool "EFI mixed-mode support"
1966 depends on EFI_STUB && X86_64
1968 Enabling this feature allows a 64-bit kernel to be booted
1969 on a 32-bit firmware, provided that your CPU supports 64-bit
1972 Note that it is not possible to boot a mixed-mode enabled
1973 kernel via the EFI boot stub - a bootloader that supports
1974 the EFI handover protocol must be used.
1978 source "kernel/Kconfig.hz"
1981 bool "kexec system call"
1984 kexec is a system call that implements the ability to shutdown your
1985 current kernel, and to start another kernel. It is like a reboot
1986 but it is independent of the system firmware. And like a reboot
1987 you can start any kernel with it, not just Linux.
1989 The name comes from the similarity to the exec system call.
1991 It is an ongoing process to be certain the hardware in a machine
1992 is properly shutdown, so do not be surprised if this code does not
1993 initially work for you. As of this writing the exact hardware
1994 interface is strongly in flux, so no good recommendation can be
1998 bool "kexec file based system call"
2003 depends on CRYPTO_SHA256=y
2005 This is new version of kexec system call. This system call is
2006 file based and takes file descriptors as system call argument
2007 for kernel and initramfs as opposed to list of segments as
2008 accepted by previous system call.
2010 config ARCH_HAS_KEXEC_PURGATORY
2014 bool "Verify kernel signature during kexec_file_load() syscall"
2015 depends on KEXEC_FILE
2018 This option makes the kexec_file_load() syscall check for a valid
2019 signature of the kernel image. The image can still be loaded without
2020 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2021 there's a signature that we can check, then it must be valid.
2023 In addition to this option, you need to enable signature
2024 verification for the corresponding kernel image type being
2025 loaded in order for this to work.
2027 config KEXEC_SIG_FORCE
2028 bool "Require a valid signature in kexec_file_load() syscall"
2029 depends on KEXEC_SIG
2031 This option makes kernel signature verification mandatory for
2032 the kexec_file_load() syscall.
2034 config KEXEC_BZIMAGE_VERIFY_SIG
2035 bool "Enable bzImage signature verification support"
2036 depends on KEXEC_SIG
2037 depends on SIGNED_PE_FILE_VERIFICATION
2038 select SYSTEM_TRUSTED_KEYRING
2040 Enable bzImage signature verification support.
2043 bool "kernel crash dumps"
2044 depends on X86_64 || (X86_32 && HIGHMEM)
2046 Generate crash dump after being started by kexec.
2047 This should be normally only set in special crash dump kernels
2048 which are loaded in the main kernel with kexec-tools into
2049 a specially reserved region and then later executed after
2050 a crash by kdump/kexec. The crash dump kernel must be compiled
2051 to a memory address not used by the main kernel or BIOS using
2052 PHYSICAL_START, or it must be built as a relocatable image
2053 (CONFIG_RELOCATABLE=y).
2054 For more details see Documentation/admin-guide/kdump/kdump.rst
2058 depends on KEXEC && HIBERNATION
2060 Jump between original kernel and kexeced kernel and invoke
2061 code in physical address mode via KEXEC
2063 config PHYSICAL_START
2064 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2067 This gives the physical address where the kernel is loaded.
2069 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2070 bzImage will decompress itself to above physical address and
2071 run from there. Otherwise, bzImage will run from the address where
2072 it has been loaded by the boot loader and will ignore above physical
2075 In normal kdump cases one does not have to set/change this option
2076 as now bzImage can be compiled as a completely relocatable image
2077 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2078 address. This option is mainly useful for the folks who don't want
2079 to use a bzImage for capturing the crash dump and want to use a
2080 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2081 to be specifically compiled to run from a specific memory area
2082 (normally a reserved region) and this option comes handy.
