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
27 config GENERIC_CMOS_UPDATE
31 config CLOCKSOURCE_WATCHDOG
35 config GENERIC_CLOCKEVENTS
39 config GENERIC_CLOCKEVENTS_BROADCAST
42 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
44 config LOCKDEP_SUPPORT
48 config STACKTRACE_SUPPORT
52 config SEMAPHORE_SLEEPERS
71 config GENERIC_ISA_DMA
84 config GENERIC_HWEIGHT
88 config ARCH_MAY_HAVE_PC_FDC
96 config RWSEM_GENERIC_SPINLOCK
99 config RWSEM_XCHGADD_ALGORITHM
102 config ARCH_HAS_ILOG2_U32
105 config ARCH_HAS_ILOG2_U64
108 config GENERIC_CALIBRATE_DELAY
111 config GENERIC_TIME_VSYSCALL
123 config ARCH_POPULATES_NODE_MAP
130 # Use the generic interrupt handling code in kernel/irq/:
131 config GENERIC_HARDIRQS
135 config GENERIC_IRQ_PROBE
139 config GENERIC_PENDING_IRQ
141 depends on GENERIC_HARDIRQS && SMP
146 depends on X86_32 && SMP && !X86_VOYAGER
151 depends on SMP && !(X86_VISWS || X86_VOYAGER || MK8)
154 config X86_BIOS_REBOOT
156 depends on X86_32 && !(X86_VISWS || X86_VOYAGER)
159 config X86_TRAMPOLINE
161 depends on X86_SMP || (X86_VOYAGER && SMP)
166 source "init/Kconfig"
168 menu "Processor type and features"
170 source "kernel/time/Kconfig"
173 bool "Symmetric multi-processing support"
175 This enables support for systems with more than one CPU. If you have
176 a system with only one CPU, like most personal computers, say N. If
177 you have a system with more than one CPU, say Y.
179 If you say N here, the kernel will run on single and multiprocessor
180 machines, but will use only one CPU of a multiprocessor machine. If
181 you say Y here, the kernel will run on many, but not all,
182 singleprocessor machines. On a singleprocessor machine, the kernel
183 will run faster if you say N here.
185 Note that if you say Y here and choose architecture "586" or
186 "Pentium" under "Processor family", the kernel will not work on 486
187 architectures. Similarly, multiprocessor kernels for the "PPro"
188 architecture may not work on all Pentium based boards.
190 People using multiprocessor machines who say Y here should also say
191 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
192 Management" code will be disabled if you say Y here.
194 See also the <file:Documentation/smp.txt>,
195 <file:Documentation/i386/IO-APIC.txt>,
196 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
197 <http://www.tldp.org/docs.html#howto>.
199 If you don't know what to do here, say N.
202 prompt "Subarchitecture Type"
208 Choose this option if your computer is a standard PC or compatible.
214 Select this for an AMD Elan processor.
216 Do not use this option for K6/Athlon/Opteron processors!
218 If unsure, choose "PC-compatible" instead.
223 select SMP if !BROKEN
225 Voyager is an MCA-based 32-way capable SMP architecture proprietary
226 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
230 If you do not specifically know you have a Voyager based machine,
231 say N here, otherwise the kernel you build will not be bootable.
234 bool "NUMAQ (IBM/Sequent)"
239 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
240 multiquad box. This changes the way that processors are bootstrapped,
241 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
242 You will need a new lynxer.elf file to flash your firmware with - send
243 email to <Martin.Bligh@us.ibm.com>.
246 bool "Summit/EXA (IBM x440)"
247 depends on X86_32 && SMP
249 This option is needed for IBM systems that use the Summit/EXA chipset.
250 In particular, it is needed for the x440.
252 If you don't have one of these computers, you should say N here.
253 If you want to build a NUMA kernel, you must select ACPI.
256 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
257 depends on X86_32 && SMP
259 This option is needed for the systems that have more than 8 CPUs
260 and if the system is not of any sub-arch type above.
262 If you don't have such a system, you should say N here.
265 bool "SGI 320/540 (Visual Workstation)"
268 The SGI Visual Workstation series is an IA32-based workstation
269 based on SGI systems chips with some legacy PC hardware attached.
271 Say Y here to create a kernel to run on the SGI 320 or 540.
273 A kernel compiled for the Visual Workstation will not run on PCs
274 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
276 config X86_GENERICARCH
277 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
280 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
281 It is intended for a generic binary kernel.
282 If you want a NUMA kernel, select ACPI. We need SRAT for NUMA.
285 bool "Support for Unisys ES7000 IA32 series"
286 depends on X86_32 && SMP
288 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
289 supposed to run on an IA32-based Unisys ES7000 system.
290 Only choose this option if you have such a system, otherwise you
294 bool "Support for ScaleMP vSMP"
295 depends on X86_64 && PCI
297 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
298 supposed to run on these EM64T-based machines. Only choose this option
299 if you have one of these machines.
303 config SCHED_NO_NO_OMIT_FRAME_POINTER
304 bool "Single-depth WCHAN output"
308 Calculate simpler /proc/<PID>/wchan values. If this option
309 is disabled then wchan values will recurse back to the
310 caller function. This provides more accurate wchan values,
311 at the expense of slightly more scheduling overhead.
313 If in doubt, say "Y".
317 depends on X86_32 && !(X86_VISWS || X86_VOYAGER)
319 This changes the kernel so it can modify itself when it is run
320 under a hypervisor, potentially improving performance significantly
321 over full virtualization. However, when run without a hypervisor
322 the kernel is theoretically slower and slightly larger.
