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
36 config FORCE_DYNAMIC_FTRACE
39 depends on FUNCTION_TRACER
42 We keep the static function tracing (!DYNAMIC_FTRACE) around
43 in order to test the non static function tracing in the
44 generic code, as other architectures still use it. But we
45 only need to keep it around for x86_64. No need to keep it
46 for x86_32. For x86_32, force DYNAMIC_FTRACE.
50 # ( Note that options that are marked 'if X86_64' could in principle be
51 # ported to 32-bit as well. )
56 # Note: keep this list sorted alphabetically
58 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
59 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
60 select ARCH_32BIT_OFF_T if X86_32
61 select ARCH_CLOCKSOURCE_INIT
62 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
63 select ARCH_HAS_DEBUG_VIRTUAL
64 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
65 select ARCH_HAS_DEVMEM_IS_ALLOWED
66 select ARCH_HAS_EARLY_DEBUG if KGDB
67 select ARCH_HAS_ELF_RANDOMIZE
68 select ARCH_HAS_FAST_MULTIPLIER
69 select ARCH_HAS_FILTER_PGPROT
70 select ARCH_HAS_FORTIFY_SOURCE
71 select ARCH_HAS_GCOV_PROFILE_ALL
72 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
73 select ARCH_HAS_MEM_ENCRYPT
74 select ARCH_HAS_MEMBARRIER_SYNC_CORE
75 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
76 select ARCH_HAS_PMEM_API if X86_64
77 select ARCH_HAS_PTE_DEVMAP if X86_64
78 select ARCH_HAS_PTE_SPECIAL
79 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
80 select ARCH_HAS_COPY_MC if X86_64
81 select ARCH_HAS_SET_MEMORY
82 select ARCH_HAS_SET_DIRECT_MAP
83 select ARCH_HAS_STRICT_KERNEL_RWX
84 select ARCH_HAS_STRICT_MODULE_RWX
85 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
86 select ARCH_HAS_SYSCALL_WRAPPER
87 select ARCH_HAS_UBSAN_SANITIZE_ALL
88 select ARCH_HAS_DEBUG_WX
89 select ARCH_HAVE_NMI_SAFE_CMPXCHG
90 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
91 select ARCH_MIGHT_HAVE_PC_PARPORT
92 select ARCH_MIGHT_HAVE_PC_SERIO
94 select ARCH_SUPPORTS_ACPI
95 select ARCH_SUPPORTS_ATOMIC_RMW
96 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
97 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
98 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
99 select ARCH_USE_BUILTIN_BSWAP
100 select ARCH_USE_QUEUED_RWLOCKS
101 select ARCH_USE_QUEUED_SPINLOCKS
102 select ARCH_USE_SYM_ANNOTATIONS
103 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
104 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
105 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
106 select ARCH_WANT_HUGE_PMD_SHARE
107 select ARCH_WANT_LD_ORPHAN_WARN
108 select ARCH_WANTS_THP_SWAP if X86_64
109 select BUILDTIME_TABLE_SORT
111 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
112 select CLOCKSOURCE_WATCHDOG
113 select DCACHE_WORD_ACCESS
114 select EDAC_ATOMIC_SCRUB
116 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
117 select GENERIC_CLOCKEVENTS_MIN_ADJUST
118 select GENERIC_CMOS_UPDATE
119 select GENERIC_CPU_AUTOPROBE
120 select GENERIC_CPU_VULNERABILITIES
121 select GENERIC_EARLY_IOREMAP
123 select GENERIC_FIND_FIRST_BIT
125 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
126 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
127 select GENERIC_IRQ_MIGRATION if SMP
128 select GENERIC_IRQ_PROBE
129 select GENERIC_IRQ_RESERVATION_MODE
130 select GENERIC_IRQ_SHOW
131 select GENERIC_PENDING_IRQ if SMP
132 select GENERIC_PTDUMP
133 select GENERIC_SMP_IDLE_THREAD
134 select GENERIC_STRNCPY_FROM_USER
135 select GENERIC_STRNLEN_USER
136 select GENERIC_TIME_VSYSCALL
137 select GENERIC_GETTIMEOFDAY
138 select GENERIC_VDSO_TIME_NS
139 select GUP_GET_PTE_LOW_HIGH if X86_PAE
140 select HARDIRQS_SW_RESEND
141 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
142 select HAVE_ACPI_APEI if ACPI
143 select HAVE_ACPI_APEI_NMI if ACPI
144 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
145 select HAVE_ARCH_AUDITSYSCALL
146 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
147 select HAVE_ARCH_JUMP_LABEL
148 select HAVE_ARCH_JUMP_LABEL_RELATIVE
149 select HAVE_ARCH_KASAN if X86_64
150 select HAVE_ARCH_KASAN_VMALLOC if X86_64
151 select HAVE_ARCH_KGDB
152 select HAVE_ARCH_MMAP_RND_BITS if MMU
153 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
154 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
155 select HAVE_ARCH_PREL32_RELOCATIONS
156 select HAVE_ARCH_SECCOMP_FILTER
157 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
158 select HAVE_ARCH_STACKLEAK
159 select HAVE_ARCH_TRACEHOOK
160 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
161 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
162 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
163 select HAVE_ARCH_VMAP_STACK if X86_64
164 select HAVE_ARCH_WITHIN_STACK_FRAMES
165 select HAVE_ASM_MODVERSIONS
166 select HAVE_CMPXCHG_DOUBLE
167 select HAVE_CMPXCHG_LOCAL
168 select HAVE_CONTEXT_TRACKING if X86_64
169 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
170 select HAVE_C_RECORDMCOUNT
171 select HAVE_DEBUG_KMEMLEAK
172 select HAVE_DMA_CONTIGUOUS
173 select HAVE_DYNAMIC_FTRACE
174 select HAVE_DYNAMIC_FTRACE_WITH_REGS
175 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
176 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
178 select HAVE_EFFICIENT_UNALIGNED_ACCESS
180 select HAVE_EXIT_THREAD
182 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
183 select HAVE_FTRACE_MCOUNT_RECORD
184 select HAVE_FUNCTION_GRAPH_TRACER
185 select HAVE_FUNCTION_TRACER
186 select HAVE_GCC_PLUGINS
187 select HAVE_HW_BREAKPOINT
189 select HAVE_IOREMAP_PROT
190 select HAVE_IRQ_TIME_ACCOUNTING
191 select HAVE_KERNEL_BZIP2
192 select HAVE_KERNEL_GZIP
193 select HAVE_KERNEL_LZ4
194 select HAVE_KERNEL_LZMA
195 select HAVE_KERNEL_LZO
196 select HAVE_KERNEL_XZ
197 select HAVE_KERNEL_ZSTD
199 select HAVE_KPROBES_ON_FTRACE
200 select HAVE_FUNCTION_ERROR_INJECTION
201 select HAVE_KRETPROBES
203 select HAVE_LIVEPATCH if X86_64
204 select HAVE_MIXED_BREAKPOINTS_REGS
205 select HAVE_MOD_ARCH_SPECIFIC
210 select HAVE_OPTPROBES
211 select HAVE_PCSPKR_PLATFORM
212 select HAVE_PERF_EVENTS
213 select HAVE_PERF_EVENTS_NMI
214 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
216 select HAVE_PERF_REGS
217 select HAVE_PERF_USER_STACK_DUMP
218 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
219 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
220 select HAVE_REGS_AND_STACK_ACCESS_API
221 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
222 select HAVE_FUNCTION_ARG_ACCESS_API
223 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
224 select HAVE_STACK_VALIDATION if X86_64
225 select HAVE_STATIC_CALL
226 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
228 select HAVE_SYSCALL_TRACEPOINTS
229 select HAVE_UNSTABLE_SCHED_CLOCK
230 select HAVE_USER_RETURN_NOTIFIER
231 select HAVE_GENERIC_VDSO
232 select HOTPLUG_SMT if SMP
233 select IRQ_FORCED_THREADING
234 select NEED_SG_DMA_LENGTH
235 select PCI_DOMAINS if PCI
236 select PCI_LOCKLESS_CONFIG if PCI
239 select RTC_MC146818_LIB
242 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
243 select SYSCTL_EXCEPTION_TRACE
244 select THREAD_INFO_IN_TASK
245 select USER_STACKTRACE_SUPPORT
247 select HAVE_ARCH_KCSAN if X86_64
248 select X86_FEATURE_NAMES if PROC_FS
249 select PROC_PID_ARCH_STATUS if PROC_FS
250 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
252 config INSTRUCTION_DECODER
254 depends on KPROBES || PERF_EVENTS || UPROBES
258 default "elf32-i386" if X86_32
259 default "elf64-x86-64" if X86_64
261 config LOCKDEP_SUPPORT
264 config STACKTRACE_SUPPORT
270 config ARCH_MMAP_RND_BITS_MIN
274 config ARCH_MMAP_RND_BITS_MAX
278 config ARCH_MMAP_RND_COMPAT_BITS_MIN
281 config ARCH_MMAP_RND_COMPAT_BITS_MAX
287 config GENERIC_ISA_DMA
289 depends on ISA_DMA_API
294 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
296 config GENERIC_BUG_RELATIVE_POINTERS
299 config ARCH_MAY_HAVE_PC_FDC
301 depends on ISA_DMA_API
303 config GENERIC_CALIBRATE_DELAY
306 config ARCH_HAS_CPU_RELAX
309 config ARCH_HAS_CACHE_LINE_SIZE
312 config ARCH_HAS_FILTER_PGPROT
315 config HAVE_SETUP_PER_CPU_AREA
318 config NEED_PER_CPU_EMBED_FIRST_CHUNK
321 config NEED_PER_CPU_PAGE_FIRST_CHUNK
324 config ARCH_HIBERNATION_POSSIBLE
327 config ARCH_SUSPEND_POSSIBLE
330 config ARCH_WANT_GENERAL_HUGETLB
339 config KASAN_SHADOW_OFFSET
342 default 0xdffffc0000000000
344 config HAVE_INTEL_TXT
346 depends on INTEL_IOMMU && ACPI
350 depends on X86_32 && SMP
354 depends on X86_64 && SMP
356 config X86_32_LAZY_GS
358 depends on X86_32 && !STACKPROTECTOR
360 config ARCH_SUPPORTS_UPROBES
363 config FIX_EARLYCON_MEM
366 config DYNAMIC_PHYSICAL_MASK
369 config PGTABLE_LEVELS
371 default 5 if X86_5LEVEL
376 config CC_HAS_SANE_STACKPROTECTOR
378 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
379 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
381 We have to make sure stack protector is unconditionally disabled if
382 the compiler produces broken code.