2084 So if you are using bzImage for capturing the crash dump,
2085 leave the value here unchanged to 0x1000000 and set
2086 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2087 for capturing the crash dump change this value to start of
2088 the reserved region. In other words, it can be set based on
2089 the "X" value as specified in the "crashkernel=YM@XM"
2090 command line boot parameter passed to the panic-ed
2091 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2092 for more details about crash dumps.
2094 Usage of bzImage for capturing the crash dump is recommended as
2095 one does not have to build two kernels. Same kernel can be used
2096 as production kernel and capture kernel. Above option should have
2097 gone away after relocatable bzImage support is introduced. But it
2098 is present because there are users out there who continue to use
2099 vmlinux for dump capture. This option should go away down the
2102 Don't change this unless you know what you are doing.
2105 bool "Build a relocatable kernel"
2108 This builds a kernel image that retains relocation information
2109 so it can be loaded someplace besides the default 1MB.
2110 The relocations tend to make the kernel binary about 10% larger,
2111 but are discarded at runtime.
2113 One use is for the kexec on panic case where the recovery kernel
2114 must live at a different physical address than the primary
2117 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2118 it has been loaded at and the compile time physical address
2119 (CONFIG_PHYSICAL_START) is used as the minimum location.
2121 config RANDOMIZE_BASE
2122 bool "Randomize the address of the kernel image (KASLR)"
2123 depends on RELOCATABLE
2126 In support of Kernel Address Space Layout Randomization (KASLR),
2127 this randomizes the physical address at which the kernel image
2128 is decompressed and the virtual address where the kernel
2129 image is mapped, as a security feature that deters exploit
2130 attempts relying on knowledge of the location of kernel
2133 On 64-bit, the kernel physical and virtual addresses are
2134 randomized separately. The physical address will be anywhere
2135 between 16MB and the top of physical memory (up to 64TB). The
2136 virtual address will be randomized from 16MB up to 1GB (9 bits
2137 of entropy). Note that this also reduces the memory space
2138 available to kernel modules from 1.5GB to 1GB.
2140 On 32-bit, the kernel physical and virtual addresses are
2141 randomized together. They will be randomized from 16MB up to
2142 512MB (8 bits of entropy).
2144 Entropy is generated using the RDRAND instruction if it is
2145 supported. If RDTSC is supported, its value is mixed into
2146 the entropy pool as well. If neither RDRAND nor RDTSC are
2147 supported, then entropy is read from the i8254 timer. The
2148 usable entropy is limited by the kernel being built using
2149 2GB addressing, and that PHYSICAL_ALIGN must be at a
2150 minimum of 2MB. As a result, only 10 bits of entropy are
2151 theoretically possible, but the implementations are further
2152 limited due to memory layouts.
2156 # Relocation on x86 needs some additional build support
2157 config X86_NEED_RELOCS
2159 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2161 config PHYSICAL_ALIGN
2162 hex "Alignment value to which kernel should be aligned"
2164 range 0x2000 0x1000000 if X86_32
2165 range 0x200000 0x1000000 if X86_64
2167 This value puts the alignment restrictions on physical address
2168 where kernel is loaded and run from. Kernel is compiled for an
2169 address which meets above alignment restriction.
2171 If bootloader loads the kernel at a non-aligned address and
2172 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2173 address aligned to above value and run from there.
2175 If bootloader loads the kernel at a non-aligned address and
2176 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2177 load address and decompress itself to the address it has been
2178 compiled for and run from there. The address for which kernel is
2179 compiled already meets above alignment restrictions. Hence the
2180 end result is that kernel runs from a physical address meeting
2181 above alignment restrictions.
2183 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2184 this value must be a multiple of 0x200000.
2186 Don't change this unless you know what you are doing.
2188 config DYNAMIC_MEMORY_LAYOUT
2191 This option makes base addresses of vmalloc and vmemmap as well as
2192 __PAGE_OFFSET movable during boot.
