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_CURRENT_STACK_POINTER
73 select ARCH_HAS_DEBUG_VIRTUAL
74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
75 select ARCH_HAS_DEVMEM_IS_ALLOWED
76 select ARCH_HAS_EARLY_DEBUG if KGDB
77 select ARCH_HAS_ELF_RANDOMIZE
78 select ARCH_HAS_FAST_MULTIPLIER
79 select ARCH_HAS_FILTER_PGPROT
80 select ARCH_HAS_FORTIFY_SOURCE
81 select ARCH_HAS_GCOV_PROFILE_ALL
82 select ARCH_HAS_KCOV if X86_64
83 select ARCH_HAS_MEM_ENCRYPT
84 select ARCH_HAS_MEMBARRIER_SYNC_CORE
85 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
86 select ARCH_HAS_PMEM_API if X86_64
87 select ARCH_HAS_PTE_DEVMAP if X86_64
88 select ARCH_HAS_PTE_SPECIAL
89 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
90 select ARCH_HAS_COPY_MC if X86_64
91 select ARCH_HAS_SET_MEMORY
92 select ARCH_HAS_SET_DIRECT_MAP
93 select ARCH_HAS_STRICT_KERNEL_RWX
94 select ARCH_HAS_STRICT_MODULE_RWX
95 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
96 select ARCH_HAS_SYSCALL_WRAPPER
97 select ARCH_HAS_UBSAN_SANITIZE_ALL
98 select ARCH_HAS_DEBUG_WX
99 select ARCH_HAS_ZONE_DMA_SET if EXPERT
100 select ARCH_HAVE_NMI_SAFE_CMPXCHG
101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
102 select ARCH_MIGHT_HAVE_PC_PARPORT
103 select ARCH_MIGHT_HAVE_PC_SERIO
104 select ARCH_STACKWALK
105 select ARCH_SUPPORTS_ACPI
106 select ARCH_SUPPORTS_ATOMIC_RMW
107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
111 select ARCH_SUPPORTS_LTO_CLANG
112 select ARCH_SUPPORTS_LTO_CLANG_THIN
113 select ARCH_USE_BUILTIN_BSWAP
114 select ARCH_USE_MEMTEST
115 select ARCH_USE_QUEUED_RWLOCKS
116 select ARCH_USE_QUEUED_SPINLOCKS
117 select ARCH_USE_SYM_ANNOTATIONS
118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
121 select ARCH_WANTS_NO_INSTR
122 select ARCH_WANT_HUGE_PMD_SHARE
123 select ARCH_WANT_LD_ORPHAN_WARN
124 select ARCH_WANTS_THP_SWAP if X86_64
125 select ARCH_HAS_PARANOID_L1D_FLUSH
126 select BUILDTIME_TABLE_SORT
128 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
129 select CLOCKSOURCE_WATCHDOG
130 select DCACHE_WORD_ACCESS
131 select DYNAMIC_SIGFRAME
132 select EDAC_ATOMIC_SCRUB
134 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
135 select GENERIC_CLOCKEVENTS_MIN_ADJUST
136 select GENERIC_CMOS_UPDATE
137 select GENERIC_CPU_AUTOPROBE
138 select GENERIC_CPU_VULNERABILITIES
139 select GENERIC_EARLY_IOREMAP
142 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
143 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
144 select GENERIC_IRQ_MIGRATION if SMP
145 select GENERIC_IRQ_PROBE
146 select GENERIC_IRQ_RESERVATION_MODE
147 select GENERIC_IRQ_SHOW
148 select GENERIC_PENDING_IRQ if SMP
149 select GENERIC_PTDUMP
150 select GENERIC_SMP_IDLE_THREAD
151 select GENERIC_TIME_VSYSCALL
152 select GENERIC_GETTIMEOFDAY
153 select GENERIC_VDSO_TIME_NS
154 select GUP_GET_PTE_LOW_HIGH if X86_PAE
155 select HARDIRQS_SW_RESEND
156 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
157 select HAVE_ACPI_APEI if ACPI
158 select HAVE_ACPI_APEI_NMI if ACPI
159 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
160 select HAVE_ARCH_AUDITSYSCALL
161 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
162 select HAVE_ARCH_JUMP_LABEL
163 select HAVE_ARCH_JUMP_LABEL_RELATIVE
164 select HAVE_ARCH_KASAN if X86_64
165 select HAVE_ARCH_KASAN_VMALLOC if X86_64
166 select HAVE_ARCH_KFENCE
167 select HAVE_ARCH_KGDB
168 select HAVE_ARCH_MMAP_RND_BITS if MMU
169 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
170 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
171 select HAVE_ARCH_PREL32_RELOCATIONS
172 select HAVE_ARCH_SECCOMP_FILTER
173 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
174 select HAVE_ARCH_STACKLEAK
175 select HAVE_ARCH_TRACEHOOK
176 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
177 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
178 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
179 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
180 select HAVE_ARCH_VMAP_STACK if X86_64
181 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
182 select HAVE_ARCH_WITHIN_STACK_FRAMES
183 select HAVE_ASM_MODVERSIONS
184 select HAVE_CMPXCHG_DOUBLE
185 select HAVE_CMPXCHG_LOCAL
186 select HAVE_CONTEXT_TRACKING if X86_64
187 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
188 select HAVE_C_RECORDMCOUNT
189 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
190 select HAVE_BUILDTIME_MCOUNT_SORT
191 select HAVE_DEBUG_KMEMLEAK
192 select HAVE_DMA_CONTIGUOUS
193 select HAVE_DYNAMIC_FTRACE
194 select HAVE_DYNAMIC_FTRACE_WITH_REGS
195 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
196 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
197 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
198 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
200 select HAVE_EFFICIENT_UNALIGNED_ACCESS
202 select HAVE_EXIT_THREAD
204 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
205 select HAVE_FTRACE_MCOUNT_RECORD
206 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
207 select HAVE_FUNCTION_TRACER
208 select HAVE_GCC_PLUGINS
209 select HAVE_HW_BREAKPOINT
210 select HAVE_IOREMAP_PROT
211 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
212 select HAVE_IRQ_TIME_ACCOUNTING
213 select HAVE_KERNEL_BZIP2
214 select HAVE_KERNEL_GZIP
215 select HAVE_KERNEL_LZ4
216 select HAVE_KERNEL_LZMA
217 select HAVE_KERNEL_LZO
218 select HAVE_KERNEL_XZ
219 select HAVE_KERNEL_ZSTD
221 select HAVE_KPROBES_ON_FTRACE
222 select HAVE_FUNCTION_ERROR_INJECTION
223 select HAVE_KRETPROBES
225 select HAVE_LIVEPATCH if X86_64
226 select HAVE_MIXED_BREAKPOINTS_REGS
227 select HAVE_MOD_ARCH_SPECIFIC
231 select HAVE_OPTPROBES
232 select HAVE_PCSPKR_PLATFORM
233 select HAVE_PERF_EVENTS
234 select HAVE_PERF_EVENTS_NMI
235 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
237 select HAVE_PERF_REGS
238 select HAVE_PERF_USER_STACK_DUMP
239 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
240 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
241 select HAVE_REGS_AND_STACK_ACCESS_API
242 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
243 select HAVE_FUNCTION_ARG_ACCESS_API
244 select HAVE_SETUP_PER_CPU_AREA
245 select HAVE_SOFTIRQ_ON_OWN_STACK
246 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
247 select HAVE_STACK_VALIDATION if X86_64
248 select HAVE_STATIC_CALL
249 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
250 select HAVE_PREEMPT_DYNAMIC
252 select HAVE_SYSCALL_TRACEPOINTS
253 select HAVE_UNSTABLE_SCHED_CLOCK
254 select HAVE_USER_RETURN_NOTIFIER
255 select HAVE_GENERIC_VDSO
256 select HOTPLUG_SMT if SMP
257 select IRQ_FORCED_THREADING
258 select NEED_PER_CPU_EMBED_FIRST_CHUNK
259 select NEED_PER_CPU_PAGE_FIRST_CHUNK
260 select NEED_SG_DMA_LENGTH
261 select PCI_DOMAINS if PCI
262 select PCI_LOCKLESS_CONFIG if PCI
265 select RTC_MC146818_LIB
268 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
269 select SYSCTL_EXCEPTION_TRACE
270 select THREAD_INFO_IN_TASK
271 select TRACE_IRQFLAGS_SUPPORT
272 select USER_STACKTRACE_SUPPORT
274 select HAVE_ARCH_KCSAN if X86_64
275 select X86_FEATURE_NAMES if PROC_FS
276 select PROC_PID_ARCH_STATUS if PROC_FS
277 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
278 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
280 config INSTRUCTION_DECODER
282 depends on KPROBES || PERF_EVENTS || UPROBES
286 default "elf32-i386" if X86_32
287 default "elf64-x86-64" if X86_64
289 config LOCKDEP_SUPPORT
292 config STACKTRACE_SUPPORT
298 config ARCH_MMAP_RND_BITS_MIN
302 config ARCH_MMAP_RND_BITS_MAX
306 config ARCH_MMAP_RND_COMPAT_BITS_MIN
309 config ARCH_MMAP_RND_COMPAT_BITS_MAX
315 config GENERIC_ISA_DMA
317 depends on ISA_DMA_API
322 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
324 config GENERIC_BUG_RELATIVE_POINTERS
327 config ARCH_MAY_HAVE_PC_FDC
329 depends on ISA_DMA_API
331 config GENERIC_CALIBRATE_DELAY
334 config ARCH_HAS_CPU_RELAX
337 config ARCH_HAS_FILTER_PGPROT
340 config ARCH_HIBERNATION_POSSIBLE
345 default 1024 if X86_64
348 config ARCH_SUSPEND_POSSIBLE
351 config ARCH_WANT_GENERAL_HUGETLB
357 config KASAN_SHADOW_OFFSET
360 default 0xdffffc0000000000
362 config HAVE_INTEL_TXT
364 depends on INTEL_IOMMU && ACPI
368 depends on X86_32 && SMP
372 depends on X86_64 && SMP
374 config ARCH_SUPPORTS_UPROBES
377 config FIX_EARLYCON_MEM
380 config DYNAMIC_PHYSICAL_MASK
383 config PGTABLE_LEVELS
385 default 5 if X86_5LEVEL
390 config CC_HAS_SANE_STACKPROTECTOR
392 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
393 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
395 We have to make sure stack protector is unconditionally disabled if
396 the compiler produces broken code or if it does not let us control
397 the segment on 32-bit kernels.
