2 mainmenu "Linux Kernel Configuration for x86"
6 bool "64-bit kernel" if ARCH = "x86"
7 default ARCH = "x86_64"
9 Say yes to build a 64-bit kernel - formerly known as x86_64
10 Say no to build a 32-bit kernel - formerly known as i386
22 config GENERIC_LOCKBREAK
28 config GENERIC_CMOS_UPDATE
31 config CLOCKSOURCE_WATCHDOG
34 config GENERIC_CLOCKEVENTS
37 config GENERIC_CLOCKEVENTS_BROADCAST
39 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
41 config LOCKDEP_SUPPORT
44 config STACKTRACE_SUPPORT
47 config SEMAPHORE_SLEEPERS
62 config GENERIC_ISA_DMA
72 config GENERIC_HWEIGHT
78 config ARCH_MAY_HAVE_PC_FDC
84 config RWSEM_GENERIC_SPINLOCK
87 config RWSEM_XCHGADD_ALGORITHM
90 config ARCH_HAS_ILOG2_U32
93 config ARCH_HAS_ILOG2_U64
96 config GENERIC_CALIBRATE_DELAY
99 config GENERIC_TIME_VSYSCALL
103 config HAVE_SETUP_PER_CPU_AREA
106 config ARCH_SUPPORTS_OPROFILE
115 config ARCH_POPULATES_NODE_MAP
122 # Use the generic interrupt handling code in kernel/irq/:
123 config GENERIC_HARDIRQS
127 config GENERIC_IRQ_PROBE
131 config GENERIC_PENDING_IRQ
133 depends on GENERIC_HARDIRQS && SMP
138 depends on SMP && ((X86_32 && !X86_VOYAGER) || X86_64)
143 depends on X86_32 && SMP
147 depends on X86_64 && SMP
152 depends on (X86_32 && !(X86_VISWS || X86_VOYAGER)) || (X86_64 && !MK8)
155 config X86_BIOS_REBOOT
157 depends on X86_32 && !(X86_VISWS || X86_VOYAGER)
160 config X86_TRAMPOLINE
162 depends on X86_SMP || (X86_VOYAGER && SMP)
167 source "init/Kconfig"
169 menu "Processor type and features"
171 source "kernel/time/Kconfig"
174 bool "Symmetric multi-processing support"
176 This enables support for systems with more than one CPU. If you have
177 a system with only one CPU, like most personal computers, say N. If
178 you have a system with more than one CPU, say Y.
180 If you say N here, the kernel will run on single and multiprocessor
181 machines, but will use only one CPU of a multiprocessor machine. If
182 you say Y here, the kernel will run on many, but not all,
183 singleprocessor machines. On a singleprocessor machine, the kernel
184 will run faster if you say N here.
186 Note that if you say Y here and choose architecture "586" or
187 "Pentium" under "Processor family", the kernel will not work on 486
188 architectures. Similarly, multiprocessor kernels for the "PPro"
189 architecture may not work on all Pentium based boards.
191 People using multiprocessor machines who say Y here should also say
192 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
193 Management" code will be disabled if you say Y here.
195 See also the <file:Documentation/smp.txt>,
196 <file:Documentation/i386/IO-APIC.txt>,
197 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
198 <http://www.tldp.org/docs.html#howto>.
200 If you don't know what to do here, say N.
203 prompt "Subarchitecture Type"
209 Choose this option if your computer is a standard PC or compatible.
215 Select this for an AMD Elan processor.
217 Do not use this option for K6/Athlon/Opteron processors!
219 If unsure, choose "PC-compatible" instead.
224 select SMP if !BROKEN
226 Voyager is an MCA-based 32-way capable SMP architecture proprietary
227 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
231 If you do not specifically know you have a Voyager based machine,
232 say N here, otherwise the kernel you build will not be bootable.
235 bool "NUMAQ (IBM/Sequent)"
240 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
241 multiquad box. This changes the way that processors are bootstrapped,
242 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
243 You will need a new lynxer.elf file to flash your firmware with - send
244 email to <Martin.Bligh@us.ibm.com>.
247 bool "Summit/EXA (IBM x440)"
248 depends on X86_32 && SMP
250 This option is needed for IBM systems that use the Summit/EXA chipset.
251 In particular, it is needed for the x440.
253 If you don't have one of these computers, you should say N here.
254 If you want to build a NUMA kernel, you must select ACPI.
257 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
258 depends on X86_32 && SMP
260 This option is needed for the systems that have more than 8 CPUs
261 and if the system is not of any sub-arch type above.
263 If you don't have such a system, you should say N here.
266 bool "SGI 320/540 (Visual Workstation)"
269 The SGI Visual Workstation series is an IA32-based workstation
270 based on SGI systems chips with some legacy PC hardware attached.
272 Say Y here to create a kernel to run on the SGI 320 or 540.
274 A kernel compiled for the Visual Workstation will not run on PCs
275 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
277 config X86_GENERICARCH
278 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
281 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
282 It is intended for a generic binary kernel.
283 If you want a NUMA kernel, select ACPI. We need SRAT for NUMA.
286 bool "Support for Unisys ES7000 IA32 series"
287 depends on X86_32 && SMP
289 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
290 supposed to run on an IA32-based Unisys ES7000 system.
291 Only choose this option if you have such a system, otherwise you
295 bool "RDC R-321x SoC"
298 select X86_REBOOTFIXUPS
302 This option is needed for RDC R-321x system-on-chip, also known
304 If you don't have one of these chips, you should say N here.
307 bool "Support for ScaleMP vSMP"
308 depends on X86_64 && PCI
310 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
311 supposed to run on these EM64T-based machines. Only choose this option
312 if you have one of these machines.