2194 config RANDOMIZE_MEMORY
2195 bool "Randomize the kernel memory sections"
2197 depends on RANDOMIZE_BASE
2198 select DYNAMIC_MEMORY_LAYOUT
2199 default RANDOMIZE_BASE
2201 Randomizes the base virtual address of kernel memory sections
2202 (physical memory mapping, vmalloc & vmemmap). This security feature
2203 makes exploits relying on predictable memory locations less reliable.
2205 The order of allocations remains unchanged. Entropy is generated in
2206 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2207 configuration have in average 30,000 different possible virtual
2208 addresses for each memory section.
2212 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2213 hex "Physical memory mapping padding" if EXPERT
2214 depends on RANDOMIZE_MEMORY
2215 default "0xa" if MEMORY_HOTPLUG
2217 range 0x1 0x40 if MEMORY_HOTPLUG
2220 Define the padding in terabytes added to the existing physical
2221 memory size during kernel memory randomization. It is useful
2222 for memory hotplug support but reduces the entropy available for
2223 address randomization.
2225 If unsure, leave at the default value.
2231 config BOOTPARAM_HOTPLUG_CPU0
2232 bool "Set default setting of cpu0_hotpluggable"
2233 depends on HOTPLUG_CPU
2235 Set whether default state of cpu0_hotpluggable is on or off.
2237 Say Y here to enable CPU0 hotplug by default. If this switch
2238 is turned on, there is no need to give cpu0_hotplug kernel
2239 parameter and the CPU0 hotplug feature is enabled by default.
2241 Please note: there are two known CPU0 dependencies if you want
2242 to enable the CPU0 hotplug feature either by this switch or by
2243 cpu0_hotplug kernel parameter.
2245 First, resume from hibernate or suspend always starts from CPU0.
2246 So hibernate and suspend are prevented if CPU0 is offline.
2248 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2249 offline if any interrupt can not migrate out of CPU0. There may
2250 be other CPU0 dependencies.
2252 Please make sure the dependencies are under your control before
2253 you enable this feature.
2255 Say N if you don't want to enable CPU0 hotplug feature by default.
2256 You still can enable the CPU0 hotplug feature at boot by kernel
2257 parameter cpu0_hotplug.
2259 config DEBUG_HOTPLUG_CPU0
2261 prompt "Debug CPU0 hotplug"
2262 depends on HOTPLUG_CPU
2264 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2265 soon as possible and boots up userspace with CPU0 offlined. User
2266 can online CPU0 back after boot time.
2268 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2269 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2270 compilation or giving cpu0_hotplug kernel parameter at boot.
2276 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2277 depends on COMPAT_32
2279 Certain buggy versions of glibc will crash if they are
2280 presented with a 32-bit vDSO that is not mapped at the address
2281 indicated in its segment table.
2283 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2284 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2285 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2286 the only released version with the bug, but OpenSUSE 9
2287 contains a buggy "glibc 2.3.2".
2289 The symptom of the bug is that everything crashes on startup, saying:
2290 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2292 Saying Y here changes the default value of the vdso32 boot
2293 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2294 This works around the glibc bug but hurts performance.
2296 If unsure, say N: if you are compiling your own kernel, you
2297 are unlikely to be using a buggy version of glibc.
2300 prompt "vsyscall table for legacy applications"
2302 default LEGACY_VSYSCALL_XONLY
2304 Legacy user code that does not know how to find the vDSO expects
2305 to be able to issue three syscalls by calling fixed addresses in
2306 kernel space. Since this location is not randomized with ASLR,
2307 it can be used to assist security vulnerability exploitation.
2309 This setting can be changed at boot time via the kernel command
2310 line parameter vsyscall=[emulate|xonly|none].
2312 On a system with recent enough glibc (2.14 or newer) and no
2313 static binaries, you can say None without a performance penalty
2314 to improve security.