399 menu "Processor type and features"
402 bool "Symmetric multi-processing support"
404 This enables support for systems with more than one CPU. If you have
405 a system with only one CPU, say N. If you have a system with more
408 If you say N here, the kernel will run on uni- and multiprocessor
409 machines, but will use only one CPU of a multiprocessor machine. If
410 you say Y here, the kernel will run on many, but not all,
411 uniprocessor machines. On a uniprocessor machine, the kernel
412 will run faster if you say N here.
414 Note that if you say Y here and choose architecture "586" or
415 "Pentium" under "Processor family", the kernel will not work on 486
416 architectures. Similarly, multiprocessor kernels for the "PPro"
417 architecture may not work on all Pentium based boards.
419 People using multiprocessor machines who say Y here should also say
420 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
421 Management" code will be disabled if you say Y here.
423 See also <file:Documentation/x86/i386/IO-APIC.rst>,
424 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
425 <http://www.tldp.org/docs.html#howto>.
427 If you don't know what to do here, say N.
429 config X86_FEATURE_NAMES
430 bool "Processor feature human-readable names" if EMBEDDED
433 This option compiles in a table of x86 feature bits and corresponding
434 names. This is required to support /proc/cpuinfo and a few kernel
435 messages. You can disable this to save space, at the expense of
436 making those few kernel messages show numeric feature bits instead.
441 bool "Support x2apic"
442 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
444 This enables x2apic support on CPUs that have this feature.
446 This allows 32-bit apic IDs (so it can support very large systems),
447 and accesses the local apic via MSRs not via mmio.
449 If you don't know what to do here, say N.
452 bool "Enable MPS table" if ACPI
454 depends on X86_LOCAL_APIC
456 For old smp systems that do not have proper acpi support. Newer systems
457 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
461 depends on X86_GOLDFISH
464 bool "Avoid speculative indirect branches in kernel"
467 Compile kernel with the retpoline compiler options to guard against
468 kernel-to-user data leaks by avoiding speculative indirect
469 branches. Requires a compiler with -mindirect-branch=thunk-extern
470 support for full protection. The kernel may run slower.
473 def_bool $(cc-option,-mharden-sls=all)
476 bool "Mitigate Straight-Line-Speculation"
477 depends on CC_HAS_SLS && X86_64
480 Compile the kernel with straight-line-speculation options to guard
481 against straight line speculation. The kernel image might be slightly
484 config X86_CPU_RESCTRL
485 bool "x86 CPU resource control support"
486 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
488 select PROC_CPU_RESCTRL if PROC_FS
490 Enable x86 CPU resource control support.
492 Provide support for the allocation and monitoring of system resources
495 Intel calls this Intel Resource Director Technology
496 (Intel(R) RDT). More information about RDT can be found in the
497 Intel x86 Architecture Software Developer Manual.
499 AMD calls this AMD Platform Quality of Service (AMD QoS).
500 More information about AMD QoS can be found in the AMD64 Technology
501 Platform Quality of Service Extensions manual.
507 bool "Support for big SMP systems with more than 8 CPUs"
510 This option is needed for the systems that have more than 8 CPUs.
512 config X86_EXTENDED_PLATFORM
513 bool "Support for extended (non-PC) x86 platforms"
516 If you disable this option then the kernel will only support
517 standard PC platforms. (which covers the vast majority of
520 If you enable this option then you'll be able to select support
521 for the following (non-PC) 32 bit x86 platforms:
522 Goldfish (Android emulator)
525 SGI 320/540 (Visual Workstation)
526 STA2X11-based (e.g. Northville)
527 Moorestown MID devices
529 If you have one of these systems, or if you want to build a
530 generic distribution kernel, say Y here - otherwise say N.
534 config X86_EXTENDED_PLATFORM
535 bool "Support for extended (non-PC) x86 platforms"
538 If you disable this option then the kernel will only support
539 standard PC platforms. (which covers the vast majority of
542 If you enable this option then you'll be able to select support
543 for the following (non-PC) 64 bit x86 platforms:
548 If you have one of these systems, or if you want to build a
549 generic distribution kernel, say Y here - otherwise say N.
551 # This is an alphabetically sorted list of 64 bit extended platforms
552 # Please maintain the alphabetic order if and when there are additions
554 bool "Numascale NumaChip"
556 depends on X86_EXTENDED_PLATFORM
559 depends on X86_X2APIC
560 depends on PCI_MMCONFIG
562 Adds support for Numascale NumaChip large-SMP systems. Needed to
563 enable more than ~168 cores.
564 If you don't have one of these, you should say N here.
568 select HYPERVISOR_GUEST
570 depends on X86_64 && PCI
571 depends on X86_EXTENDED_PLATFORM
574 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
575 supposed to run on these EM64T-based machines. Only choose this option
576 if you have one of these machines.
579 bool "SGI Ultraviolet"
581 depends on X86_EXTENDED_PLATFORM
584 depends on KEXEC_CORE
585 depends on X86_X2APIC
588 This option is needed in order to support SGI Ultraviolet systems.
589 If you don't have one of these, you should say N here.
591 # Following is an alphabetically sorted list of 32 bit extended platforms
592 # Please maintain the alphabetic order if and when there are additions
595 bool "Goldfish (Virtual Platform)"
596 depends on X86_EXTENDED_PLATFORM
598 Enable support for the Goldfish virtual platform used primarily
599 for Android development. Unless you are building for the Android
600 Goldfish emulator say N here.
603 bool "CE4100 TV platform"
605 depends on PCI_GODIRECT
606 depends on X86_IO_APIC
608 depends on X86_EXTENDED_PLATFORM
609 select X86_REBOOTFIXUPS
611 select OF_EARLY_FLATTREE
613 Select for the Intel CE media processor (CE4100) SOC.
614 This option compiles in support for the CE4100 SOC for settop
615 boxes and media devices.
618 bool "Intel MID platform support"
619 depends on X86_EXTENDED_PLATFORM
620 depends on X86_PLATFORM_DEVICES
622 depends on X86_64 || (PCI_GOANY && X86_32)
623 depends on X86_IO_APIC
628 Select to build a kernel capable of supporting Intel MID (Mobile
629 Internet Device) platform systems which do not have the PCI legacy
630 interfaces. If you are building for a PC class system say N here.
632 Intel MID platforms are based on an Intel processor and chipset which
633 consume less power than most of the x86 derivatives.
635 config X86_INTEL_QUARK
636 bool "Intel Quark platform support"
638 depends on X86_EXTENDED_PLATFORM
639 depends on X86_PLATFORM_DEVICES
643 depends on X86_IO_APIC
648 Select to include support for Quark X1000 SoC.
649 Say Y here if you have a Quark based system such as the Arduino
650 compatible Intel Galileo.
652 config X86_INTEL_LPSS
653 bool "Intel Low Power Subsystem Support"
654 depends on X86 && ACPI && PCI
659 Select to build support for Intel Low Power Subsystem such as
660 found on Intel Lynxpoint PCH. Selecting this option enables
661 things like clock tree (common clock framework) and pincontrol
662 which are needed by the LPSS peripheral drivers.
664 config X86_AMD_PLATFORM_DEVICE
665 bool "AMD ACPI2Platform devices support"
670 Select to interpret AMD specific ACPI device to platform device
671 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
672 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
673 implemented under PINCTRL subsystem.
676 tristate "Intel SoC IOSF Sideband support for SoC platforms"
679 This option enables sideband register access support for Intel SoC
680 platforms. On these platforms the IOSF sideband is used in lieu of
681 MSR's for some register accesses, mostly but not limited to thermal
682 and power. Drivers may query the availability of this device to
683 determine if they need the sideband in order to work on these
684 platforms. The sideband is available on the following SoC products.
685 This list is not meant to be exclusive.
690 You should say Y if you are running a kernel on one of these SoC's.
692 config IOSF_MBI_DEBUG
693 bool "Enable IOSF sideband access through debugfs"
694 depends on IOSF_MBI && DEBUG_FS
696 Select this option to expose the IOSF sideband access registers (MCR,
697 MDR, MCRX) through debugfs to write and read register information from
698 different units on the SoC. This is most useful for obtaining device
699 state information for debug and analysis. As this is a general access
700 mechanism, users of this option would have specific knowledge of the
701 device they want to access.
703 If you don't require the option or are in doubt, say N.
706 bool "RDC R-321x SoC"
708 depends on X86_EXTENDED_PLATFORM
710 select X86_REBOOTFIXUPS
712 This option is needed for RDC R-321x system-on-chip, also known
714 If you don't have one of these chips, you should say N here.
716 config X86_32_NON_STANDARD
717 bool "Support non-standard 32-bit SMP architectures"
718 depends on X86_32 && SMP
719 depends on X86_EXTENDED_PLATFORM
721 This option compiles in the bigsmp and STA2X11 default
722 subarchitectures. It is intended for a generic binary
723 kernel. If you select them all, kernel will probe it one by
724 one and will fallback to default.
726 # Alphabetically sorted list of Non standard 32 bit platforms
728 config X86_SUPPORTS_MEMORY_FAILURE
730 # MCE code calls memory_failure():
732 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
733 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
734 depends on X86_64 || !SPARSEMEM
735 select ARCH_SUPPORTS_MEMORY_FAILURE
738 bool "STA2X11 Companion Chip Support"
739 depends on X86_32_NON_STANDARD && PCI
744 This adds support for boards based on the STA2X11 IO-Hub,
745 a.k.a. "ConneXt". The chip is used in place of the standard
746 PC chipset, so all "standard" peripherals are missing. If this
747 option is selected the kernel will still be able to boot on
748 standard PC machines.
751 tristate "Eurobraille/Iris poweroff module"
754 The Iris machines from EuroBraille do not have APM or ACPI support
755 to shut themselves down properly. A special I/O sequence is
756 needed to do so, which is what this module does at
759 This is only for Iris machines from EuroBraille.
763 config SCHED_OMIT_FRAME_POINTER
765 prompt "Single-depth WCHAN output"
768 Calculate simpler /proc/<PID>/wchan values. If this option
769 is disabled then wchan values will recurse back to the
770 caller function. This provides more accurate wchan values,
771 at the expense of slightly more scheduling overhead.