316 config SCHED_NO_NO_OMIT_FRAME_POINTER
318 prompt "Single-depth WCHAN output"
321 Calculate simpler /proc/<PID>/wchan values. If this option
322 is disabled then wchan values will recurse back to the
323 caller function. This provides more accurate wchan values,
324 at the expense of slightly more scheduling overhead.
326 If in doubt, say "Y".
328 menuconfig PARAVIRT_GUEST
329 bool "Paravirtualized guest support"
331 Say Y here to get to see options related to running Linux under
332 various hypervisors. This option alone does not add any kernel code.
334 If you say N, all options in this submenu will be skipped and disabled.
338 source "arch/x86/xen/Kconfig"
341 bool "VMI Guest support"
344 depends on !(X86_VISWS || X86_VOYAGER)
346 VMI provides a paravirtualized interface to the VMware ESX server
347 (it could be used by other hypervisors in theory too, but is not
348 at the moment), by linking the kernel to a GPL-ed ROM module
349 provided by the hypervisor.
351 source "arch/x86/lguest/Kconfig"
354 bool "Enable paravirtualization code"
355 depends on !(X86_VISWS || X86_VOYAGER)
357 This changes the kernel so it can modify itself when it is run
358 under a hypervisor, potentially improving performance significantly
359 over full virtualization. However, when run without a hypervisor
360 the kernel is theoretically slower and slightly larger.
366 depends on X86_32 && ACPI && NUMA && (X86_SUMMIT || X86_GENERICARCH)
369 config HAVE_ARCH_PARSE_SRAT
373 config X86_SUMMIT_NUMA
375 depends on X86_32 && NUMA && (X86_SUMMIT || X86_GENERICARCH)
377 config X86_CYCLONE_TIMER
379 depends on X86_32 && X86_SUMMIT || X86_GENERICARCH
381 config ES7000_CLUSTERED_APIC
383 depends on SMP && X86_ES7000 && MPENTIUMIII
385 source "arch/x86/Kconfig.cpu"
389 prompt "HPET Timer Support" if X86_32
391 Use the IA-PC HPET (High Precision Event Timer) to manage
392 time in preference to the PIT and RTC, if a HPET is
394 HPET is the next generation timer replacing legacy 8254s.
395 The HPET provides a stable time base on SMP
396 systems, unlike the TSC, but it is more expensive to access,
397 as it is off-chip. You can find the HPET spec at
398 <http://www.intel.com/hardwaredesign/hpetspec.htm>.
400 You can safely choose Y here. However, HPET will only be
401 activated if the platform and the BIOS support this feature.
402 Otherwise the 8254 will be used for timing services.
404 Choose N to continue using the legacy 8254 timer.
406 config HPET_EMULATE_RTC
408 depends on HPET_TIMER && (RTC=y || RTC=m)
410 # Mark as embedded because too many people got it wrong.
411 # The code disables itself when not needed.
413 bool "GART IOMMU support" if EMBEDDED
417 depends on X86_64 && PCI
419 Support for full DMA access of devices with 32bit memory access only
420 on systems with more than 3GB. This is usually needed for USB,
421 sound, many IDE/SATA chipsets and some other devices.
422 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
423 based hardware IOMMU and a software bounce buffer based IOMMU used
424 on Intel systems and as fallback.
425 The code is only active when needed (enough memory and limited
426 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
430 bool "IBM Calgary IOMMU support"
432 depends on X86_64 && PCI && EXPERIMENTAL
434 Support for hardware IOMMUs in IBM's xSeries x366 and x460
435 systems. Needed to run systems with more than 3GB of memory
436 properly with 32-bit PCI devices that do not support DAC
437 (Double Address Cycle). Calgary also supports bus level
438 isolation, where all DMAs pass through the IOMMU. This
439 prevents them from going anywhere except their intended
440 destination. This catches hard-to-find kernel bugs and
441 mis-behaving drivers and devices that do not use the DMA-API
442 properly to set up their DMA buffers. The IOMMU can be
443 turned off at boot time with the iommu=off parameter.
444 Normally the kernel will make the right choice by itself.
447 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
449 prompt "Should Calgary be enabled by default?"
450 depends on CALGARY_IOMMU
452 Should Calgary be enabled by default? if you choose 'y', Calgary
453 will be used (if it exists). If you choose 'n', Calgary will not be
454 used even if it exists. If you choose 'n' and would like to use
455 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
458 # need this always selected by IOMMU for the VIA workaround
462 Support for software bounce buffers used on x86-64 systems
463 which don't have a hardware IOMMU (e.g. the current generation
464 of Intel's x86-64 CPUs). Using this PCI devices which can only
465 access 32-bits of memory can be used on systems with more than
466 3 GB of memory. If unsure, say Y.
470 int "Maximum number of CPUs (2-255)"
473 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
476 This allows you to specify the maximum number of CPUs which this
477 kernel will support. The maximum supported value is 255 and the
478 minimum value which makes sense is 2.
480 This is purely to save memory - each supported CPU adds
481 approximately eight kilobytes to the kernel image.
484 bool "SMT (Hyperthreading) scheduler support"
485 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
487 SMT scheduler support improves the CPU scheduler's decision making
488 when dealing with Intel Pentium 4 chips with HyperThreading at a
489 cost of slightly increased overhead in some places. If unsure say
494 prompt "Multi-core scheduler support"
495 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
497 Multi-core scheduler support improves the CPU scheduler's decision
498 making when dealing with multi-core CPU chips at a cost of slightly
499 increased overhead in some places. If unsure say N here.
