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)
475 bool "Mitigate Straight-Line-Speculation"
476 depends on CC_HAS_SLS && X86_64
479 Compile the kernel with straight-line-speculation options to guard
480 against straight line speculation. The kernel image might be slightly
483 config X86_CPU_RESCTRL
484 bool "x86 CPU resource control support"
485 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
487 select PROC_CPU_RESCTRL if PROC_FS
489 Enable x86 CPU resource control support.
491 Provide support for the allocation and monitoring of system resources
494 Intel calls this Intel Resource Director Technology
495 (Intel(R) RDT). More information about RDT can be found in the
496 Intel x86 Architecture Software Developer Manual.
498 AMD calls this AMD Platform Quality of Service (AMD QoS).
499 More information about AMD QoS can be found in the AMD64 Technology
500 Platform Quality of Service Extensions manual.
506 bool "Support for big SMP systems with more than 8 CPUs"
509 This option is needed for the systems that have more than 8 CPUs.
511 config X86_EXTENDED_PLATFORM
512 bool "Support for extended (non-PC) x86 platforms"
515 If you disable this option then the kernel will only support
516 standard PC platforms. (which covers the vast majority of
519 If you enable this option then you'll be able to select support
520 for the following (non-PC) 32 bit x86 platforms:
521 Goldfish (Android emulator)
524 SGI 320/540 (Visual Workstation)
525 STA2X11-based (e.g. Northville)
526 Moorestown MID devices
528 If you have one of these systems, or if you want to build a
529 generic distribution kernel, say Y here - otherwise say N.
533 config X86_EXTENDED_PLATFORM
534 bool "Support for extended (non-PC) x86 platforms"
537 If you disable this option then the kernel will only support
538 standard PC platforms. (which covers the vast majority of
541 If you enable this option then you'll be able to select support
542 for the following (non-PC) 64 bit x86 platforms:
547 If you have one of these systems, or if you want to build a
548 generic distribution kernel, say Y here - otherwise say N.
550 # This is an alphabetically sorted list of 64 bit extended platforms
551 # Please maintain the alphabetic order if and when there are additions
553 bool "Numascale NumaChip"
555 depends on X86_EXTENDED_PLATFORM
558 depends on X86_X2APIC
559 depends on PCI_MMCONFIG
561 Adds support for Numascale NumaChip large-SMP systems. Needed to
562 enable more than ~168 cores.
563 If you don't have one of these, you should say N here.
567 select HYPERVISOR_GUEST
569 depends on X86_64 && PCI
570 depends on X86_EXTENDED_PLATFORM
573 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
574 supposed to run on these EM64T-based machines. Only choose this option
575 if you have one of these machines.
578 bool "SGI Ultraviolet"
580 depends on X86_EXTENDED_PLATFORM
583 depends on KEXEC_CORE
584 depends on X86_X2APIC
587 This option is needed in order to support SGI Ultraviolet systems.
588 If you don't have one of these, you should say N here.
590 # Following is an alphabetically sorted list of 32 bit extended platforms
591 # Please maintain the alphabetic order if and when there are additions
594 bool "Goldfish (Virtual Platform)"
595 depends on X86_EXTENDED_PLATFORM
597 Enable support for the Goldfish virtual platform used primarily
598 for Android development. Unless you are building for the Android
599 Goldfish emulator say N here.
602 bool "CE4100 TV platform"
604 depends on PCI_GODIRECT
605 depends on X86_IO_APIC
607 depends on X86_EXTENDED_PLATFORM
608 select X86_REBOOTFIXUPS
610 select OF_EARLY_FLATTREE
612 Select for the Intel CE media processor (CE4100) SOC.
613 This option compiles in support for the CE4100 SOC for settop
614 boxes and media devices.
617 bool "Intel MID platform support"
618 depends on X86_EXTENDED_PLATFORM
619 depends on X86_PLATFORM_DEVICES
621 depends on X86_64 || (PCI_GOANY && X86_32)
622 depends on X86_IO_APIC
627 select MFD_INTEL_MSIC
629 Select to build a kernel capable of supporting Intel MID (Mobile
630 Internet Device) platform systems which do not have the PCI legacy
631 interfaces. If you are building for a PC class system say N here.
633 Intel MID platforms are based on an Intel processor and chipset which
634 consume less power than most of the x86 derivatives.
636 config X86_INTEL_QUARK
637 bool "Intel Quark platform support"
639 depends on X86_EXTENDED_PLATFORM
640 depends on X86_PLATFORM_DEVICES
644 depends on X86_IO_APIC
649 Select to include support for Quark X1000 SoC.
650 Say Y here if you have a Quark based system such as the Arduino
651 compatible Intel Galileo.
653 config X86_INTEL_LPSS
654 bool "Intel Low Power Subsystem Support"
655 depends on X86 && ACPI && PCI
660 Select to build support for Intel Low Power Subsystem such as
661 found on Intel Lynxpoint PCH. Selecting this option enables
662 things like clock tree (common clock framework) and pincontrol
663 which are needed by the LPSS peripheral drivers.
665 config X86_AMD_PLATFORM_DEVICE
666 bool "AMD ACPI2Platform devices support"
671 Select to interpret AMD specific ACPI device to platform device
672 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
673 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
674 implemented under PINCTRL subsystem.
677 tristate "Intel SoC IOSF Sideband support for SoC platforms"
680 This option enables sideband register access support for Intel SoC
681 platforms. On these platforms the IOSF sideband is used in lieu of
682 MSR's for some register accesses, mostly but not limited to thermal
683 and power. Drivers may query the availability of this device to
684 determine if they need the sideband in order to work on these
685 platforms. The sideband is available on the following SoC products.
686 This list is not meant to be exclusive.
691 You should say Y if you are running a kernel on one of these SoC's.
693 config IOSF_MBI_DEBUG
694 bool "Enable IOSF sideband access through debugfs"
695 depends on IOSF_MBI && DEBUG_FS
697 Select this option to expose the IOSF sideband access registers (MCR,
698 MDR, MCRX) through debugfs to write and read register information from
699 different units on the SoC. This is most useful for obtaining device
700 state information for debug and analysis. As this is a general access
701 mechanism, users of this option would have specific knowledge of the
702 device they want to access.
704 If you don't require the option or are in doubt, say N.
707 bool "RDC R-321x SoC"
709 depends on X86_EXTENDED_PLATFORM
711 select X86_REBOOTFIXUPS
713 This option is needed for RDC R-321x system-on-chip, also known
715 If you don't have one of these chips, you should say N here.
717 config X86_32_NON_STANDARD
718 bool "Support non-standard 32-bit SMP architectures"
719 depends on X86_32 && SMP
720 depends on X86_EXTENDED_PLATFORM
722 This option compiles in the bigsmp and STA2X11 default
723 subarchitectures. It is intended for a generic binary
724 kernel. If you select them all, kernel will probe it one by
725 one and will fallback to default.
727 # Alphabetically sorted list of Non standard 32 bit platforms
729 config X86_SUPPORTS_MEMORY_FAILURE
731 # MCE code calls memory_failure():
733 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
734 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
735 depends on X86_64 || !SPARSEMEM
736 select ARCH_SUPPORTS_MEMORY_FAILURE
739 bool "STA2X11 Companion Chip Support"
740 depends on X86_32_NON_STANDARD && PCI
745 This adds support for boards based on the STA2X11 IO-Hub,
746 a.k.a. "ConneXt". The chip is used in place of the standard
747 PC chipset, so all "standard" peripherals are missing. If this
748 option is selected the kernel will still be able to boot on
749 standard PC machines.
752 tristate "Eurobraille/Iris poweroff module"
755 The Iris machines from EuroBraille do not have APM or ACPI support
756 to shut themselves down properly. A special I/O sequence is
757 needed to do so, which is what this module does at
760 This is only for Iris machines from EuroBraille.
764 config SCHED_OMIT_FRAME_POINTER
766 prompt "Single-depth WCHAN output"
769 Calculate simpler /proc/<PID>/wchan values. If this option
770 is disabled then wchan values will recurse back to the
771 caller function. This provides more accurate wchan values,
772 at the expense of slightly more scheduling overhead.
774 If in doubt, say "Y".
776 menuconfig HYPERVISOR_GUEST
777 bool "Linux guest support"
779 Say Y here to enable options for running Linux under various hyper-
780 visors. This option enables basic hypervisor detection and platform
783 If you say N, all options in this submenu will be skipped and
784 disabled, and Linux guest support won't be built in.
789 bool "Enable paravirtualization code"
790 depends on HAVE_STATIC_CALL
792 This changes the kernel so it can modify itself when it is run
793 under a hypervisor, potentially improving performance significantly
794 over full virtualization. However, when run without a hypervisor
795 the kernel is theoretically slower and slightly larger.