384 menu "Processor type and features"
387 bool "DMA memory allocation support" if EXPERT
390 DMA memory allocation support allows devices with less than 32-bit
391 addressing to allocate within the first 16MB of address space.
392 Disable if no such devices will be used.
397 bool "Symmetric multi-processing support"
399 This enables support for systems with more than one CPU. If you have
400 a system with only one CPU, say N. If you have a system with more
403 If you say N here, the kernel will run on uni- and multiprocessor
404 machines, but will use only one CPU of a multiprocessor machine. If
405 you say Y here, the kernel will run on many, but not all,
406 uniprocessor machines. On a uniprocessor machine, the kernel
407 will run faster if you say N here.
409 Note that if you say Y here and choose architecture "586" or
410 "Pentium" under "Processor family", the kernel will not work on 486
411 architectures. Similarly, multiprocessor kernels for the "PPro"
412 architecture may not work on all Pentium based boards.
414 People using multiprocessor machines who say Y here should also say
415 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
416 Management" code will be disabled if you say Y here.
418 See also <file:Documentation/x86/i386/IO-APIC.rst>,
419 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
420 <http://www.tldp.org/docs.html#howto>.
422 If you don't know what to do here, say N.
424 config X86_FEATURE_NAMES
425 bool "Processor feature human-readable names" if EMBEDDED
428 This option compiles in a table of x86 feature bits and corresponding
429 names. This is required to support /proc/cpuinfo and a few kernel
430 messages. You can disable this to save space, at the expense of
431 making those few kernel messages show numeric feature bits instead.
436 bool "Support x2apic"
437 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
439 This enables x2apic support on CPUs that have this feature.
441 This allows 32-bit apic IDs (so it can support very large systems),
442 and accesses the local apic via MSRs not via mmio.
444 If you don't know what to do here, say N.
447 bool "Enable MPS table" if ACPI
449 depends on X86_LOCAL_APIC
451 For old smp systems that do not have proper acpi support. Newer systems
452 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
456 depends on X86_GOLDFISH
459 bool "Avoid speculative indirect branches in kernel"
462 Compile kernel with the retpoline compiler options to guard against
463 kernel-to-user data leaks by avoiding speculative indirect
464 branches. Requires a compiler with -mindirect-branch=thunk-extern
465 support for full protection. The kernel may run slower.
467 config X86_CPU_RESCTRL
468 bool "x86 CPU resource control support"
469 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
471 select PROC_CPU_RESCTRL if PROC_FS
473 Enable x86 CPU resource control support.
475 Provide support for the allocation and monitoring of system resources
478 Intel calls this Intel Resource Director Technology
479 (Intel(R) RDT). More information about RDT can be found in the
480 Intel x86 Architecture Software Developer Manual.
482 AMD calls this AMD Platform Quality of Service (AMD QoS).
483 More information about AMD QoS can be found in the AMD64 Technology
484 Platform Quality of Service Extensions manual.
490 bool "Support for big SMP systems with more than 8 CPUs"
493 This option is needed for the systems that have more than 8 CPUs.
495 config X86_EXTENDED_PLATFORM
496 bool "Support for extended (non-PC) x86 platforms"
499 If you disable this option then the kernel will only support
500 standard PC platforms. (which covers the vast majority of
503 If you enable this option then you'll be able to select support
504 for the following (non-PC) 32 bit x86 platforms:
505 Goldfish (Android emulator)
508 SGI 320/540 (Visual Workstation)
509 STA2X11-based (e.g. Northville)
510 Moorestown MID devices
512 If you have one of these systems, or if you want to build a
513 generic distribution kernel, say Y here - otherwise say N.
517 config X86_EXTENDED_PLATFORM
518 bool "Support for extended (non-PC) x86 platforms"
521 If you disable this option then the kernel will only support
522 standard PC platforms. (which covers the vast majority of
525 If you enable this option then you'll be able to select support
526 for the following (non-PC) 64 bit x86 platforms:
531 If you have one of these systems, or if you want to build a
532 generic distribution kernel, say Y here - otherwise say N.
534 # This is an alphabetically sorted list of 64 bit extended platforms
535 # Please maintain the alphabetic order if and when there are additions
537 bool "Numascale NumaChip"
539 depends on X86_EXTENDED_PLATFORM
542 depends on X86_X2APIC
543 depends on PCI_MMCONFIG
545 Adds support for Numascale NumaChip large-SMP systems. Needed to
546 enable more than ~168 cores.
547 If you don't have one of these, you should say N here.
551 select HYPERVISOR_GUEST
553 depends on X86_64 && PCI
554 depends on X86_EXTENDED_PLATFORM
557 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
558 supposed to run on these EM64T-based machines. Only choose this option
559 if you have one of these machines.
562 bool "SGI Ultraviolet"
564 depends on X86_EXTENDED_PLATFORM
567 depends on X86_X2APIC
570 This option is needed in order to support SGI Ultraviolet systems.
571 If you don't have one of these, you should say N here.
573 # Following is an alphabetically sorted list of 32 bit extended platforms
574 # Please maintain the alphabetic order if and when there are additions
577 bool "Goldfish (Virtual Platform)"
578 depends on X86_EXTENDED_PLATFORM
580 Enable support for the Goldfish virtual platform used primarily
581 for Android development. Unless you are building for the Android
582 Goldfish emulator say N here.
585 bool "CE4100 TV platform"
587 depends on PCI_GODIRECT
588 depends on X86_IO_APIC
590 depends on X86_EXTENDED_PLATFORM
591 select X86_REBOOTFIXUPS
593 select OF_EARLY_FLATTREE
595 Select for the Intel CE media processor (CE4100) SOC.
596 This option compiles in support for the CE4100 SOC for settop
597 boxes and media devices.
600 bool "Intel MID platform support"
601 depends on X86_EXTENDED_PLATFORM
602 depends on X86_PLATFORM_DEVICES
604 depends on X86_64 || (PCI_GOANY && X86_32)
605 depends on X86_IO_APIC
610 select MFD_INTEL_MSIC
612 Select to build a kernel capable of supporting Intel MID (Mobile
613 Internet Device) platform systems which do not have the PCI legacy
614 interfaces. If you are building for a PC class system say N here.
616 Intel MID platforms are based on an Intel processor and chipset which
617 consume less power than most of the x86 derivatives.
619 config X86_INTEL_QUARK
620 bool "Intel Quark platform support"
622 depends on X86_EXTENDED_PLATFORM
623 depends on X86_PLATFORM_DEVICES
627 depends on X86_IO_APIC
632 Select to include support for Quark X1000 SoC.
633 Say Y here if you have a Quark based system such as the Arduino
634 compatible Intel Galileo.
636 config X86_INTEL_LPSS
637 bool "Intel Low Power Subsystem Support"
638 depends on X86 && ACPI && PCI
643 Select to build support for Intel Low Power Subsystem such as
644 found on Intel Lynxpoint PCH. Selecting this option enables
645 things like clock tree (common clock framework) and pincontrol
646 which are needed by the LPSS peripheral drivers.
648 config X86_AMD_PLATFORM_DEVICE
649 bool "AMD ACPI2Platform devices support"
654 Select to interpret AMD specific ACPI device to platform device
655 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
656 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
657 implemented under PINCTRL subsystem.
660 tristate "Intel SoC IOSF Sideband support for SoC platforms"
663 This option enables sideband register access support for Intel SoC
664 platforms. On these platforms the IOSF sideband is used in lieu of
665 MSR's for some register accesses, mostly but not limited to thermal
666 and power. Drivers may query the availability of this device to
667 determine if they need the sideband in order to work on these
668 platforms. The sideband is available on the following SoC products.
669 This list is not meant to be exclusive.
674 You should say Y if you are running a kernel on one of these SoC's.
676 config IOSF_MBI_DEBUG
677 bool "Enable IOSF sideband access through debugfs"
678 depends on IOSF_MBI && DEBUG_FS
680 Select this option to expose the IOSF sideband access registers (MCR,
681 MDR, MCRX) through debugfs to write and read register information from
682 different units on the SoC. This is most useful for obtaining device
683 state information for debug and analysis. As this is a general access
684 mechanism, users of this option would have specific knowledge of the
685 device they want to access.
687 If you don't require the option or are in doubt, say N.
690 bool "RDC R-321x SoC"
692 depends on X86_EXTENDED_PLATFORM
694 select X86_REBOOTFIXUPS
696 This option is needed for RDC R-321x system-on-chip, also known
698 If you don't have one of these chips, you should say N here.
700 config X86_32_NON_STANDARD
701 bool "Support non-standard 32-bit SMP architectures"
702 depends on X86_32 && SMP
703 depends on X86_EXTENDED_PLATFORM
705 This option compiles in the bigsmp and STA2X11 default
706 subarchitectures. It is intended for a generic binary
707 kernel. If you select them all, kernel will probe it one by
708 one and will fallback to default.