501 source "kernel/Kconfig.preempt"
504 bool "Local APIC support on uniprocessors"
505 depends on X86_32 && !SMP && !(X86_VISWS || X86_VOYAGER || X86_GENERICARCH)
507 A local APIC (Advanced Programmable Interrupt Controller) is an
508 integrated interrupt controller in the CPU. If you have a single-CPU
509 system which has a processor with a local APIC, you can say Y here to
510 enable and use it. If you say Y here even though your machine doesn't
511 have a local APIC, then the kernel will still run with no slowdown at
512 all. The local APIC supports CPU-generated self-interrupts (timer,
513 performance counters), and the NMI watchdog which detects hard
517 bool "IO-APIC support on uniprocessors"
518 depends on X86_UP_APIC
520 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
521 SMP-capable replacement for PC-style interrupt controllers. Most
522 SMP systems and many recent uniprocessor systems have one.
524 If you have a single-CPU system with an IO-APIC, you can say Y here
525 to use it. If you say Y here even though your machine doesn't have
526 an IO-APIC, then the kernel will still run with no slowdown at all.
528 config X86_LOCAL_APIC
530 depends on X86_64 || (X86_32 && (X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER) || X86_GENERICARCH))
534 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER)) || X86_GENERICARCH))
536 config X86_VISWS_APIC
538 depends on X86_32 && X86_VISWS
541 bool "Machine Check Exception"
542 depends on !X86_VOYAGER
544 Machine Check Exception support allows the processor to notify the
545 kernel if it detects a problem (e.g. overheating, component failure).
546 The action the kernel takes depends on the severity of the problem,
547 ranging from a warning message on the console, to halting the machine.
548 Your processor must be a Pentium or newer to support this - check the
549 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
550 have a design flaw which leads to false MCE events - hence MCE is
551 disabled on all P5 processors, unless explicitly enabled with "mce"
552 as a boot argument. Similarly, if MCE is built in and creates a
553 problem on some new non-standard machine, you can boot with "nomce"
554 to disable it. MCE support simply ignores non-MCE processors like
555 the 386 and 486, so nearly everyone can say Y here.
559 prompt "Intel MCE features"
560 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
562 Additional support for intel specific MCE features such as
567 prompt "AMD MCE features"
568 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
570 Additional support for AMD specific MCE features such as
571 the DRAM Error Threshold.
573 config X86_MCE_NONFATAL
574 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
575 depends on X86_32 && X86_MCE
577 Enabling this feature starts a timer that triggers every 5 seconds which
578 will look at the machine check registers to see if anything happened.
579 Non-fatal problems automatically get corrected (but still logged).
580 Disable this if you don't want to see these messages.
581 Seeing the messages this option prints out may be indicative of dying
582 or out-of-spec (ie, overclocked) hardware.
583 This option only does something on certain CPUs.
584 (AMD Athlon/Duron and Intel Pentium 4)
586 config X86_MCE_P4THERMAL
587 bool "check for P4 thermal throttling interrupt."
588 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
590 Enabling this feature will cause a message to be printed when the P4
591 enters thermal throttling.
594 bool "Enable VM86 support" if EMBEDDED
598 This option is required by programs like DOSEMU to run 16-bit legacy
599 code on X86 processors. It also may be needed by software like
600 XFree86 to initialize some video cards via BIOS. Disabling this
601 option saves about 6k.
604 tristate "Toshiba Laptop support"
607 This adds a driver to safely access the System Management Mode of
608 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
609 not work on models with a Phoenix BIOS. The System Management Mode
610 is used to set the BIOS and power saving options on Toshiba portables.
612 For information on utilities to make use of this driver see the
613 Toshiba Linux utilities web site at:
614 <http://www.buzzard.org.uk/toshiba/>.
616 Say Y if you intend to run this kernel on a Toshiba portable.
620 tristate "Dell laptop support"
623 This adds a driver to safely access the System Management Mode
624 of the CPU on the Dell Inspiron 8000. The System Management Mode
625 is used to read cpu temperature and cooling fan status and to
626 control the fans on the I8K portables.
628 This driver has been tested only on the Inspiron 8000 but it may
629 also work with other Dell laptops. You can force loading on other
630 models by passing the parameter `force=1' to the module. Use at
633 For information on utilities to make use of this driver see the
634 I8K Linux utilities web site at:
635 <http://people.debian.org/~dz/i8k/>
637 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
640 config X86_REBOOTFIXUPS
642 prompt "Enable X86 board specific fixups for reboot"
643 depends on X86_32 && X86
645 This enables chipset and/or board specific fixups to be done
646 in order to get reboot to work correctly. This is only needed on
647 some combinations of hardware and BIOS. The symptom, for which
648 this config is intended, is when reboot ends with a stalled/hung
651 Currently, the only fixup is for the Geode machines using
652 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
654 Say Y if you want to enable the fixup. Currently, it's safe to
655 enable this option even if you don't need it.
659 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
662 If you say Y here, you will be able to update the microcode on
663 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
664 Pentium III, Pentium 4, Xeon etc. You will obviously need the
665 actual microcode binary data itself which is not shipped with the
668 For latest news and information on obtaining all the required
669 ingredients for this driver, check:
670 <http://www.urbanmyth.org/microcode/>.
672 To compile this driver as a module, choose M here: the
673 module will be called microcode.