324 menuconfig PARAVIRT_GUEST
325 bool "Paravirtualized guest support"
328 Say Y here to get to see options related to running Linux under
329 various hypervisors. This option alone does not add any kernel code.
331 If you say N, all options in this submenu will be skipped and disabled.
335 source "arch/x86/xen/Kconfig"
338 bool "VMI Guest support"
340 depends on !(X86_VISWS || X86_VOYAGER)
342 VMI provides a paravirtualized interface to the VMware ESX server
343 (it could be used by other hypervisors in theory too, but is not
344 at the moment), by linking the kernel to a GPL-ed ROM module
345 provided by the hypervisor.
347 source "arch/x86/lguest/Kconfig"
354 depends on X86_32 && ACPI && NUMA && (X86_SUMMIT || X86_GENERICARCH)
357 config HAVE_ARCH_PARSE_SRAT
362 config X86_SUMMIT_NUMA
365 depends on X86_32 && NUMA && (X86_SUMMIT || X86_GENERICARCH)
367 config X86_CYCLONE_TIMER
370 depends on X86_32 && X86_SUMMIT || X86_GENERICARCH
372 config ES7000_CLUSTERED_APIC
375 depends on SMP && X86_ES7000 && MPENTIUMIII
377 source "arch/x86/Kconfig.cpu"
381 prompt "HPET Timer Support" if X86_32
384 Use the IA-PC HPET (High Precision Event Timer) to manage
385 time in preference to the PIT and RTC, if a HPET is
387 HPET is the next generation timer replacing legacy 8254s.
388 The HPET provides a stable time base on SMP
389 systems, unlike the TSC, but it is more expensive to access,
390 as it is off-chip. You can find the HPET spec at
391 <http://www.intel.com/hardwaredesign/hpetspec.htm>.
393 You can safely choose Y here. However, HPET will only be
394 activated if the platform and the BIOS support this feature.
395 Otherwise the 8254 will be used for timing services.
397 Choose N to continue using the legacy 8254 timer.
399 config HPET_EMULATE_RTC
401 depends on HPET_TIMER && RTC=y
404 # Mark as embedded because too many people got it wrong.
405 # The code disables itself when not needed.
407 bool "GART IOMMU support" if EMBEDDED
411 depends on X86_64 && PCI
413 Support for full DMA access of devices with 32bit memory access only
414 on systems with more than 3GB. This is usually needed for USB,
415 sound, many IDE/SATA chipsets and some other devices.
416 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
417 based hardware IOMMU and a software bounce buffer based IOMMU used
418 on Intel systems and as fallback.
419 The code is only active when needed (enough memory and limited
420 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
424 bool "IBM Calgary IOMMU support"
426 depends on X86_64 && PCI && EXPERIMENTAL
428 Support for hardware IOMMUs in IBM's xSeries x366 and x460
429 systems. Needed to run systems with more than 3GB of memory
430 properly with 32-bit PCI devices that do not support DAC
431 (Double Address Cycle). Calgary also supports bus level
432 isolation, where all DMAs pass through the IOMMU. This
433 prevents them from going anywhere except their intended
434 destination. This catches hard-to-find kernel bugs and
435 mis-behaving drivers and devices that do not use the DMA-API
436 properly to set up their DMA buffers. The IOMMU can be
437 turned off at boot time with the iommu=off parameter.
438 Normally the kernel will make the right choice by itself.
441 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
442 bool "Should Calgary be enabled by default?"
444 depends on CALGARY_IOMMU
446 Should Calgary be enabled by default? if you choose 'y', Calgary
447 will be used (if it exists). If you choose 'n', Calgary will not be
448 used even if it exists. If you choose 'n' and would like to use
449 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
452 # need this always selected by IOMMU for the VIA workaround
456 Support for software bounce buffers used on x86-64 systems
457 which don't have a hardware IOMMU (e.g. the current generation
458 of Intel's x86-64 CPUs). Using this PCI devices which can only
459 access 32-bits of memory can be used on systems with more than
460 3 GB of memory. If unsure, say Y.
464 int "Maximum number of CPUs (2-255)"
467 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
470 This allows you to specify the maximum number of CPUs which this
471 kernel will support. The maximum supported value is 255 and the
472 minimum value which makes sense is 2.
474 This is purely to save memory - each supported CPU adds
475 approximately eight kilobytes to the kernel image.
478 bool "SMT (Hyperthreading) scheduler support"
479 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
481 SMT scheduler support improves the CPU scheduler's decision making
482 when dealing with Intel Pentium 4 chips with HyperThreading at a
483 cost of slightly increased overhead in some places. If unsure say
487 bool "Multi-core scheduler support"
488 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
491 Multi-core scheduler support improves the CPU scheduler's decision
492 making when dealing with multi-core CPU chips at a cost of slightly
493 increased overhead in some places. If unsure say N here.
495 source "kernel/Kconfig.preempt"
498 bool "Local APIC support on uniprocessors"
499 depends on X86_32 && !SMP && !(X86_VISWS || X86_VOYAGER || X86_GENERICARCH)
501 A local APIC (Advanced Programmable Interrupt Controller) is an
502 integrated interrupt controller in the CPU. If you have a single-CPU
503 system which has a processor with a local APIC, you can say Y here to
504 enable and use it. If you say Y here even though your machine doesn't
505 have a local APIC, then the kernel will still run with no slowdown at
506 all. The local APIC supports CPU-generated self-interrupts (timer,
507 performance counters), and the NMI watchdog which detects hard
511 bool "IO-APIC support on uniprocessors"
512 depends on X86_UP_APIC
514 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
515 SMP-capable replacement for PC-style interrupt controllers. Most
516 SMP systems and many recent uniprocessor systems have one.
518 If you have a single-CPU system with an IO-APIC, you can say Y here
519 to use it. If you say Y here even though your machine doesn't have
520 an IO-APIC, then the kernel will still run with no slowdown at all.