710 # Alphabetically sorted list of Non standard 32 bit platforms
712 config X86_SUPPORTS_MEMORY_FAILURE
714 # MCE code calls memory_failure():
716 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
717 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
718 depends on X86_64 || !SPARSEMEM
719 select ARCH_SUPPORTS_MEMORY_FAILURE
722 bool "STA2X11 Companion Chip Support"
723 depends on X86_32_NON_STANDARD && PCI
728 This adds support for boards based on the STA2X11 IO-Hub,
729 a.k.a. "ConneXt". The chip is used in place of the standard
730 PC chipset, so all "standard" peripherals are missing. If this
731 option is selected the kernel will still be able to boot on
732 standard PC machines.
735 tristate "Eurobraille/Iris poweroff module"
738 The Iris machines from EuroBraille do not have APM or ACPI support
739 to shut themselves down properly. A special I/O sequence is
740 needed to do so, which is what this module does at
743 This is only for Iris machines from EuroBraille.
747 config SCHED_OMIT_FRAME_POINTER
749 prompt "Single-depth WCHAN output"
752 Calculate simpler /proc/<PID>/wchan values. If this option
753 is disabled then wchan values will recurse back to the
754 caller function. This provides more accurate wchan values,
755 at the expense of slightly more scheduling overhead.
757 If in doubt, say "Y".
759 menuconfig HYPERVISOR_GUEST
760 bool "Linux guest support"
762 Say Y here to enable options for running Linux under various hyper-
763 visors. This option enables basic hypervisor detection and platform
766 If you say N, all options in this submenu will be skipped and
767 disabled, and Linux guest support won't be built in.
772 bool "Enable paravirtualization code"
774 This changes the kernel so it can modify itself when it is run
775 under a hypervisor, potentially improving performance significantly
776 over full virtualization. However, when run without a hypervisor
777 the kernel is theoretically slower and slightly larger.
782 config PARAVIRT_DEBUG
783 bool "paravirt-ops debugging"
784 depends on PARAVIRT && DEBUG_KERNEL
786 Enable to debug paravirt_ops internals. Specifically, BUG if
787 a paravirt_op is missing when it is called.
789 config PARAVIRT_SPINLOCKS
790 bool "Paravirtualization layer for spinlocks"
791 depends on PARAVIRT && SMP
793 Paravirtualized spinlocks allow a pvops backend to replace the
794 spinlock implementation with something virtualization-friendly
795 (for example, block the virtual CPU rather than spinning).
797 It has a minimal impact on native kernels and gives a nice performance
798 benefit on paravirtualized KVM / Xen kernels.
800 If you are unsure how to answer this question, answer Y.
802 config X86_HV_CALLBACK_VECTOR
805 source "arch/x86/xen/Kconfig"
808 bool "KVM Guest support (including kvmclock)"
810 select PARAVIRT_CLOCK
811 select ARCH_CPUIDLE_HALTPOLL
812 select X86_HV_CALLBACK_VECTOR
815 This option enables various optimizations for running under the KVM
816 hypervisor. It includes a paravirtualized clock, so that instead
817 of relying on a PIT (or probably other) emulation by the
818 underlying device model, the host provides the guest with
819 timing infrastructure such as time of day, and system time
821 config ARCH_CPUIDLE_HALTPOLL
823 prompt "Disable host haltpoll when loading haltpoll driver"
825 If virtualized under KVM, disable host haltpoll.
828 bool "Support for running PVH guests"
830 This option enables the PVH entry point for guest virtual machines
831 as specified in the x86/HVM direct boot ABI.
833 config PARAVIRT_TIME_ACCOUNTING
834 bool "Paravirtual steal time accounting"
837 Select this option to enable fine granularity task steal time
838 accounting. Time spent executing other tasks in parallel with
839 the current vCPU is discounted from the vCPU power. To account for
840 that, there can be a small performance impact.
842 If in doubt, say N here.
844 config PARAVIRT_CLOCK
847 config JAILHOUSE_GUEST
848 bool "Jailhouse non-root cell support"
849 depends on X86_64 && PCI
852 This option allows to run Linux as guest in a Jailhouse non-root
853 cell. You can leave this option disabled if you only want to start
854 Jailhouse and run Linux afterwards in the root cell.
857 bool "ACRN Guest support"
859 select X86_HV_CALLBACK_VECTOR
861 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
862 a flexible, lightweight reference open-source hypervisor, built with
863 real-time and safety-criticality in mind. It is built for embedded
864 IOT with small footprint and real-time features. More details can be
865 found in https://projectacrn.org/.
867 endif #HYPERVISOR_GUEST
869 source "arch/x86/Kconfig.cpu"
873 prompt "HPET Timer Support" if X86_32
875 Use the IA-PC HPET (High Precision Event Timer) to manage
876 time in preference to the PIT and RTC, if a HPET is
878 HPET is the next generation timer replacing legacy 8254s.
879 The HPET provides a stable time base on SMP
880 systems, unlike the TSC, but it is more expensive to access,
881 as it is off-chip. The interface used is documented
882 in the HPET spec, revision 1.
884 You can safely choose Y here. However, HPET will only be
885 activated if the platform and the BIOS support this feature.
886 Otherwise the 8254 will be used for timing services.
888 Choose N to continue using the legacy 8254 timer.
890 config HPET_EMULATE_RTC
892 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
894 # Mark as expert because too many people got it wrong.
895 # The code disables itself when not needed.
898 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
899 bool "Enable DMI scanning" if EXPERT
901 Enabled scanning of DMI to identify machine quirks. Say Y
902 here unless you have verified that your setup is not
903 affected by entries in the DMI blacklist. Required by PNP
907 bool "Old AMD GART IOMMU support"
911 depends on X86_64 && PCI && AMD_NB
913 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
914 GART based hardware IOMMUs.
916 The GART supports full DMA access for devices with 32-bit access
917 limitations, on systems with more than 3 GB. This is usually needed
918 for USB, sound, many IDE/SATA chipsets and some other devices.
920 Newer systems typically have a modern AMD IOMMU, supported via
921 the CONFIG_AMD_IOMMU=y config option.
923 In normal configurations this driver is only active when needed:
924 there's more than 3 GB of memory and the system contains a
925 32-bit limited device.
930 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
931 depends on X86_64 && SMP && DEBUG_KERNEL
932 select CPUMASK_OFFSTACK
934 Enable maximum number of CPUS and NUMA Nodes for this architecture.
938 # The maximum number of CPUs supported:
940 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
941 # and which can be configured interactively in the
942 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
944 # The ranges are different on 32-bit and 64-bit kernels, depending on
945 # hardware capabilities and scalability features of the kernel.
947 # ( If MAXSMP is enabled we just use the highest possible value and disable
948 # interactive configuration. )
951 config NR_CPUS_RANGE_BEGIN
953 default NR_CPUS_RANGE_END if MAXSMP
957 config NR_CPUS_RANGE_END
960 default 64 if SMP && X86_BIGSMP
961 default 8 if SMP && !X86_BIGSMP
964 config NR_CPUS_RANGE_END
967 default 8192 if SMP && CPUMASK_OFFSTACK
968 default 512 if SMP && !CPUMASK_OFFSTACK
971 config NR_CPUS_DEFAULT
974 default 32 if X86_BIGSMP
978 config NR_CPUS_DEFAULT
981 default 8192 if MAXSMP
986 int "Maximum number of CPUs" if SMP && !MAXSMP
987 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
988 default NR_CPUS_DEFAULT
990 This allows you to specify the maximum number of CPUs which this
991 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
992 supported value is 8192, otherwise the maximum value is 512. The
993 minimum value which makes sense is 2.
995 This is purely to save memory: each supported CPU adds about 8KB
1003 prompt "Multi-core scheduler support"
1006 Multi-core scheduler support improves the CPU scheduler's decision
1007 making when dealing with multi-core CPU chips at a cost of slightly
1008 increased overhead in some places. If unsure say N here.
1010 config SCHED_MC_PRIO
1011 bool "CPU core priorities scheduler support"
1012 depends on SCHED_MC && CPU_SUP_INTEL
1013 select X86_INTEL_PSTATE
1017 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1018 core ordering determined at manufacturing time, which allows
1019 certain cores to reach higher turbo frequencies (when running
1020 single threaded workloads) than others.
1022 Enabling this kernel feature teaches the scheduler about
1023 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1024 scheduler's CPU selection logic accordingly, so that higher
1025 overall system performance can be achieved.
1027 This feature will have no effect on CPUs without this feature.
1029 If unsure say Y here.
1033 depends on !SMP && X86_LOCAL_APIC
1036 bool "Local APIC support on uniprocessors" if !PCI_MSI
1038 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1040 A local APIC (Advanced Programmable Interrupt Controller) is an
1041 integrated interrupt controller in the CPU. If you have a single-CPU
1042 system which has a processor with a local APIC, you can say Y here to
1043 enable and use it. If you say Y here even though your machine doesn't
1044 have a local APIC, then the kernel will still run with no slowdown at
1045 all. The local APIC supports CPU-generated self-interrupts (timer,
1046 performance counters), and the NMI watchdog which detects hard
1049 config X86_UP_IOAPIC
1050 bool "IO-APIC support on uniprocessors"
1051 depends on X86_UP_APIC
1053 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1054 SMP-capable replacement for PC-style interrupt controllers. Most
1055 SMP systems and many recent uniprocessor systems have one.
1057 If you have a single-CPU system with an IO-APIC, you can say Y here
1058 to use it. If you say Y here even though your machine doesn't have
1059 an IO-APIC, then the kernel will still run with no slowdown at all.