675 config MICROCODE_OLD_INTERFACE
680 tristate "/dev/cpu/*/msr - Model-specific register support"
682 This device gives privileged processes access to the x86
683 Model-Specific Registers (MSRs). It is a character device with
684 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
685 MSR accesses are directed to a specific CPU on multi-processor
689 tristate "/dev/cpu/*/cpuid - CPU information support"
691 This device gives processes access to the x86 CPUID instruction to
692 be executed on a specific processor. It is a character device
693 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
697 prompt "High Memory Support"
698 default HIGHMEM4G if !X86_NUMAQ
699 default HIGHMEM64G if X86_NUMAQ
704 depends on !X86_NUMAQ
706 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
707 However, the address space of 32-bit x86 processors is only 4
708 Gigabytes large. That means that, if you have a large amount of
709 physical memory, not all of it can be "permanently mapped" by the
710 kernel. The physical memory that's not permanently mapped is called
713 If you are compiling a kernel which will never run on a machine with
714 more than 1 Gigabyte total physical RAM, answer "off" here (default
715 choice and suitable for most users). This will result in a "3GB/1GB"
716 split: 3GB are mapped so that each process sees a 3GB virtual memory
717 space and the remaining part of the 4GB virtual memory space is used
718 by the kernel to permanently map as much physical memory as
721 If the machine has between 1 and 4 Gigabytes physical RAM, then
724 If more than 4 Gigabytes is used then answer "64GB" here. This
725 selection turns Intel PAE (Physical Address Extension) mode on.
726 PAE implements 3-level paging on IA32 processors. PAE is fully
727 supported by Linux, PAE mode is implemented on all recent Intel
728 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
729 then the kernel will not boot on CPUs that don't support PAE!
731 The actual amount of total physical memory will either be
732 auto detected or can be forced by using a kernel command line option
733 such as "mem=256M". (Try "man bootparam" or see the documentation of
734 your boot loader (lilo or loadlin) about how to pass options to the
735 kernel at boot time.)
737 If unsure, say "off".
741 depends on !X86_NUMAQ
743 Select this if you have a 32-bit processor and between 1 and 4
744 gigabytes of physical RAM.
748 depends on !M386 && !M486
751 Select this if you have a 32-bit processor and more than 4
752 gigabytes of physical RAM.
757 depends on EXPERIMENTAL
758 prompt "Memory split" if EMBEDDED
762 Select the desired split between kernel and user memory.
764 If the address range available to the kernel is less than the
765 physical memory installed, the remaining memory will be available
766 as "high memory". Accessing high memory is a little more costly
767 than low memory, as it needs to be mapped into the kernel first.
768 Note that increasing the kernel address space limits the range
769 available to user programs, making the address space there
770 tighter. Selecting anything other than the default 3G/1G split
771 will also likely make your kernel incompatible with binary-only
774 If you are not absolutely sure what you are doing, leave this
778 bool "3G/1G user/kernel split"
779 config VMSPLIT_3G_OPT
781 bool "3G/1G user/kernel split (for full 1G low memory)"
783 bool "2G/2G user/kernel split"
784 config VMSPLIT_2G_OPT
786 bool "2G/2G user/kernel split (for full 2G low memory)"
788 bool "1G/3G user/kernel split"
793 default 0xB0000000 if VMSPLIT_3G_OPT
794 default 0x80000000 if VMSPLIT_2G
795 default 0x78000000 if VMSPLIT_2G_OPT
796 default 0x40000000 if VMSPLIT_1G
802 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
806 prompt "PAE (Physical Address Extension) Support"
807 depends on X86_32 && !HIGHMEM4G
808 select RESOURCES_64BIT
810 PAE is required for NX support, and furthermore enables
811 larger swapspace support for non-overcommit purposes. It
812 has the cost of more pagetable lookup overhead, and also
813 consumes more pagetable space per process.
815 # Common NUMA Features
817 bool "Numa Memory Allocation and Scheduler Support (EXPERIMENTAL)"
819 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT || X86_GENERICARCH) && ACPI) && EXPERIMENTAL)
821 default y if (X86_NUMAQ || X86_SUMMIT)
823 Enable NUMA (Non Uniform Memory Access) support.
824 The kernel will try to allocate memory used by a CPU on the
825 local memory controller of the CPU and add some more
826 NUMA awareness to the kernel.
828 For i386 this is currently highly experimental and should be only
829 used for kernel development. It might also cause boot failures.
830 For x86_64 this is recommended on all multiprocessor Opteron systems.
831 If the system is EM64T, you should say N unless your system is
834 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
835 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
839 prompt "Old style AMD Opteron NUMA detection"
840 depends on X86_64 && NUMA && PCI
842 Enable K8 NUMA node topology detection. You should say Y here if
843 you have a multi processor AMD K8 system. This uses an old
844 method to read the NUMA configuration directly from the builtin
845 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
846 instead, which also takes priority if both are compiled in.
848 config X86_64_ACPI_NUMA
850 prompt "ACPI NUMA detection"
851 depends on X86_64 && NUMA && ACPI && PCI
854 Enable ACPI SRAT based node topology detection.
857 bool "NUMA emulation"
858 depends on X86_64 && NUMA
860 Enable NUMA emulation. A flat machine will be split
861 into virtual nodes when booted with "numa=fake=N", where N is the
862 number of nodes. This is only useful for debugging.