522 config X86_LOCAL_APIC
524 depends on X86_64 || (X86_32 && (X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER) || X86_GENERICARCH))
529 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER)) || X86_GENERICARCH))
532 config X86_VISWS_APIC
534 depends on X86_32 && X86_VISWS
538 bool "Machine Check Exception"
539 depends on !X86_VOYAGER
541 Machine Check Exception support allows the processor to notify the
542 kernel if it detects a problem (e.g. overheating, component failure).
543 The action the kernel takes depends on the severity of the problem,
544 ranging from a warning message on the console, to halting the machine.
545 Your processor must be a Pentium or newer to support this - check the
546 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
547 have a design flaw which leads to false MCE events - hence MCE is
548 disabled on all P5 processors, unless explicitly enabled with "mce"
549 as a boot argument. Similarly, if MCE is built in and creates a
550 problem on some new non-standard machine, you can boot with "nomce"
551 to disable it. MCE support simply ignores non-MCE processors like
552 the 386 and 486, so nearly everyone can say Y here.
555 bool "Intel MCE features"
556 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
559 Additional support for intel specific MCE features such as
563 bool "AMD MCE features"
564 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
567 Additional support for AMD specific MCE features such as
568 the DRAM Error Threshold.
570 config X86_MCE_NONFATAL
571 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
572 depends on X86_32 && X86_MCE
574 Enabling this feature starts a timer that triggers every 5 seconds which
575 will look at the machine check registers to see if anything happened.
576 Non-fatal problems automatically get corrected (but still logged).
577 Disable this if you don't want to see these messages.
578 Seeing the messages this option prints out may be indicative of dying
579 or out-of-spec (ie, overclocked) hardware.
580 This option only does something on certain CPUs.
581 (AMD Athlon/Duron and Intel Pentium 4)
583 config X86_MCE_P4THERMAL
584 bool "check for P4 thermal throttling interrupt."
585 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
587 Enabling this feature will cause a message to be printed when the P4
588 enters thermal throttling.
591 bool "Enable VM86 support" if EMBEDDED
595 This option is required by programs like DOSEMU to run 16-bit legacy
596 code on X86 processors. It also may be needed by software like
597 XFree86 to initialize some video cards via BIOS. Disabling this
598 option saves about 6k.
601 tristate "Toshiba Laptop support"
604 This adds a driver to safely access the System Management Mode of
605 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
606 not work on models with a Phoenix BIOS. The System Management Mode
607 is used to set the BIOS and power saving options on Toshiba portables.
609 For information on utilities to make use of this driver see the
610 Toshiba Linux utilities web site at:
611 <http://www.buzzard.org.uk/toshiba/>.
613 Say Y if you intend to run this kernel on a Toshiba portable.
617 tristate "Dell laptop support"
620 This adds a driver to safely access the System Management Mode
621 of the CPU on the Dell Inspiron 8000. The System Management Mode
622 is used to read cpu temperature and cooling fan status and to
623 control the fans on the I8K portables.
625 This driver has been tested only on the Inspiron 8000 but it may
626 also work with other Dell laptops. You can force loading on other
627 models by passing the parameter `force=1' to the module. Use at
630 For information on utilities to make use of this driver see the
631 I8K Linux utilities web site at:
632 <http://people.debian.org/~dz/i8k/>
634 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
637 config X86_REBOOTFIXUPS
638 bool "Enable X86 board specific fixups for reboot"
639 depends on X86_32 && X86
642 This enables chipset and/or board specific fixups to be done
643 in order to get reboot to work correctly. This is only needed on
644 some combinations of hardware and BIOS. The symptom, for which
645 this config is intended, is when reboot ends with a stalled/hung
648 Currently, the only fixup is for the Geode machines using
649 CS5530A and CS5536 chipsets.
651 Say Y if you want to enable the fixup. Currently, it's safe to
652 enable this option even if you don't need it.
656 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
659 If you say Y here, you will be able to update the microcode on
660 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
661 Pentium III, Pentium 4, Xeon etc. You will obviously need the
662 actual microcode binary data itself which is not shipped with the
665 For latest news and information on obtaining all the required
666 ingredients for this driver, check:
667 <http://www.urbanmyth.org/microcode/>.
669 To compile this driver as a module, choose M here: the
670 module will be called microcode.
672 config MICROCODE_OLD_INTERFACE
678 tristate "/dev/cpu/*/msr - Model-specific register support"
680 This device gives privileged processes access to the x86
681 Model-Specific Registers (MSRs). It is a character device with
682 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
683 MSR accesses are directed to a specific CPU on multi-processor
687 tristate "/dev/cpu/*/cpuid - CPU information support"
689 This device gives processes access to the x86 CPUID instruction to
690 be executed on a specific processor. It is a character device
691 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
695 prompt "High Memory Support"
696 default HIGHMEM4G if !X86_NUMAQ
697 default HIGHMEM64G if X86_NUMAQ
702 depends on !X86_NUMAQ
704 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
705 However, the address space of 32-bit x86 processors is only 4
706 Gigabytes large. That means that, if you have a large amount of
707 physical memory, not all of it can be "permanently mapped" by the
708 kernel. The physical memory that's not permanently mapped is called
711 If you are compiling a kernel which will never run on a machine with
712 more than 1 Gigabyte total physical RAM, answer "off" here (default
713 choice and suitable for most users). This will result in a "3GB/1GB"
714 split: 3GB are mapped so that each process sees a 3GB virtual memory
715 space and the remaining part of the 4GB virtual memory space is used
716 by the kernel to permanently map as much physical memory as
719 If the machine has between 1 and 4 Gigabytes physical RAM, then
722 If more than 4 Gigabytes is used then answer "64GB" here. This
723 selection turns Intel PAE (Physical Address Extension) mode on.
