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
75 config ARCH_MAY_HAVE_PC_FDC
81 config RWSEM_GENERIC_SPINLOCK
84 config RWSEM_XCHGADD_ALGORITHM
87 config ARCH_HAS_ILOG2_U32
90 config ARCH_HAS_ILOG2_U64
93 config GENERIC_CALIBRATE_DELAY
96 config GENERIC_TIME_VSYSCALL
100 config ARCH_SUPPORTS_OPROFILE
109 config ARCH_POPULATES_NODE_MAP
116 # Use the generic interrupt handling code in kernel/irq/:
117 config GENERIC_HARDIRQS
121 config GENERIC_IRQ_PROBE
125 config GENERIC_PENDING_IRQ
127 depends on GENERIC_HARDIRQS && SMP
132 depends on SMP && ((X86_32 && !X86_VOYAGER) || X86_64)
137 depends on X86_32 && SMP
141 depends on X86_64 && SMP
146 depends on (X86_32 && !(X86_VISWS || X86_VOYAGER)) || (X86_64 && !MK8)
149 config X86_BIOS_REBOOT
151 depends on X86_32 && !(X86_VISWS || X86_VOYAGER)
154 config X86_TRAMPOLINE
156 depends on X86_SMP || (X86_VOYAGER && SMP)
161 source "init/Kconfig"
163 menu "Processor type and features"
165 source "kernel/time/Kconfig"
168 bool "Symmetric multi-processing support"
170 This enables support for systems with more than one CPU. If you have
171 a system with only one CPU, like most personal computers, say N. If
172 you have a system with more than one CPU, say Y.
174 If you say N here, the kernel will run on single and multiprocessor
175 machines, but will use only one CPU of a multiprocessor machine. If
176 you say Y here, the kernel will run on many, but not all,
177 singleprocessor machines. On a singleprocessor machine, the kernel
178 will run faster if you say N here.
180 Note that if you say Y here and choose architecture "586" or
181 "Pentium" under "Processor family", the kernel will not work on 486
182 architectures. Similarly, multiprocessor kernels for the "PPro"
183 architecture may not work on all Pentium based boards.
185 People using multiprocessor machines who say Y here should also say
186 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
187 Management" code will be disabled if you say Y here.
189 See also the <file:Documentation/smp.txt>,
190 <file:Documentation/i386/IO-APIC.txt>,
191 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
192 <http://www.tldp.org/docs.html#howto>.
194 If you don't know what to do here, say N.
197 prompt "Subarchitecture Type"
203 Choose this option if your computer is a standard PC or compatible.
209 Select this for an AMD Elan processor.
211 Do not use this option for K6/Athlon/Opteron processors!
213 If unsure, choose "PC-compatible" instead.
218 select SMP if !BROKEN
220 Voyager is an MCA-based 32-way capable SMP architecture proprietary
221 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
225 If you do not specifically know you have a Voyager based machine,
226 say N here, otherwise the kernel you build will not be bootable.
229 bool "NUMAQ (IBM/Sequent)"
234 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
235 multiquad box. This changes the way that processors are bootstrapped,
236 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
237 You will need a new lynxer.elf file to flash your firmware with - send
238 email to <Martin.Bligh@us.ibm.com>.
241 bool "Summit/EXA (IBM x440)"
242 depends on X86_32 && SMP
244 This option is needed for IBM systems that use the Summit/EXA chipset.
245 In particular, it is needed for the x440.
247 If you don't have one of these computers, you should say N here.
248 If you want to build a NUMA kernel, you must select ACPI.
251 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
252 depends on X86_32 && SMP
254 This option is needed for the systems that have more than 8 CPUs
255 and if the system is not of any sub-arch type above.
257 If you don't have such a system, you should say N here.
260 bool "SGI 320/540 (Visual Workstation)"
263 The SGI Visual Workstation series is an IA32-based workstation
264 based on SGI systems chips with some legacy PC hardware attached.
266 Say Y here to create a kernel to run on the SGI 320 or 540.
268 A kernel compiled for the Visual Workstation will not run on PCs
269 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
271 config X86_GENERICARCH
272 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
275 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
276 It is intended for a generic binary kernel.
277 If you want a NUMA kernel, select ACPI. We need SRAT for NUMA.
280 bool "Support for Unisys ES7000 IA32 series"
281 depends on X86_32 && SMP
283 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
284 supposed to run on an IA32-based Unisys ES7000 system.