867 default "6" if X86_64
868 default "4" if X86_NUMAQ
870 depends on NEED_MULTIPLE_NODES
872 config HAVE_ARCH_BOOTMEM_NODE
874 depends on X86_32 && NUMA
876 config ARCH_HAVE_MEMORY_PRESENT
878 depends on X86_32 && DISCONTIGMEM
880 config NEED_NODE_MEMMAP_SIZE
882 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
884 config HAVE_ARCH_ALLOC_REMAP
886 depends on X86_32 && NUMA
888 config ARCH_FLATMEM_ENABLE
890 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && X86_PC && !NUMA
892 config ARCH_DISCONTIGMEM_ENABLE
894 depends on NUMA && X86_32
896 config ARCH_DISCONTIGMEM_DEFAULT
898 depends on NUMA && X86_32
900 config ARCH_SPARSEMEM_DEFAULT
904 config ARCH_SPARSEMEM_ENABLE
906 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC)
907 select SPARSEMEM_STATIC if X86_32
908 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
910 config ARCH_SELECT_MEMORY_MODEL
912 depends on ARCH_SPARSEMEM_ENABLE
914 config ARCH_MEMORY_PROBE
916 depends on MEMORY_HOTPLUG
921 bool "Allocate 3rd-level pagetables from highmem"
922 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
924 The VM uses one page table entry for each page of physical memory.
925 For systems with a lot of RAM, this can be wasteful of precious
926 low memory. Setting this option will put user-space page table
927 entries in high memory.
929 config MATH_EMULATION
931 prompt "Math emulation" if X86_32
933 Linux can emulate a math coprocessor (used for floating point
934 operations) if you don't have one. 486DX and Pentium processors have
935 a math coprocessor built in, 486SX and 386 do not, unless you added
936 a 487DX or 387, respectively. (The messages during boot time can
937 give you some hints here ["man dmesg"].) Everyone needs either a
938 coprocessor or this emulation.
940 If you don't have a math coprocessor, you need to say Y here; if you
941 say Y here even though you have a coprocessor, the coprocessor will
942 be used nevertheless. (This behavior can be changed with the kernel
943 command line option "no387", which comes handy if your coprocessor
944 is broken. Try "man bootparam" or see the documentation of your boot
945 loader (lilo or loadlin) about how to pass options to the kernel at
946 boot time.) This means that it is a good idea to say Y here if you
947 intend to use this kernel on different machines.
949 More information about the internals of the Linux math coprocessor
950 emulation can be found in <file:arch/x86/math-emu/README>.
952 If you are not sure, say Y; apart from resulting in a 66 KB bigger
953 kernel, it won't hurt.
956 bool "MTRR (Memory Type Range Register) support"
958 On Intel P6 family processors (Pentium Pro, Pentium II and later)
959 the Memory Type Range Registers (MTRRs) may be used to control
960 processor access to memory ranges. This is most useful if you have
961 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
962 allows bus write transfers to be combined into a larger transfer
963 before bursting over the PCI/AGP bus. This can increase performance
964 of image write operations 2.5 times or more. Saying Y here creates a
965 /proc/mtrr file which may be used to manipulate your processor's
966 MTRRs. Typically the X server should use this.
968 This code has a reasonably generic interface so that similar
969 control registers on other processors can be easily supported
972 The Cyrix 6x86, 6x86MX and M II processors have Address Range
973 Registers (ARRs) which provide a similar functionality to MTRRs. For
974 these, the ARRs are used to emulate the MTRRs.
975 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
976 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
977 write-combining. All of these processors are supported by this code
978 and it makes sense to say Y here if you have one of them.
980 Saying Y here also fixes a problem with buggy SMP BIOSes which only
981 set the MTRRs for the boot CPU and not for the secondary CPUs. This
982 can lead to all sorts of problems, so it's good to say Y here.
984 You can safely say Y even if your machine doesn't have MTRRs, you'll
985 just add about 9 KB to your kernel.
987 See <file:Documentation/mtrr.txt> for more information.
991 prompt "EFI runtime service support"
994 This enables the kernel to use EFI runtime services that are
995 available (such as the EFI variable services).
997 This option is only useful on systems that have EFI firmware.
998 In addition, you should use the latest ELILO loader available
999 at <http://elilo.sourceforge.net> in order to take advantage
1000 of EFI runtime services. However, even with this option, the
1001 resultant kernel should continue to boot on existing non-EFI
1006 prompt "Enable kernel irq balancing"
1007 depends on X86_32 && SMP && X86_IO_APIC
1009 The default yes will allow the kernel to do irq load balancing.
1010 Saying no will keep the kernel from doing irq load balancing.
1014 prompt "Enable seccomp to safely compute untrusted bytecode"
1017 This kernel feature is useful for number crunching applications
1018 that may need to compute untrusted bytecode during their
1019 execution. By using pipes or other transports made available to
1020 the process as file descriptors supporting the read/write
1021 syscalls, it's possible to isolate those applications in
1022 their own address space using seccomp. Once seccomp is
1023 enabled via /proc/<pid>/seccomp, it cannot be disabled
1024 and the task is only allowed to execute a few safe syscalls
1025 defined by each seccomp mode.
1027 If unsure, say Y. Only embedded should say N here.
1029 config CC_STACKPROTECTOR
1030 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1031 depends on X86_64 && EXPERIMENTAL
1033 This option turns on the -fstack-protector GCC feature. This
1034 feature puts, at the beginning of critical functions, a canary
1035 value on the stack just before the return address, and validates
1036 the value just before actually returning. Stack based buffer
1037 overflows (that need to overwrite this return address) now also
1038 overwrite the canary, which gets detected and the attack is then
1039 neutralized via a kernel panic.
1041 This feature requires gcc version 4.2 or above, or a distribution
1042 gcc with the feature backported. Older versions are automatically
1043 detected and for those versions, this configuration option is ignored.
1045 config CC_STACKPROTECTOR_ALL
1046 bool "Use stack-protector for all functions"
1047 depends on CC_STACKPROTECTOR
1049 Normally, GCC only inserts the canary value protection for
1050 functions that use large-ish on-stack buffers. By enabling
1051 this option, GCC will be asked to do this for ALL functions.