773 If in doubt, say "Y".
775 menuconfig HYPERVISOR_GUEST
776 bool "Linux guest support"
778 Say Y here to enable options for running Linux under various hyper-
779 visors. This option enables basic hypervisor detection and platform
782 If you say N, all options in this submenu will be skipped and
783 disabled, and Linux guest support won't be built in.
788 bool "Enable paravirtualization code"
789 depends on HAVE_STATIC_CALL
791 This changes the kernel so it can modify itself when it is run
792 under a hypervisor, potentially improving performance significantly
793 over full virtualization. However, when run without a hypervisor
794 the kernel is theoretically slower and slightly larger.
799 config PARAVIRT_DEBUG
800 bool "paravirt-ops debugging"
801 depends on PARAVIRT && DEBUG_KERNEL
803 Enable to debug paravirt_ops internals. Specifically, BUG if
804 a paravirt_op is missing when it is called.
806 config PARAVIRT_SPINLOCKS
807 bool "Paravirtualization layer for spinlocks"
808 depends on PARAVIRT && SMP
810 Paravirtualized spinlocks allow a pvops backend to replace the
811 spinlock implementation with something virtualization-friendly
812 (for example, block the virtual CPU rather than spinning).
814 It has a minimal impact on native kernels and gives a nice performance
815 benefit on paravirtualized KVM / Xen kernels.
817 If you are unsure how to answer this question, answer Y.
819 config X86_HV_CALLBACK_VECTOR
822 source "arch/x86/xen/Kconfig"
825 bool "KVM Guest support (including kvmclock)"
827 select PARAVIRT_CLOCK
828 select ARCH_CPUIDLE_HALTPOLL
829 select X86_HV_CALLBACK_VECTOR
832 This option enables various optimizations for running under the KVM
833 hypervisor. It includes a paravirtualized clock, so that instead
834 of relying on a PIT (or probably other) emulation by the
835 underlying device model, the host provides the guest with
836 timing infrastructure such as time of day, and system time
838 config ARCH_CPUIDLE_HALTPOLL
840 prompt "Disable host haltpoll when loading haltpoll driver"
842 If virtualized under KVM, disable host haltpoll.
845 bool "Support for running PVH guests"
847 This option enables the PVH entry point for guest virtual machines
848 as specified in the x86/HVM direct boot ABI.
850 config PARAVIRT_TIME_ACCOUNTING
851 bool "Paravirtual steal time accounting"
854 Select this option to enable fine granularity task steal time
855 accounting. Time spent executing other tasks in parallel with
856 the current vCPU is discounted from the vCPU power. To account for
857 that, there can be a small performance impact.
859 If in doubt, say N here.
861 config PARAVIRT_CLOCK
864 config JAILHOUSE_GUEST
865 bool "Jailhouse non-root cell support"
866 depends on X86_64 && PCI
869 This option allows to run Linux as guest in a Jailhouse non-root
870 cell. You can leave this option disabled if you only want to start
871 Jailhouse and run Linux afterwards in the root cell.
874 bool "ACRN Guest support"
876 select X86_HV_CALLBACK_VECTOR
878 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
879 a flexible, lightweight reference open-source hypervisor, built with
880 real-time and safety-criticality in mind. It is built for embedded
881 IOT with small footprint and real-time features. More details can be
882 found in https://projectacrn.org/.
884 endif #HYPERVISOR_GUEST
886 source "arch/x86/Kconfig.cpu"
890 prompt "HPET Timer Support" if X86_32
892 Use the IA-PC HPET (High Precision Event Timer) to manage
893 time in preference to the PIT and RTC, if a HPET is
895 HPET is the next generation timer replacing legacy 8254s.
896 The HPET provides a stable time base on SMP
897 systems, unlike the TSC, but it is more expensive to access,
898 as it is off-chip. The interface used is documented
899 in the HPET spec, revision 1.
901 You can safely choose Y here. However, HPET will only be
902 activated if the platform and the BIOS support this feature.
903 Otherwise the 8254 will be used for timing services.
905 Choose N to continue using the legacy 8254 timer.
907 config HPET_EMULATE_RTC
909 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
911 # Mark as expert because too many people got it wrong.
912 # The code disables itself when not needed.
915 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
916 bool "Enable DMI scanning" if EXPERT
918 Enabled scanning of DMI to identify machine quirks. Say Y
919 here unless you have verified that your setup is not
920 affected by entries in the DMI blacklist. Required by PNP
924 bool "Old AMD GART IOMMU support"
928 depends on X86_64 && PCI && AMD_NB
930 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
931 GART based hardware IOMMUs.
933 The GART supports full DMA access for devices with 32-bit access
934 limitations, on systems with more than 3 GB. This is usually needed
935 for USB, sound, many IDE/SATA chipsets and some other devices.
937 Newer systems typically have a modern AMD IOMMU, supported via
938 the CONFIG_AMD_IOMMU=y config option.
940 In normal configurations this driver is only active when needed:
941 there's more than 3 GB of memory and the system contains a
942 32-bit limited device.
947 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
948 depends on X86_64 && SMP && DEBUG_KERNEL
949 select CPUMASK_OFFSTACK
951 Enable maximum number of CPUS and NUMA Nodes for this architecture.
955 # The maximum number of CPUs supported:
957 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
958 # and which can be configured interactively in the
959 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
961 # The ranges are different on 32-bit and 64-bit kernels, depending on
962 # hardware capabilities and scalability features of the kernel.
964 # ( If MAXSMP is enabled we just use the highest possible value and disable
965 # interactive configuration. )
968 config NR_CPUS_RANGE_BEGIN
970 default NR_CPUS_RANGE_END if MAXSMP
974 config NR_CPUS_RANGE_END
977 default 64 if SMP && X86_BIGSMP
978 default 8 if SMP && !X86_BIGSMP
981 config NR_CPUS_RANGE_END
984 default 8192 if SMP && CPUMASK_OFFSTACK
985 default 512 if SMP && !CPUMASK_OFFSTACK
988 config NR_CPUS_DEFAULT
991 default 32 if X86_BIGSMP
995 config NR_CPUS_DEFAULT
998 default 8192 if MAXSMP
1003 int "Maximum number of CPUs" if SMP && !MAXSMP
1004 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1005 default NR_CPUS_DEFAULT
1007 This allows you to specify the maximum number of CPUs which this
1008 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1009 supported value is 8192, otherwise the maximum value is 512. The
1010 minimum value which makes sense is 2.
1012 This is purely to save memory: each supported CPU adds about 8KB
1013 to the kernel image.
1015 config SCHED_CLUSTER
1016 bool "Cluster scheduler support"
1020 Cluster scheduler support improves the CPU scheduler's decision
1021 making when dealing with machines that have clusters of CPUs.
1022 Cluster usually means a couple of CPUs which are placed closely
1023 by sharing mid-level caches, last-level cache tags or internal
1031 prompt "Multi-core scheduler support"
1034 Multi-core scheduler support improves the CPU scheduler's decision
1035 making when dealing with multi-core CPU chips at a cost of slightly
1036 increased overhead in some places. If unsure say N here.
1038 config SCHED_MC_PRIO
1039 bool "CPU core priorities scheduler support"
1040 depends on SCHED_MC && CPU_SUP_INTEL
1041 select X86_INTEL_PSTATE
1045 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1046 core ordering determined at manufacturing time, which allows
1047 certain cores to reach higher turbo frequencies (when running
1048 single threaded workloads) than others.
1050 Enabling this kernel feature teaches the scheduler about
1051 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1052 scheduler's CPU selection logic accordingly, so that higher
1053 overall system performance can be achieved.
1055 This feature will have no effect on CPUs without this feature.
1057 If unsure say Y here.
1061 depends on !SMP && X86_LOCAL_APIC
1064 bool "Local APIC support on uniprocessors" if !PCI_MSI
1066 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1068 A local APIC (Advanced Programmable Interrupt Controller) is an
1069 integrated interrupt controller in the CPU. If you have a single-CPU
1070 system which has a processor with a local APIC, you can say Y here to
1071 enable and use it. If you say Y here even though your machine doesn't
1072 have a local APIC, then the kernel will still run with no slowdown at
1073 all. The local APIC supports CPU-generated self-interrupts (timer,
1074 performance counters), and the NMI watchdog which detects hard
1077 config X86_UP_IOAPIC
1078 bool "IO-APIC support on uniprocessors"
1079 depends on X86_UP_APIC
1081 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1082 SMP-capable replacement for PC-style interrupt controllers. Most
1083 SMP systems and many recent uniprocessor systems have one.
1085 If you have a single-CPU system with an IO-APIC, you can say Y here
1086 to use it. If you say Y here even though your machine doesn't have
1087 an IO-APIC, then the kernel will still run with no slowdown at all.
1089 config X86_LOCAL_APIC
1091 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1092 select IRQ_DOMAIN_HIERARCHY
1093 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1097 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1099 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1100 bool "Reroute for broken boot IRQs"
1101 depends on X86_IO_APIC
1103 This option enables a workaround that fixes a source of
1104 spurious interrupts. This is recommended when threaded
1105 interrupt handling is used on systems where the generation of
1106 superfluous "boot interrupts" cannot be disabled.
1108 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1109 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1110 kernel does during interrupt handling). On chipsets where this
1111 boot IRQ generation cannot be disabled, this workaround keeps
1112 the original IRQ line masked so that only the equivalent "boot
1113 IRQ" is delivered to the CPUs. The workaround also tells the
1114 kernel to set up the IRQ handler on the boot IRQ line. In this
1115 way only one interrupt is delivered to the kernel. Otherwise
1116 the spurious second interrupt may cause the kernel to bring
1117 down (vital) interrupt lines.
1119 Only affects "broken" chipsets. Interrupt sharing may be
1120 increased on these systems.
1123 bool "Machine Check / overheating reporting"
1124 select GENERIC_ALLOCATOR
1127 Machine Check support allows the processor to notify the
1128 kernel if it detects a problem (e.g. overheating, data corruption).
1129 The action the kernel takes depends on the severity of the problem,
1130 ranging from warning messages to halting the machine.