1061 config X86_LOCAL_APIC
1063 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1064 select IRQ_DOMAIN_HIERARCHY
1065 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1069 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1071 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1072 bool "Reroute for broken boot IRQs"
1073 depends on X86_IO_APIC
1075 This option enables a workaround that fixes a source of
1076 spurious interrupts. This is recommended when threaded
1077 interrupt handling is used on systems where the generation of
1078 superfluous "boot interrupts" cannot be disabled.
1080 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1081 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1082 kernel does during interrupt handling). On chipsets where this
1083 boot IRQ generation cannot be disabled, this workaround keeps
1084 the original IRQ line masked so that only the equivalent "boot
1085 IRQ" is delivered to the CPUs. The workaround also tells the
1086 kernel to set up the IRQ handler on the boot IRQ line. In this
1087 way only one interrupt is delivered to the kernel. Otherwise
1088 the spurious second interrupt may cause the kernel to bring
1089 down (vital) interrupt lines.
1091 Only affects "broken" chipsets. Interrupt sharing may be
1092 increased on these systems.
1095 bool "Machine Check / overheating reporting"
1096 select GENERIC_ALLOCATOR
1099 Machine Check support allows the processor to notify the
1100 kernel if it detects a problem (e.g. overheating, data corruption).
1101 The action the kernel takes depends on the severity of the problem,
1102 ranging from warning messages to halting the machine.
1104 config X86_MCELOG_LEGACY
1105 bool "Support for deprecated /dev/mcelog character device"
1108 Enable support for /dev/mcelog which is needed by the old mcelog
1109 userspace logging daemon. Consider switching to the new generation
1112 config X86_MCE_INTEL
1114 prompt "Intel MCE features"
1115 depends on X86_MCE && X86_LOCAL_APIC
1117 Additional support for intel specific MCE features such as
1118 the thermal monitor.
1122 prompt "AMD MCE features"
1123 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1125 Additional support for AMD specific MCE features such as
1126 the DRAM Error Threshold.
1128 config X86_ANCIENT_MCE
1129 bool "Support for old Pentium 5 / WinChip machine checks"
1130 depends on X86_32 && X86_MCE
1132 Include support for machine check handling on old Pentium 5 or WinChip
1133 systems. These typically need to be enabled explicitly on the command
1136 config X86_MCE_THRESHOLD
1137 depends on X86_MCE_AMD || X86_MCE_INTEL
1140 config X86_MCE_INJECT
1141 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1142 tristate "Machine check injector support"
1144 Provide support for injecting machine checks for testing purposes.
1145 If you don't know what a machine check is and you don't do kernel
1146 QA it is safe to say n.
1148 config X86_THERMAL_VECTOR
1150 depends on X86_MCE_INTEL
1152 source "arch/x86/events/Kconfig"
1154 config X86_LEGACY_VM86
1155 bool "Legacy VM86 support"
1158 This option allows user programs to put the CPU into V8086
1159 mode, which is an 80286-era approximation of 16-bit real mode.
1161 Some very old versions of X and/or vbetool require this option
1162 for user mode setting. Similarly, DOSEMU will use it if
1163 available to accelerate real mode DOS programs. However, any
1164 recent version of DOSEMU, X, or vbetool should be fully
1165 functional even without kernel VM86 support, as they will all
1166 fall back to software emulation. Nevertheless, if you are using
1167 a 16-bit DOS program where 16-bit performance matters, vm86
1168 mode might be faster than emulation and you might want to
1171 Note that any app that works on a 64-bit kernel is unlikely to
1172 need this option, as 64-bit kernels don't, and can't, support
1173 V8086 mode. This option is also unrelated to 16-bit protected
1174 mode and is not needed to run most 16-bit programs under Wine.
1176 Enabling this option increases the complexity of the kernel
1177 and slows down exception handling a tiny bit.
1179 If unsure, say N here.
1183 default X86_LEGACY_VM86
1186 bool "Enable support for 16-bit segments" if EXPERT
1188 depends on MODIFY_LDT_SYSCALL
1190 This option is required by programs like Wine to run 16-bit
1191 protected mode legacy code on x86 processors. Disabling
1192 this option saves about 300 bytes on i386, or around 6K text
1193 plus 16K runtime memory on x86-64,
1197 depends on X86_16BIT && X86_32
1201 depends on X86_16BIT && X86_64
1203 config X86_VSYSCALL_EMULATION
1204 bool "Enable vsyscall emulation" if EXPERT
1208 This enables emulation of the legacy vsyscall page. Disabling
1209 it is roughly equivalent to booting with vsyscall=none, except
1210 that it will also disable the helpful warning if a program
1211 tries to use a vsyscall. With this option set to N, offending
1212 programs will just segfault, citing addresses of the form
1215 This option is required by many programs built before 2013, and
1216 care should be used even with newer programs if set to N.
1218 Disabling this option saves about 7K of kernel size and
1219 possibly 4K of additional runtime pagetable memory.
1221 config X86_IOPL_IOPERM
1222 bool "IOPERM and IOPL Emulation"
1225 This enables the ioperm() and iopl() syscalls which are necessary
1226 for legacy applications.
1228 Legacy IOPL support is an overbroad mechanism which allows user
1229 space aside of accessing all 65536 I/O ports also to disable
1230 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1231 capabilities and permission from potentially active security
1234 The emulation restricts the functionality of the syscall to
1235 only allowing the full range I/O port access, but prevents the
1236 ability to disable interrupts from user space which would be
1237 granted if the hardware IOPL mechanism would be used.
1240 tristate "Toshiba Laptop support"
1243 This adds a driver to safely access the System Management Mode of
1244 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1245 not work on models with a Phoenix BIOS. The System Management Mode
1246 is used to set the BIOS and power saving options on Toshiba portables.
1248 For information on utilities to make use of this driver see the
1249 Toshiba Linux utilities web site at:
1250 <http://www.buzzard.org.uk/toshiba/>.
1252 Say Y if you intend to run this kernel on a Toshiba portable.
1256 tristate "Dell i8k legacy laptop support"
1258 select SENSORS_DELL_SMM
1260 This option enables legacy /proc/i8k userspace interface in hwmon
1261 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1262 temperature and allows controlling fan speeds of Dell laptops via
1263 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1264 it reports also power and hotkey status. For fan speed control is
1265 needed userspace package i8kutils.
1267 Say Y if you intend to run this kernel on old Dell laptops or want to
1268 use userspace package i8kutils.
1271 config X86_REBOOTFIXUPS
1272 bool "Enable X86 board specific fixups for reboot"
1275 This enables chipset and/or board specific fixups to be done
1276 in order to get reboot to work correctly. This is only needed on
1277 some combinations of hardware and BIOS. The symptom, for which
1278 this config is intended, is when reboot ends with a stalled/hung
1281 Currently, the only fixup is for the Geode machines using
1282 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1284 Say Y if you want to enable the fixup. Currently, it's safe to
1285 enable this option even if you don't need it.
1289 bool "CPU microcode loading support"
1291 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1293 If you say Y here, you will be able to update the microcode on
1294 Intel and AMD processors. The Intel support is for the IA32 family,
1295 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1296 AMD support is for families 0x10 and later. You will obviously need
1297 the actual microcode binary data itself which is not shipped with
1300 The preferred method to load microcode from a detached initrd is described
1301 in Documentation/x86/microcode.rst. For that you need to enable
1302 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1303 initrd for microcode blobs.
1305 In addition, you can build the microcode into the kernel. For that you
1306 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1309 config MICROCODE_INTEL
1310 bool "Intel microcode loading support"
1311 depends on MICROCODE
1314 This options enables microcode patch loading support for Intel
1317 For the current Intel microcode data package go to
1318 <https://downloadcenter.intel.com> and search for
1319 'Linux Processor Microcode Data File'.
1321 config MICROCODE_AMD
1322 bool "AMD microcode loading support"
1323 depends on MICROCODE
1325 If you select this option, microcode patch loading support for AMD
1326 processors will be enabled.
1328 config MICROCODE_OLD_INTERFACE
1329 bool "Ancient loading interface (DEPRECATED)"
1331 depends on MICROCODE
1333 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1334 which was used by userspace tools like iucode_tool and microcode.ctl.
1335 It is inadequate because it runs too late to be able to properly
1336 load microcode on a machine and it needs special tools. Instead, you
1337 should've switched to the early loading method with the initrd or
1338 builtin microcode by now: Documentation/x86/microcode.rst
1341 tristate "/dev/cpu/*/msr - Model-specific register support"
1343 This device gives privileged processes access to the x86
1344 Model-Specific Registers (MSRs). It is a character device with
1345 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1346 MSR accesses are directed to a specific CPU on multi-processor
1350 tristate "/dev/cpu/*/cpuid - CPU information support"
1352 This device gives processes access to the x86 CPUID instruction to
1353 be executed on a specific processor. It is a character device
1354 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1358 prompt "High Memory Support"
1365 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1366 However, the address space of 32-bit x86 processors is only 4
1367 Gigabytes large. That means that, if you have a large amount of
1368 physical memory, not all of it can be "permanently mapped" by the
1369 kernel. The physical memory that's not permanently mapped is called
1372 If you are compiling a kernel which will never run on a machine with
1373 more than 1 Gigabyte total physical RAM, answer "off" here (default
1374 choice and suitable for most users). This will result in a "3GB/1GB"
1375 split: 3GB are mapped so that each process sees a 3GB virtual memory
1376 space and the remaining part of the 4GB virtual memory space is used
1377 by the kernel to permanently map as much physical memory as
1380 If the machine has between 1 and 4 Gigabytes physical RAM, then
1383 If more than 4 Gigabytes is used then answer "64GB" here. This
1384 selection turns Intel PAE (Physical Address Extension) mode on.