800 config PARAVIRT_DEBUG
801 bool "paravirt-ops debugging"
802 depends on PARAVIRT && DEBUG_KERNEL
804 Enable to debug paravirt_ops internals. Specifically, BUG if
805 a paravirt_op is missing when it is called.
807 config PARAVIRT_SPINLOCKS
808 bool "Paravirtualization layer for spinlocks"
809 depends on PARAVIRT && SMP
811 Paravirtualized spinlocks allow a pvops backend to replace the
812 spinlock implementation with something virtualization-friendly
813 (for example, block the virtual CPU rather than spinning).
815 It has a minimal impact on native kernels and gives a nice performance
816 benefit on paravirtualized KVM / Xen kernels.
818 If you are unsure how to answer this question, answer Y.
820 config X86_HV_CALLBACK_VECTOR
823 source "arch/x86/xen/Kconfig"
826 bool "KVM Guest support (including kvmclock)"
828 select PARAVIRT_CLOCK
829 select ARCH_CPUIDLE_HALTPOLL
830 select X86_HV_CALLBACK_VECTOR
833 This option enables various optimizations for running under the KVM
834 hypervisor. It includes a paravirtualized clock, so that instead
835 of relying on a PIT (or probably other) emulation by the
836 underlying device model, the host provides the guest with
837 timing infrastructure such as time of day, and system time
839 config ARCH_CPUIDLE_HALTPOLL
841 prompt "Disable host haltpoll when loading haltpoll driver"
843 If virtualized under KVM, disable host haltpoll.
846 bool "Support for running PVH guests"
848 This option enables the PVH entry point for guest virtual machines
849 as specified in the x86/HVM direct boot ABI.
851 config PARAVIRT_TIME_ACCOUNTING
852 bool "Paravirtual steal time accounting"
855 Select this option to enable fine granularity task steal time
856 accounting. Time spent executing other tasks in parallel with
857 the current vCPU is discounted from the vCPU power. To account for
858 that, there can be a small performance impact.
860 If in doubt, say N here.
862 config PARAVIRT_CLOCK
865 config JAILHOUSE_GUEST
866 bool "Jailhouse non-root cell support"
867 depends on X86_64 && PCI
870 This option allows to run Linux as guest in a Jailhouse non-root
871 cell. You can leave this option disabled if you only want to start
872 Jailhouse and run Linux afterwards in the root cell.
875 bool "ACRN Guest support"
877 select X86_HV_CALLBACK_VECTOR
879 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
880 a flexible, lightweight reference open-source hypervisor, built with
881 real-time and safety-criticality in mind. It is built for embedded
882 IOT with small footprint and real-time features. More details can be
883 found in https://projectacrn.org/.
885 endif #HYPERVISOR_GUEST
887 source "arch/x86/Kconfig.cpu"
891 prompt "HPET Timer Support" if X86_32
893 Use the IA-PC HPET (High Precision Event Timer) to manage
894 time in preference to the PIT and RTC, if a HPET is
896 HPET is the next generation timer replacing legacy 8254s.
897 The HPET provides a stable time base on SMP
898 systems, unlike the TSC, but it is more expensive to access,
899 as it is off-chip. The interface used is documented
900 in the HPET spec, revision 1.
902 You can safely choose Y here. However, HPET will only be
903 activated if the platform and the BIOS support this feature.
904 Otherwise the 8254 will be used for timing services.
906 Choose N to continue using the legacy 8254 timer.
908 config HPET_EMULATE_RTC
910 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
912 # Mark as expert because too many people got it wrong.
913 # The code disables itself when not needed.
916 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
917 bool "Enable DMI scanning" if EXPERT
919 Enabled scanning of DMI to identify machine quirks. Say Y
920 here unless you have verified that your setup is not
921 affected by entries in the DMI blacklist. Required by PNP
925 bool "Old AMD GART IOMMU support"
929 depends on X86_64 && PCI && AMD_NB
931 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
932 GART based hardware IOMMUs.
934 The GART supports full DMA access for devices with 32-bit access
935 limitations, on systems with more than 3 GB. This is usually needed
936 for USB, sound, many IDE/SATA chipsets and some other devices.
938 Newer systems typically have a modern AMD IOMMU, supported via
939 the CONFIG_AMD_IOMMU=y config option.
941 In normal configurations this driver is only active when needed:
942 there's more than 3 GB of memory and the system contains a
943 32-bit limited device.
948 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
949 depends on X86_64 && SMP && DEBUG_KERNEL
950 select CPUMASK_OFFSTACK
952 Enable maximum number of CPUS and NUMA Nodes for this architecture.
956 # The maximum number of CPUs supported:
958 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
959 # and which can be configured interactively in the
960 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
962 # The ranges are different on 32-bit and 64-bit kernels, depending on
963 # hardware capabilities and scalability features of the kernel.
965 # ( If MAXSMP is enabled we just use the highest possible value and disable
966 # interactive configuration. )
969 config NR_CPUS_RANGE_BEGIN
971 default NR_CPUS_RANGE_END if MAXSMP
975 config NR_CPUS_RANGE_END
978 default 64 if SMP && X86_BIGSMP
979 default 8 if SMP && !X86_BIGSMP
982 config NR_CPUS_RANGE_END
985 default 8192 if SMP && CPUMASK_OFFSTACK
986 default 512 if SMP && !CPUMASK_OFFSTACK
989 config NR_CPUS_DEFAULT
992 default 32 if X86_BIGSMP
996 config NR_CPUS_DEFAULT
999 default 8192 if MAXSMP
1004 int "Maximum number of CPUs" if SMP && !MAXSMP
1005 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1006 default NR_CPUS_DEFAULT
1008 This allows you to specify the maximum number of CPUs which this
1009 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1010 supported value is 8192, otherwise the maximum value is 512. The
1011 minimum value which makes sense is 2.
1013 This is purely to save memory: each supported CPU adds about 8KB
1014 to the kernel image.
1021 prompt "Multi-core scheduler support"
1024 Multi-core scheduler support improves the CPU scheduler's decision
1025 making when dealing with multi-core CPU chips at a cost of slightly
1026 increased overhead in some places. If unsure say N here.
1028 config SCHED_MC_PRIO
1029 bool "CPU core priorities scheduler support"
1030 depends on SCHED_MC && CPU_SUP_INTEL
1031 select X86_INTEL_PSTATE
1035 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1036 core ordering determined at manufacturing time, which allows
1037 certain cores to reach higher turbo frequencies (when running
1038 single threaded workloads) than others.
1040 Enabling this kernel feature teaches the scheduler about
1041 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1042 scheduler's CPU selection logic accordingly, so that higher
1043 overall system performance can be achieved.
1045 This feature will have no effect on CPUs without this feature.
1047 If unsure say Y here.
1051 depends on !SMP && X86_LOCAL_APIC
1054 bool "Local APIC support on uniprocessors" if !PCI_MSI
1056 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1058 A local APIC (Advanced Programmable Interrupt Controller) is an
1059 integrated interrupt controller in the CPU. If you have a single-CPU
1060 system which has a processor with a local APIC, you can say Y here to
1061 enable and use it. If you say Y here even though your machine doesn't
1062 have a local APIC, then the kernel will still run with no slowdown at
1063 all. The local APIC supports CPU-generated self-interrupts (timer,
1064 performance counters), and the NMI watchdog which detects hard
1067 config X86_UP_IOAPIC
1068 bool "IO-APIC support on uniprocessors"
1069 depends on X86_UP_APIC
1071 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1072 SMP-capable replacement for PC-style interrupt controllers. Most
1073 SMP systems and many recent uniprocessor systems have one.
1075 If you have a single-CPU system with an IO-APIC, you can say Y here
1076 to use it. If you say Y here even though your machine doesn't have
1077 an IO-APIC, then the kernel will still run with no slowdown at all.
1079 config X86_LOCAL_APIC
1081 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1082 select IRQ_DOMAIN_HIERARCHY
1083 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1087 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1089 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1090 bool "Reroute for broken boot IRQs"
1091 depends on X86_IO_APIC
1093 This option enables a workaround that fixes a source of
1094 spurious interrupts. This is recommended when threaded
1095 interrupt handling is used on systems where the generation of
1096 superfluous "boot interrupts" cannot be disabled.