1053 source kernel/Kconfig.hz
1056 bool "kexec system call"
1058 kexec is a system call that implements the ability to shutdown your
1059 current kernel, and to start another kernel. It is like a reboot
1060 but it is independent of the system firmware. And like a reboot
1061 you can start any kernel with it, not just Linux.
1063 The name comes from the similarity to the exec system call.
1065 It is an ongoing process to be certain the hardware in a machine
1066 is properly shutdown, so do not be surprised if this code does not
1067 initially work for you. It may help to enable device hotplugging
1068 support. As of this writing the exact hardware interface is
1069 strongly in flux, so no good recommendation can be made.
1072 bool "kernel crash dumps (EXPERIMENTAL)"
1073 depends on EXPERIMENTAL
1074 depends on X86_64 || (X86_32 && HIGHMEM)
1076 Generate crash dump after being started by kexec.
1077 This should be normally only set in special crash dump kernels
1078 which are loaded in the main kernel with kexec-tools into
1079 a specially reserved region and then later executed after
1080 a crash by kdump/kexec. The crash dump kernel must be compiled
1081 to a memory address not used by the main kernel or BIOS using
1082 PHYSICAL_START, or it must be built as a relocatable image
1083 (CONFIG_RELOCATABLE=y).
1084 For more details see Documentation/kdump/kdump.txt
1086 config PHYSICAL_START
1087 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1088 default "0x1000000" if X86_NUMAQ
1089 default "0x200000" if X86_64
1092 This gives the physical address where the kernel is loaded.
1094 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1095 bzImage will decompress itself to above physical address and
1096 run from there. Otherwise, bzImage will run from the address where
1097 it has been loaded by the boot loader and will ignore above physical
1100 In normal kdump cases one does not have to set/change this option
1101 as now bzImage can be compiled as a completely relocatable image
1102 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1103 address. This option is mainly useful for the folks who don't want
1104 to use a bzImage for capturing the crash dump and want to use a
1105 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1106 to be specifically compiled to run from a specific memory area
1107 (normally a reserved region) and this option comes handy.
1109 So if you are using bzImage for capturing the crash dump, leave
1110 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1111 Otherwise if you plan to use vmlinux for capturing the crash dump
1112 change this value to start of the reserved region (Typically 16MB
1113 0x1000000). In other words, it can be set based on the "X" value as
1114 specified in the "crashkernel=YM@XM" command line boot parameter
1115 passed to the panic-ed kernel. Typically this parameter is set as
1116 crashkernel=64M@16M. Please take a look at
1117 Documentation/kdump/kdump.txt for more details about crash dumps.
1119 Usage of bzImage for capturing the crash dump is recommended as
1120 one does not have to build two kernels. Same kernel can be used
1121 as production kernel and capture kernel. Above option should have
1122 gone away after relocatable bzImage support is introduced. But it
1123 is present because there are users out there who continue to use
1124 vmlinux for dump capture. This option should go away down the
1127 Don't change this unless you know what you are doing.
1130 bool "Build a relocatable kernel (EXPERIMENTAL)"
1131 depends on EXPERIMENTAL
1133 This builds a kernel image that retains relocation information
1134 so it can be loaded someplace besides the default 1MB.
1135 The relocations tend to make the kernel binary about 10% larger,
1136 but are discarded at runtime.
1138 One use is for the kexec on panic case where the recovery kernel
1139 must live at a different physical address than the primary
1142 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1143 it has been loaded at and the compile time physical address
1144 (CONFIG_PHYSICAL_START) is ignored.
1146 config PHYSICAL_ALIGN
1148 prompt "Alignment value to which kernel should be aligned" if X86_32
1149 default "0x100000" if X86_32
1150 default "0x200000" if X86_64
1151 range 0x2000 0x400000
1153 This value puts the alignment restrictions on physical address
1154 where kernel is loaded and run from. Kernel is compiled for an
1155 address which meets above alignment restriction.
1157 If bootloader loads the kernel at a non-aligned address and
1158 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1159 address aligned to above value and run from there.
1161 If bootloader loads the kernel at a non-aligned address and
1162 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1163 load address and decompress itself to the address it has been
1164 compiled for and run from there. The address for which kernel is
1165 compiled already meets above alignment restrictions. Hence the
1166 end result is that kernel runs from a physical address meeting
1167 above alignment restrictions.
1169 Don't change this unless you know what you are doing.
1172 bool "Support for suspend on SMP and hot-pluggable CPUs (EXPERIMENTAL)"
1173 depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER
1175 Say Y here to experiment with turning CPUs off and on, and to
1176 enable suspend on SMP systems. CPUs can be controlled through
1177 /sys/devices/system/cpu.
1178 Say N if you want to disable CPU hotplug and don't need to
1183 prompt "Compat VDSO support"
1184 depends on X86_32 || IA32_EMULATION
1186 Map the 32-bit VDSO to the predictable old-style address too.
1188 Say N here if you are running a sufficiently recent glibc
1189 version (2.3.3 or later), to remove the high-mapped
1190 VDSO mapping and to exclusively use the randomized VDSO.
1196 config ARCH_ENABLE_MEMORY_HOTPLUG
1198 depends on X86_64 || (X86_32 && HIGHMEM)
1200 config HAVE_ARCH_EARLY_PFN_TO_NID
1204 menu "Power management options"
1205 depends on !X86_VOYAGER
1207 config ARCH_HIBERNATION_HEADER
1209 depends on X86_64 && HIBERNATION
1211 source "kernel/power/Kconfig"
1213 source "drivers/acpi/Kconfig"
1218 depends on APM || APM_MODULE
1221 tristate "APM (Advanced Power Management) BIOS support"
1222 depends on X86_32 && PM_SLEEP && !X86_VISWS
1224 APM is a BIOS specification for saving power using several different
1225 techniques. This is mostly useful for battery powered laptops with
1226 APM compliant BIOSes. If you say Y here, the system time will be
1227 reset after a RESUME operation, the /proc/apm device will provide
1228 battery status information, and user-space programs will receive
1229 notification of APM "events" (e.g. battery status change).