1132 config X86_MCELOG_LEGACY
1133 bool "Support for deprecated /dev/mcelog character device"
1136 Enable support for /dev/mcelog which is needed by the old mcelog
1137 userspace logging daemon. Consider switching to the new generation
1140 config X86_MCE_INTEL
1142 prompt "Intel MCE features"
1143 depends on X86_MCE && X86_LOCAL_APIC
1145 Additional support for intel specific MCE features such as
1146 the thermal monitor.
1150 prompt "AMD MCE features"
1151 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1153 Additional support for AMD specific MCE features such as
1154 the DRAM Error Threshold.
1156 config X86_ANCIENT_MCE
1157 bool "Support for old Pentium 5 / WinChip machine checks"
1158 depends on X86_32 && X86_MCE
1160 Include support for machine check handling on old Pentium 5 or WinChip
1161 systems. These typically need to be enabled explicitly on the command
1164 config X86_MCE_THRESHOLD
1165 depends on X86_MCE_AMD || X86_MCE_INTEL
1168 config X86_MCE_INJECT
1169 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1170 tristate "Machine check injector support"
1172 Provide support for injecting machine checks for testing purposes.
1173 If you don't know what a machine check is and you don't do kernel
1174 QA it is safe to say n.
1176 source "arch/x86/events/Kconfig"
1178 config X86_LEGACY_VM86
1179 bool "Legacy VM86 support"
1182 This option allows user programs to put the CPU into V8086
1183 mode, which is an 80286-era approximation of 16-bit real mode.
1185 Some very old versions of X and/or vbetool require this option
1186 for user mode setting. Similarly, DOSEMU will use it if
1187 available to accelerate real mode DOS programs. However, any
1188 recent version of DOSEMU, X, or vbetool should be fully
1189 functional even without kernel VM86 support, as they will all
1190 fall back to software emulation. Nevertheless, if you are using
1191 a 16-bit DOS program where 16-bit performance matters, vm86
1192 mode might be faster than emulation and you might want to
1195 Note that any app that works on a 64-bit kernel is unlikely to
1196 need this option, as 64-bit kernels don't, and can't, support
1197 V8086 mode. This option is also unrelated to 16-bit protected
1198 mode and is not needed to run most 16-bit programs under Wine.
1200 Enabling this option increases the complexity of the kernel
1201 and slows down exception handling a tiny bit.
1203 If unsure, say N here.
1207 default X86_LEGACY_VM86
1210 bool "Enable support for 16-bit segments" if EXPERT
1212 depends on MODIFY_LDT_SYSCALL
1214 This option is required by programs like Wine to run 16-bit
1215 protected mode legacy code on x86 processors. Disabling
1216 this option saves about 300 bytes on i386, or around 6K text
1217 plus 16K runtime memory on x86-64,
1221 depends on X86_16BIT && X86_32
1225 depends on X86_16BIT && X86_64
1227 config X86_VSYSCALL_EMULATION
1228 bool "Enable vsyscall emulation" if EXPERT
1232 This enables emulation of the legacy vsyscall page. Disabling
1233 it is roughly equivalent to booting with vsyscall=none, except
1234 that it will also disable the helpful warning if a program
1235 tries to use a vsyscall. With this option set to N, offending
1236 programs will just segfault, citing addresses of the form
1239 This option is required by many programs built before 2013, and
1240 care should be used even with newer programs if set to N.
1242 Disabling this option saves about 7K of kernel size and
1243 possibly 4K of additional runtime pagetable memory.
1245 config X86_IOPL_IOPERM
1246 bool "IOPERM and IOPL Emulation"
1249 This enables the ioperm() and iopl() syscalls which are necessary
1250 for legacy applications.
1252 Legacy IOPL support is an overbroad mechanism which allows user
1253 space aside of accessing all 65536 I/O ports also to disable
1254 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1255 capabilities and permission from potentially active security
1258 The emulation restricts the functionality of the syscall to
1259 only allowing the full range I/O port access, but prevents the
1260 ability to disable interrupts from user space which would be
1261 granted if the hardware IOPL mechanism would be used.
1264 tristate "Toshiba Laptop support"
1267 This adds a driver to safely access the System Management Mode of
1268 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1269 not work on models with a Phoenix BIOS. The System Management Mode
1270 is used to set the BIOS and power saving options on Toshiba portables.
1272 For information on utilities to make use of this driver see the
1273 Toshiba Linux utilities web site at:
1274 <http://www.buzzard.org.uk/toshiba/>.
1276 Say Y if you intend to run this kernel on a Toshiba portable.
1280 tristate "Dell i8k legacy laptop support"
1283 select SENSORS_DELL_SMM
1285 This option enables legacy /proc/i8k userspace interface in hwmon
1286 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1287 temperature and allows controlling fan speeds of Dell laptops via
1288 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1289 it reports also power and hotkey status. For fan speed control is
1290 needed userspace package i8kutils.
1292 Say Y if you intend to run this kernel on old Dell laptops or want to
1293 use userspace package i8kutils.
1296 config X86_REBOOTFIXUPS
1297 bool "Enable X86 board specific fixups for reboot"
1300 This enables chipset and/or board specific fixups to be done
1301 in order to get reboot to work correctly. This is only needed on
1302 some combinations of hardware and BIOS. The symptom, for which
1303 this config is intended, is when reboot ends with a stalled/hung
1306 Currently, the only fixup is for the Geode machines using
1307 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1309 Say Y if you want to enable the fixup. Currently, it's safe to
1310 enable this option even if you don't need it.
1314 bool "CPU microcode loading support"
1316 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1318 If you say Y here, you will be able to update the microcode on
1319 Intel and AMD processors. The Intel support is for the IA32 family,
1320 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1321 AMD support is for families 0x10 and later. You will obviously need
1322 the actual microcode binary data itself which is not shipped with
1325 The preferred method to load microcode from a detached initrd is described
1326 in Documentation/x86/microcode.rst. For that you need to enable
1327 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1328 initrd for microcode blobs.
1330 In addition, you can build the microcode into the kernel. For that you
1331 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1334 config MICROCODE_INTEL
1335 bool "Intel microcode loading support"
1336 depends on MICROCODE
1339 This options enables microcode patch loading support for Intel
1342 For the current Intel microcode data package go to
1343 <https://downloadcenter.intel.com> and search for
1344 'Linux Processor Microcode Data File'.
1346 config MICROCODE_AMD
1347 bool "AMD microcode loading support"
1348 depends on MICROCODE
1350 If you select this option, microcode patch loading support for AMD
1351 processors will be enabled.
1353 config MICROCODE_OLD_INTERFACE
1354 bool "Ancient loading interface (DEPRECATED)"
1356 depends on MICROCODE
1358 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1359 which was used by userspace tools like iucode_tool and microcode.ctl.
1360 It is inadequate because it runs too late to be able to properly
1361 load microcode on a machine and it needs special tools. Instead, you
1362 should've switched to the early loading method with the initrd or
1363 builtin microcode by now: Documentation/x86/microcode.rst
1366 tristate "/dev/cpu/*/msr - Model-specific register support"
1368 This device gives privileged processes access to the x86
1369 Model-Specific Registers (MSRs). It is a character device with
1370 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1371 MSR accesses are directed to a specific CPU on multi-processor
1375 tristate "/dev/cpu/*/cpuid - CPU information support"
1377 This device gives processes access to the x86 CPUID instruction to
1378 be executed on a specific processor. It is a character device
1379 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1383 prompt "High Memory Support"
1390 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1391 However, the address space of 32-bit x86 processors is only 4
1392 Gigabytes large. That means that, if you have a large amount of
1393 physical memory, not all of it can be "permanently mapped" by the
1394 kernel. The physical memory that's not permanently mapped is called
1397 If you are compiling a kernel which will never run on a machine with
1398 more than 1 Gigabyte total physical RAM, answer "off" here (default
1399 choice and suitable for most users). This will result in a "3GB/1GB"
1400 split: 3GB are mapped so that each process sees a 3GB virtual memory
1401 space and the remaining part of the 4GB virtual memory space is used
1402 by the kernel to permanently map as much physical memory as
1405 If the machine has between 1 and 4 Gigabytes physical RAM, then
1408 If more than 4 Gigabytes is used then answer "64GB" here. This
1409 selection turns Intel PAE (Physical Address Extension) mode on.
1410 PAE implements 3-level paging on IA32 processors. PAE is fully
1411 supported by Linux, PAE mode is implemented on all recent Intel
1412 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1413 then the kernel will not boot on CPUs that don't support PAE!
1415 The actual amount of total physical memory will either be
1416 auto detected or can be forced by using a kernel command line option
1417 such as "mem=256M". (Try "man bootparam" or see the documentation of
1418 your boot loader (lilo or loadlin) about how to pass options to the
1419 kernel at boot time.)
1421 If unsure, say "off".
1426 Select this if you have a 32-bit processor and between 1 and 4
1427 gigabytes of physical RAM.
1431 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1434 Select this if you have a 32-bit processor and more than 4
1435 gigabytes of physical RAM.
1440 prompt "Memory split" if EXPERT
1444 Select the desired split between kernel and user memory.
1446 If the address range available to the kernel is less than the
1447 physical memory installed, the remaining memory will be available
1448 as "high memory". Accessing high memory is a little more costly
1449 than low memory, as it needs to be mapped into the kernel first.
1450 Note that increasing the kernel address space limits the range
1451 available to user programs, making the address space there
1452 tighter. Selecting anything other than the default 3G/1G split
1453 will also likely make your kernel incompatible with binary-only
1456 If you are not absolutely sure what you are doing, leave this
1460 bool "3G/1G user/kernel split"
1461 config VMSPLIT_3G_OPT
1463 bool "3G/1G user/kernel split (for full 1G low memory)"
1465 bool "2G/2G user/kernel split"
1466 config VMSPLIT_2G_OPT
1468 bool "2G/2G user/kernel split (for full 2G low memory)"
1470 bool "1G/3G user/kernel split"
1475 default 0xB0000000 if VMSPLIT_3G_OPT
1476 default 0x80000000 if VMSPLIT_2G
1477 default 0x78000000 if VMSPLIT_2G_OPT
1478 default 0x40000000 if VMSPLIT_1G
1484 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1487 bool "PAE (Physical Address Extension) Support"
1488 depends on X86_32 && !HIGHMEM4G
1489 select PHYS_ADDR_T_64BIT
1492 PAE is required for NX support, and furthermore enables
1493 larger swapspace support for non-overcommit purposes. It
1494 has the cost of more pagetable lookup overhead, and also
1495 consumes more pagetable space per process.