1098 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1099 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1100 kernel does during interrupt handling). On chipsets where this
1101 boot IRQ generation cannot be disabled, this workaround keeps
1102 the original IRQ line masked so that only the equivalent "boot
1103 IRQ" is delivered to the CPUs. The workaround also tells the
1104 kernel to set up the IRQ handler on the boot IRQ line. In this
1105 way only one interrupt is delivered to the kernel. Otherwise
1106 the spurious second interrupt may cause the kernel to bring
1107 down (vital) interrupt lines.
1109 Only affects "broken" chipsets. Interrupt sharing may be
1110 increased on these systems.
1113 bool "Machine Check / overheating reporting"
1114 select GENERIC_ALLOCATOR
1117 Machine Check support allows the processor to notify the
1118 kernel if it detects a problem (e.g. overheating, data corruption).
1119 The action the kernel takes depends on the severity of the problem,
1120 ranging from warning messages to halting the machine.
1122 config X86_MCELOG_LEGACY
1123 bool "Support for deprecated /dev/mcelog character device"
1126 Enable support for /dev/mcelog which is needed by the old mcelog
1127 userspace logging daemon. Consider switching to the new generation
1130 config X86_MCE_INTEL
1132 prompt "Intel MCE features"
1133 depends on X86_MCE && X86_LOCAL_APIC
1135 Additional support for intel specific MCE features such as
1136 the thermal monitor.
1140 prompt "AMD MCE features"
1141 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1143 Additional support for AMD specific MCE features such as
1144 the DRAM Error Threshold.
1146 config X86_ANCIENT_MCE
1147 bool "Support for old Pentium 5 / WinChip machine checks"
1148 depends on X86_32 && X86_MCE
1150 Include support for machine check handling on old Pentium 5 or WinChip
1151 systems. These typically need to be enabled explicitly on the command
1154 config X86_MCE_THRESHOLD
1155 depends on X86_MCE_AMD || X86_MCE_INTEL
1158 config X86_MCE_INJECT
1159 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1160 tristate "Machine check injector support"
1162 Provide support for injecting machine checks for testing purposes.
1163 If you don't know what a machine check is and you don't do kernel
1164 QA it is safe to say n.
1166 source "arch/x86/events/Kconfig"
1168 config X86_LEGACY_VM86
1169 bool "Legacy VM86 support"
1172 This option allows user programs to put the CPU into V8086
1173 mode, which is an 80286-era approximation of 16-bit real mode.
1175 Some very old versions of X and/or vbetool require this option
1176 for user mode setting. Similarly, DOSEMU will use it if
1177 available to accelerate real mode DOS programs. However, any
1178 recent version of DOSEMU, X, or vbetool should be fully
1179 functional even without kernel VM86 support, as they will all
1180 fall back to software emulation. Nevertheless, if you are using
1181 a 16-bit DOS program where 16-bit performance matters, vm86
1182 mode might be faster than emulation and you might want to
1185 Note that any app that works on a 64-bit kernel is unlikely to
1186 need this option, as 64-bit kernels don't, and can't, support
1187 V8086 mode. This option is also unrelated to 16-bit protected
1188 mode and is not needed to run most 16-bit programs under Wine.
1190 Enabling this option increases the complexity of the kernel
1191 and slows down exception handling a tiny bit.
1193 If unsure, say N here.
1197 default X86_LEGACY_VM86
1200 bool "Enable support for 16-bit segments" if EXPERT
1202 depends on MODIFY_LDT_SYSCALL
1204 This option is required by programs like Wine to run 16-bit
1205 protected mode legacy code on x86 processors. Disabling
1206 this option saves about 300 bytes on i386, or around 6K text
1207 plus 16K runtime memory on x86-64,
1211 depends on X86_16BIT && X86_32
1215 depends on X86_16BIT && X86_64
1217 config X86_VSYSCALL_EMULATION
1218 bool "Enable vsyscall emulation" if EXPERT
1222 This enables emulation of the legacy vsyscall page. Disabling
1223 it is roughly equivalent to booting with vsyscall=none, except
1224 that it will also disable the helpful warning if a program
1225 tries to use a vsyscall. With this option set to N, offending
1226 programs will just segfault, citing addresses of the form
1229 This option is required by many programs built before 2013, and
1230 care should be used even with newer programs if set to N.
1232 Disabling this option saves about 7K of kernel size and
1233 possibly 4K of additional runtime pagetable memory.
1235 config X86_IOPL_IOPERM
1236 bool "IOPERM and IOPL Emulation"
1239 This enables the ioperm() and iopl() syscalls which are necessary
1240 for legacy applications.
1242 Legacy IOPL support is an overbroad mechanism which allows user
1243 space aside of accessing all 65536 I/O ports also to disable
1244 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1245 capabilities and permission from potentially active security
1248 The emulation restricts the functionality of the syscall to
1249 only allowing the full range I/O port access, but prevents the
1250 ability to disable interrupts from user space which would be
1251 granted if the hardware IOPL mechanism would be used.
1254 tristate "Toshiba Laptop support"
1257 This adds a driver to safely access the System Management Mode of
1258 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1259 not work on models with a Phoenix BIOS. The System Management Mode
1260 is used to set the BIOS and power saving options on Toshiba portables.
1262 For information on utilities to make use of this driver see the
1263 Toshiba Linux utilities web site at:
1264 <http://www.buzzard.org.uk/toshiba/>.
1266 Say Y if you intend to run this kernel on a Toshiba portable.
1270 tristate "Dell i8k legacy laptop support"
1273 select SENSORS_DELL_SMM
1275 This option enables legacy /proc/i8k userspace interface in hwmon
1276 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1277 temperature and allows controlling fan speeds of Dell laptops via
1278 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1279 it reports also power and hotkey status. For fan speed control is
1280 needed userspace package i8kutils.
1282 Say Y if you intend to run this kernel on old Dell laptops or want to
1283 use userspace package i8kutils.
1286 config X86_REBOOTFIXUPS
1287 bool "Enable X86 board specific fixups for reboot"
1290 This enables chipset and/or board specific fixups to be done
1291 in order to get reboot to work correctly. This is only needed on
1292 some combinations of hardware and BIOS. The symptom, for which
1293 this config is intended, is when reboot ends with a stalled/hung
1296 Currently, the only fixup is for the Geode machines using
1297 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1299 Say Y if you want to enable the fixup. Currently, it's safe to
1300 enable this option even if you don't need it.
1304 bool "CPU microcode loading support"
1306 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1308 If you say Y here, you will be able to update the microcode on
1309 Intel and AMD processors. The Intel support is for the IA32 family,
1310 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1311 AMD support is for families 0x10 and later. You will obviously need
1312 the actual microcode binary data itself which is not shipped with
1315 The preferred method to load microcode from a detached initrd is described
1316 in Documentation/x86/microcode.rst. For that you need to enable
1317 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1318 initrd for microcode blobs.
1320 In addition, you can build the microcode into the kernel. For that you
1321 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1324 config MICROCODE_INTEL
1325 bool "Intel microcode loading support"
1326 depends on CPU_SUP_INTEL && MICROCODE
1329 This options enables microcode patch loading support for Intel
1332 For the current Intel microcode data package go to
1333 <https://downloadcenter.intel.com> and search for
1334 'Linux Processor Microcode Data File'.
1336 config MICROCODE_AMD
1337 bool "AMD microcode loading support"
1338 depends on CPU_SUP_AMD && MICROCODE
1340 If you select this option, microcode patch loading support for AMD
1341 processors will be enabled.
1343 config MICROCODE_OLD_INTERFACE
1344 bool "Ancient loading interface (DEPRECATED)"
1346 depends on MICROCODE
1348 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1349 which was used by userspace tools like iucode_tool and microcode.ctl.
1350 It is inadequate because it runs too late to be able to properly
1351 load microcode on a machine and it needs special tools. Instead, you
1352 should've switched to the early loading method with the initrd or
1353 builtin microcode by now: Documentation/x86/microcode.rst
1356 tristate "/dev/cpu/*/msr - Model-specific register support"
1358 This device gives privileged processes access to the x86
1359 Model-Specific Registers (MSRs). It is a character device with
1360 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1361 MSR accesses are directed to a specific CPU on multi-processor
1365 tristate "/dev/cpu/*/cpuid - CPU information support"
1367 This device gives processes access to the x86 CPUID instruction to
1368 be executed on a specific processor. It is a character device
1369 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1373 prompt "High Memory Support"
1380 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1381 However, the address space of 32-bit x86 processors is only 4
1382 Gigabytes large. That means that, if you have a large amount of
1383 physical memory, not all of it can be "permanently mapped" by the
1384 kernel. The physical memory that's not permanently mapped is called
1387 If you are compiling a kernel which will never run on a machine with
1388 more than 1 Gigabyte total physical RAM, answer "off" here (default
1389 choice and suitable for most users). This will result in a "3GB/1GB"
1390 split: 3GB are mapped so that each process sees a 3GB virtual memory
1391 space and the remaining part of the 4GB virtual memory space is used
1392 by the kernel to permanently map as much physical memory as
1395 If the machine has between 1 and 4 Gigabytes physical RAM, then
1398 If more than 4 Gigabytes is used then answer "64GB" here. This
1399 selection turns Intel PAE (Physical Address Extension) mode on.