724 PAE implements 3-level paging on IA32 processors. PAE is fully
725 supported by Linux, PAE mode is implemented on all recent Intel
726 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
727 then the kernel will not boot on CPUs that don't support PAE!
729 The actual amount of total physical memory will either be
730 auto detected or can be forced by using a kernel command line option
731 such as "mem=256M". (Try "man bootparam" or see the documentation of
732 your boot loader (lilo or loadlin) about how to pass options to the
733 kernel at boot time.)
735 If unsure, say "off".
739 depends on !X86_NUMAQ
741 Select this if you have a 32-bit processor and between 1 and 4
742 gigabytes of physical RAM.
746 depends on !M386 && !M486
749 Select this if you have a 32-bit processor and more than 4
750 gigabytes of physical RAM.
755 depends on EXPERIMENTAL
756 prompt "Memory split" if EMBEDDED
760 Select the desired split between kernel and user memory.
762 If the address range available to the kernel is less than the
763 physical memory installed, the remaining memory will be available
764 as "high memory". Accessing high memory is a little more costly
765 than low memory, as it needs to be mapped into the kernel first.
766 Note that increasing the kernel address space limits the range
767 available to user programs, making the address space there
768 tighter. Selecting anything other than the default 3G/1G split
769 will also likely make your kernel incompatible with binary-only
772 If you are not absolutely sure what you are doing, leave this
776 bool "3G/1G user/kernel split"
777 config VMSPLIT_3G_OPT
779 bool "3G/1G user/kernel split (for full 1G low memory)"
781 bool "2G/2G user/kernel split"
782 config VMSPLIT_2G_OPT
784 bool "2G/2G user/kernel split (for full 2G low memory)"
786 bool "1G/3G user/kernel split"
791 default 0xB0000000 if VMSPLIT_3G_OPT
792 default 0x80000000 if VMSPLIT_2G
793 default 0x78000000 if VMSPLIT_2G_OPT
794 default 0x40000000 if VMSPLIT_1G
800 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
804 bool "PAE (Physical Address Extension) Support"
806 depends on X86_32 && !HIGHMEM4G
807 select RESOURCES_64BIT
809 PAE is required for NX support, and furthermore enables
810 larger swapspace support for non-overcommit purposes. It
811 has the cost of more pagetable lookup overhead, and also
812 consumes more pagetable space per process.
814 # Common NUMA Features
816 bool "Numa Memory Allocation and Scheduler Support (EXPERIMENTAL)"
818 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT || X86_GENERICARCH) && ACPI) && EXPERIMENTAL)
820 default y if (X86_NUMAQ || X86_SUMMIT)
822 Enable NUMA (Non Uniform Memory Access) support.
823 The kernel will try to allocate memory used by a CPU on the
824 local memory controller of the CPU and add some more
825 NUMA awareness to the kernel.
827 For i386 this is currently highly experimental and should be only
828 used for kernel development. It might also cause boot failures.
829 For x86_64 this is recommended on all multiprocessor Opteron systems.
830 If the system is EM64T, you should say N unless your system is
833 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
834 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
837 bool "Old style AMD Opteron NUMA detection"
838 depends on X86_64 && NUMA && PCI
841 Enable K8 NUMA node topology detection. You should say Y here if
842 you have a multi processor AMD K8 system. This uses an old
843 method to read the NUMA configuration directly from the builtin
844 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
845 instead, which also takes priority if both are compiled in.
847 config X86_64_ACPI_NUMA
848 bool "ACPI NUMA detection"
849 depends on X86_64 && NUMA && ACPI && PCI
853 Enable ACPI SRAT based node topology detection.
856 bool "NUMA emulation"
857 depends on X86_64 && NUMA
859 Enable NUMA emulation. A flat machine will be split
860 into virtual nodes when booted with "numa=fake=N", where N is the
861 number of nodes. This is only useful for debugging.
865 default "6" if X86_64
866 default "4" if X86_NUMAQ
868 depends on NEED_MULTIPLE_NODES
870 config HAVE_ARCH_BOOTMEM_NODE
872 depends on X86_32 && NUMA
875 config ARCH_HAVE_MEMORY_PRESENT
877 depends on X86_32 && DISCONTIGMEM
880 config NEED_NODE_MEMMAP_SIZE
882 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
885 config HAVE_ARCH_ALLOC_REMAP
887 depends on X86_32 && NUMA
890 config ARCH_FLATMEM_ENABLE
892 depends on (X86_32 && ARCH_SELECT_MEMORY_MODEL && X86_PC) || (X86_64 && !NUMA)
894 config ARCH_DISCONTIGMEM_ENABLE
898 config ARCH_DISCONTIGMEM_DEFAULT
902 config ARCH_SPARSEMEM_ENABLE
904 depends on NUMA || (EXPERIMENTAL && (X86_PC || X86_64))
905 select SPARSEMEM_STATIC if X86_32
906 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
908 config ARCH_SELECT_MEMORY_MODEL
910 depends on X86_32 && ARCH_SPARSEMEM_ENABLE
912 config ARCH_MEMORY_PROBE
914 depends on MEMORY_HOTPLUG
919 bool "Allocate 3rd-level pagetables from highmem"
920 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
922 The VM uses one page table entry for each page of physical memory.
923 For systems with a lot of RAM, this can be wasteful of precious
924 low memory. Setting this option will put user-space page table
925 entries in high memory.