285 Only choose this option if you have such a system, otherwise you
289 bool "Support for ScaleMP vSMP"
290 depends on X86_64 && PCI
292 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
293 supposed to run on these EM64T-based machines. Only choose this option
294 if you have one of these machines.
298 config SCHED_NO_NO_OMIT_FRAME_POINTER
300 prompt "Single-depth WCHAN output"
303 Calculate simpler /proc/<PID>/wchan values. If this option
304 is disabled then wchan values will recurse back to the
305 caller function. This provides more accurate wchan values,
306 at the expense of slightly more scheduling overhead.
308 If in doubt, say "Y".
312 depends on X86_32 && !(X86_VISWS || X86_VOYAGER)
314 This changes the kernel so it can modify itself when it is run
315 under a hypervisor, potentially improving performance significantly
316 over full virtualization. However, when run without a hypervisor
317 the kernel is theoretically slower and slightly larger.
319 menuconfig PARAVIRT_GUEST
320 bool "Paravirtualized guest support"
323 Say Y here to get to see options related to running Linux under
324 various hypervisors. This option alone does not add any kernel code.
326 If you say N, all options in this submenu will be skipped and disabled.
330 source "arch/x86/xen/Kconfig"
333 bool "VMI Guest support"
335 depends on !(X86_VISWS || X86_VOYAGER)
337 VMI provides a paravirtualized interface to the VMware ESX server
338 (it could be used by other hypervisors in theory too, but is not
339 at the moment), by linking the kernel to a GPL-ed ROM module
340 provided by the hypervisor.
342 source "arch/x86/lguest/Kconfig"
348 depends on X86_32 && ACPI && NUMA && (X86_SUMMIT || X86_GENERICARCH)
351 config HAVE_ARCH_PARSE_SRAT
355 config X86_SUMMIT_NUMA
357 depends on X86_32 && NUMA && (X86_SUMMIT || X86_GENERICARCH)
359 config X86_CYCLONE_TIMER
361 depends on X86_32 && X86_SUMMIT || X86_GENERICARCH
363 config ES7000_CLUSTERED_APIC
365 depends on SMP && X86_ES7000 && MPENTIUMIII
367 source "arch/x86/Kconfig.cpu"
371 prompt "HPET Timer Support" if X86_32
373 Use the IA-PC HPET (High Precision Event Timer) to manage
374 time in preference to the PIT and RTC, if a HPET is
376 HPET is the next generation timer replacing legacy 8254s.
377 The HPET provides a stable time base on SMP
378 systems, unlike the TSC, but it is more expensive to access,
379 as it is off-chip. You can find the HPET spec at
380 <http://www.intel.com/hardwaredesign/hpetspec.htm>.
382 You can safely choose Y here. However, HPET will only be
383 activated if the platform and the BIOS support this feature.
384 Otherwise the 8254 will be used for timing services.
386 Choose N to continue using the legacy 8254 timer.
388 config HPET_EMULATE_RTC
390 depends on HPET_TIMER && RTC=y
392 # Mark as embedded because too many people got it wrong.
393 # The code disables itself when not needed.
395 bool "GART IOMMU support" if EMBEDDED
399 depends on X86_64 && PCI
401 Support for full DMA access of devices with 32bit memory access only
402 on systems with more than 3GB. This is usually needed for USB,
403 sound, many IDE/SATA chipsets and some other devices.
404 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
405 based hardware IOMMU and a software bounce buffer based IOMMU used
406 on Intel systems and as fallback.
407 The code is only active when needed (enough memory and limited
408 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
412 bool "IBM Calgary IOMMU support"
414 depends on X86_64 && PCI && EXPERIMENTAL
416 Support for hardware IOMMUs in IBM's xSeries x366 and x460
417 systems. Needed to run systems with more than 3GB of memory
418 properly with 32-bit PCI devices that do not support DAC
419 (Double Address Cycle). Calgary also supports bus level
420 isolation, where all DMAs pass through the IOMMU. This
421 prevents them from going anywhere except their intended
422 destination. This catches hard-to-find kernel bugs and
423 mis-behaving drivers and devices that do not use the DMA-API
424 properly to set up their DMA buffers. The IOMMU can be
425 turned off at boot time with the iommu=off parameter.