1400 PAE implements 3-level paging on IA32 processors. PAE is fully
1401 supported by Linux, PAE mode is implemented on all recent Intel
1402 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1403 then the kernel will not boot on CPUs that don't support PAE!
1405 The actual amount of total physical memory will either be
1406 auto detected or can be forced by using a kernel command line option
1407 such as "mem=256M". (Try "man bootparam" or see the documentation of
1408 your boot loader (lilo or loadlin) about how to pass options to the
1409 kernel at boot time.)
1411 If unsure, say "off".
1416 Select this if you have a 32-bit processor and between 1 and 4
1417 gigabytes of physical RAM.
1421 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1424 Select this if you have a 32-bit processor and more than 4
1425 gigabytes of physical RAM.
1430 prompt "Memory split" if EXPERT
1434 Select the desired split between kernel and user memory.
1436 If the address range available to the kernel is less than the
1437 physical memory installed, the remaining memory will be available
1438 as "high memory". Accessing high memory is a little more costly
1439 than low memory, as it needs to be mapped into the kernel first.
1440 Note that increasing the kernel address space limits the range
1441 available to user programs, making the address space there
1442 tighter. Selecting anything other than the default 3G/1G split
1443 will also likely make your kernel incompatible with binary-only
1446 If you are not absolutely sure what you are doing, leave this
1450 bool "3G/1G user/kernel split"
1451 config VMSPLIT_3G_OPT
1453 bool "3G/1G user/kernel split (for full 1G low memory)"
1455 bool "2G/2G user/kernel split"
1456 config VMSPLIT_2G_OPT
1458 bool "2G/2G user/kernel split (for full 2G low memory)"
1460 bool "1G/3G user/kernel split"
1465 default 0xB0000000 if VMSPLIT_3G_OPT
1466 default 0x80000000 if VMSPLIT_2G
1467 default 0x78000000 if VMSPLIT_2G_OPT
1468 default 0x40000000 if VMSPLIT_1G
1474 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1477 bool "PAE (Physical Address Extension) Support"
1478 depends on X86_32 && !HIGHMEM4G
1479 select PHYS_ADDR_T_64BIT
1482 PAE is required for NX support, and furthermore enables
1483 larger swapspace support for non-overcommit purposes. It
1484 has the cost of more pagetable lookup overhead, and also
1485 consumes more pagetable space per process.
1488 bool "Enable 5-level page tables support"
1490 select DYNAMIC_MEMORY_LAYOUT
1491 select SPARSEMEM_VMEMMAP
1494 5-level paging enables access to larger address space:
1495 upto 128 PiB of virtual address space and 4 PiB of
1496 physical address space.
1498 It will be supported by future Intel CPUs.
1500 A kernel with the option enabled can be booted on machines that
1501 support 4- or 5-level paging.
1503 See Documentation/x86/x86_64/5level-paging.rst for more
1508 config X86_DIRECT_GBPAGES
1512 Certain kernel features effectively disable kernel
1513 linear 1 GB mappings (even if the CPU otherwise
1514 supports them), so don't confuse the user by printing
1515 that we have them enabled.
1517 config X86_CPA_STATISTICS
1518 bool "Enable statistic for Change Page Attribute"
1521 Expose statistics about the Change Page Attribute mechanism, which
1522 helps to determine the effectiveness of preserving large and huge
1523 page mappings when mapping protections are changed.
1525 config AMD_MEM_ENCRYPT
1526 bool "AMD Secure Memory Encryption (SME) support"
1527 depends on X86_64 && CPU_SUP_AMD
1528 select DMA_COHERENT_POOL
1529 select DYNAMIC_PHYSICAL_MASK
1530 select ARCH_USE_MEMREMAP_PROT
1531 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1532 select INSTRUCTION_DECODER
1533 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1534 select ARCH_HAS_CC_PLATFORM
1536 Say yes to enable support for the encryption of system memory.
1537 This requires an AMD processor that supports Secure Memory
1540 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1541 bool "Activate AMD Secure Memory Encryption (SME) by default"
1542 depends on AMD_MEM_ENCRYPT
1544 Say yes to have system memory encrypted by default if running on
1545 an AMD processor that supports Secure Memory Encryption (SME).
1547 If set to Y, then the encryption of system memory can be
1548 deactivated with the mem_encrypt=off command line option.
1550 If set to N, then the encryption of system memory can be
1551 activated with the mem_encrypt=on command line option.
1553 # Common NUMA Features
1555 bool "NUMA Memory Allocation and Scheduler Support"
1557 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1558 default y if X86_BIGSMP
1560 Enable NUMA (Non-Uniform Memory Access) support.
1562 The kernel will try to allocate memory used by a CPU on the
1563 local memory controller of the CPU and add some more
1564 NUMA awareness to the kernel.
1566 For 64-bit this is recommended if the system is Intel Core i7
1567 (or later), AMD Opteron, or EM64T NUMA.
1569 For 32-bit this is only needed if you boot a 32-bit
1570 kernel on a 64-bit NUMA platform.
1572 Otherwise, you should say N.
1576 prompt "Old style AMD Opteron NUMA detection"
1577 depends on X86_64 && NUMA && PCI
1579 Enable AMD NUMA node topology detection. You should say Y here if
1580 you have a multi processor AMD system. This uses an old method to
1581 read the NUMA configuration directly from the builtin Northbridge
1582 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1583 which also takes priority if both are compiled in.
1585 config X86_64_ACPI_NUMA
1587 prompt "ACPI NUMA detection"
1588 depends on X86_64 && NUMA && ACPI && PCI
1591 Enable ACPI SRAT based node topology detection.
1594 bool "NUMA emulation"
1597 Enable NUMA emulation. A flat machine will be split
1598 into virtual nodes when booted with "numa=fake=N", where N is the
1599 number of nodes. This is only useful for debugging.
1602 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1604 default "10" if MAXSMP
1605 default "6" if X86_64
1609 Specify the maximum number of NUMA Nodes available on the target
1610 system. Increases memory reserved to accommodate various tables.
1612 config ARCH_FLATMEM_ENABLE
1614 depends on X86_32 && !NUMA
1616 config ARCH_SPARSEMEM_ENABLE
1618 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1619 select SPARSEMEM_STATIC if X86_32
1620 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1622 config ARCH_SPARSEMEM_DEFAULT
1623 def_bool X86_64 || (NUMA && X86_32)
1625 config ARCH_SELECT_MEMORY_MODEL
1627 depends on ARCH_SPARSEMEM_ENABLE
1629 config ARCH_MEMORY_PROBE
1630 bool "Enable sysfs memory/probe interface"
1631 depends on X86_64 && MEMORY_HOTPLUG
1633 This option enables a sysfs memory/probe interface for testing.
1634 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1635 If you are unsure how to answer this question, answer N.
1637 config ARCH_PROC_KCORE_TEXT
1639 depends on X86_64 && PROC_KCORE
1641 config ILLEGAL_POINTER_VALUE
1644 default 0xdead000000000000 if X86_64
1646 config X86_PMEM_LEGACY_DEVICE
1649 config X86_PMEM_LEGACY
1650 tristate "Support non-standard NVDIMMs and ADR protected memory"
1651 depends on PHYS_ADDR_T_64BIT
1653 select X86_PMEM_LEGACY_DEVICE
1654 select NUMA_KEEP_MEMINFO if NUMA
1657 Treat memory marked using the non-standard e820 type of 12 as used
1658 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1659 The kernel will offer these regions to the 'pmem' driver so
1660 they can be used for persistent storage.
1665 bool "Allocate 3rd-level pagetables from highmem"
1668 The VM uses one page table entry for each page of physical memory.
1669 For systems with a lot of RAM, this can be wasteful of precious
1670 low memory. Setting this option will put user-space page table
1671 entries in high memory.
1673 config X86_CHECK_BIOS_CORRUPTION
1674 bool "Check for low memory corruption"
1676 Periodically check for memory corruption in low memory, which
1677 is suspected to be caused by BIOS. Even when enabled in the
1678 configuration, it is disabled at runtime. Enable it by
1679 setting "memory_corruption_check=1" on the kernel command
1680 line. By default it scans the low 64k of memory every 60
1681 seconds; see the memory_corruption_check_size and
1682 memory_corruption_check_period parameters in
1683 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1685 When enabled with the default parameters, this option has
1686 almost no overhead, as it reserves a relatively small amount
1687 of memory and scans it infrequently. It both detects corruption
1688 and prevents it from affecting the running system.