1231 If you select "Y" here, you can disable actual use of the APM
1232 BIOS by passing the "apm=off" option to the kernel at boot time.
1234 Note that the APM support is almost completely disabled for
1235 machines with more than one CPU.
1237 In order to use APM, you will need supporting software. For location
1238 and more information, read <file:Documentation/pm.txt> and the
1239 Battery Powered Linux mini-HOWTO, available from
1240 <http://www.tldp.org/docs.html#howto>.
1242 This driver does not spin down disk drives (see the hdparm(8)
1243 manpage ("man 8 hdparm") for that), and it doesn't turn off
1244 VESA-compliant "green" monitors.
1246 This driver does not support the TI 4000M TravelMate and the ACER
1247 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1248 desktop machines also don't have compliant BIOSes, and this driver
1249 may cause those machines to panic during the boot phase.
1251 Generally, if you don't have a battery in your machine, there isn't
1252 much point in using this driver and you should say N. If you get
1253 random kernel OOPSes or reboots that don't seem to be related to
1254 anything, try disabling/enabling this option (or disabling/enabling
1257 Some other things you should try when experiencing seemingly random,
1260 1) make sure that you have enough swap space and that it is
1262 2) pass the "no-hlt" option to the kernel
1263 3) switch on floating point emulation in the kernel and pass
1264 the "no387" option to the kernel
1265 4) pass the "floppy=nodma" option to the kernel
1266 5) pass the "mem=4M" option to the kernel (thereby disabling
1267 all but the first 4 MB of RAM)
1268 6) make sure that the CPU is not over clocked.
1269 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1270 8) disable the cache from your BIOS settings
1271 9) install a fan for the video card or exchange video RAM
1272 10) install a better fan for the CPU
1273 11) exchange RAM chips
1274 12) exchange the motherboard.
1276 To compile this driver as a module, choose M here: the
1277 module will be called apm.
1281 config APM_IGNORE_USER_SUSPEND
1282 bool "Ignore USER SUSPEND"
1284 This option will ignore USER SUSPEND requests. On machines with a
1285 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1286 series notebooks, it is necessary to say Y because of a BIOS bug.
1288 config APM_DO_ENABLE
1289 bool "Enable PM at boot time"
1291 Enable APM features at boot time. From page 36 of the APM BIOS
1292 specification: "When disabled, the APM BIOS does not automatically
1293 power manage devices, enter the Standby State, enter the Suspend
1294 State, or take power saving steps in response to CPU Idle calls."
1295 This driver will make CPU Idle calls when Linux is idle (unless this
1296 feature is turned off -- see "Do CPU IDLE calls", below). This
1297 should always save battery power, but more complicated APM features
1298 will be dependent on your BIOS implementation. You may need to turn
1299 this option off if your computer hangs at boot time when using APM
1300 support, or if it beeps continuously instead of suspending. Turn
1301 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1302 T400CDT. This is off by default since most machines do fine without
1306 bool "Make CPU Idle calls when idle"
1308 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1309 On some machines, this can activate improved power savings, such as
1310 a slowed CPU clock rate, when the machine is idle. These idle calls
1311 are made after the idle loop has run for some length of time (e.g.,
1312 333 mS). On some machines, this will cause a hang at boot time or
1313 whenever the CPU becomes idle. (On machines with more than one CPU,
1314 this option does nothing.)
1316 config APM_DISPLAY_BLANK
1317 bool "Enable console blanking using APM"
1319 Enable console blanking using the APM. Some laptops can use this to
1320 turn off the LCD backlight when the screen blanker of the Linux
1321 virtual console blanks the screen. Note that this is only used by
1322 the virtual console screen blanker, and won't turn off the backlight
1323 when using the X Window system. This also doesn't have anything to
1324 do with your VESA-compliant power-saving monitor. Further, this
1325 option doesn't work for all laptops -- it might not turn off your
1326 backlight at all, or it might print a lot of errors to the console,
1327 especially if you are using gpm.
1329 config APM_ALLOW_INTS
1330 bool "Allow interrupts during APM BIOS calls"
1332 Normally we disable external interrupts while we are making calls to
1333 the APM BIOS as a measure to lessen the effects of a badly behaving
1334 BIOS implementation. The BIOS should reenable interrupts if it
1335 needs to. Unfortunately, some BIOSes do not -- especially those in
1336 many of the newer IBM Thinkpads. If you experience hangs when you
1337 suspend, try setting this to Y. Otherwise, say N.
1339 config APM_REAL_MODE_POWER_OFF
1340 bool "Use real mode APM BIOS call to power off"
1342 Use real mode APM BIOS calls to switch off the computer. This is
1343 a work-around for a number of buggy BIOSes. Switch this option on if
1344 your computer crashes instead of powering off properly.
1348 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1350 source "drivers/cpuidle/Kconfig"
1355 menu "Bus options (PCI etc.)"
1358 bool "PCI support" if !X86_VISWS
1359 depends on !X86_VOYAGER
1361 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1363 Find out whether you have a PCI motherboard. PCI is the name of a
1364 bus system, i.e. the way the CPU talks to the other stuff inside
1365 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1366 VESA. If you have PCI, say Y, otherwise N.