2316 If unsure, select "Emulate execution only".
2318 config LEGACY_VSYSCALL_EMULATE
2319 bool "Full emulation"
2321 The kernel traps and emulates calls into the fixed vsyscall
2322 address mapping. This makes the mapping non-executable, but
2323 it still contains readable known contents, which could be
2324 used in certain rare security vulnerability exploits. This
2325 configuration is recommended when using legacy userspace
2326 that still uses vsyscalls along with legacy binary
2327 instrumentation tools that require code to be readable.
2329 An example of this type of legacy userspace is running
2330 Pin on an old binary that still uses vsyscalls.
2332 config LEGACY_VSYSCALL_XONLY
2333 bool "Emulate execution only"
2335 The kernel traps and emulates calls into the fixed vsyscall
2336 address mapping and does not allow reads. This
2337 configuration is recommended when userspace might use the
2338 legacy vsyscall area but support for legacy binary
2339 instrumentation of legacy code is not needed. It mitigates
2340 certain uses of the vsyscall area as an ASLR-bypassing
2343 config LEGACY_VSYSCALL_NONE
2346 There will be no vsyscall mapping at all. This will
2347 eliminate any risk of ASLR bypass due to the vsyscall
2348 fixed address mapping. Attempts to use the vsyscalls
2349 will be reported to dmesg, so that either old or
2350 malicious userspace programs can be identified.
2355 bool "Built-in kernel command line"
2357 Allow for specifying boot arguments to the kernel at
2358 build time. On some systems (e.g. embedded ones), it is
2359 necessary or convenient to provide some or all of the
2360 kernel boot arguments with the kernel itself (that is,
2361 to not rely on the boot loader to provide them.)
2363 To compile command line arguments into the kernel,
2364 set this option to 'Y', then fill in the
2365 boot arguments in CONFIG_CMDLINE.
2367 Systems with fully functional boot loaders (i.e. non-embedded)
2368 should leave this option set to 'N'.
2371 string "Built-in kernel command string"
2372 depends on CMDLINE_BOOL
2375 Enter arguments here that should be compiled into the kernel
2376 image and used at boot time. If the boot loader provides a
2377 command line at boot time, it is appended to this string to
2378 form the full kernel command line, when the system boots.
2380 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2381 change this behavior.
2383 In most cases, the command line (whether built-in or provided
2384 by the boot loader) should specify the device for the root
2387 config CMDLINE_OVERRIDE
2388 bool "Built-in command line overrides boot loader arguments"
2389 depends on CMDLINE_BOOL && CMDLINE != ""
2391 Set this option to 'Y' to have the kernel ignore the boot loader
2392 command line, and use ONLY the built-in command line.
2394 This is used to work around broken boot loaders. This should
2395 be set to 'N' under normal conditions.
2397 config MODIFY_LDT_SYSCALL
2398 bool "Enable the LDT (local descriptor table)" if EXPERT
2401 Linux can allow user programs to install a per-process x86
2402 Local Descriptor Table (LDT) using the modify_ldt(2) system
2403 call. This is required to run 16-bit or segmented code such as
2404 DOSEMU or some Wine programs. It is also used by some very old
2405 threading libraries.
2407 Enabling this feature adds a small amount of overhead to
2408 context switches and increases the low-level kernel attack
2409 surface. Disabling it removes the modify_ldt(2) system call.
2411 Saying 'N' here may make sense for embedded or server kernels.
2413 config STRICT_SIGALTSTACK_SIZE
2414 bool "Enforce strict size checking for sigaltstack"
2415 depends on DYNAMIC_SIGFRAME
2417 For historical reasons MINSIGSTKSZ is a constant which became
2418 already too small with AVX512 support. Add a mechanism to
2419 enforce strict checking of the sigaltstack size against the
2420 real size of the FPU frame. This option enables the check
2421 by default. It can also be controlled via the kernel command
2422 line option 'strict_sas_size' independent of this config
2423 switch. Enabling it might break existing applications which
2424 allocate a too small sigaltstack but 'work' because they
2425 never get a signal delivered.