1690 It is, however, intended as a diagnostic tool; if repeatable
1691 BIOS-originated corruption always affects the same memory,
1692 you can use memmap= to prevent the kernel from using that
1695 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1696 bool "Set the default setting of memory_corruption_check"
1697 depends on X86_CHECK_BIOS_CORRUPTION
1700 Set whether the default state of memory_corruption_check is
1703 config MATH_EMULATION
1705 depends on MODIFY_LDT_SYSCALL
1706 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1708 Linux can emulate a math coprocessor (used for floating point
1709 operations) if you don't have one. 486DX and Pentium processors have
1710 a math coprocessor built in, 486SX and 386 do not, unless you added
1711 a 487DX or 387, respectively. (The messages during boot time can
1712 give you some hints here ["man dmesg"].) Everyone needs either a
1713 coprocessor or this emulation.
1715 If you don't have a math coprocessor, you need to say Y here; if you
1716 say Y here even though you have a coprocessor, the coprocessor will
1717 be used nevertheless. (This behavior can be changed with the kernel
1718 command line option "no387", which comes handy if your coprocessor
1719 is broken. Try "man bootparam" or see the documentation of your boot
1720 loader (lilo or loadlin) about how to pass options to the kernel at
1721 boot time.) This means that it is a good idea to say Y here if you
1722 intend to use this kernel on different machines.
1724 More information about the internals of the Linux math coprocessor
1725 emulation can be found in <file:arch/x86/math-emu/README>.
1727 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1728 kernel, it won't hurt.
1732 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1734 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1735 the Memory Type Range Registers (MTRRs) may be used to control
1736 processor access to memory ranges. This is most useful if you have
1737 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1738 allows bus write transfers to be combined into a larger transfer
1739 before bursting over the PCI/AGP bus. This can increase performance
1740 of image write operations 2.5 times or more. Saying Y here creates a
1741 /proc/mtrr file which may be used to manipulate your processor's
1742 MTRRs. Typically the X server should use this.
1744 This code has a reasonably generic interface so that similar
1745 control registers on other processors can be easily supported
1748 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1749 Registers (ARRs) which provide a similar functionality to MTRRs. For
1750 these, the ARRs are used to emulate the MTRRs.
1751 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1752 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1753 write-combining. All of these processors are supported by this code
1754 and it makes sense to say Y here if you have one of them.
1756 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1757 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1758 can lead to all sorts of problems, so it's good to say Y here.
1760 You can safely say Y even if your machine doesn't have MTRRs, you'll
1761 just add about 9 KB to your kernel.
1763 See <file:Documentation/x86/mtrr.rst> for more information.
1765 config MTRR_SANITIZER
1767 prompt "MTRR cleanup support"
1770 Convert MTRR layout from continuous to discrete, so X drivers can
1771 add writeback entries.
1773 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1774 The largest mtrr entry size for a continuous block can be set with
1779 config MTRR_SANITIZER_ENABLE_DEFAULT
1780 int "MTRR cleanup enable value (0-1)"
1783 depends on MTRR_SANITIZER
1785 Enable mtrr cleanup default value
1787 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1788 int "MTRR cleanup spare reg num (0-7)"
1791 depends on MTRR_SANITIZER
1793 mtrr cleanup spare entries default, it can be changed via
1794 mtrr_spare_reg_nr=N on the kernel command line.
1798 prompt "x86 PAT support" if EXPERT
1801 Use PAT attributes to setup page level cache control.
1803 PATs are the modern equivalents of MTRRs and are much more
1804 flexible than MTRRs.
1806 Say N here if you see bootup problems (boot crash, boot hang,
1807 spontaneous reboots) or a non-working video driver.
1811 config ARCH_USES_PG_UNCACHED
1817 prompt "x86 architectural random number generator" if EXPERT
1819 Enable the x86 architectural RDRAND instruction
1820 (Intel Bull Mountain technology) to generate random numbers.
1821 If supported, this is a high bandwidth, cryptographically
1822 secure hardware random number generator.
1826 prompt "Supervisor Mode Access Prevention" if EXPERT
1828 Supervisor Mode Access Prevention (SMAP) is a security
1829 feature in newer Intel processors. There is a small
1830 performance cost if this enabled and turned on; there is
1831 also a small increase in the kernel size if this is enabled.
1837 prompt "User Mode Instruction Prevention" if EXPERT
1839 User Mode Instruction Prevention (UMIP) is a security feature in
1840 some x86 processors. If enabled, a general protection fault is
1841 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1842 executed in user mode. These instructions unnecessarily expose
1843 information about the hardware state.
1845 The vast majority of applications do not use these instructions.
1846 For the very few that do, software emulation is provided in
1847 specific cases in protected and virtual-8086 modes. Emulated
1850 config X86_INTEL_MEMORY_PROTECTION_KEYS
1851 prompt "Memory Protection Keys"
1853 # Note: only available in 64-bit mode
1854 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1855 select ARCH_USES_HIGH_VMA_FLAGS
1856 select ARCH_HAS_PKEYS
1858 Memory Protection Keys provides a mechanism for enforcing
1859 page-based protections, but without requiring modification of the
1860 page tables when an application changes protection domains.
1862 For details, see Documentation/core-api/protection-keys.rst
1867 prompt "TSX enable mode"
1868 depends on CPU_SUP_INTEL
1869 default X86_INTEL_TSX_MODE_OFF
1871 Intel's TSX (Transactional Synchronization Extensions) feature
1872 allows to optimize locking protocols through lock elision which
1873 can lead to a noticeable performance boost.
1875 On the other hand it has been shown that TSX can be exploited
1876 to form side channel attacks (e.g. TAA) and chances are there
1877 will be more of those attacks discovered in the future.
1879 Therefore TSX is not enabled by default (aka tsx=off). An admin
1880 might override this decision by tsx=on the command line parameter.
1881 Even with TSX enabled, the kernel will attempt to enable the best
1882 possible TAA mitigation setting depending on the microcode available
1883 for the particular machine.
1885 This option allows to set the default tsx mode between tsx=on, =off
1886 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1889 Say off if not sure, auto if TSX is in use but it should be used on safe
1890 platforms or on if TSX is in use and the security aspect of tsx is not
1893 config X86_INTEL_TSX_MODE_OFF
1896 TSX is disabled if possible - equals to tsx=off command line parameter.
1898 config X86_INTEL_TSX_MODE_ON
1901 TSX is always enabled on TSX capable HW - equals the tsx=on command
1904 config X86_INTEL_TSX_MODE_AUTO
1907 TSX is enabled on TSX capable HW that is believed to be safe against
1908 side channel attacks- equals the tsx=auto command line parameter.
1912 bool "Software Guard eXtensions (SGX)"
1913 depends on X86_64 && CPU_SUP_INTEL
1915 depends on CRYPTO_SHA256=y
1918 select NUMA_KEEP_MEMINFO if NUMA
1920 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1921 that can be used by applications to set aside private regions of code
1922 and data, referred to as enclaves. An enclave's private memory can
1923 only be accessed by code running within the enclave. Accesses from
1924 outside the enclave, including other enclaves, are disallowed by
1930 bool "EFI runtime service support"
1933 select EFI_RUNTIME_WRAPPERS
1934 select ARCH_USE_MEMREMAP_PROT
1936 This enables the kernel to use EFI runtime services that are
1937 available (such as the EFI variable services).
1939 This option is only useful on systems that have EFI firmware.
1940 In addition, you should use the latest ELILO loader available
1941 at <http://elilo.sourceforge.net> in order to take advantage
1942 of EFI runtime services. However, even with this option, the
1943 resultant kernel should continue to boot on existing non-EFI
1947 bool "EFI stub support"
1948 depends on EFI && !X86_USE_3DNOW
1949 depends on $(cc-option,-mabi=ms) || X86_32
1952 This kernel feature allows a bzImage to be loaded directly
1953 by EFI firmware without the use of a bootloader.
1955 See Documentation/admin-guide/efi-stub.rst for more information.
1958 bool "EFI mixed-mode support"
1959 depends on EFI_STUB && X86_64
1961 Enabling this feature allows a 64-bit kernel to be booted
1962 on a 32-bit firmware, provided that your CPU supports 64-bit
1965 Note that it is not possible to boot a mixed-mode enabled
1966 kernel via the EFI boot stub - a bootloader that supports
1967 the EFI handover protocol must be used.