1385 PAE implements 3-level paging on IA32 processors. PAE is fully
1386 supported by Linux, PAE mode is implemented on all recent Intel
1387 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1388 then the kernel will not boot on CPUs that don't support PAE!
1390 The actual amount of total physical memory will either be
1391 auto detected or can be forced by using a kernel command line option
1392 such as "mem=256M". (Try "man bootparam" or see the documentation of
1393 your boot loader (lilo or loadlin) about how to pass options to the
1394 kernel at boot time.)
1396 If unsure, say "off".
1401 Select this if you have a 32-bit processor and between 1 and 4
1402 gigabytes of physical RAM.
1406 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1409 Select this if you have a 32-bit processor and more than 4
1410 gigabytes of physical RAM.
1415 prompt "Memory split" if EXPERT
1419 Select the desired split between kernel and user memory.
1421 If the address range available to the kernel is less than the
1422 physical memory installed, the remaining memory will be available
1423 as "high memory". Accessing high memory is a little more costly
1424 than low memory, as it needs to be mapped into the kernel first.
1425 Note that increasing the kernel address space limits the range
1426 available to user programs, making the address space there
1427 tighter. Selecting anything other than the default 3G/1G split
1428 will also likely make your kernel incompatible with binary-only
1431 If you are not absolutely sure what you are doing, leave this
1435 bool "3G/1G user/kernel split"
1436 config VMSPLIT_3G_OPT
1438 bool "3G/1G user/kernel split (for full 1G low memory)"
1440 bool "2G/2G user/kernel split"
1441 config VMSPLIT_2G_OPT
1443 bool "2G/2G user/kernel split (for full 2G low memory)"
1445 bool "1G/3G user/kernel split"
1450 default 0xB0000000 if VMSPLIT_3G_OPT
1451 default 0x80000000 if VMSPLIT_2G
1452 default 0x78000000 if VMSPLIT_2G_OPT
1453 default 0x40000000 if VMSPLIT_1G
1459 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1462 bool "PAE (Physical Address Extension) Support"
1463 depends on X86_32 && !HIGHMEM4G
1464 select PHYS_ADDR_T_64BIT
1467 PAE is required for NX support, and furthermore enables
1468 larger swapspace support for non-overcommit purposes. It
1469 has the cost of more pagetable lookup overhead, and also
1470 consumes more pagetable space per process.
1473 bool "Enable 5-level page tables support"
1475 select DYNAMIC_MEMORY_LAYOUT
1476 select SPARSEMEM_VMEMMAP
1479 5-level paging enables access to larger address space:
1480 upto 128 PiB of virtual address space and 4 PiB of
1481 physical address space.
1483 It will be supported by future Intel CPUs.
1485 A kernel with the option enabled can be booted on machines that
1486 support 4- or 5-level paging.
1488 See Documentation/x86/x86_64/5level-paging.rst for more
1493 config X86_DIRECT_GBPAGES
1497 Certain kernel features effectively disable kernel
1498 linear 1 GB mappings (even if the CPU otherwise
1499 supports them), so don't confuse the user by printing
1500 that we have them enabled.
1502 config X86_CPA_STATISTICS
1503 bool "Enable statistic for Change Page Attribute"
1506 Expose statistics about the Change Page Attribute mechanism, which
1507 helps to determine the effectiveness of preserving large and huge
1508 page mappings when mapping protections are changed.
1510 config AMD_MEM_ENCRYPT
1511 bool "AMD Secure Memory Encryption (SME) support"
1512 depends on X86_64 && CPU_SUP_AMD
1513 select DMA_COHERENT_POOL
1514 select DYNAMIC_PHYSICAL_MASK
1515 select ARCH_USE_MEMREMAP_PROT
1516 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1517 select INSTRUCTION_DECODER
1519 Say yes to enable support for the encryption of system memory.
1520 This requires an AMD processor that supports Secure Memory
1523 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1524 bool "Activate AMD Secure Memory Encryption (SME) by default"
1526 depends on AMD_MEM_ENCRYPT
1528 Say yes to have system memory encrypted by default if running on
1529 an AMD processor that supports Secure Memory Encryption (SME).
1531 If set to Y, then the encryption of system memory can be
1532 deactivated with the mem_encrypt=off command line option.
1534 If set to N, then the encryption of system memory can be
1535 activated with the mem_encrypt=on command line option.
1537 # Common NUMA Features
1539 bool "NUMA Memory Allocation and Scheduler Support"
1541 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1542 default y if X86_BIGSMP
1544 Enable NUMA (Non-Uniform Memory Access) support.
1546 The kernel will try to allocate memory used by a CPU on the
1547 local memory controller of the CPU and add some more
1548 NUMA awareness to the kernel.
1550 For 64-bit this is recommended if the system is Intel Core i7
1551 (or later), AMD Opteron, or EM64T NUMA.
1553 For 32-bit this is only needed if you boot a 32-bit
1554 kernel on a 64-bit NUMA platform.
1556 Otherwise, you should say N.
1560 prompt "Old style AMD Opteron NUMA detection"
1561 depends on X86_64 && NUMA && PCI
1563 Enable AMD NUMA node topology detection. You should say Y here if
1564 you have a multi processor AMD system. This uses an old method to
1565 read the NUMA configuration directly from the builtin Northbridge
1566 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1567 which also takes priority if both are compiled in.
1569 config X86_64_ACPI_NUMA
1571 prompt "ACPI NUMA detection"
1572 depends on X86_64 && NUMA && ACPI && PCI
1575 Enable ACPI SRAT based node topology detection.
1578 bool "NUMA emulation"
1581 Enable NUMA emulation. A flat machine will be split
1582 into virtual nodes when booted with "numa=fake=N", where N is the
1583 number of nodes. This is only useful for debugging.
1586 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1588 default "10" if MAXSMP
1589 default "6" if X86_64
1591 depends on NEED_MULTIPLE_NODES
1593 Specify the maximum number of NUMA Nodes available on the target
1594 system. Increases memory reserved to accommodate various tables.
1596 config ARCH_FLATMEM_ENABLE
1598 depends on X86_32 && !NUMA
1600 config ARCH_SPARSEMEM_ENABLE
1602 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1603 select SPARSEMEM_STATIC if X86_32
1604 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1606 config ARCH_SPARSEMEM_DEFAULT
1607 def_bool X86_64 || (NUMA && X86_32)
1609 config ARCH_SELECT_MEMORY_MODEL
1611 depends on ARCH_SPARSEMEM_ENABLE
1613 config ARCH_MEMORY_PROBE
1614 bool "Enable sysfs memory/probe interface"
1615 depends on X86_64 && MEMORY_HOTPLUG
1617 This option enables a sysfs memory/probe interface for testing.
1618 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1619 If you are unsure how to answer this question, answer N.
1621 config ARCH_PROC_KCORE_TEXT
1623 depends on X86_64 && PROC_KCORE
1625 config ILLEGAL_POINTER_VALUE
1628 default 0xdead000000000000 if X86_64
1630 config X86_PMEM_LEGACY_DEVICE
1633 config X86_PMEM_LEGACY
1634 tristate "Support non-standard NVDIMMs and ADR protected memory"
1635 depends on PHYS_ADDR_T_64BIT
1637 select X86_PMEM_LEGACY_DEVICE
1638 select NUMA_KEEP_MEMINFO if NUMA
1641 Treat memory marked using the non-standard e820 type of 12 as used
1642 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1643 The kernel will offer these regions to the 'pmem' driver so
1644 they can be used for persistent storage.
1649 bool "Allocate 3rd-level pagetables from highmem"
1652 The VM uses one page table entry for each page of physical memory.
1653 For systems with a lot of RAM, this can be wasteful of precious
1654 low memory. Setting this option will put user-space page table
1655 entries in high memory.
1657 config X86_CHECK_BIOS_CORRUPTION
1658 bool "Check for low memory corruption"
1660 Periodically check for memory corruption in low memory, which
1661 is suspected to be caused by BIOS. Even when enabled in the
1662 configuration, it is disabled at runtime. Enable it by
1663 setting "memory_corruption_check=1" on the kernel command
1664 line. By default it scans the low 64k of memory every 60
1665 seconds; see the memory_corruption_check_size and
1666 memory_corruption_check_period parameters in
1667 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1669 When enabled with the default parameters, this option has
1670 almost no overhead, as it reserves a relatively small amount
1671 of memory and scans it infrequently. It both detects corruption
1672 and prevents it from affecting the running system.
1674 It is, however, intended as a diagnostic tool; if repeatable
1675 BIOS-originated corruption always affects the same memory,
1676 you can use memmap= to prevent the kernel from using that
1679 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1680 bool "Set the default setting of memory_corruption_check"
1681 depends on X86_CHECK_BIOS_CORRUPTION
1684 Set whether the default state of memory_corruption_check is
1687 config X86_RESERVE_LOW
1688 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1692 Specify the amount of low memory to reserve for the BIOS.
1694 The first page contains BIOS data structures that the kernel
1695 must not use, so that page must always be reserved.
1697 By default we reserve the first 64K of physical RAM, as a
1698 number of BIOSes are known to corrupt that memory range
1699 during events such as suspend/resume or monitor cable
1700 insertion, so it must not be used by the kernel.
1702 You can set this to 4 if you are absolutely sure that you
1703 trust the BIOS to get all its memory reservations and usages
1704 right. If you know your BIOS have problems beyond the
1705 default 64K area, you can set this to 640 to avoid using the
1706 entire low memory range.