426 Normally the kernel will make the right choice by itself.
429 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
431 prompt "Should Calgary be enabled by default?"
432 depends on CALGARY_IOMMU
434 Should Calgary be enabled by default? if you choose 'y', Calgary
435 will be used (if it exists). If you choose 'n', Calgary will not be
436 used even if it exists. If you choose 'n' and would like to use
437 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
440 # need this always selected by IOMMU for the VIA workaround
444 Support for software bounce buffers used on x86-64 systems
445 which don't have a hardware IOMMU (e.g. the current generation
446 of Intel's x86-64 CPUs). Using this PCI devices which can only
447 access 32-bits of memory can be used on systems with more than
448 3 GB of memory. If unsure, say Y.
452 int "Maximum number of CPUs (2-255)"
455 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
458 This allows you to specify the maximum number of CPUs which this
459 kernel will support. The maximum supported value is 255 and the
460 minimum value which makes sense is 2.
462 This is purely to save memory - each supported CPU adds
463 approximately eight kilobytes to the kernel image.
466 bool "SMT (Hyperthreading) scheduler support"
467 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
469 SMT scheduler support improves the CPU scheduler's decision making
470 when dealing with Intel Pentium 4 chips with HyperThreading at a
471 cost of slightly increased overhead in some places. If unsure say
476 prompt "Multi-core scheduler support"
477 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
479 Multi-core scheduler support improves the CPU scheduler's decision
480 making when dealing with multi-core CPU chips at a cost of slightly
481 increased overhead in some places. If unsure say N here.
483 source "kernel/Kconfig.preempt"
486 bool "Local APIC support on uniprocessors"
487 depends on X86_32 && !SMP && !(X86_VISWS || X86_VOYAGER || X86_GENERICARCH)
489 A local APIC (Advanced Programmable Interrupt Controller) is an
490 integrated interrupt controller in the CPU. If you have a single-CPU
491 system which has a processor with a local APIC, you can say Y here to
492 enable and use it. If you say Y here even though your machine doesn't
493 have a local APIC, then the kernel will still run with no slowdown at
494 all. The local APIC supports CPU-generated self-interrupts (timer,
495 performance counters), and the NMI watchdog which detects hard
499 bool "IO-APIC support on uniprocessors"
500 depends on X86_UP_APIC
502 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
503 SMP-capable replacement for PC-style interrupt controllers. Most
504 SMP systems and many recent uniprocessor systems have one.
506 If you have a single-CPU system with an IO-APIC, you can say Y here
507 to use it. If you say Y here even though your machine doesn't have
508 an IO-APIC, then the kernel will still run with no slowdown at all.
510 config X86_LOCAL_APIC
512 depends on X86_64 || (X86_32 && (X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER) || X86_GENERICARCH))
516 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER)) || X86_GENERICARCH))
518 config X86_VISWS_APIC
520 depends on X86_32 && X86_VISWS
523 bool "Machine Check Exception"
524 depends on !X86_VOYAGER
526 Machine Check Exception support allows the processor to notify the
527 kernel if it detects a problem (e.g. overheating, component failure).
528 The action the kernel takes depends on the severity of the problem,
529 ranging from a warning message on the console, to halting the machine.
530 Your processor must be a Pentium or newer to support this - check the
531 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
532 have a design flaw which leads to false MCE events - hence MCE is
533 disabled on all P5 processors, unless explicitly enabled with "mce"
534 as a boot argument. Similarly, if MCE is built in and creates a
535 problem on some new non-standard machine, you can boot with "nomce"
536 to disable it. MCE support simply ignores non-MCE processors like
537 the 386 and 486, so nearly everyone can say Y here.
541 prompt "Intel MCE features"
542 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
544 Additional support for intel specific MCE features such as
549 prompt "AMD MCE features"
550 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
552 Additional support for AMD specific MCE features such as
553 the DRAM Error Threshold.
555 config X86_MCE_NONFATAL
556 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
557 depends on X86_32 && X86_MCE
559 Enabling this feature starts a timer that triggers every 5 seconds which
560 will look at the machine check registers to see if anything happened.