1971 source "kernel/Kconfig.hz"
1974 bool "kexec system call"
1977 kexec is a system call that implements the ability to shutdown your
1978 current kernel, and to start another kernel. It is like a reboot
1979 but it is independent of the system firmware. And like a reboot
1980 you can start any kernel with it, not just Linux.
1982 The name comes from the similarity to the exec system call.
1984 It is an ongoing process to be certain the hardware in a machine
1985 is properly shutdown, so do not be surprised if this code does not
1986 initially work for you. As of this writing the exact hardware
1987 interface is strongly in flux, so no good recommendation can be
1991 bool "kexec file based system call"
1996 depends on CRYPTO_SHA256=y
1998 This is new version of kexec system call. This system call is
1999 file based and takes file descriptors as system call argument
2000 for kernel and initramfs as opposed to list of segments as
2001 accepted by previous system call.
2003 config ARCH_HAS_KEXEC_PURGATORY
2007 bool "Verify kernel signature during kexec_file_load() syscall"
2008 depends on KEXEC_FILE
2011 This option makes the kexec_file_load() syscall check for a valid
2012 signature of the kernel image. The image can still be loaded without
2013 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2014 there's a signature that we can check, then it must be valid.
2016 In addition to this option, you need to enable signature
2017 verification for the corresponding kernel image type being
2018 loaded in order for this to work.
2020 config KEXEC_SIG_FORCE
2021 bool "Require a valid signature in kexec_file_load() syscall"
2022 depends on KEXEC_SIG
2024 This option makes kernel signature verification mandatory for
2025 the kexec_file_load() syscall.
2027 config KEXEC_BZIMAGE_VERIFY_SIG
2028 bool "Enable bzImage signature verification support"
2029 depends on KEXEC_SIG
2030 depends on SIGNED_PE_FILE_VERIFICATION
2031 select SYSTEM_TRUSTED_KEYRING
2033 Enable bzImage signature verification support.
2036 bool "kernel crash dumps"
2037 depends on X86_64 || (X86_32 && HIGHMEM)
2039 Generate crash dump after being started by kexec.
2040 This should be normally only set in special crash dump kernels
2041 which are loaded in the main kernel with kexec-tools into
2042 a specially reserved region and then later executed after
2043 a crash by kdump/kexec. The crash dump kernel must be compiled
2044 to a memory address not used by the main kernel or BIOS using
2045 PHYSICAL_START, or it must be built as a relocatable image
2046 (CONFIG_RELOCATABLE=y).
2047 For more details see Documentation/admin-guide/kdump/kdump.rst
2051 depends on KEXEC && HIBERNATION
2053 Jump between original kernel and kexeced kernel and invoke
2054 code in physical address mode via KEXEC
2056 config PHYSICAL_START
2057 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2060 This gives the physical address where the kernel is loaded.
2062 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2063 bzImage will decompress itself to above physical address and
2064 run from there. Otherwise, bzImage will run from the address where
2065 it has been loaded by the boot loader and will ignore above physical
2068 In normal kdump cases one does not have to set/change this option
2069 as now bzImage can be compiled as a completely relocatable image
2070 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2071 address. This option is mainly useful for the folks who don't want
2072 to use a bzImage for capturing the crash dump and want to use a
2073 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2074 to be specifically compiled to run from a specific memory area
2075 (normally a reserved region) and this option comes handy.
2077 So if you are using bzImage for capturing the crash dump,
2078 leave the value here unchanged to 0x1000000 and set
2079 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2080 for capturing the crash dump change this value to start of
2081 the reserved region. In other words, it can be set based on
2082 the "X" value as specified in the "crashkernel=YM@XM"
2083 command line boot parameter passed to the panic-ed
2084 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2085 for more details about crash dumps.
2087 Usage of bzImage for capturing the crash dump is recommended as
2088 one does not have to build two kernels. Same kernel can be used
2089 as production kernel and capture kernel. Above option should have
2090 gone away after relocatable bzImage support is introduced. But it
2091 is present because there are users out there who continue to use
2092 vmlinux for dump capture. This option should go away down the
2095 Don't change this unless you know what you are doing.
2098 bool "Build a relocatable kernel"
2101 This builds a kernel image that retains relocation information
2102 so it can be loaded someplace besides the default 1MB.
2103 The relocations tend to make the kernel binary about 10% larger,
2104 but are discarded at runtime.
2106 One use is for the kexec on panic case where the recovery kernel
2107 must live at a different physical address than the primary
2110 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2111 it has been loaded at and the compile time physical address
2112 (CONFIG_PHYSICAL_START) is used as the minimum location.
2114 config RANDOMIZE_BASE
2115 bool "Randomize the address of the kernel image (KASLR)"
2116 depends on RELOCATABLE
2119 In support of Kernel Address Space Layout Randomization (KASLR),
2120 this randomizes the physical address at which the kernel image
2121 is decompressed and the virtual address where the kernel
2122 image is mapped, as a security feature that deters exploit
2123 attempts relying on knowledge of the location of kernel
2126 On 64-bit, the kernel physical and virtual addresses are
2127 randomized separately. The physical address will be anywhere
2128 between 16MB and the top of physical memory (up to 64TB). The
2129 virtual address will be randomized from 16MB up to 1GB (9 bits
2130 of entropy). Note that this also reduces the memory space
2131 available to kernel modules from 1.5GB to 1GB.
2133 On 32-bit, the kernel physical and virtual addresses are
2134 randomized together. They will be randomized from 16MB up to
2135 512MB (8 bits of entropy).
2137 Entropy is generated using the RDRAND instruction if it is
2138 supported. If RDTSC is supported, its value is mixed into
2139 the entropy pool as well. If neither RDRAND nor RDTSC are
2140 supported, then entropy is read from the i8254 timer. The
2141 usable entropy is limited by the kernel being built using
2142 2GB addressing, and that PHYSICAL_ALIGN must be at a
2143 minimum of 2MB. As a result, only 10 bits of entropy are
2144 theoretically possible, but the implementations are further
2145 limited due to memory layouts.
2149 # Relocation on x86 needs some additional build support
2150 config X86_NEED_RELOCS
2152 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2154 config PHYSICAL_ALIGN
2155 hex "Alignment value to which kernel should be aligned"
2157 range 0x2000 0x1000000 if X86_32
2158 range 0x200000 0x1000000 if X86_64
2160 This value puts the alignment restrictions on physical address
2161 where kernel is loaded and run from. Kernel is compiled for an
2162 address which meets above alignment restriction.
2164 If bootloader loads the kernel at a non-aligned address and
2165 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2166 address aligned to above value and run from there.
2168 If bootloader loads the kernel at a non-aligned address and
2169 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2170 load address and decompress itself to the address it has been
2171 compiled for and run from there. The address for which kernel is
2172 compiled already meets above alignment restrictions. Hence the
2173 end result is that kernel runs from a physical address meeting
2174 above alignment restrictions.
2176 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2177 this value must be a multiple of 0x200000.
2179 Don't change this unless you know what you are doing.
2181 config DYNAMIC_MEMORY_LAYOUT
2184 This option makes base addresses of vmalloc and vmemmap as well as
2185 __PAGE_OFFSET movable during boot.
2187 config RANDOMIZE_MEMORY
2188 bool "Randomize the kernel memory sections"
2190 depends on RANDOMIZE_BASE
2191 select DYNAMIC_MEMORY_LAYOUT
2192 default RANDOMIZE_BASE
2194 Randomizes the base virtual address of kernel memory sections
2195 (physical memory mapping, vmalloc & vmemmap). This security feature
2196 makes exploits relying on predictable memory locations less reliable.
2198 The order of allocations remains unchanged. Entropy is generated in
2199 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2200 configuration have in average 30,000 different possible virtual
2201 addresses for each memory section.
2205 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2206 hex "Physical memory mapping padding" if EXPERT
2207 depends on RANDOMIZE_MEMORY
2208 default "0xa" if MEMORY_HOTPLUG
2210 range 0x1 0x40 if MEMORY_HOTPLUG
2213 Define the padding in terabytes added to the existing physical
2214 memory size during kernel memory randomization. It is useful
2215 for memory hotplug support but reduces the entropy available for
2216 address randomization.
2218 If unsure, leave at the default value.
2224 config BOOTPARAM_HOTPLUG_CPU0
2225 bool "Set default setting of cpu0_hotpluggable"
2226 depends on HOTPLUG_CPU
2228 Set whether default state of cpu0_hotpluggable is on or off.
2230 Say Y here to enable CPU0 hotplug by default. If this switch
2231 is turned on, there is no need to give cpu0_hotplug kernel
2232 parameter and the CPU0 hotplug feature is enabled by default.