1498 bool "Enable 5-level page tables support"
1500 select DYNAMIC_MEMORY_LAYOUT
1501 select SPARSEMEM_VMEMMAP
1504 5-level paging enables access to larger address space:
1505 upto 128 PiB of virtual address space and 4 PiB of
1506 physical address space.
1508 It will be supported by future Intel CPUs.
1510 A kernel with the option enabled can be booted on machines that
1511 support 4- or 5-level paging.
1513 See Documentation/x86/x86_64/5level-paging.rst for more
1518 config X86_DIRECT_GBPAGES
1522 Certain kernel features effectively disable kernel
1523 linear 1 GB mappings (even if the CPU otherwise
1524 supports them), so don't confuse the user by printing
1525 that we have them enabled.
1527 config X86_CPA_STATISTICS
1528 bool "Enable statistic for Change Page Attribute"
1531 Expose statistics about the Change Page Attribute mechanism, which
1532 helps to determine the effectiveness of preserving large and huge
1533 page mappings when mapping protections are changed.
1535 config X86_MEM_ENCRYPT
1536 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1537 select DYNAMIC_PHYSICAL_MASK
1538 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1541 config AMD_MEM_ENCRYPT
1542 bool "AMD Secure Memory Encryption (SME) support"
1543 depends on X86_64 && CPU_SUP_AMD
1544 select DMA_COHERENT_POOL
1545 select ARCH_USE_MEMREMAP_PROT
1546 select INSTRUCTION_DECODER
1547 select ARCH_HAS_CC_PLATFORM
1548 select X86_MEM_ENCRYPT
1550 Say yes to enable support for the encryption of system memory.
1551 This requires an AMD processor that supports Secure Memory
1554 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1555 bool "Activate AMD Secure Memory Encryption (SME) by default"
1556 depends on AMD_MEM_ENCRYPT
1558 Say yes to have system memory encrypted by default if running on
1559 an AMD processor that supports Secure Memory Encryption (SME).
1561 If set to Y, then the encryption of system memory can be
1562 deactivated with the mem_encrypt=off command line option.
1564 If set to N, then the encryption of system memory can be
1565 activated with the mem_encrypt=on command line option.
1567 # Common NUMA Features
1569 bool "NUMA Memory Allocation and Scheduler Support"
1571 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1572 default y if X86_BIGSMP
1573 select USE_PERCPU_NUMA_NODE_ID
1575 Enable NUMA (Non-Uniform Memory Access) support.
1577 The kernel will try to allocate memory used by a CPU on the
1578 local memory controller of the CPU and add some more
1579 NUMA awareness to the kernel.
1581 For 64-bit this is recommended if the system is Intel Core i7
1582 (or later), AMD Opteron, or EM64T NUMA.
1584 For 32-bit this is only needed if you boot a 32-bit
1585 kernel on a 64-bit NUMA platform.
1587 Otherwise, you should say N.
1591 prompt "Old style AMD Opteron NUMA detection"
1592 depends on X86_64 && NUMA && PCI
1594 Enable AMD NUMA node topology detection. You should say Y here if
1595 you have a multi processor AMD system. This uses an old method to
1596 read the NUMA configuration directly from the builtin Northbridge
1597 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1598 which also takes priority if both are compiled in.
1600 config X86_64_ACPI_NUMA
1602 prompt "ACPI NUMA detection"
1603 depends on X86_64 && NUMA && ACPI && PCI
1606 Enable ACPI SRAT based node topology detection.
1609 bool "NUMA emulation"
1612 Enable NUMA emulation. A flat machine will be split
1613 into virtual nodes when booted with "numa=fake=N", where N is the
1614 number of nodes. This is only useful for debugging.
1617 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1619 default "10" if MAXSMP
1620 default "6" if X86_64
1624 Specify the maximum number of NUMA Nodes available on the target
1625 system. Increases memory reserved to accommodate various tables.
1627 config ARCH_FLATMEM_ENABLE
1629 depends on X86_32 && !NUMA
1631 config ARCH_SPARSEMEM_ENABLE
1633 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1634 select SPARSEMEM_STATIC if X86_32
1635 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1637 config ARCH_SPARSEMEM_DEFAULT
1638 def_bool X86_64 || (NUMA && X86_32)
1640 config ARCH_SELECT_MEMORY_MODEL
1642 depends on ARCH_SPARSEMEM_ENABLE
1644 config ARCH_MEMORY_PROBE
1645 bool "Enable sysfs memory/probe interface"
1646 depends on MEMORY_HOTPLUG
1648 This option enables a sysfs memory/probe interface for testing.
1649 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1650 If you are unsure how to answer this question, answer N.
1652 config ARCH_PROC_KCORE_TEXT
1654 depends on X86_64 && PROC_KCORE
1656 config ILLEGAL_POINTER_VALUE
1659 default 0xdead000000000000 if X86_64
1661 config X86_PMEM_LEGACY_DEVICE
1664 config X86_PMEM_LEGACY
1665 tristate "Support non-standard NVDIMMs and ADR protected memory"
1666 depends on PHYS_ADDR_T_64BIT
1668 select X86_PMEM_LEGACY_DEVICE
1669 select NUMA_KEEP_MEMINFO if NUMA
1672 Treat memory marked using the non-standard e820 type of 12 as used
1673 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1674 The kernel will offer these regions to the 'pmem' driver so
1675 they can be used for persistent storage.
1680 bool "Allocate 3rd-level pagetables from highmem"
1683 The VM uses one page table entry for each page of physical memory.
1684 For systems with a lot of RAM, this can be wasteful of precious
1685 low memory. Setting this option will put user-space page table
1686 entries in high memory.
1688 config X86_CHECK_BIOS_CORRUPTION
1689 bool "Check for low memory corruption"
1691 Periodically check for memory corruption in low memory, which
1692 is suspected to be caused by BIOS. Even when enabled in the
1693 configuration, it is disabled at runtime. Enable it by
1694 setting "memory_corruption_check=1" on the kernel command
1695 line. By default it scans the low 64k of memory every 60
1696 seconds; see the memory_corruption_check_size and
1697 memory_corruption_check_period parameters in
1698 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1700 When enabled with the default parameters, this option has
1701 almost no overhead, as it reserves a relatively small amount
1702 of memory and scans it infrequently. It both detects corruption
1703 and prevents it from affecting the running system.
1705 It is, however, intended as a diagnostic tool; if repeatable
1706 BIOS-originated corruption always affects the same memory,
1707 you can use memmap= to prevent the kernel from using that
1710 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1711 bool "Set the default setting of memory_corruption_check"
1712 depends on X86_CHECK_BIOS_CORRUPTION
1715 Set whether the default state of memory_corruption_check is
1718 config MATH_EMULATION
1720 depends on MODIFY_LDT_SYSCALL
1721 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1723 Linux can emulate a math coprocessor (used for floating point
1724 operations) if you don't have one. 486DX and Pentium processors have
1725 a math coprocessor built in, 486SX and 386 do not, unless you added
1726 a 487DX or 387, respectively. (The messages during boot time can
1727 give you some hints here ["man dmesg"].) Everyone needs either a
1728 coprocessor or this emulation.
1730 If you don't have a math coprocessor, you need to say Y here; if you
1731 say Y here even though you have a coprocessor, the coprocessor will
1732 be used nevertheless. (This behavior can be changed with the kernel
1733 command line option "no387", which comes handy if your coprocessor
1734 is broken. Try "man bootparam" or see the documentation of your boot
1735 loader (lilo or loadlin) about how to pass options to the kernel at
1736 boot time.) This means that it is a good idea to say Y here if you
1737 intend to use this kernel on different machines.
1739 More information about the internals of the Linux math coprocessor
1740 emulation can be found in <file:arch/x86/math-emu/README>.
1742 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1743 kernel, it won't hurt.
1747 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1749 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1750 the Memory Type Range Registers (MTRRs) may be used to control
1751 processor access to memory ranges. This is most useful if you have
1752 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1753 allows bus write transfers to be combined into a larger transfer
1754 before bursting over the PCI/AGP bus. This can increase performance
1755 of image write operations 2.5 times or more. Saying Y here creates a
1756 /proc/mtrr file which may be used to manipulate your processor's
1757 MTRRs. Typically the X server should use this.
1759 This code has a reasonably generic interface so that similar
1760 control registers on other processors can be easily supported
1763 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1764 Registers (ARRs) which provide a similar functionality to MTRRs. For
1765 these, the ARRs are used to emulate the MTRRs.
1766 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1767 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1768 write-combining. All of these processors are supported by this code
1769 and it makes sense to say Y here if you have one of them.
1771 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1772 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1773 can lead to all sorts of problems, so it's good to say Y here.
1775 You can safely say Y even if your machine doesn't have MTRRs, you'll
1776 just add about 9 KB to your kernel.
1778 See <file:Documentation/x86/mtrr.rst> for more information.
1780 config MTRR_SANITIZER
1782 prompt "MTRR cleanup support"
1785 Convert MTRR layout from continuous to discrete, so X drivers can
1786 add writeback entries.
1788 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1789 The largest mtrr entry size for a continuous block can be set with
1794 config MTRR_SANITIZER_ENABLE_DEFAULT
1795 int "MTRR cleanup enable value (0-1)"
1798 depends on MTRR_SANITIZER
1800 Enable mtrr cleanup default value
1802 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1803 int "MTRR cleanup spare reg num (0-7)"
1806 depends on MTRR_SANITIZER
1808 mtrr cleanup spare entries default, it can be changed via
1809 mtrr_spare_reg_nr=N on the kernel command line.
1813 prompt "x86 PAT support" if EXPERT
1816 Use PAT attributes to setup page level cache control.
1818 PATs are the modern equivalents of MTRRs and are much more
1819 flexible than MTRRs.
1821 Say N here if you see bootup problems (boot crash, boot hang,
1822 spontaneous reboots) or a non-working video driver.