2427 Say 'N' unless you want to really enforce this check.
2429 source "kernel/livepatch/Kconfig"
2433 config ARCH_HAS_ADD_PAGES
2435 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2437 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2440 config USE_PERCPU_NUMA_NODE_ID
2444 menu "Power management and ACPI options"
2446 config ARCH_HIBERNATION_HEADER
2448 depends on HIBERNATION
2450 source "kernel/power/Kconfig"
2452 source "drivers/acpi/Kconfig"
2459 tristate "APM (Advanced Power Management) BIOS support"
2460 depends on X86_32 && PM_SLEEP
2462 APM is a BIOS specification for saving power using several different
2463 techniques. This is mostly useful for battery powered laptops with
2464 APM compliant BIOSes. If you say Y here, the system time will be
2465 reset after a RESUME operation, the /proc/apm device will provide
2466 battery status information, and user-space programs will receive
2467 notification of APM "events" (e.g. battery status change).
2469 If you select "Y" here, you can disable actual use of the APM
2470 BIOS by passing the "apm=off" option to the kernel at boot time.
2472 Note that the APM support is almost completely disabled for
2473 machines with more than one CPU.
2475 In order to use APM, you will need supporting software. For location
2476 and more information, read <file:Documentation/power/apm-acpi.rst>
2477 and the Battery Powered Linux mini-HOWTO, available from
2478 <http://www.tldp.org/docs.html#howto>.
2480 This driver does not spin down disk drives (see the hdparm(8)
2481 manpage ("man 8 hdparm") for that), and it doesn't turn off
2482 VESA-compliant "green" monitors.
2484 This driver does not support the TI 4000M TravelMate and the ACER
2485 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2486 desktop machines also don't have compliant BIOSes, and this driver
2487 may cause those machines to panic during the boot phase.
2489 Generally, if you don't have a battery in your machine, there isn't
2490 much point in using this driver and you should say N. If you get
2491 random kernel OOPSes or reboots that don't seem to be related to
2492 anything, try disabling/enabling this option (or disabling/enabling
2495 Some other things you should try when experiencing seemingly random,
2498 1) make sure that you have enough swap space and that it is
2500 2) pass the "no-hlt" option to the kernel
2501 3) switch on floating point emulation in the kernel and pass
2502 the "no387" option to the kernel
2503 4) pass the "floppy=nodma" option to the kernel
2504 5) pass the "mem=4M" option to the kernel (thereby disabling
2505 all but the first 4 MB of RAM)
2506 6) make sure that the CPU is not over clocked.
2507 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2508 8) disable the cache from your BIOS settings
2509 9) install a fan for the video card or exchange video RAM
2510 10) install a better fan for the CPU
2511 11) exchange RAM chips
2512 12) exchange the motherboard.
2514 To compile this driver as a module, choose M here: the
2515 module will be called apm.
2519 config APM_IGNORE_USER_SUSPEND
2520 bool "Ignore USER SUSPEND"
2522 This option will ignore USER SUSPEND requests. On machines with a
2523 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2524 series notebooks, it is necessary to say Y because of a BIOS bug.
2526 config APM_DO_ENABLE
2527 bool "Enable PM at boot time"
2529 Enable APM features at boot time. From page 36 of the APM BIOS
2530 specification: "When disabled, the APM BIOS does not automatically
2531 power manage devices, enter the Standby State, enter the Suspend
2532 State, or take power saving steps in response to CPU Idle calls."
2533 This driver will make CPU Idle calls when Linux is idle (unless this
2534 feature is turned off -- see "Do CPU IDLE calls", below). This
2535 should always save battery power, but more complicated APM features
2536 will be dependent on your BIOS implementation. You may need to turn
2537 this option off if your computer hangs at boot time when using APM
2538 support, or if it beeps continuously instead of suspending. Turn
2539 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2540 T400CDT. This is off by default since most machines do fine without
2545 bool "Make CPU Idle calls when idle"
2547 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2548 On some machines, this can activate improved power savings, such as
2549 a slowed CPU clock rate, when the machine is idle. These idle calls
2550 are made after the idle loop has run for some length of time (e.g.,
2551 333 mS). On some machines, this will cause a hang at boot time or
2552 whenever the CPU becomes idle. (On machines with more than one CPU,
2553 this option does nothing.)