2234 Please note: there are two known CPU0 dependencies if you want
2235 to enable the CPU0 hotplug feature either by this switch or by
2236 cpu0_hotplug kernel parameter.
2238 First, resume from hibernate or suspend always starts from CPU0.
2239 So hibernate and suspend are prevented if CPU0 is offline.
2241 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2242 offline if any interrupt can not migrate out of CPU0. There may
2243 be other CPU0 dependencies.
2245 Please make sure the dependencies are under your control before
2246 you enable this feature.
2248 Say N if you don't want to enable CPU0 hotplug feature by default.
2249 You still can enable the CPU0 hotplug feature at boot by kernel
2250 parameter cpu0_hotplug.
2252 config DEBUG_HOTPLUG_CPU0
2254 prompt "Debug CPU0 hotplug"
2255 depends on HOTPLUG_CPU
2257 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2258 soon as possible and boots up userspace with CPU0 offlined. User
2259 can online CPU0 back after boot time.
2261 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2262 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2263 compilation or giving cpu0_hotplug kernel parameter at boot.
2269 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2270 depends on COMPAT_32
2272 Certain buggy versions of glibc will crash if they are
2273 presented with a 32-bit vDSO that is not mapped at the address
2274 indicated in its segment table.
2276 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2277 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2278 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2279 the only released version with the bug, but OpenSUSE 9
2280 contains a buggy "glibc 2.3.2".
2282 The symptom of the bug is that everything crashes on startup, saying:
2283 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2285 Saying Y here changes the default value of the vdso32 boot
2286 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2287 This works around the glibc bug but hurts performance.
2289 If unsure, say N: if you are compiling your own kernel, you
2290 are unlikely to be using a buggy version of glibc.
2293 prompt "vsyscall table for legacy applications"
2295 default LEGACY_VSYSCALL_XONLY
2297 Legacy user code that does not know how to find the vDSO expects
2298 to be able to issue three syscalls by calling fixed addresses in
2299 kernel space. Since this location is not randomized with ASLR,
2300 it can be used to assist security vulnerability exploitation.
2302 This setting can be changed at boot time via the kernel command
2303 line parameter vsyscall=[emulate|xonly|none].
2305 On a system with recent enough glibc (2.14 or newer) and no
2306 static binaries, you can say None without a performance penalty
2307 to improve security.
2309 If unsure, select "Emulate execution only".
2311 config LEGACY_VSYSCALL_EMULATE
2312 bool "Full emulation"
2314 The kernel traps and emulates calls into the fixed vsyscall
2315 address mapping. This makes the mapping non-executable, but
2316 it still contains readable known contents, which could be
2317 used in certain rare security vulnerability exploits. This
2318 configuration is recommended when using legacy userspace
2319 that still uses vsyscalls along with legacy binary
2320 instrumentation tools that require code to be readable.
2322 An example of this type of legacy userspace is running
2323 Pin on an old binary that still uses vsyscalls.
2325 config LEGACY_VSYSCALL_XONLY
2326 bool "Emulate execution only"
2328 The kernel traps and emulates calls into the fixed vsyscall
2329 address mapping and does not allow reads. This
2330 configuration is recommended when userspace might use the
2331 legacy vsyscall area but support for legacy binary
2332 instrumentation of legacy code is not needed. It mitigates
2333 certain uses of the vsyscall area as an ASLR-bypassing
2336 config LEGACY_VSYSCALL_NONE
2339 There will be no vsyscall mapping at all. This will
2340 eliminate any risk of ASLR bypass due to the vsyscall
2341 fixed address mapping. Attempts to use the vsyscalls
2342 will be reported to dmesg, so that either old or
2343 malicious userspace programs can be identified.
2348 bool "Built-in kernel command line"
2350 Allow for specifying boot arguments to the kernel at
2351 build time. On some systems (e.g. embedded ones), it is
2352 necessary or convenient to provide some or all of the
2353 kernel boot arguments with the kernel itself (that is,
2354 to not rely on the boot loader to provide them.)
2356 To compile command line arguments into the kernel,
2357 set this option to 'Y', then fill in the
2358 boot arguments in CONFIG_CMDLINE.
2360 Systems with fully functional boot loaders (i.e. non-embedded)
2361 should leave this option set to 'N'.
2364 string "Built-in kernel command string"
2365 depends on CMDLINE_BOOL
2368 Enter arguments here that should be compiled into the kernel
2369 image and used at boot time. If the boot loader provides a
2370 command line at boot time, it is appended to this string to
2371 form the full kernel command line, when the system boots.
2373 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2374 change this behavior.
2376 In most cases, the command line (whether built-in or provided
2377 by the boot loader) should specify the device for the root
2380 config CMDLINE_OVERRIDE
2381 bool "Built-in command line overrides boot loader arguments"
2382 depends on CMDLINE_BOOL && CMDLINE != ""
2384 Set this option to 'Y' to have the kernel ignore the boot loader
2385 command line, and use ONLY the built-in command line.
2387 This is used to work around broken boot loaders. This should
2388 be set to 'N' under normal conditions.
2390 config MODIFY_LDT_SYSCALL
2391 bool "Enable the LDT (local descriptor table)" if EXPERT
2394 Linux can allow user programs to install a per-process x86
2395 Local Descriptor Table (LDT) using the modify_ldt(2) system
2396 call. This is required to run 16-bit or segmented code such as
2397 DOSEMU or some Wine programs. It is also used by some very old
2398 threading libraries.
2400 Enabling this feature adds a small amount of overhead to
2401 context switches and increases the low-level kernel attack
2402 surface. Disabling it removes the modify_ldt(2) system call.
2404 Saying 'N' here may make sense for embedded or server kernels.
2406 source "kernel/livepatch/Kconfig"
2410 config ARCH_HAS_ADD_PAGES
2412 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2414 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2417 config USE_PERCPU_NUMA_NODE_ID
2421 menu "Power management and ACPI options"
2423 config ARCH_HIBERNATION_HEADER
2425 depends on HIBERNATION
2427 source "kernel/power/Kconfig"
2429 source "drivers/acpi/Kconfig"
2436 tristate "APM (Advanced Power Management) BIOS support"
2437 depends on X86_32 && PM_SLEEP
2439 APM is a BIOS specification for saving power using several different
2440 techniques. This is mostly useful for battery powered laptops with
2441 APM compliant BIOSes. If you say Y here, the system time will be
2442 reset after a RESUME operation, the /proc/apm device will provide
2443 battery status information, and user-space programs will receive
2444 notification of APM "events" (e.g. battery status change).
2446 If you select "Y" here, you can disable actual use of the APM
2447 BIOS by passing the "apm=off" option to the kernel at boot time.
2449 Note that the APM support is almost completely disabled for
2450 machines with more than one CPU.
2452 In order to use APM, you will need supporting software. For location
2453 and more information, read <file:Documentation/power/apm-acpi.rst>
2454 and the Battery Powered Linux mini-HOWTO, available from
2455 <http://www.tldp.org/docs.html#howto>.
2457 This driver does not spin down disk drives (see the hdparm(8)
2458 manpage ("man 8 hdparm") for that), and it doesn't turn off
2459 VESA-compliant "green" monitors.
2461 This driver does not support the TI 4000M TravelMate and the ACER
2462 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2463 desktop machines also don't have compliant BIOSes, and this driver
2464 may cause those machines to panic during the boot phase.
2466 Generally, if you don't have a battery in your machine, there isn't
2467 much point in using this driver and you should say N. If you get
2468 random kernel OOPSes or reboots that don't seem to be related to
2469 anything, try disabling/enabling this option (or disabling/enabling
2472 Some other things you should try when experiencing seemingly random,
2475 1) make sure that you have enough swap space and that it is
2477 2) pass the "no-hlt" option to the kernel
2478 3) switch on floating point emulation in the kernel and pass
2479 the "no387" option to the kernel
2480 4) pass the "floppy=nodma" option to the kernel
2481 5) pass the "mem=4M" option to the kernel (thereby disabling
2482 all but the first 4 MB of RAM)
2483 6) make sure that the CPU is not over clocked.
2484 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2485 8) disable the cache from your BIOS settings
2486 9) install a fan for the video card or exchange video RAM
2487 10) install a better fan for the CPU
2488 11) exchange RAM chips
2489 12) exchange the motherboard.
2491 To compile this driver as a module, choose M here: the
2492 module will be called apm.
2496 config APM_IGNORE_USER_SUSPEND
2497 bool "Ignore USER SUSPEND"
2499 This option will ignore USER SUSPEND requests. On machines with a
2500 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2501 series notebooks, it is necessary to say Y because of a BIOS bug.