1708 If you have doubts about the BIOS (e.g. suspend/resume does
1709 not work or there's kernel crashes after certain hardware
1710 hotplug events) then you might want to enable
1711 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1712 typical corruption patterns.
1714 Leave this to the default value of 64 if you are unsure.
1716 config MATH_EMULATION
1718 depends on MODIFY_LDT_SYSCALL
1719 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1721 Linux can emulate a math coprocessor (used for floating point
1722 operations) if you don't have one. 486DX and Pentium processors have
1723 a math coprocessor built in, 486SX and 386 do not, unless you added
1724 a 487DX or 387, respectively. (The messages during boot time can
1725 give you some hints here ["man dmesg"].) Everyone needs either a
1726 coprocessor or this emulation.
1728 If you don't have a math coprocessor, you need to say Y here; if you
1729 say Y here even though you have a coprocessor, the coprocessor will
1730 be used nevertheless. (This behavior can be changed with the kernel
1731 command line option "no387", which comes handy if your coprocessor
1732 is broken. Try "man bootparam" or see the documentation of your boot
1733 loader (lilo or loadlin) about how to pass options to the kernel at
1734 boot time.) This means that it is a good idea to say Y here if you
1735 intend to use this kernel on different machines.
1737 More information about the internals of the Linux math coprocessor
1738 emulation can be found in <file:arch/x86/math-emu/README>.
1740 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1741 kernel, it won't hurt.
1745 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1747 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1748 the Memory Type Range Registers (MTRRs) may be used to control
1749 processor access to memory ranges. This is most useful if you have
1750 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1751 allows bus write transfers to be combined into a larger transfer
1752 before bursting over the PCI/AGP bus. This can increase performance
1753 of image write operations 2.5 times or more. Saying Y here creates a
1754 /proc/mtrr file which may be used to manipulate your processor's
1755 MTRRs. Typically the X server should use this.
1757 This code has a reasonably generic interface so that similar
1758 control registers on other processors can be easily supported
1761 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1762 Registers (ARRs) which provide a similar functionality to MTRRs. For
1763 these, the ARRs are used to emulate the MTRRs.
1764 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1765 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1766 write-combining. All of these processors are supported by this code
1767 and it makes sense to say Y here if you have one of them.
1769 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1770 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1771 can lead to all sorts of problems, so it's good to say Y here.
1773 You can safely say Y even if your machine doesn't have MTRRs, you'll
1774 just add about 9 KB to your kernel.
1776 See <file:Documentation/x86/mtrr.rst> for more information.
1778 config MTRR_SANITIZER
1780 prompt "MTRR cleanup support"
1783 Convert MTRR layout from continuous to discrete, so X drivers can
1784 add writeback entries.
1786 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1787 The largest mtrr entry size for a continuous block can be set with
1792 config MTRR_SANITIZER_ENABLE_DEFAULT
1793 int "MTRR cleanup enable value (0-1)"
1796 depends on MTRR_SANITIZER
1798 Enable mtrr cleanup default value
1800 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1801 int "MTRR cleanup spare reg num (0-7)"
1804 depends on MTRR_SANITIZER
1806 mtrr cleanup spare entries default, it can be changed via
1807 mtrr_spare_reg_nr=N on the kernel command line.
1811 prompt "x86 PAT support" if EXPERT
1814 Use PAT attributes to setup page level cache control.
1816 PATs are the modern equivalents of MTRRs and are much more
1817 flexible than MTRRs.
1819 Say N here if you see bootup problems (boot crash, boot hang,
1820 spontaneous reboots) or a non-working video driver.
1824 config ARCH_USES_PG_UNCACHED
1830 prompt "x86 architectural random number generator" if EXPERT
1832 Enable the x86 architectural RDRAND instruction
1833 (Intel Bull Mountain technology) to generate random numbers.
1834 If supported, this is a high bandwidth, cryptographically
1835 secure hardware random number generator.
1839 prompt "Supervisor Mode Access Prevention" if EXPERT
1841 Supervisor Mode Access Prevention (SMAP) is a security
1842 feature in newer Intel processors. There is a small
1843 performance cost if this enabled and turned on; there is
1844 also a small increase in the kernel size if this is enabled.
1850 prompt "User Mode Instruction Prevention" if EXPERT
1852 User Mode Instruction Prevention (UMIP) is a security feature in
1853 some x86 processors. If enabled, a general protection fault is
1854 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1855 executed in user mode. These instructions unnecessarily expose
1856 information about the hardware state.
1858 The vast majority of applications do not use these instructions.
1859 For the very few that do, software emulation is provided in
1860 specific cases in protected and virtual-8086 modes. Emulated
1863 config X86_INTEL_MEMORY_PROTECTION_KEYS
1864 prompt "Memory Protection Keys"
1866 # Note: only available in 64-bit mode
1867 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1868 select ARCH_USES_HIGH_VMA_FLAGS
1869 select ARCH_HAS_PKEYS
1871 Memory Protection Keys provides a mechanism for enforcing
1872 page-based protections, but without requiring modification of the
1873 page tables when an application changes protection domains.
1875 For details, see Documentation/core-api/protection-keys.rst
1880 prompt "TSX enable mode"
1881 depends on CPU_SUP_INTEL
1882 default X86_INTEL_TSX_MODE_OFF
1884 Intel's TSX (Transactional Synchronization Extensions) feature
1885 allows to optimize locking protocols through lock elision which
1886 can lead to a noticeable performance boost.
1888 On the other hand it has been shown that TSX can be exploited
1889 to form side channel attacks (e.g. TAA) and chances are there
1890 will be more of those attacks discovered in the future.
1892 Therefore TSX is not enabled by default (aka tsx=off). An admin
1893 might override this decision by tsx=on the command line parameter.
1894 Even with TSX enabled, the kernel will attempt to enable the best
1895 possible TAA mitigation setting depending on the microcode available
1896 for the particular machine.
1898 This option allows to set the default tsx mode between tsx=on, =off
1899 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1902 Say off if not sure, auto if TSX is in use but it should be used on safe
1903 platforms or on if TSX is in use and the security aspect of tsx is not
1906 config X86_INTEL_TSX_MODE_OFF
1909 TSX is disabled if possible - equals to tsx=off command line parameter.
1911 config X86_INTEL_TSX_MODE_ON
1914 TSX is always enabled on TSX capable HW - equals the tsx=on command
1917 config X86_INTEL_TSX_MODE_AUTO
1920 TSX is enabled on TSX capable HW that is believed to be safe against
1921 side channel attacks- equals the tsx=auto command line parameter.
1925 bool "Software Guard eXtensions (SGX)"
1926 depends on X86_64 && CPU_SUP_INTEL
1928 depends on CRYPTO_SHA256=y
1932 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1933 that can be used by applications to set aside private regions of code
1934 and data, referred to as enclaves. An enclave's private memory can
1935 only be accessed by code running within the enclave. Accesses from
1936 outside the enclave, including other enclaves, are disallowed by
1942 bool "EFI runtime service support"
1945 select EFI_RUNTIME_WRAPPERS
1947 This enables the kernel to use EFI runtime services that are
1948 available (such as the EFI variable services).
1950 This option is only useful on systems that have EFI firmware.
1951 In addition, you should use the latest ELILO loader available
1952 at <http://elilo.sourceforge.net> in order to take advantage
1953 of EFI runtime services. However, even with this option, the
1954 resultant kernel should continue to boot on existing non-EFI
1958 bool "EFI stub support"
1959 depends on EFI && !X86_USE_3DNOW
1960 depends on $(cc-option,-mabi=ms) || X86_32
1963 This kernel feature allows a bzImage to be loaded directly
1964 by EFI firmware without the use of a bootloader.
1966 See Documentation/admin-guide/efi-stub.rst for more information.
1969 bool "EFI mixed-mode support"
1970 depends on EFI_STUB && X86_64
1972 Enabling this feature allows a 64-bit kernel to be booted
1973 on a 32-bit firmware, provided that your CPU supports 64-bit
1976 Note that it is not possible to boot a mixed-mode enabled
1977 kernel via the EFI boot stub - a bootloader that supports
1978 the EFI handover protocol must be used.
1982 source "kernel/Kconfig.hz"
1985 bool "kexec system call"
1988 kexec is a system call that implements the ability to shutdown your
1989 current kernel, and to start another kernel. It is like a reboot
1990 but it is independent of the system firmware. And like a reboot
1991 you can start any kernel with it, not just Linux.
1993 The name comes from the similarity to the exec system call.
1995 It is an ongoing process to be certain the hardware in a machine
1996 is properly shutdown, so do not be surprised if this code does not
1997 initially work for you. As of this writing the exact hardware
1998 interface is strongly in flux, so no good recommendation can be
2002 bool "kexec file based system call"
2007 depends on CRYPTO_SHA256=y
2009 This is new version of kexec system call. This system call is
2010 file based and takes file descriptors as system call argument
2011 for kernel and initramfs as opposed to list of segments as
2012 accepted by previous system call.
2014 config ARCH_HAS_KEXEC_PURGATORY
2018 bool "Verify kernel signature during kexec_file_load() syscall"
2019 depends on KEXEC_FILE
2022 This option makes the kexec_file_load() syscall check for a valid
2023 signature of the kernel image. The image can still be loaded without
2024 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2025 there's a signature that we can check, then it must be valid.
2027 In addition to this option, you need to enable signature
2028 verification for the corresponding kernel image type being
2029 loaded in order for this to work.
2031 config KEXEC_SIG_FORCE
2032 bool "Require a valid signature in kexec_file_load() syscall"
2033 depends on KEXEC_SIG
2035 This option makes kernel signature verification mandatory for
2036 the kexec_file_load() syscall.