1368 The PCI-HOWTO, available from
1369 <http://www.tldp.org/docs.html#howto>, contains valuable
1370 information about which PCI hardware does work under Linux and which
1374 prompt "PCI access mode"
1375 depends on X86_32 && PCI && !X86_VISWS
1378 On PCI systems, the BIOS can be used to detect the PCI devices and
1379 determine their configuration. However, some old PCI motherboards
1380 have BIOS bugs and may crash if this is done. Also, some embedded
1381 PCI-based systems don't have any BIOS at all. Linux can also try to
1382 detect the PCI hardware directly without using the BIOS.
1384 With this option, you can specify how Linux should detect the
1385 PCI devices. If you choose "BIOS", the BIOS will be used,
1386 if you choose "Direct", the BIOS won't be used, and if you
1387 choose "MMConfig", then PCI Express MMCONFIG will be used.
1388 If you choose "Any", the kernel will try MMCONFIG, then the
1389 direct access method and falls back to the BIOS if that doesn't
1390 work. If unsure, go with the default, which is "Any".
1395 config PCI_GOMMCONFIG
1408 depends on X86_32 && !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1410 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1413 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1417 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1424 bool "Support mmconfig PCI config space access"
1425 depends on X86_64 && PCI && ACPI
1428 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1429 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1431 DMA remapping (DMAR) devices support enables independent address
1432 translations for Direct Memory Access (DMA) from devices.
1433 These DMA remapping devices are reported via ACPI tables
1434 and include PCI device scope covered by these DMA
1439 prompt "Support for Graphics workaround"
1442 Current Graphics drivers tend to use physical address
1443 for DMA and avoid using DMA APIs. Setting this config
1444 option permits the IOMMU driver to set a unity map for
1445 all the OS-visible memory. Hence the driver can continue
1446 to use physical addresses for DMA.
1448 config DMAR_FLOPPY_WA
1452 Floppy disk drivers are know to bypass DMA API calls
1453 thereby failing to work when IOMMU is enabled. This
1454 workaround will setup a 1:1 mapping for the first
1455 16M to make floppy (an ISA device) work.
1457 source "drivers/pci/pcie/Kconfig"
1459 source "drivers/pci/Kconfig"
1461 # x86_64 have no ISA slots, but do have ISA-style DMA.
1469 depends on !(X86_VOYAGER || X86_VISWS)
1471 Find out whether you have ISA slots on your motherboard. ISA is the
1472 name of a bus system, i.e. the way the CPU talks to the other stuff
1473 inside your box. Other bus systems are PCI, EISA, MicroChannel
1474 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1475 newer boards don't support it. If you have ISA, say Y, otherwise N.
1481 The Extended Industry Standard Architecture (EISA) bus was
1482 developed as an open alternative to the IBM MicroChannel bus.
1484 The EISA bus provided some of the features of the IBM MicroChannel
1485 bus while maintaining backward compatibility with cards made for
1486 the older ISA bus. The EISA bus saw limited use between 1988 and
1487 1995 when it was made obsolete by the PCI bus.
1489 Say Y here if you are building a kernel for an EISA-based machine.
1493 source "drivers/eisa/Kconfig"
1496 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1497 default y if X86_VOYAGER
1499 MicroChannel Architecture is found in some IBM PS/2 machines and
1500 laptops. It is a bus system similar to PCI or ISA. See
1501 <file:Documentation/mca.txt> (and especially the web page given
1502 there) before attempting to build an MCA bus kernel.
1504 source "drivers/mca/Kconfig"
1507 tristate "NatSemi SCx200 support"
1508 depends on !X86_VOYAGER
1510 This provides basic support for National Semiconductor's
1511 (now AMD's) Geode processors. The driver probes for the
1512 PCI-IDs of several on-chip devices, so its a good dependency
1513 for other scx200_* drivers.
1515 If compiled as a module, the driver is named scx200.
1517 config SCx200HR_TIMER
1518 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1519 depends on SCx200 && GENERIC_TIME
1522 This driver provides a clocksource built upon the on-chip
1523 27MHz high-resolution timer. Its also a workaround for
1524 NSC Geode SC-1100's buggy TSC, which loses time when the
1525 processor goes idle (as is done by the scheduler). The
1526 other workaround is idle=poll boot option.
1528 config GEODE_MFGPT_TIMER
1530 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1531 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1533 This driver provides a clock event source based on the MFGPT
1534 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1535 MFGPTs have a better resolution and max interval than the
1536 generic PIT, and are suitable for use as high-res timers.
1542 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1544 source "drivers/pcmcia/Kconfig"
1546 source "drivers/pci/hotplug/Kconfig"
1551 menu "Executable file formats / Emulations"
1553 source "fs/Kconfig.binfmt"
1555 config IA32_EMULATION
1556 bool "IA32 Emulation"
1558 select COMPAT_BINFMT_ELF
1560 Include code to run 32-bit programs under a 64-bit kernel. You should
1561 likely turn this on, unless you're 100% sure that you don't have any
1562 32-bit programs left.
1565 tristate "IA32 a.out support"
1566 depends on IA32_EMULATION
1568 Support old a.out binaries in the 32bit emulation.
1572 depends on IA32_EMULATION
1574 config COMPAT_FOR_U64_ALIGNMENT
1578 config SYSVIPC_COMPAT
1580 depends on X86_64 && COMPAT && SYSVIPC
1585 source "net/Kconfig"
1587 source "drivers/Kconfig"
1589 source "drivers/firmware/Kconfig"
1593 source "kernel/Kconfig.instrumentation"
1595 source "arch/x86/Kconfig.debug"
1597 source "security/Kconfig"
1599 source "crypto/Kconfig"
1601 source "lib/Kconfig"