2503 config APM_DO_ENABLE
2504 bool "Enable PM at boot time"
2506 Enable APM features at boot time. From page 36 of the APM BIOS
2507 specification: "When disabled, the APM BIOS does not automatically
2508 power manage devices, enter the Standby State, enter the Suspend
2509 State, or take power saving steps in response to CPU Idle calls."
2510 This driver will make CPU Idle calls when Linux is idle (unless this
2511 feature is turned off -- see "Do CPU IDLE calls", below). This
2512 should always save battery power, but more complicated APM features
2513 will be dependent on your BIOS implementation. You may need to turn
2514 this option off if your computer hangs at boot time when using APM
2515 support, or if it beeps continuously instead of suspending. Turn
2516 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2517 T400CDT. This is off by default since most machines do fine without
2522 bool "Make CPU Idle calls when idle"
2524 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2525 On some machines, this can activate improved power savings, such as
2526 a slowed CPU clock rate, when the machine is idle. These idle calls
2527 are made after the idle loop has run for some length of time (e.g.,
2528 333 mS). On some machines, this will cause a hang at boot time or
2529 whenever the CPU becomes idle. (On machines with more than one CPU,
2530 this option does nothing.)
2532 config APM_DISPLAY_BLANK
2533 bool "Enable console blanking using APM"
2535 Enable console blanking using the APM. Some laptops can use this to
2536 turn off the LCD backlight when the screen blanker of the Linux
2537 virtual console blanks the screen. Note that this is only used by
2538 the virtual console screen blanker, and won't turn off the backlight
2539 when using the X Window system. This also doesn't have anything to
2540 do with your VESA-compliant power-saving monitor. Further, this
2541 option doesn't work for all laptops -- it might not turn off your
2542 backlight at all, or it might print a lot of errors to the console,
2543 especially if you are using gpm.
2545 config APM_ALLOW_INTS
2546 bool "Allow interrupts during APM BIOS calls"
2548 Normally we disable external interrupts while we are making calls to
2549 the APM BIOS as a measure to lessen the effects of a badly behaving
2550 BIOS implementation. The BIOS should reenable interrupts if it
2551 needs to. Unfortunately, some BIOSes do not -- especially those in
2552 many of the newer IBM Thinkpads. If you experience hangs when you
2553 suspend, try setting this to Y. Otherwise, say N.
2557 source "drivers/cpufreq/Kconfig"
2559 source "drivers/cpuidle/Kconfig"
2561 source "drivers/idle/Kconfig"
2566 menu "Bus options (PCI etc.)"
2569 prompt "PCI access mode"
2570 depends on X86_32 && PCI
2573 On PCI systems, the BIOS can be used to detect the PCI devices and
2574 determine their configuration. However, some old PCI motherboards
2575 have BIOS bugs and may crash if this is done. Also, some embedded
2576 PCI-based systems don't have any BIOS at all. Linux can also try to
2577 detect the PCI hardware directly without using the BIOS.
2579 With this option, you can specify how Linux should detect the
2580 PCI devices. If you choose "BIOS", the BIOS will be used,
2581 if you choose "Direct", the BIOS won't be used, and if you
2582 choose "MMConfig", then PCI Express MMCONFIG will be used.
2583 If you choose "Any", the kernel will try MMCONFIG, then the
2584 direct access method and falls back to the BIOS if that doesn't
2585 work. If unsure, go with the default, which is "Any".
2590 config PCI_GOMMCONFIG
2607 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2609 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2612 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2615 bool "Support mmconfig PCI config space access" if X86_64
2617 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2618 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2622 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2626 depends on PCI && XEN
2628 config MMCONF_FAM10H
2630 depends on X86_64 && PCI_MMCONFIG && ACPI
2632 config PCI_CNB20LE_QUIRK
2633 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2636 Read the PCI windows out of the CNB20LE host bridge. This allows
2637 PCI hotplug to work on systems with the CNB20LE chipset which do
2640 There's no public spec for this chipset, and this functionality
2641 is known to be incomplete.
2643 You should say N unless you know you need this.
2646 bool "ISA bus support on modern systems" if EXPERT
2648 Expose ISA bus device drivers and options available for selection and
2649 configuration. Enable this option if your target machine has an ISA
2650 bus. ISA is an older system, displaced by PCI and newer bus
2651 architectures -- if your target machine is modern, it probably does
2652 not have an ISA bus.
2656 # x86_64 have no ISA slots, but can have ISA-style DMA.
2658 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2661 Enables ISA-style DMA support for devices requiring such controllers.
2669 Find out whether you have ISA slots on your motherboard. ISA is the
2670 name of a bus system, i.e. the way the CPU talks to the other stuff
2671 inside your box. Other bus systems are PCI, EISA, MicroChannel
2672 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2673 newer boards don't support it. If you have ISA, say Y, otherwise N.
2676 tristate "NatSemi SCx200 support"
2678 This provides basic support for National Semiconductor's
2679 (now AMD's) Geode processors. The driver probes for the
2680 PCI-IDs of several on-chip devices, so its a good dependency
2681 for other scx200_* drivers.
2683 If compiled as a module, the driver is named scx200.
2685 config SCx200HR_TIMER
2686 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2690 This driver provides a clocksource built upon the on-chip
2691 27MHz high-resolution timer. Its also a workaround for
2692 NSC Geode SC-1100's buggy TSC, which loses time when the
2693 processor goes idle (as is done by the scheduler). The
2694 other workaround is idle=poll boot option.
2697 bool "One Laptop Per Child support"
2705 Add support for detecting the unique features of the OLPC
2709 bool "OLPC XO-1 Power Management"
2710 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2712 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2715 bool "OLPC XO-1 Real Time Clock"
2716 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2718 Add support for the XO-1 real time clock, which can be used as a
2719 programmable wakeup source.
2722 bool "OLPC XO-1 SCI extras"
2723 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2727 Add support for SCI-based features of the OLPC XO-1 laptop:
2728 - EC-driven system wakeups
2732 - AC adapter status updates
2733 - Battery status updates
2735 config OLPC_XO15_SCI
2736 bool "OLPC XO-1.5 SCI extras"
2737 depends on OLPC && ACPI
2740 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2741 - EC-driven system wakeups
2742 - AC adapter status updates
2743 - Battery status updates
2746 bool "PCEngines ALIX System Support (LED setup)"
2749 This option enables system support for the PCEngines ALIX.
2750 At present this just sets up LEDs for GPIO control on
2751 ALIX2/3/6 boards. However, other system specific setup should
2754 Note: You must still enable the drivers for GPIO and LED support
2755 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2757 Note: You have to set alix.force=1 for boards with Award BIOS.
2760 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2763 This option enables system support for the Soekris Engineering net5501.
2766 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2770 This option enables system support for the Traverse Technologies GEOS.
2773 bool "Technologic Systems TS-5500 platform support"
2775 select CHECK_SIGNATURE
2779 This option enables system support for the Technologic Systems TS-5500.
2785 depends on CPU_SUP_AMD && PCI
2790 menu "Binary Emulations"
2792 config IA32_EMULATION
2793 bool "IA32 Emulation"
2795 select ARCH_WANT_OLD_COMPAT_IPC
2797 select COMPAT_OLD_SIGACTION
2799 Include code to run legacy 32-bit programs under a
2800 64-bit kernel. You should likely turn this on, unless you're
2801 100% sure that you don't have any 32-bit programs left.
2804 tristate "IA32 a.out support"
2805 depends on IA32_EMULATION
2808 Support old a.out binaries in the 32bit emulation.
2811 bool "x32 ABI for 64-bit mode"
2813 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2814 # compressed debug sections to x86_x32 properly:
2815 # https://github.com/ClangBuiltLinux/linux/issues/514
2816 # https://github.com/ClangBuiltLinux/linux/issues/1141
2817 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2819 Include code to run binaries for the x32 native 32-bit ABI
2820 for 64-bit processors. An x32 process gets access to the
2821 full 64-bit register file and wide data path while leaving
2822 pointers at 32 bits for smaller memory footprint.
2824 You will need a recent binutils (2.22 or later) with
2825 elf32_x86_64 support enabled to compile a kernel with this
2830 depends on IA32_EMULATION || X86_32
2832 select OLD_SIGSUSPEND3
2836 depends on IA32_EMULATION || X86_X32
2839 config COMPAT_FOR_U64_ALIGNMENT
2842 config SYSVIPC_COMPAT
2850 config HAVE_ATOMIC_IOMAP
2854 source "arch/x86/kvm/Kconfig"
2856 source "arch/x86/Kconfig.assembler"