2038 config KEXEC_BZIMAGE_VERIFY_SIG
2039 bool "Enable bzImage signature verification support"
2040 depends on KEXEC_SIG
2041 depends on SIGNED_PE_FILE_VERIFICATION
2042 select SYSTEM_TRUSTED_KEYRING
2044 Enable bzImage signature verification support.
2047 bool "kernel crash dumps"
2048 depends on X86_64 || (X86_32 && HIGHMEM)
2050 Generate crash dump after being started by kexec.
2051 This should be normally only set in special crash dump kernels
2052 which are loaded in the main kernel with kexec-tools into
2053 a specially reserved region and then later executed after
2054 a crash by kdump/kexec. The crash dump kernel must be compiled
2055 to a memory address not used by the main kernel or BIOS using
2056 PHYSICAL_START, or it must be built as a relocatable image
2057 (CONFIG_RELOCATABLE=y).
2058 For more details see Documentation/admin-guide/kdump/kdump.rst
2062 depends on KEXEC && HIBERNATION
2064 Jump between original kernel and kexeced kernel and invoke
2065 code in physical address mode via KEXEC
2067 config PHYSICAL_START
2068 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2071 This gives the physical address where the kernel is loaded.
2073 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2074 bzImage will decompress itself to above physical address and
2075 run from there. Otherwise, bzImage will run from the address where
2076 it has been loaded by the boot loader and will ignore above physical
2079 In normal kdump cases one does not have to set/change this option
2080 as now bzImage can be compiled as a completely relocatable image
2081 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2082 address. This option is mainly useful for the folks who don't want
2083 to use a bzImage for capturing the crash dump and want to use a
2084 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2085 to be specifically compiled to run from a specific memory area
2086 (normally a reserved region) and this option comes handy.
2088 So if you are using bzImage for capturing the crash dump,
2089 leave the value here unchanged to 0x1000000 and set
2090 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2091 for capturing the crash dump change this value to start of
2092 the reserved region. In other words, it can be set based on
2093 the "X" value as specified in the "crashkernel=YM@XM"
2094 command line boot parameter passed to the panic-ed
2095 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2096 for more details about crash dumps.
2098 Usage of bzImage for capturing the crash dump is recommended as
2099 one does not have to build two kernels. Same kernel can be used
2100 as production kernel and capture kernel. Above option should have
2101 gone away after relocatable bzImage support is introduced. But it
2102 is present because there are users out there who continue to use
2103 vmlinux for dump capture. This option should go away down the
2106 Don't change this unless you know what you are doing.
2109 bool "Build a relocatable kernel"
2112 This builds a kernel image that retains relocation information
2113 so it can be loaded someplace besides the default 1MB.
2114 The relocations tend to make the kernel binary about 10% larger,
2115 but are discarded at runtime.
2117 One use is for the kexec on panic case where the recovery kernel
2118 must live at a different physical address than the primary
2121 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2122 it has been loaded at and the compile time physical address
2123 (CONFIG_PHYSICAL_START) is used as the minimum location.
2125 config RANDOMIZE_BASE
2126 bool "Randomize the address of the kernel image (KASLR)"
2127 depends on RELOCATABLE
2130 In support of Kernel Address Space Layout Randomization (KASLR),
2131 this randomizes the physical address at which the kernel image
2132 is decompressed and the virtual address where the kernel
2133 image is mapped, as a security feature that deters exploit
2134 attempts relying on knowledge of the location of kernel
2137 On 64-bit, the kernel physical and virtual addresses are
2138 randomized separately. The physical address will be anywhere
2139 between 16MB and the top of physical memory (up to 64TB). The
2140 virtual address will be randomized from 16MB up to 1GB (9 bits
2141 of entropy). Note that this also reduces the memory space
2142 available to kernel modules from 1.5GB to 1GB.
2144 On 32-bit, the kernel physical and virtual addresses are
2145 randomized together. They will be randomized from 16MB up to
2146 512MB (8 bits of entropy).
2148 Entropy is generated using the RDRAND instruction if it is
2149 supported. If RDTSC is supported, its value is mixed into
2150 the entropy pool as well. If neither RDRAND nor RDTSC are
2151 supported, then entropy is read from the i8254 timer. The
2152 usable entropy is limited by the kernel being built using
2153 2GB addressing, and that PHYSICAL_ALIGN must be at a
2154 minimum of 2MB. As a result, only 10 bits of entropy are
2155 theoretically possible, but the implementations are further
2156 limited due to memory layouts.
2160 # Relocation on x86 needs some additional build support
2161 config X86_NEED_RELOCS
2163 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2165 config PHYSICAL_ALIGN
2166 hex "Alignment value to which kernel should be aligned"
2168 range 0x2000 0x1000000 if X86_32
2169 range 0x200000 0x1000000 if X86_64
2171 This value puts the alignment restrictions on physical address
2172 where kernel is loaded and run from. Kernel is compiled for an
2173 address which meets above alignment restriction.
2175 If bootloader loads the kernel at a non-aligned address and
2176 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2177 address aligned to above value and run from there.
2179 If bootloader loads the kernel at a non-aligned address and
2180 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2181 load address and decompress itself to the address it has been
2182 compiled for and run from there. The address for which kernel is
2183 compiled already meets above alignment restrictions. Hence the
2184 end result is that kernel runs from a physical address meeting
2185 above alignment restrictions.
2187 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2188 this value must be a multiple of 0x200000.
2190 Don't change this unless you know what you are doing.
2192 config DYNAMIC_MEMORY_LAYOUT
2195 This option makes base addresses of vmalloc and vmemmap as well as
2196 __PAGE_OFFSET movable during boot.
2198 config RANDOMIZE_MEMORY
2199 bool "Randomize the kernel memory sections"
2201 depends on RANDOMIZE_BASE
2202 select DYNAMIC_MEMORY_LAYOUT
2203 default RANDOMIZE_BASE
2205 Randomizes the base virtual address of kernel memory sections
2206 (physical memory mapping, vmalloc & vmemmap). This security feature
2207 makes exploits relying on predictable memory locations less reliable.
2209 The order of allocations remains unchanged. Entropy is generated in
2210 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2211 configuration have in average 30,000 different possible virtual
2212 addresses for each memory section.
2216 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2217 hex "Physical memory mapping padding" if EXPERT
2218 depends on RANDOMIZE_MEMORY
2219 default "0xa" if MEMORY_HOTPLUG
2221 range 0x1 0x40 if MEMORY_HOTPLUG
2224 Define the padding in terabytes added to the existing physical
2225 memory size during kernel memory randomization. It is useful
2226 for memory hotplug support but reduces the entropy available for
2227 address randomization.
2229 If unsure, leave at the default value.
2235 config BOOTPARAM_HOTPLUG_CPU0
2236 bool "Set default setting of cpu0_hotpluggable"
2237 depends on HOTPLUG_CPU
2239 Set whether default state of cpu0_hotpluggable is on or off.
2241 Say Y here to enable CPU0 hotplug by default. If this switch
2242 is turned on, there is no need to give cpu0_hotplug kernel
2243 parameter and the CPU0 hotplug feature is enabled by default.
2245 Please note: there are two known CPU0 dependencies if you want
2246 to enable the CPU0 hotplug feature either by this switch or by
2247 cpu0_hotplug kernel parameter.
2249 First, resume from hibernate or suspend always starts from CPU0.
2250 So hibernate and suspend are prevented if CPU0 is offline.
2252 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2253 offline if any interrupt can not migrate out of CPU0. There may
2254 be other CPU0 dependencies.
2256 Please make sure the dependencies are under your control before
2257 you enable this feature.
2259 Say N if you don't want to enable CPU0 hotplug feature by default.
2260 You still can enable the CPU0 hotplug feature at boot by kernel
2261 parameter cpu0_hotplug.
2263 config DEBUG_HOTPLUG_CPU0
2265 prompt "Debug CPU0 hotplug"
2266 depends on HOTPLUG_CPU
2268 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2269 soon as possible and boots up userspace with CPU0 offlined. User
2270 can online CPU0 back after boot time.
2272 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2273 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2274 compilation or giving cpu0_hotplug kernel parameter at boot.
2280 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2281 depends on COMPAT_32
2283 Certain buggy versions of glibc will crash if they are
2284 presented with a 32-bit vDSO that is not mapped at the address
2285 indicated in its segment table.
2287 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2288 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2289 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2290 the only released version with the bug, but OpenSUSE 9
2291 contains a buggy "glibc 2.3.2".
2293 The symptom of the bug is that everything crashes on startup, saying:
2294 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2296 Saying Y here changes the default value of the vdso32 boot
2297 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2298 This works around the glibc bug but hurts performance.
2300 If unsure, say N: if you are compiling your own kernel, you
2301 are unlikely to be using a buggy version of glibc.
2304 prompt "vsyscall table for legacy applications"
2306 default LEGACY_VSYSCALL_XONLY
2308 Legacy user code that does not know how to find the vDSO expects
2309 to be able to issue three syscalls by calling fixed addresses in
2310 kernel space. Since this location is not randomized with ASLR,
2311 it can be used to assist security vulnerability exploitation.
2313 This setting can be changed at boot time via the kernel command
2314 line parameter vsyscall=[emulate|xonly|none].
2316 On a system with recent enough glibc (2.14 or newer) and no
2317 static binaries, you can say None without a performance penalty
2318 to improve security.