1826 config ARCH_USES_PG_UNCACHED
1832 prompt "x86 architectural random number generator" if EXPERT
1834 Enable the x86 architectural RDRAND instruction
1835 (Intel Bull Mountain technology) to generate random numbers.
1836 If supported, this is a high bandwidth, cryptographically
1837 secure hardware random number generator.
1841 prompt "Supervisor Mode Access Prevention" if EXPERT
1843 Supervisor Mode Access Prevention (SMAP) is a security
1844 feature in newer Intel processors. There is a small
1845 performance cost if this enabled and turned on; there is
1846 also a small increase in the kernel size if this is enabled.
1852 prompt "User Mode Instruction Prevention" if EXPERT
1854 User Mode Instruction Prevention (UMIP) is a security feature in
1855 some x86 processors. If enabled, a general protection fault is
1856 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1857 executed in user mode. These instructions unnecessarily expose
1858 information about the hardware state.
1860 The vast majority of applications do not use these instructions.
1861 For the very few that do, software emulation is provided in
1862 specific cases in protected and virtual-8086 modes. Emulated
1865 config X86_INTEL_MEMORY_PROTECTION_KEYS
1866 prompt "Memory Protection Keys"
1868 # Note: only available in 64-bit mode
1869 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1870 select ARCH_USES_HIGH_VMA_FLAGS
1871 select ARCH_HAS_PKEYS
1873 Memory Protection Keys provides a mechanism for enforcing
1874 page-based protections, but without requiring modification of the
1875 page tables when an application changes protection domains.
1877 For details, see Documentation/core-api/protection-keys.rst
1882 prompt "TSX enable mode"
1883 depends on CPU_SUP_INTEL
1884 default X86_INTEL_TSX_MODE_OFF
1886 Intel's TSX (Transactional Synchronization Extensions) feature
1887 allows to optimize locking protocols through lock elision which
1888 can lead to a noticeable performance boost.
1890 On the other hand it has been shown that TSX can be exploited
1891 to form side channel attacks (e.g. TAA) and chances are there
1892 will be more of those attacks discovered in the future.
1894 Therefore TSX is not enabled by default (aka tsx=off). An admin
1895 might override this decision by tsx=on the command line parameter.
1896 Even with TSX enabled, the kernel will attempt to enable the best
1897 possible TAA mitigation setting depending on the microcode available
1898 for the particular machine.
1900 This option allows to set the default tsx mode between tsx=on, =off
1901 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1904 Say off if not sure, auto if TSX is in use but it should be used on safe
1905 platforms or on if TSX is in use and the security aspect of tsx is not
1908 config X86_INTEL_TSX_MODE_OFF
1911 TSX is disabled if possible - equals to tsx=off command line parameter.
1913 config X86_INTEL_TSX_MODE_ON
1916 TSX is always enabled on TSX capable HW - equals the tsx=on command
1919 config X86_INTEL_TSX_MODE_AUTO
1922 TSX is enabled on TSX capable HW that is believed to be safe against
1923 side channel attacks- equals the tsx=auto command line parameter.
1927 bool "Software Guard eXtensions (SGX)"
1928 depends on X86_64 && CPU_SUP_INTEL
1930 depends on CRYPTO_SHA256=y
1933 select NUMA_KEEP_MEMINFO if NUMA
1936 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1937 that can be used by applications to set aside private regions of code
1938 and data, referred to as enclaves. An enclave's private memory can
1939 only be accessed by code running within the enclave. Accesses from
1940 outside the enclave, including other enclaves, are disallowed by
1946 bool "EFI runtime service support"
1949 select EFI_RUNTIME_WRAPPERS
1950 select ARCH_USE_MEMREMAP_PROT
1952 This enables the kernel to use EFI runtime services that are
1953 available (such as the EFI variable services).
1955 This option is only useful on systems that have EFI firmware.
1956 In addition, you should use the latest ELILO loader available
1957 at <http://elilo.sourceforge.net> in order to take advantage
1958 of EFI runtime services. However, even with this option, the
1959 resultant kernel should continue to boot on existing non-EFI
1963 bool "EFI stub support"
1965 depends on $(cc-option,-mabi=ms) || X86_32
1968 This kernel feature allows a bzImage to be loaded directly
1969 by EFI firmware without the use of a bootloader.
1971 See Documentation/admin-guide/efi-stub.rst for more information.
1974 bool "EFI mixed-mode support"
1975 depends on EFI_STUB && X86_64
1977 Enabling this feature allows a 64-bit kernel to be booted
1978 on a 32-bit firmware, provided that your CPU supports 64-bit
1981 Note that it is not possible to boot a mixed-mode enabled
1982 kernel via the EFI boot stub - a bootloader that supports
1983 the EFI handover protocol must be used.
1987 source "kernel/Kconfig.hz"
1990 bool "kexec system call"
1993 kexec is a system call that implements the ability to shutdown your
1994 current kernel, and to start another kernel. It is like a reboot
1995 but it is independent of the system firmware. And like a reboot
1996 you can start any kernel with it, not just Linux.
1998 The name comes from the similarity to the exec system call.
2000 It is an ongoing process to be certain the hardware in a machine
2001 is properly shutdown, so do not be surprised if this code does not
2002 initially work for you. As of this writing the exact hardware
2003 interface is strongly in flux, so no good recommendation can be
2007 bool "kexec file based system call"
2012 depends on CRYPTO_SHA256=y
2014 This is new version of kexec system call. This system call is
2015 file based and takes file descriptors as system call argument
2016 for kernel and initramfs as opposed to list of segments as
2017 accepted by previous system call.
2019 config ARCH_HAS_KEXEC_PURGATORY
2023 bool "Verify kernel signature during kexec_file_load() syscall"
2024 depends on KEXEC_FILE
2027 This option makes the kexec_file_load() syscall check for a valid
2028 signature of the kernel image. The image can still be loaded without
2029 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2030 there's a signature that we can check, then it must be valid.
2032 In addition to this option, you need to enable signature
2033 verification for the corresponding kernel image type being
2034 loaded in order for this to work.
2036 config KEXEC_SIG_FORCE
2037 bool "Require a valid signature in kexec_file_load() syscall"
2038 depends on KEXEC_SIG
2040 This option makes kernel signature verification mandatory for
2041 the kexec_file_load() syscall.
2043 config KEXEC_BZIMAGE_VERIFY_SIG
2044 bool "Enable bzImage signature verification support"
2045 depends on KEXEC_SIG
2046 depends on SIGNED_PE_FILE_VERIFICATION
2047 select SYSTEM_TRUSTED_KEYRING
2049 Enable bzImage signature verification support.
2052 bool "kernel crash dumps"
2053 depends on X86_64 || (X86_32 && HIGHMEM)
2055 Generate crash dump after being started by kexec.
2056 This should be normally only set in special crash dump kernels
2057 which are loaded in the main kernel with kexec-tools into
2058 a specially reserved region and then later executed after
2059 a crash by kdump/kexec. The crash dump kernel must be compiled
2060 to a memory address not used by the main kernel or BIOS using
2061 PHYSICAL_START, or it must be built as a relocatable image
2062 (CONFIG_RELOCATABLE=y).
2063 For more details see Documentation/admin-guide/kdump/kdump.rst
2067 depends on KEXEC && HIBERNATION
2069 Jump between original kernel and kexeced kernel and invoke
2070 code in physical address mode via KEXEC
2072 config PHYSICAL_START
2073 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2076 This gives the physical address where the kernel is loaded.
2078 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2079 bzImage will decompress itself to above physical address and
2080 run from there. Otherwise, bzImage will run from the address where
2081 it has been loaded by the boot loader and will ignore above physical
2084 In normal kdump cases one does not have to set/change this option
2085 as now bzImage can be compiled as a completely relocatable image
2086 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2087 address. This option is mainly useful for the folks who don't want
2088 to use a bzImage for capturing the crash dump and want to use a
2089 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2090 to be specifically compiled to run from a specific memory area
2091 (normally a reserved region) and this option comes handy.
2093 So if you are using bzImage for capturing the crash dump,
2094 leave the value here unchanged to 0x1000000 and set
2095 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2096 for capturing the crash dump change this value to start of
2097 the reserved region. In other words, it can be set based on
2098 the "X" value as specified in the "crashkernel=YM@XM"
2099 command line boot parameter passed to the panic-ed
2100 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2101 for more details about crash dumps.
2103 Usage of bzImage for capturing the crash dump is recommended as
2104 one does not have to build two kernels. Same kernel can be used
2105 as production kernel and capture kernel. Above option should have
2106 gone away after relocatable bzImage support is introduced. But it
2107 is present because there are users out there who continue to use
2108 vmlinux for dump capture. This option should go away down the
2111 Don't change this unless you know what you are doing.
2114 bool "Build a relocatable kernel"
2117 This builds a kernel image that retains relocation information
2118 so it can be loaded someplace besides the default 1MB.
2119 The relocations tend to make the kernel binary about 10% larger,
2120 but are discarded at runtime.
2122 One use is for the kexec on panic case where the recovery kernel
2123 must live at a different physical address than the primary
2126 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2127 it has been loaded at and the compile time physical address
2128 (CONFIG_PHYSICAL_START) is used as the minimum location.
2130 config RANDOMIZE_BASE
2131 bool "Randomize the address of the kernel image (KASLR)"
2132 depends on RELOCATABLE
2135 In support of Kernel Address Space Layout Randomization (KASLR),
2136 this randomizes the physical address at which the kernel image
2137 is decompressed and the virtual address where the kernel
2138 image is mapped, as a security feature that deters exploit
2139 attempts relying on knowledge of the location of kernel
2142 On 64-bit, the kernel physical and virtual addresses are
2143 randomized separately. The physical address will be anywhere
2144 between 16MB and the top of physical memory (up to 64TB). The
2145 virtual address will be randomized from 16MB up to 1GB (9 bits
2146 of entropy). Note that this also reduces the memory space
2147 available to kernel modules from 1.5GB to 1GB.
2149 On 32-bit, the kernel physical and virtual addresses are
2150 randomized together. They will be randomized from 16MB up to
2151 512MB (8 bits of entropy).