927 config MATH_EMULATION
929 prompt "Math emulation" if X86_32
931 Linux can emulate a math coprocessor (used for floating point
932 operations) if you don't have one. 486DX and Pentium processors have
933 a math coprocessor built in, 486SX and 386 do not, unless you added
934 a 487DX or 387, respectively. (The messages during boot time can
935 give you some hints here ["man dmesg"].) Everyone needs either a
936 coprocessor or this emulation.
938 If you don't have a math coprocessor, you need to say Y here; if you
939 say Y here even though you have a coprocessor, the coprocessor will
940 be used nevertheless. (This behavior can be changed with the kernel
941 command line option "no387", which comes handy if your coprocessor
942 is broken. Try "man bootparam" or see the documentation of your boot
943 loader (lilo or loadlin) about how to pass options to the kernel at
944 boot time.) This means that it is a good idea to say Y here if you
945 intend to use this kernel on different machines.
947 More information about the internals of the Linux math coprocessor
948 emulation can be found in <file:arch/x86/math-emu/README>.
950 If you are not sure, say Y; apart from resulting in a 66 KB bigger
951 kernel, it won't hurt.
954 bool "MTRR (Memory Type Range Register) support"
956 On Intel P6 family processors (Pentium Pro, Pentium II and later)
957 the Memory Type Range Registers (MTRRs) may be used to control
958 processor access to memory ranges. This is most useful if you have
959 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
960 allows bus write transfers to be combined into a larger transfer
961 before bursting over the PCI/AGP bus. This can increase performance
962 of image write operations 2.5 times or more. Saying Y here creates a
963 /proc/mtrr file which may be used to manipulate your processor's
964 MTRRs. Typically the X server should use this.
966 This code has a reasonably generic interface so that similar
967 control registers on other processors can be easily supported
970 The Cyrix 6x86, 6x86MX and M II processors have Address Range
971 Registers (ARRs) which provide a similar functionality to MTRRs. For
972 these, the ARRs are used to emulate the MTRRs.
973 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
974 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
975 write-combining. All of these processors are supported by this code
976 and it makes sense to say Y here if you have one of them.
978 Saying Y here also fixes a problem with buggy SMP BIOSes which only
979 set the MTRRs for the boot CPU and not for the secondary CPUs. This
980 can lead to all sorts of problems, so it's good to say Y here.
982 You can safely say Y even if your machine doesn't have MTRRs, you'll
983 just add about 9 KB to your kernel.
985 See <file:Documentation/mtrr.txt> for more information.
988 bool "Boot from EFI support"
989 depends on X86_32 && ACPI
992 This enables the kernel to boot on EFI platforms using
993 system configuration information passed to it from the firmware.
994 This also enables the kernel to use any 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 and will result in a kernel image that is ~8k larger. In addition,
999 you must use the latest ELILO loader available at
1000 <http://elilo.sourceforge.net> in order to take advantage of
1001 kernel initialization using EFI information (neither GRUB nor LILO know
1002 anything about EFI). However, even with this option, the resultant
1003 kernel should continue to boot on existing non-EFI platforms.
1006 bool "Enable kernel irq balancing"
1007 depends on X86_32 && SMP && X86_IO_APIC
1010 The default yes will allow the kernel to do irq load balancing.
1011 Saying no will keep the kernel from doing irq load balancing.
1013 # turning this on wastes a bunch of space.
1014 # Summit needs it only when NUMA is on
1017 depends on X86_32 && (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
1021 bool "Enable seccomp to safely compute untrusted bytecode"
1025 This kernel feature is useful for number crunching applications
1026 that may need to compute untrusted bytecode during their
1027 execution. By using pipes or other transports made available to
1028 the process as file descriptors supporting the read/write
1029 syscalls, it's possible to isolate those applications in
1030 their own address space using seccomp. Once seccomp is
1031 enabled via /proc/<pid>/seccomp, it cannot be disabled
1032 and the task is only allowed to execute a few safe syscalls
1033 defined by each seccomp mode.
1035 If unsure, say Y. Only embedded should say N here.
1037 config CC_STACKPROTECTOR
1038 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1039 depends on X86_64 && EXPERIMENTAL
1041 This option turns on the -fstack-protector GCC feature. This
1042 feature puts, at the beginning of critical functions, a canary
1043 value on the stack just before the return address, and validates
1044 the value just before actually returning. Stack based buffer
1045 overflows (that need to overwrite this return address) now also
1046 overwrite the canary, which gets detected and the attack is then
1047 neutralized via a kernel panic.
1049 This feature requires gcc version 4.2 or above, or a distribution
1050 gcc with the feature backported. Older versions are automatically
1051 detected and for those versions, this configuration option is ignored.
1053 config CC_STACKPROTECTOR_ALL
1054 bool "Use stack-protector for all functions"
1055 depends on CC_STACKPROTECTOR
1057 Normally, GCC only inserts the canary value protection for
1058 functions that use large-ish on-stack buffers. By enabling
1059 this option, GCC will be asked to do this for ALL functions.
1061 source kernel/Kconfig.hz
1064 bool "kexec system call"
1066 kexec is a system call that implements the ability to shutdown your
1067 current kernel, and to start another kernel. It is like a reboot
1068 but it is independent of the system firmware. And like a reboot
1069 you can start any kernel with it, not just Linux.