2555 config APM_DISPLAY_BLANK
2556 bool "Enable console blanking using APM"
2558 Enable console blanking using the APM. Some laptops can use this to
2559 turn off the LCD backlight when the screen blanker of the Linux
2560 virtual console blanks the screen. Note that this is only used by
2561 the virtual console screen blanker, and won't turn off the backlight
2562 when using the X Window system. This also doesn't have anything to
2563 do with your VESA-compliant power-saving monitor. Further, this
2564 option doesn't work for all laptops -- it might not turn off your
2565 backlight at all, or it might print a lot of errors to the console,
2566 especially if you are using gpm.
2568 config APM_ALLOW_INTS
2569 bool "Allow interrupts during APM BIOS calls"
2571 Normally we disable external interrupts while we are making calls to
2572 the APM BIOS as a measure to lessen the effects of a badly behaving
2573 BIOS implementation. The BIOS should reenable interrupts if it
2574 needs to. Unfortunately, some BIOSes do not -- especially those in
2575 many of the newer IBM Thinkpads. If you experience hangs when you
2576 suspend, try setting this to Y. Otherwise, say N.
2580 source "drivers/cpufreq/Kconfig"
2582 source "drivers/cpuidle/Kconfig"
2584 source "drivers/idle/Kconfig"
2589 menu "Bus options (PCI etc.)"
2592 prompt "PCI access mode"
2593 depends on X86_32 && PCI
2596 On PCI systems, the BIOS can be used to detect the PCI devices and
2597 determine their configuration. However, some old PCI motherboards
2598 have BIOS bugs and may crash if this is done. Also, some embedded
2599 PCI-based systems don't have any BIOS at all. Linux can also try to
2600 detect the PCI hardware directly without using the BIOS.
2602 With this option, you can specify how Linux should detect the
2603 PCI devices. If you choose "BIOS", the BIOS will be used,
2604 if you choose "Direct", the BIOS won't be used, and if you
2605 choose "MMConfig", then PCI Express MMCONFIG will be used.
2606 If you choose "Any", the kernel will try MMCONFIG, then the
2607 direct access method and falls back to the BIOS if that doesn't
2608 work. If unsure, go with the default, which is "Any".
2613 config PCI_GOMMCONFIG
2630 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2632 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2635 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2638 bool "Support mmconfig PCI config space access" if X86_64
2640 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2641 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2645 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2649 depends on PCI && XEN
2651 config MMCONF_FAM10H
2653 depends on X86_64 && PCI_MMCONFIG && ACPI
2655 config PCI_CNB20LE_QUIRK
2656 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2659 Read the PCI windows out of the CNB20LE host bridge. This allows
2660 PCI hotplug to work on systems with the CNB20LE chipset which do
2663 There's no public spec for this chipset, and this functionality
2664 is known to be incomplete.
2666 You should say N unless you know you need this.
2669 bool "ISA bus support on modern systems" if EXPERT
2671 Expose ISA bus device drivers and options available for selection and
2672 configuration. Enable this option if your target machine has an ISA
2673 bus. ISA is an older system, displaced by PCI and newer bus
2674 architectures -- if your target machine is modern, it probably does
2675 not have an ISA bus.
2679 # x86_64 have no ISA slots, but can have ISA-style DMA.
2681 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2684 Enables ISA-style DMA support for devices requiring such controllers.