2153 Entropy is generated using the RDRAND instruction if it is
2154 supported. If RDTSC is supported, its value is mixed into
2155 the entropy pool as well. If neither RDRAND nor RDTSC are
2156 supported, then entropy is read from the i8254 timer. The
2157 usable entropy is limited by the kernel being built using
2158 2GB addressing, and that PHYSICAL_ALIGN must be at a
2159 minimum of 2MB. As a result, only 10 bits of entropy are
2160 theoretically possible, but the implementations are further
2161 limited due to memory layouts.
2165 # Relocation on x86 needs some additional build support
2166 config X86_NEED_RELOCS
2168 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2170 config PHYSICAL_ALIGN
2171 hex "Alignment value to which kernel should be aligned"
2173 range 0x2000 0x1000000 if X86_32
2174 range 0x200000 0x1000000 if X86_64
2176 This value puts the alignment restrictions on physical address
2177 where kernel is loaded and run from. Kernel is compiled for an
2178 address which meets above alignment restriction.
2180 If bootloader loads the kernel at a non-aligned address and
2181 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2182 address aligned to above value and run from there.
2184 If bootloader loads the kernel at a non-aligned address and
2185 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2186 load address and decompress itself to the address it has been
2187 compiled for and run from there. The address for which kernel is
2188 compiled already meets above alignment restrictions. Hence the
2189 end result is that kernel runs from a physical address meeting
2190 above alignment restrictions.
2192 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2193 this value must be a multiple of 0x200000.
2195 Don't change this unless you know what you are doing.
2197 config DYNAMIC_MEMORY_LAYOUT
2200 This option makes base addresses of vmalloc and vmemmap as well as
2201 __PAGE_OFFSET movable during boot.
2203 config RANDOMIZE_MEMORY
2204 bool "Randomize the kernel memory sections"
2206 depends on RANDOMIZE_BASE
2207 select DYNAMIC_MEMORY_LAYOUT
2208 default RANDOMIZE_BASE
2210 Randomizes the base virtual address of kernel memory sections
2211 (physical memory mapping, vmalloc & vmemmap). This security feature
2212 makes exploits relying on predictable memory locations less reliable.
2214 The order of allocations remains unchanged. Entropy is generated in
2215 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2216 configuration have in average 30,000 different possible virtual
2217 addresses for each memory section.
2221 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2222 hex "Physical memory mapping padding" if EXPERT
2223 depends on RANDOMIZE_MEMORY
2224 default "0xa" if MEMORY_HOTPLUG
2226 range 0x1 0x40 if MEMORY_HOTPLUG
2229 Define the padding in terabytes added to the existing physical
2230 memory size during kernel memory randomization. It is useful
2231 for memory hotplug support but reduces the entropy available for
2232 address randomization.
2234 If unsure, leave at the default value.
2240 config BOOTPARAM_HOTPLUG_CPU0
2241 bool "Set default setting of cpu0_hotpluggable"
2242 depends on HOTPLUG_CPU
2244 Set whether default state of cpu0_hotpluggable is on or off.
2246 Say Y here to enable CPU0 hotplug by default. If this switch
2247 is turned on, there is no need to give cpu0_hotplug kernel
2248 parameter and the CPU0 hotplug feature is enabled by default.
2250 Please note: there are two known CPU0 dependencies if you want
2251 to enable the CPU0 hotplug feature either by this switch or by
2252 cpu0_hotplug kernel parameter.
2254 First, resume from hibernate or suspend always starts from CPU0.
2255 So hibernate and suspend are prevented if CPU0 is offline.
2257 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2258 offline if any interrupt can not migrate out of CPU0. There may
2259 be other CPU0 dependencies.
2261 Please make sure the dependencies are under your control before
2262 you enable this feature.
2264 Say N if you don't want to enable CPU0 hotplug feature by default.
2265 You still can enable the CPU0 hotplug feature at boot by kernel
2266 parameter cpu0_hotplug.
2268 config DEBUG_HOTPLUG_CPU0
2270 prompt "Debug CPU0 hotplug"
2271 depends on HOTPLUG_CPU
2273 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2274 soon as possible and boots up userspace with CPU0 offlined. User
2275 can online CPU0 back after boot time.
2277 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2278 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2279 compilation or giving cpu0_hotplug kernel parameter at boot.
2285 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2286 depends on COMPAT_32
2288 Certain buggy versions of glibc will crash if they are
2289 presented with a 32-bit vDSO that is not mapped at the address
2290 indicated in its segment table.
2292 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2293 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2294 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2295 the only released version with the bug, but OpenSUSE 9
2296 contains a buggy "glibc 2.3.2".
2298 The symptom of the bug is that everything crashes on startup, saying:
2299 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2301 Saying Y here changes the default value of the vdso32 boot
2302 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2303 This works around the glibc bug but hurts performance.
2305 If unsure, say N: if you are compiling your own kernel, you
2306 are unlikely to be using a buggy version of glibc.
2309 prompt "vsyscall table for legacy applications"
2311 default LEGACY_VSYSCALL_XONLY
2313 Legacy user code that does not know how to find the vDSO expects
2314 to be able to issue three syscalls by calling fixed addresses in
2315 kernel space. Since this location is not randomized with ASLR,
2316 it can be used to assist security vulnerability exploitation.
2318 This setting can be changed at boot time via the kernel command
2319 line parameter vsyscall=[emulate|xonly|none].
2321 On a system with recent enough glibc (2.14 or newer) and no
2322 static binaries, you can say None without a performance penalty
2323 to improve security.
2325 If unsure, select "Emulate execution only".
2327 config LEGACY_VSYSCALL_EMULATE
2328 bool "Full emulation"
2330 The kernel traps and emulates calls into the fixed vsyscall
2331 address mapping. This makes the mapping non-executable, but
2332 it still contains readable known contents, which could be
2333 used in certain rare security vulnerability exploits. This
2334 configuration is recommended when using legacy userspace
2335 that still uses vsyscalls along with legacy binary
2336 instrumentation tools that require code to be readable.
2338 An example of this type of legacy userspace is running
2339 Pin on an old binary that still uses vsyscalls.
2341 config LEGACY_VSYSCALL_XONLY
2342 bool "Emulate execution only"
2344 The kernel traps and emulates calls into the fixed vsyscall
2345 address mapping and does not allow reads. This
2346 configuration is recommended when userspace might use the
2347 legacy vsyscall area but support for legacy binary
2348 instrumentation of legacy code is not needed. It mitigates
2349 certain uses of the vsyscall area as an ASLR-bypassing
2352 config LEGACY_VSYSCALL_NONE
2355 There will be no vsyscall mapping at all. This will
2356 eliminate any risk of ASLR bypass due to the vsyscall
2357 fixed address mapping. Attempts to use the vsyscalls
2358 will be reported to dmesg, so that either old or
2359 malicious userspace programs can be identified.
2364 bool "Built-in kernel command line"
2366 Allow for specifying boot arguments to the kernel at
2367 build time. On some systems (e.g. embedded ones), it is
2368 necessary or convenient to provide some or all of the
2369 kernel boot arguments with the kernel itself (that is,
2370 to not rely on the boot loader to provide them.)
2372 To compile command line arguments into the kernel,
2373 set this option to 'Y', then fill in the
2374 boot arguments in CONFIG_CMDLINE.
2376 Systems with fully functional boot loaders (i.e. non-embedded)
2377 should leave this option set to 'N'.
2380 string "Built-in kernel command string"
2381 depends on CMDLINE_BOOL
2384 Enter arguments here that should be compiled into the kernel
2385 image and used at boot time. If the boot loader provides a
2386 command line at boot time, it is appended to this string to
2387 form the full kernel command line, when the system boots.
2389 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2390 change this behavior.
2392 In most cases, the command line (whether built-in or provided
2393 by the boot loader) should specify the device for the root
2396 config CMDLINE_OVERRIDE
2397 bool "Built-in command line overrides boot loader arguments"
2398 depends on CMDLINE_BOOL && CMDLINE != ""
2400 Set this option to 'Y' to have the kernel ignore the boot loader
2401 command line, and use ONLY the built-in command line.
2403 This is used to work around broken boot loaders. This should
2404 be set to 'N' under normal conditions.
2406 config MODIFY_LDT_SYSCALL
2407 bool "Enable the LDT (local descriptor table)" if EXPERT
2410 Linux can allow user programs to install a per-process x86
2411 Local Descriptor Table (LDT) using the modify_ldt(2) system
2412 call. This is required to run 16-bit or segmented code such as
2413 DOSEMU or some Wine programs. It is also used by some very old
2414 threading libraries.
2416 Enabling this feature adds a small amount of overhead to
2417 context switches and increases the low-level kernel attack
2418 surface. Disabling it removes the modify_ldt(2) system call.
2420 Saying 'N' here may make sense for embedded or server kernels.
2422 config STRICT_SIGALTSTACK_SIZE
2423 bool "Enforce strict size checking for sigaltstack"
2424 depends on DYNAMIC_SIGFRAME
2426 For historical reasons MINSIGSTKSZ is a constant which became
2427 already too small with AVX512 support. Add a mechanism to
2428 enforce strict checking of the sigaltstack size against the
2429 real size of the FPU frame. This option enables the check
2430 by default. It can also be controlled via the kernel command
2431 line option 'strict_sas_size' independent of this config
2432 switch. Enabling it might break existing applications which
2433 allocate a too small sigaltstack but 'work' because they
2434 never get a signal delivered.
2436 Say 'N' unless you want to really enforce this check.
2438 source "kernel/livepatch/Kconfig"
2442 config ARCH_HAS_ADD_PAGES
2444 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2446 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2449 menu "Power management and ACPI options"
2451 config ARCH_HIBERNATION_HEADER
2453 depends on HIBERNATION
2455 source "kernel/power/Kconfig"
2457 source "drivers/acpi/Kconfig"
2464 tristate "APM (Advanced Power Management) BIOS support"
2465 depends on X86_32 && PM_SLEEP
2467 APM is a BIOS specification for saving power using several different
2468 techniques. This is mostly useful for battery powered laptops with
2469 APM compliant BIOSes. If you say Y here, the system time will be
2470 reset after a RESUME operation, the /proc/apm device will provide
2471 battery status information, and user-space programs will receive
2472 notification of APM "events" (e.g. battery status change).
2474 If you select "Y" here, you can disable actual use of the APM
2475 BIOS by passing the "apm=off" option to the kernel at boot time.
2477 Note that the APM support is almost completely disabled for
2478 machines with more than one CPU.