1071 The name comes from the similarity to the exec system call.
1073 It is an ongoing process to be certain the hardware in a machine
1074 is properly shutdown, so do not be surprised if this code does not
1075 initially work for you. It may help to enable device hotplugging
1076 support. As of this writing the exact hardware interface is
1077 strongly in flux, so no good recommendation can be made.
1080 bool "kernel crash dumps (EXPERIMENTAL)"
1081 depends on EXPERIMENTAL
1082 depends on X86_64 || (X86_32 && HIGHMEM)
1084 Generate crash dump after being started by kexec.
1085 This should be normally only set in special crash dump kernels
1086 which are loaded in the main kernel with kexec-tools into
1087 a specially reserved region and then later executed after
1088 a crash by kdump/kexec. The crash dump kernel must be compiled
1089 to a memory address not used by the main kernel or BIOS using
1090 PHYSICAL_START, or it must be built as a relocatable image
1091 (CONFIG_RELOCATABLE=y).
1092 For more details see Documentation/kdump/kdump.txt
1094 config PHYSICAL_START
1095 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1096 default "0x1000000" if X86_NUMAQ
1097 default "0x200000" if X86_64
1100 This gives the physical address where the kernel is loaded.
1102 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1103 bzImage will decompress itself to above physical address and
1104 run from there. Otherwise, bzImage will run from the address where
1105 it has been loaded by the boot loader and will ignore above physical
1108 In normal kdump cases one does not have to set/change this option
1109 as now bzImage can be compiled as a completely relocatable image
1110 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1111 address. This option is mainly useful for the folks who don't want
1112 to use a bzImage for capturing the crash dump and want to use a
1113 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1114 to be specifically compiled to run from a specific memory area
1115 (normally a reserved region) and this option comes handy.
1117 So if you are using bzImage for capturing the crash dump, leave
1118 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1119 Otherwise if you plan to use vmlinux for capturing the crash dump
1120 change this value to start of the reserved region (Typically 16MB
1121 0x1000000). In other words, it can be set based on the "X" value as
1122 specified in the "crashkernel=YM@XM" command line boot parameter
1123 passed to the panic-ed kernel. Typically this parameter is set as
1124 crashkernel=64M@16M. Please take a look at
1125 Documentation/kdump/kdump.txt for more details about crash dumps.
1127 Usage of bzImage for capturing the crash dump is recommended as
1128 one does not have to build two kernels. Same kernel can be used
1129 as production kernel and capture kernel. Above option should have
1130 gone away after relocatable bzImage support is introduced. But it
1131 is present because there are users out there who continue to use
1132 vmlinux for dump capture. This option should go away down the
1135 Don't change this unless you know what you are doing.
1138 bool "Build a relocatable kernel (EXPERIMENTAL)"
1139 depends on EXPERIMENTAL
1141 This builds a kernel image that retains relocation information
1142 so it can be loaded someplace besides the default 1MB.
1143 The relocations tend to make the kernel binary about 10% larger,
1144 but are discarded at runtime.
1146 One use is for the kexec on panic case where the recovery kernel
1147 must live at a different physical address than the primary
1150 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1151 it has been loaded at and the compile time physical address
1152 (CONFIG_PHYSICAL_START) is ignored.
1154 config PHYSICAL_ALIGN
1156 prompt "Alignment value to which kernel should be aligned" if X86_32
1157 default "0x100000" if X86_32
1158 default "0x200000" if X86_64
1159 range 0x2000 0x400000
1161 This value puts the alignment restrictions on physical address
1162 where kernel is loaded and run from. Kernel is compiled for an
1163 address which meets above alignment restriction.
1165 If bootloader loads the kernel at a non-aligned address and
1166 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1167 address aligned to above value and run from there.
1169 If bootloader loads the kernel at a non-aligned address and
1170 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1171 load address and decompress itself to the address it has been
1172 compiled for and run from there. The address for which kernel is
1173 compiled already meets above alignment restrictions. Hence the
1174 end result is that kernel runs from a physical address meeting
1175 above alignment restrictions.
1177 Don't change this unless you know what you are doing.
1180 bool "Support for suspend on SMP and hot-pluggable CPUs (EXPERIMENTAL)"
1181 depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER
1183 Say Y here to experiment with turning CPUs off and on, and to
1184 enable suspend on SMP systems. CPUs can be controlled through
1185 /sys/devices/system/cpu.
1186 Say N if you want to disable CPU hotplug and don't need to
1190 bool "Compat VDSO support"
1194 Map the VDSO to the predictable old-style address too.
1196 Say N here if you are running a sufficiently recent glibc
1197 version (2.3.3 or later), to remove the high-mapped
1198 VDSO mapping and to exclusively use the randomized VDSO.
1204 config ARCH_ENABLE_MEMORY_HOTPLUG
1206 depends on X86_64 || (X86_32 && HIGHMEM)
1208 config MEMORY_HOTPLUG_RESERVE
1210 depends on (MEMORY_HOTPLUG && DISCONTIGMEM)
1212 config HAVE_ARCH_EARLY_PFN_TO_NID
1216 config OUT_OF_LINE_PFN_TO_PAGE
1218 depends on DISCONTIGMEM
1220 menu "Power management options"
1221 depends on !X86_VOYAGER
1223 config ARCH_HIBERNATION_HEADER
1225 depends on X86_64 && HIBERNATION
1228 source "kernel/power/Kconfig"
1230 source "drivers/acpi/Kconfig"
1233 tristate "APM (Advanced Power Management) BIOS support"
1234 depends on X86_32 && PM_SLEEP && !X86_VISWS
1236 APM is a BIOS specification for saving power using several different
1237 techniques. This is mostly useful for battery powered laptops with
1238 APM compliant BIOSes. If you say Y here, the system time will be
1239 reset after a RESUME operation, the /proc/apm device will provide
1240 battery status information, and user-space programs will receive
1241 notification of APM "events" (e.g. battery status change).