2692 Find out whether you have ISA slots on your motherboard. ISA is the
2693 name of a bus system, i.e. the way the CPU talks to the other stuff
2694 inside your box. Other bus systems are PCI, EISA, MicroChannel
2695 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2696 newer boards don't support it. If you have ISA, say Y, otherwise N.
2699 tristate "NatSemi SCx200 support"
2701 This provides basic support for National Semiconductor's
2702 (now AMD's) Geode processors. The driver probes for the
2703 PCI-IDs of several on-chip devices, so its a good dependency
2704 for other scx200_* drivers.
2706 If compiled as a module, the driver is named scx200.
2708 config SCx200HR_TIMER
2709 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2713 This driver provides a clocksource built upon the on-chip
2714 27MHz high-resolution timer. Its also a workaround for
2715 NSC Geode SC-1100's buggy TSC, which loses time when the
2716 processor goes idle (as is done by the scheduler). The
2717 other workaround is idle=poll boot option.
2720 bool "One Laptop Per Child support"
2728 Add support for detecting the unique features of the OLPC
2732 bool "OLPC XO-1 Power Management"
2733 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2735 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2738 bool "OLPC XO-1 Real Time Clock"
2739 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2741 Add support for the XO-1 real time clock, which can be used as a
2742 programmable wakeup source.
2745 bool "OLPC XO-1 SCI extras"
2746 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2750 Add support for SCI-based features of the OLPC XO-1 laptop:
2751 - EC-driven system wakeups
2755 - AC adapter status updates
2756 - Battery status updates
2758 config OLPC_XO15_SCI
2759 bool "OLPC XO-1.5 SCI extras"
2760 depends on OLPC && ACPI
2763 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2764 - EC-driven system wakeups
2765 - AC adapter status updates
2766 - Battery status updates
2769 bool "PCEngines ALIX System Support (LED setup)"
2772 This option enables system support for the PCEngines ALIX.
2773 At present this just sets up LEDs for GPIO control on
2774 ALIX2/3/6 boards. However, other system specific setup should
2777 Note: You must still enable the drivers for GPIO and LED support
2778 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2780 Note: You have to set alix.force=1 for boards with Award BIOS.
2783 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2786 This option enables system support for the Soekris Engineering net5501.
2789 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2793 This option enables system support for the Traverse Technologies GEOS.
2796 bool "Technologic Systems TS-5500 platform support"
2798 select CHECK_SIGNATURE
2802 This option enables system support for the Technologic Systems TS-5500.
2808 depends on CPU_SUP_AMD && PCI
2813 menu "Binary Emulations"
2815 config IA32_EMULATION
2816 bool "IA32 Emulation"
2818 select ARCH_WANT_OLD_COMPAT_IPC
2820 select COMPAT_OLD_SIGACTION
2822 Include code to run legacy 32-bit programs under a
2823 64-bit kernel. You should likely turn this on, unless you're
2824 100% sure that you don't have any 32-bit programs left.
2827 tristate "IA32 a.out support"
2828 depends on IA32_EMULATION
2831 Support old a.out binaries in the 32bit emulation.
2834 bool "x32 ABI for 64-bit mode"
2837 Include code to run binaries for the x32 native 32-bit ABI
2838 for 64-bit processors. An x32 process gets access to the
2839 full 64-bit register file and wide data path while leaving
2840 pointers at 32 bits for smaller memory footprint.
2842 You will need a recent binutils (2.22 or later) with
2843 elf32_x86_64 support enabled to compile a kernel with this
2848 depends on IA32_EMULATION || X86_32
2850 select OLD_SIGSUSPEND3
2854 depends on IA32_EMULATION || X86_X32
2857 config COMPAT_FOR_U64_ALIGNMENT
2860 config SYSVIPC_COMPAT
2868 config HAVE_ATOMIC_IOMAP
2872 source "arch/x86/kvm/Kconfig"
2874 source "arch/x86/Kconfig.assembler"