2480 In order to use APM, you will need supporting software. For location
2481 and more information, read <file:Documentation/power/apm-acpi.rst>
2482 and the Battery Powered Linux mini-HOWTO, available from
2483 <http://www.tldp.org/docs.html#howto>.
2485 This driver does not spin down disk drives (see the hdparm(8)
2486 manpage ("man 8 hdparm") for that), and it doesn't turn off
2487 VESA-compliant "green" monitors.
2489 This driver does not support the TI 4000M TravelMate and the ACER
2490 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2491 desktop machines also don't have compliant BIOSes, and this driver
2492 may cause those machines to panic during the boot phase.
2494 Generally, if you don't have a battery in your machine, there isn't
2495 much point in using this driver and you should say N. If you get
2496 random kernel OOPSes or reboots that don't seem to be related to
2497 anything, try disabling/enabling this option (or disabling/enabling
2500 Some other things you should try when experiencing seemingly random,
2503 1) make sure that you have enough swap space and that it is
2505 2) pass the "no-hlt" option to the kernel
2506 3) switch on floating point emulation in the kernel and pass
2507 the "no387" option to the kernel
2508 4) pass the "floppy=nodma" option to the kernel
2509 5) pass the "mem=4M" option to the kernel (thereby disabling
2510 all but the first 4 MB of RAM)
2511 6) make sure that the CPU is not over clocked.
2512 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2513 8) disable the cache from your BIOS settings
2514 9) install a fan for the video card or exchange video RAM
2515 10) install a better fan for the CPU
2516 11) exchange RAM chips
2517 12) exchange the motherboard.
2519 To compile this driver as a module, choose M here: the
2520 module will be called apm.
2524 config APM_IGNORE_USER_SUSPEND
2525 bool "Ignore USER SUSPEND"
2527 This option will ignore USER SUSPEND requests. On machines with a
2528 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2529 series notebooks, it is necessary to say Y because of a BIOS bug.
2531 config APM_DO_ENABLE
2532 bool "Enable PM at boot time"
2534 Enable APM features at boot time. From page 36 of the APM BIOS
2535 specification: "When disabled, the APM BIOS does not automatically
2536 power manage devices, enter the Standby State, enter the Suspend
2537 State, or take power saving steps in response to CPU Idle calls."
2538 This driver will make CPU Idle calls when Linux is idle (unless this
2539 feature is turned off -- see "Do CPU IDLE calls", below). This
2540 should always save battery power, but more complicated APM features
2541 will be dependent on your BIOS implementation. You may need to turn
2542 this option off if your computer hangs at boot time when using APM
2543 support, or if it beeps continuously instead of suspending. Turn
2544 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2545 T400CDT. This is off by default since most machines do fine without
2550 bool "Make CPU Idle calls when idle"
2552 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2553 On some machines, this can activate improved power savings, such as
2554 a slowed CPU clock rate, when the machine is idle. These idle calls
2555 are made after the idle loop has run for some length of time (e.g.,
2556 333 mS). On some machines, this will cause a hang at boot time or
2557 whenever the CPU becomes idle. (On machines with more than one CPU,
2558 this option does nothing.)
2560 config APM_DISPLAY_BLANK
2561 bool "Enable console blanking using APM"
2563 Enable console blanking using the APM. Some laptops can use this to
2564 turn off the LCD backlight when the screen blanker of the Linux
2565 virtual console blanks the screen. Note that this is only used by
2566 the virtual console screen blanker, and won't turn off the backlight
2567 when using the X Window system. This also doesn't have anything to
2568 do with your VESA-compliant power-saving monitor. Further, this
2569 option doesn't work for all laptops -- it might not turn off your
2570 backlight at all, or it might print a lot of errors to the console,
2571 especially if you are using gpm.
2573 config APM_ALLOW_INTS
2574 bool "Allow interrupts during APM BIOS calls"
2576 Normally we disable external interrupts while we are making calls to
2577 the APM BIOS as a measure to lessen the effects of a badly behaving
2578 BIOS implementation. The BIOS should reenable interrupts if it
2579 needs to. Unfortunately, some BIOSes do not -- especially those in
2580 many of the newer IBM Thinkpads. If you experience hangs when you
2581 suspend, try setting this to Y. Otherwise, say N.
2585 source "drivers/cpufreq/Kconfig"
2587 source "drivers/cpuidle/Kconfig"
2589 source "drivers/idle/Kconfig"
2594 menu "Bus options (PCI etc.)"
2597 prompt "PCI access mode"
2598 depends on X86_32 && PCI
2601 On PCI systems, the BIOS can be used to detect the PCI devices and
2602 determine their configuration. However, some old PCI motherboards
2603 have BIOS bugs and may crash if this is done. Also, some embedded
2604 PCI-based systems don't have any BIOS at all. Linux can also try to
2605 detect the PCI hardware directly without using the BIOS.
2607 With this option, you can specify how Linux should detect the
2608 PCI devices. If you choose "BIOS", the BIOS will be used,
2609 if you choose "Direct", the BIOS won't be used, and if you
2610 choose "MMConfig", then PCI Express MMCONFIG will be used.
2611 If you choose "Any", the kernel will try MMCONFIG, then the
2612 direct access method and falls back to the BIOS if that doesn't
2613 work. If unsure, go with the default, which is "Any".
2618 config PCI_GOMMCONFIG
2635 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2637 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2640 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2643 bool "Support mmconfig PCI config space access" if X86_64
2645 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2646 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2650 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2654 depends on PCI && XEN
2656 config MMCONF_FAM10H
2658 depends on X86_64 && PCI_MMCONFIG && ACPI
2660 config PCI_CNB20LE_QUIRK
2661 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2664 Read the PCI windows out of the CNB20LE host bridge. This allows
2665 PCI hotplug to work on systems with the CNB20LE chipset which do
2668 There's no public spec for this chipset, and this functionality
2669 is known to be incomplete.
2671 You should say N unless you know you need this.
2674 bool "ISA bus support on modern systems" if EXPERT
2676 Expose ISA bus device drivers and options available for selection and
2677 configuration. Enable this option if your target machine has an ISA
2678 bus. ISA is an older system, displaced by PCI and newer bus
2679 architectures -- if your target machine is modern, it probably does
2680 not have an ISA bus.
2684 # x86_64 have no ISA slots, but can have ISA-style DMA.
2686 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2689 Enables ISA-style DMA support for devices requiring such controllers.
2697 Find out whether you have ISA slots on your motherboard. ISA is the
2698 name of a bus system, i.e. the way the CPU talks to the other stuff
2699 inside your box. Other bus systems are PCI, EISA, MicroChannel
2700 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2701 newer boards don't support it. If you have ISA, say Y, otherwise N.
2704 tristate "NatSemi SCx200 support"
2706 This provides basic support for National Semiconductor's
2707 (now AMD's) Geode processors. The driver probes for the
2708 PCI-IDs of several on-chip devices, so its a good dependency
2709 for other scx200_* drivers.
2711 If compiled as a module, the driver is named scx200.
2713 config SCx200HR_TIMER
2714 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2718 This driver provides a clocksource built upon the on-chip
2719 27MHz high-resolution timer. Its also a workaround for
2720 NSC Geode SC-1100's buggy TSC, which loses time when the
2721 processor goes idle (as is done by the scheduler). The
2722 other workaround is idle=poll boot option.
2725 bool "One Laptop Per Child support"
2733 Add support for detecting the unique features of the OLPC
2737 bool "OLPC XO-1 Power Management"
2738 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2740 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2743 bool "OLPC XO-1 Real Time Clock"
2744 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2746 Add support for the XO-1 real time clock, which can be used as a
2747 programmable wakeup source.
2750 bool "OLPC XO-1 SCI extras"
2751 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2755 Add support for SCI-based features of the OLPC XO-1 laptop:
2756 - EC-driven system wakeups
2760 - AC adapter status updates
2761 - Battery status updates
2763 config OLPC_XO15_SCI
2764 bool "OLPC XO-1.5 SCI extras"
2765 depends on OLPC && ACPI
2768 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2769 - EC-driven system wakeups
2770 - AC adapter status updates
2771 - Battery status updates
2774 bool "PCEngines ALIX System Support (LED setup)"
2777 This option enables system support for the PCEngines ALIX.
2778 At present this just sets up LEDs for GPIO control on
2779 ALIX2/3/6 boards. However, other system specific setup should
2782 Note: You must still enable the drivers for GPIO and LED support
2783 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2785 Note: You have to set alix.force=1 for boards with Award BIOS.
2788 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2791 This option enables system support for the Soekris Engineering net5501.
2794 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2798 This option enables system support for the Traverse Technologies GEOS.
2801 bool "Technologic Systems TS-5500 platform support"
2803 select CHECK_SIGNATURE
2807 This option enables system support for the Technologic Systems TS-5500.
2813 depends on CPU_SUP_AMD && PCI
2818 menu "Binary Emulations"
2820 config IA32_EMULATION
2821 bool "IA32 Emulation"
2823 select ARCH_WANT_OLD_COMPAT_IPC
2825 select COMPAT_OLD_SIGACTION
2827 Include code to run legacy 32-bit programs under a
2828 64-bit kernel. You should likely turn this on, unless you're
2829 100% sure that you don't have any 32-bit programs left.
2832 tristate "IA32 a.out support"
2833 depends on IA32_EMULATION
2836 Support old a.out binaries in the 32bit emulation.
2839 bool "x32 ABI for 64-bit mode"
2842 Include code to run binaries for the x32 native 32-bit ABI
2843 for 64-bit processors. An x32 process gets access to the
2844 full 64-bit register file and wide data path while leaving
2845 pointers at 32 bits for smaller memory footprint.
2847 You will need a recent binutils (2.22 or later) with
2848 elf32_x86_64 support enabled to compile a kernel with this
2853 depends on IA32_EMULATION || X86_32
2855 select OLD_SIGSUSPEND3
2859 depends on IA32_EMULATION || X86_X32
2862 config COMPAT_FOR_U64_ALIGNMENT
2865 config SYSVIPC_COMPAT
2873 config HAVE_ATOMIC_IOMAP
2877 source "arch/x86/kvm/Kconfig"
2879 source "arch/x86/Kconfig.assembler"