1243 If you select "Y" here, you can disable actual use of the APM
1244 BIOS by passing the "apm=off" option to the kernel at boot time.
1246 Note that the APM support is almost completely disabled for
1247 machines with more than one CPU.
1249 In order to use APM, you will need supporting software. For location
1250 and more information, read <file:Documentation/pm.txt> and the
1251 Battery Powered Linux mini-HOWTO, available from
1252 <http://www.tldp.org/docs.html#howto>.
1254 This driver does not spin down disk drives (see the hdparm(8)
1255 manpage ("man 8 hdparm") for that), and it doesn't turn off
1256 VESA-compliant "green" monitors.
1258 This driver does not support the TI 4000M TravelMate and the ACER
1259 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1260 desktop machines also don't have compliant BIOSes, and this driver
1261 may cause those machines to panic during the boot phase.
1263 Generally, if you don't have a battery in your machine, there isn't
1264 much point in using this driver and you should say N. If you get
1265 random kernel OOPSes or reboots that don't seem to be related to
1266 anything, try disabling/enabling this option (or disabling/enabling
1269 Some other things you should try when experiencing seemingly random,
1272 1) make sure that you have enough swap space and that it is
1274 2) pass the "no-hlt" option to the kernel
1275 3) switch on floating point emulation in the kernel and pass
1276 the "no387" option to the kernel
1277 4) pass the "floppy=nodma" option to the kernel
1278 5) pass the "mem=4M" option to the kernel (thereby disabling
1279 all but the first 4 MB of RAM)
1280 6) make sure that the CPU is not over clocked.
1281 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1282 8) disable the cache from your BIOS settings
1283 9) install a fan for the video card or exchange video RAM
1284 10) install a better fan for the CPU
1285 11) exchange RAM chips
1286 12) exchange the motherboard.
1288 To compile this driver as a module, choose M here: the
1289 module will be called apm.
1293 config APM_IGNORE_USER_SUSPEND
1294 bool "Ignore USER SUSPEND"
1296 This option will ignore USER SUSPEND requests. On machines with a
1297 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1298 series notebooks, it is necessary to say Y because of a BIOS bug.
1300 config APM_DO_ENABLE
1301 bool "Enable PM at boot time"
1303 Enable APM features at boot time. From page 36 of the APM BIOS
1304 specification: "When disabled, the APM BIOS does not automatically
1305 power manage devices, enter the Standby State, enter the Suspend
1306 State, or take power saving steps in response to CPU Idle calls."
1307 This driver will make CPU Idle calls when Linux is idle (unless this
1308 feature is turned off -- see "Do CPU IDLE calls", below). This
1309 should always save battery power, but more complicated APM features
1310 will be dependent on your BIOS implementation. You may need to turn
1311 this option off if your computer hangs at boot time when using APM
1312 support, or if it beeps continuously instead of suspending. Turn
1313 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1314 T400CDT. This is off by default since most machines do fine without
1318 bool "Make CPU Idle calls when idle"
1320 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1321 On some machines, this can activate improved power savings, such as
1322 a slowed CPU clock rate, when the machine is idle. These idle calls
1323 are made after the idle loop has run for some length of time (e.g.,
1324 333 mS). On some machines, this will cause a hang at boot time or
1325 whenever the CPU becomes idle. (On machines with more than one CPU,
1326 this option does nothing.)
1328 config APM_DISPLAY_BLANK
1329 bool "Enable console blanking using APM"
1331 Enable console blanking using the APM. Some laptops can use this to
1332 turn off the LCD backlight when the screen blanker of the Linux
1333 virtual console blanks the screen. Note that this is only used by
1334 the virtual console screen blanker, and won't turn off the backlight
1335 when using the X Window system. This also doesn't have anything to
1336 do with your VESA-compliant power-saving monitor. Further, this
1337 option doesn't work for all laptops -- it might not turn off your
1338 backlight at all, or it might print a lot of errors to the console,
1339 especially if you are using gpm.
1341 config APM_ALLOW_INTS
1342 bool "Allow interrupts during APM BIOS calls"
1344 Normally we disable external interrupts while we are making calls to
1345 the APM BIOS as a measure to lessen the effects of a badly behaving
1346 BIOS implementation. The BIOS should reenable interrupts if it
1347 needs to. Unfortunately, some BIOSes do not -- especially those in
1348 many of the newer IBM Thinkpads. If you experience hangs when you
1349 suspend, try setting this to Y. Otherwise, say N.
1351 config APM_REAL_MODE_POWER_OFF
1352 bool "Use real mode APM BIOS call to power off"
1354 Use real mode APM BIOS calls to switch off the computer. This is
1355 a work-around for a number of buggy BIOSes. Switch this option on if
1356 your computer crashes instead of powering off properly.
1360 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1362 source "drivers/cpuidle/Kconfig"
1367 menu "Bus options (PCI etc.)"
1370 bool "PCI support" if !X86_VISWS
1371 depends on !X86_VOYAGER
1372 default y if X86_VISWS
1373 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1375 Find out whether you have a PCI motherboard. PCI is the name of a
1376 bus system, i.e. the way the CPU talks to the other stuff inside
1377 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1378 VESA. If you have PCI, say Y, otherwise N.