2320 If unsure, select "Emulate execution only".
2322 config LEGACY_VSYSCALL_EMULATE
2323 bool "Full emulation"
2325 The kernel traps and emulates calls into the fixed vsyscall
2326 address mapping. This makes the mapping non-executable, but
2327 it still contains readable known contents, which could be
2328 used in certain rare security vulnerability exploits. This
2329 configuration is recommended when using legacy userspace
2330 that still uses vsyscalls along with legacy binary
2331 instrumentation tools that require code to be readable.
2333 An example of this type of legacy userspace is running
2334 Pin on an old binary that still uses vsyscalls.
2336 config LEGACY_VSYSCALL_XONLY
2337 bool "Emulate execution only"
2339 The kernel traps and emulates calls into the fixed vsyscall
2340 address mapping and does not allow reads. This
2341 configuration is recommended when userspace might use the
2342 legacy vsyscall area but support for legacy binary
2343 instrumentation of legacy code is not needed. It mitigates
2344 certain uses of the vsyscall area as an ASLR-bypassing
2347 config LEGACY_VSYSCALL_NONE
2350 There will be no vsyscall mapping at all. This will
2351 eliminate any risk of ASLR bypass due to the vsyscall
2352 fixed address mapping. Attempts to use the vsyscalls
2353 will be reported to dmesg, so that either old or
2354 malicious userspace programs can be identified.
2359 bool "Built-in kernel command line"
2361 Allow for specifying boot arguments to the kernel at
2362 build time. On some systems (e.g. embedded ones), it is
2363 necessary or convenient to provide some or all of the
2364 kernel boot arguments with the kernel itself (that is,
2365 to not rely on the boot loader to provide them.)
2367 To compile command line arguments into the kernel,
2368 set this option to 'Y', then fill in the
2369 boot arguments in CONFIG_CMDLINE.
2371 Systems with fully functional boot loaders (i.e. non-embedded)
2372 should leave this option set to 'N'.
2375 string "Built-in kernel command string"
2376 depends on CMDLINE_BOOL
2379 Enter arguments here that should be compiled into the kernel
2380 image and used at boot time. If the boot loader provides a
2381 command line at boot time, it is appended to this string to
2382 form the full kernel command line, when the system boots.
2384 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2385 change this behavior.
2387 In most cases, the command line (whether built-in or provided
2388 by the boot loader) should specify the device for the root
2391 config CMDLINE_OVERRIDE
2392 bool "Built-in command line overrides boot loader arguments"
2393 depends on CMDLINE_BOOL && CMDLINE != ""
2395 Set this option to 'Y' to have the kernel ignore the boot loader
2396 command line, and use ONLY the built-in command line.
2398 This is used to work around broken boot loaders. This should
2399 be set to 'N' under normal conditions.
2401 config MODIFY_LDT_SYSCALL
2402 bool "Enable the LDT (local descriptor table)" if EXPERT
2405 Linux can allow user programs to install a per-process x86
2406 Local Descriptor Table (LDT) using the modify_ldt(2) system
2407 call. This is required to run 16-bit or segmented code such as
2408 DOSEMU or some Wine programs. It is also used by some very old
2409 threading libraries.
2411 Enabling this feature adds a small amount of overhead to
2412 context switches and increases the low-level kernel attack
2413 surface. Disabling it removes the modify_ldt(2) system call.
2415 Saying 'N' here may make sense for embedded or server kernels.
2417 source "kernel/livepatch/Kconfig"
2421 config ARCH_HAS_ADD_PAGES
2423 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2425 config ARCH_ENABLE_MEMORY_HOTPLUG
2427 depends on X86_64 || (X86_32 && HIGHMEM)
2429 config ARCH_ENABLE_MEMORY_HOTREMOVE
2431 depends on MEMORY_HOTPLUG
2433 config USE_PERCPU_NUMA_NODE_ID
2437 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2439 depends on X86_64 || X86_PAE
2441 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2443 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2445 config ARCH_ENABLE_THP_MIGRATION
2447 depends on X86_64 && TRANSPARENT_HUGEPAGE
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
2657 config MMCONF_FAM10H
2659 depends on X86_64 && PCI_MMCONFIG && ACPI
2661 config PCI_CNB20LE_QUIRK
2662 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2665 Read the PCI windows out of the CNB20LE host bridge. This allows
2666 PCI hotplug to work on systems with the CNB20LE chipset which do
2669 There's no public spec for this chipset, and this functionality
2670 is known to be incomplete.
2672 You should say N unless you know you need this.
2675 bool "ISA bus support on modern systems" if EXPERT
2677 Expose ISA bus device drivers and options available for selection and
2678 configuration. Enable this option if your target machine has an ISA
2679 bus. ISA is an older system, displaced by PCI and newer bus
2680 architectures -- if your target machine is modern, it probably does
2681 not have an ISA bus.
2685 # x86_64 have no ISA slots, but can have ISA-style DMA.
2687 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2690 Enables ISA-style DMA support for devices requiring such controllers.
2698 Find out whether you have ISA slots on your motherboard. ISA is the
2699 name of a bus system, i.e. the way the CPU talks to the other stuff
2700 inside your box. Other bus systems are PCI, EISA, MicroChannel
2701 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2702 newer boards don't support it. If you have ISA, say Y, otherwise N.
2705 tristate "NatSemi SCx200 support"
2707 This provides basic support for National Semiconductor's
2708 (now AMD's) Geode processors. The driver probes for the
2709 PCI-IDs of several on-chip devices, so its a good dependency
2710 for other scx200_* drivers.
2712 If compiled as a module, the driver is named scx200.
2714 config SCx200HR_TIMER
2715 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2719 This driver provides a clocksource built upon the on-chip
2720 27MHz high-resolution timer. Its also a workaround for
2721 NSC Geode SC-1100's buggy TSC, which loses time when the
2722 processor goes idle (as is done by the scheduler). The
2723 other workaround is idle=poll boot option.
2726 bool "One Laptop Per Child support"
2734 Add support for detecting the unique features of the OLPC
2738 bool "OLPC XO-1 Power Management"
2739 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2741 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2744 bool "OLPC XO-1 Real Time Clock"
2745 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2747 Add support for the XO-1 real time clock, which can be used as a
2748 programmable wakeup source.
2751 bool "OLPC XO-1 SCI extras"
2752 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2756 Add support for SCI-based features of the OLPC XO-1 laptop:
2757 - EC-driven system wakeups
2761 - AC adapter status updates
2762 - Battery status updates
2764 config OLPC_XO15_SCI
2765 bool "OLPC XO-1.5 SCI extras"
2766 depends on OLPC && ACPI
2769 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2770 - EC-driven system wakeups
2771 - AC adapter status updates
2772 - Battery status updates
2775 bool "PCEngines ALIX System Support (LED setup)"
2778 This option enables system support for the PCEngines ALIX.
2779 At present this just sets up LEDs for GPIO control on
2780 ALIX2/3/6 boards. However, other system specific setup should
2783 Note: You must still enable the drivers for GPIO and LED support
2784 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2786 Note: You have to set alix.force=1 for boards with Award BIOS.
2789 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2792 This option enables system support for the Soekris Engineering net5501.
2795 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2799 This option enables system support for the Traverse Technologies GEOS.
2802 bool "Technologic Systems TS-5500 platform support"
2804 select CHECK_SIGNATURE
2808 This option enables system support for the Technologic Systems TS-5500.
2814 depends on CPU_SUP_AMD && PCI
2817 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2819 Firmwares often provide initial graphics framebuffers so the BIOS,
2820 bootloader or kernel can show basic video-output during boot for
2821 user-guidance and debugging. Historically, x86 used the VESA BIOS
2822 Extensions and EFI-framebuffers for this, which are mostly limited
2824 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2825 framebuffers so the new generic system-framebuffer drivers can be
2826 used on x86. If the framebuffer is not compatible with the generic
2827 modes, it is advertised as fallback platform framebuffer so legacy
2828 drivers like efifb, vesafb and uvesafb can pick it up.
2829 If this option is not selected, all system framebuffers are always
2830 marked as fallback platform framebuffers as usual.
2832 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2833 not be able to pick up generic system framebuffers if this option
2834 is selected. You are highly encouraged to enable simplefb as
2835 replacement if you select this option. simplefb can correctly deal
2836 with generic system framebuffers. But you should still keep vesafb
2837 and others enabled as fallback if a system framebuffer is
2838 incompatible with simplefb.
2845 menu "Binary Emulations"
2847 config IA32_EMULATION
2848 bool "IA32 Emulation"
2850 select ARCH_WANT_OLD_COMPAT_IPC
2852 select COMPAT_BINFMT_ELF
2853 select COMPAT_OLD_SIGACTION
2855 Include code to run legacy 32-bit programs under a
2856 64-bit kernel. You should likely turn this on, unless you're
2857 100% sure that you don't have any 32-bit programs left.
2860 tristate "IA32 a.out support"
2861 depends on IA32_EMULATION
2864 Support old a.out binaries in the 32bit emulation.
2867 bool "x32 ABI for 64-bit mode"
2870 Include code to run binaries for the x32 native 32-bit ABI
2871 for 64-bit processors. An x32 process gets access to the
2872 full 64-bit register file and wide data path while leaving
2873 pointers at 32 bits for smaller memory footprint.
2875 You will need a recent binutils (2.22 or later) with
2876 elf32_x86_64 support enabled to compile a kernel with this
2881 depends on IA32_EMULATION || X86_32
2883 select OLD_SIGSUSPEND3
2887 depends on IA32_EMULATION || X86_X32
2890 config COMPAT_FOR_U64_ALIGNMENT
2893 config SYSVIPC_COMPAT
2901 config HAVE_ATOMIC_IOMAP
2905 source "drivers/firmware/Kconfig"
2907 source "arch/x86/kvm/Kconfig"
2909 source "arch/x86/Kconfig.assembler"