1380 The PCI-HOWTO, available from
1381 <http://www.tldp.org/docs.html#howto>, contains valuable
1382 information about which PCI hardware does work under Linux and which
1386 prompt "PCI access mode"
1387 depends on X86_32 && PCI && !X86_VISWS
1390 On PCI systems, the BIOS can be used to detect the PCI devices and
1391 determine their configuration. However, some old PCI motherboards
1392 have BIOS bugs and may crash if this is done. Also, some embedded
1393 PCI-based systems don't have any BIOS at all. Linux can also try to
1394 detect the PCI hardware directly without using the BIOS.
1396 With this option, you can specify how Linux should detect the
1397 PCI devices. If you choose "BIOS", the BIOS will be used,
1398 if you choose "Direct", the BIOS won't be used, and if you
1399 choose "MMConfig", then PCI Express MMCONFIG will be used.
1400 If you choose "Any", the kernel will try MMCONFIG, then the
1401 direct access method and falls back to the BIOS if that doesn't
1402 work. If unsure, go with the default, which is "Any".
1407 config PCI_GOMMCONFIG
1420 depends on X86_32 && !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1423 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1426 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1431 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1440 bool "Support mmconfig PCI config space access"
1441 depends on X86_64 && PCI && ACPI
1444 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1445 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1447 DMA remapping (DMAR) devices support enables independent address
1448 translations for Direct Memory Access (DMA) from devices.
1449 These DMA remapping devices are reported via ACPI tables
1450 and include PCI device scope covered by these DMA
1454 bool "Support for Graphics workaround"
1458 Current Graphics drivers tend to use physical address
1459 for DMA and avoid using DMA APIs. Setting this config
1460 option permits the IOMMU driver to set a unity map for
1461 all the OS-visible memory. Hence the driver can continue
1462 to use physical addresses for DMA.
1464 config DMAR_FLOPPY_WA
1469 Floppy disk drivers are know to bypass DMA API calls
1470 thereby failing to work when IOMMU is enabled. This
1471 workaround will setup a 1:1 mapping for the first
1472 16M to make floppy (an ISA device) work.
1474 source "drivers/pci/pcie/Kconfig"
1476 source "drivers/pci/Kconfig"
1478 # x86_64 have no ISA slots, but do have ISA-style DMA.
1487 depends on !(X86_VOYAGER || X86_VISWS)
1489 Find out whether you have ISA slots on your motherboard. ISA is the
1490 name of a bus system, i.e. the way the CPU talks to the other stuff
1491 inside your box. Other bus systems are PCI, EISA, MicroChannel
1492 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1493 newer boards don't support it. If you have ISA, say Y, otherwise N.
1499 The Extended Industry Standard Architecture (EISA) bus was
1500 developed as an open alternative to the IBM MicroChannel bus.
1502 The EISA bus provided some of the features of the IBM MicroChannel
1503 bus while maintaining backward compatibility with cards made for
1504 the older ISA bus. The EISA bus saw limited use between 1988 and
1505 1995 when it was made obsolete by the PCI bus.
1507 Say Y here if you are building a kernel for an EISA-based machine.
1511 source "drivers/eisa/Kconfig"
1514 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1515 default y if X86_VOYAGER
1517 MicroChannel Architecture is found in some IBM PS/2 machines and
1518 laptops. It is a bus system similar to PCI or ISA. See
1519 <file:Documentation/mca.txt> (and especially the web page given
1520 there) before attempting to build an MCA bus kernel.
1522 source "drivers/mca/Kconfig"
1525 tristate "NatSemi SCx200 support"
1526 depends on !X86_VOYAGER
1528 This provides basic support for National Semiconductor's
1529 (now AMD's) Geode processors. The driver probes for the
1530 PCI-IDs of several on-chip devices, so its a good dependency
1531 for other scx200_* drivers.
1533 If compiled as a module, the driver is named scx200.
1535 config SCx200HR_TIMER
1536 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1537 depends on SCx200 && GENERIC_TIME
1540 This driver provides a clocksource built upon the on-chip
1541 27MHz high-resolution timer. Its also a workaround for
1542 NSC Geode SC-1100's buggy TSC, which loses time when the
1543 processor goes idle (as is done by the scheduler). The
1544 other workaround is idle=poll boot option.
1546 config GEODE_MFGPT_TIMER
1547 bool "Geode Multi-Function General Purpose Timer (MFGPT) events"
1548 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1551 This driver provides a clock event source based on the MFGPT
1552 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1553 MFGPTs have a better resolution and max interval than the
1554 generic PIT, and are suitable for use as high-res timers.
1560 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1562 source "drivers/pcmcia/Kconfig"
1564 source "drivers/pci/hotplug/Kconfig"
1569 menu "Executable file formats / Emulations"
1571 source "fs/Kconfig.binfmt"
1573 config IA32_EMULATION
1574 bool "IA32 Emulation"
1577 Include code to run 32-bit programs under a 64-bit kernel. You should
1578 likely turn this on, unless you're 100% sure that you don't have any
1579 32-bit programs left.
1582 tristate "IA32 a.out support"
1583 depends on IA32_EMULATION
1585 Support old a.out binaries in the 32bit emulation.
1589 depends on IA32_EMULATION
1592 config COMPAT_FOR_U64_ALIGNMENT
1596 config SYSVIPC_COMPAT
1598 depends on X86_64 && COMPAT && SYSVIPC
1604 source "net/Kconfig"
1606 source "drivers/Kconfig"
1608 source "drivers/firmware/Kconfig"
1612 source "kernel/Kconfig.instrumentation"
1614 source "arch/x86/Kconfig.debug"
1616 source "security/Kconfig"
1618 source "crypto/Kconfig"
1620 source "lib/Kconfig"
projects / linux-2.6 / blob