561 Non-fatal problems automatically get corrected (but still logged).
562 Disable this if you don't want to see these messages.
563 Seeing the messages this option prints out may be indicative of dying
564 or out-of-spec (ie, overclocked) hardware.
565 This option only does something on certain CPUs.
566 (AMD Athlon/Duron and Intel Pentium 4)
568 config X86_MCE_P4THERMAL
569 bool "check for P4 thermal throttling interrupt."
570 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
572 Enabling this feature will cause a message to be printed when the P4
573 enters thermal throttling.
576 bool "Enable VM86 support" if EMBEDDED
580 This option is required by programs like DOSEMU to run 16-bit legacy
581 code on X86 processors. It also may be needed by software like
582 XFree86 to initialize some video cards via BIOS. Disabling this
583 option saves about 6k.
586 tristate "Toshiba Laptop support"
589 This adds a driver to safely access the System Management Mode of
590 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
591 not work on models with a Phoenix BIOS. The System Management Mode
592 is used to set the BIOS and power saving options on Toshiba portables.
594 For information on utilities to make use of this driver see the
595 Toshiba Linux utilities web site at:
596 <http://www.buzzard.org.uk/toshiba/>.
598 Say Y if you intend to run this kernel on a Toshiba portable.
602 tristate "Dell laptop support"
605 This adds a driver to safely access the System Management Mode
606 of the CPU on the Dell Inspiron 8000. The System Management Mode
607 is used to read cpu temperature and cooling fan status and to
608 control the fans on the I8K portables.
610 This driver has been tested only on the Inspiron 8000 but it may
611 also work with other Dell laptops. You can force loading on other
612 models by passing the parameter `force=1' to the module. Use at
615 For information on utilities to make use of this driver see the
616 I8K Linux utilities web site at:
617 <http://people.debian.org/~dz/i8k/>
619 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
622 config X86_REBOOTFIXUPS
624 prompt "Enable X86 board specific fixups for reboot"
625 depends on X86_32 && X86
627 This enables chipset and/or board specific fixups to be done
628 in order to get reboot to work correctly. This is only needed on
629 some combinations of hardware and BIOS. The symptom, for which
630 this config is intended, is when reboot ends with a stalled/hung
633 Currently, the only fixup is for the Geode machines using
634 CS5530A and CS5536 chipsets.
636 Say Y if you want to enable the fixup. Currently, it's safe to
637 enable this option even if you don't need it.
641 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
644 If you say Y here, you will be able to update the microcode on
645 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
646 Pentium III, Pentium 4, Xeon etc. You will obviously need the
647 actual microcode binary data itself which is not shipped with the
650 For latest news and information on obtaining all the required
651 ingredients for this driver, check:
652 <http://www.urbanmyth.org/microcode/>.
654 To compile this driver as a module, choose M here: the
655 module will be called microcode.
657 config MICROCODE_OLD_INTERFACE
662 tristate "/dev/cpu/*/msr - Model-specific register support"
664 This device gives privileged processes access to the x86
665 Model-Specific Registers (MSRs). It is a character device with
666 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
667 MSR accesses are directed to a specific CPU on multi-processor
671 tristate "/dev/cpu/*/cpuid - CPU information support"
673 This device gives processes access to the x86 CPUID instruction to
674 be executed on a specific processor. It is a character device
675 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
679 prompt "High Memory Support"
680 default HIGHMEM4G if !X86_NUMAQ
681 default HIGHMEM64G if X86_NUMAQ
686 depends on !X86_NUMAQ
688 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
689 However, the address space of 32-bit x86 processors is only 4
690 Gigabytes large. That means that, if you have a large amount of
691 physical memory, not all of it can be "permanently mapped" by the
692 kernel. The physical memory that's not permanently mapped is called
695 If you are compiling a kernel which will never run on a machine with
696 more than 1 Gigabyte total physical RAM, answer "off" here (default
697 choice and suitable for most users). This will result in a "3GB/1GB"
698 split: 3GB are mapped so that each process sees a 3GB virtual memory
699 space and the remaining part of the 4GB virtual memory space is used
700 by the kernel to permanently map as much physical memory as
703 If the machine has between 1 and 4 Gigabytes physical RAM, then
706 If more than 4 Gigabytes is used then answer "64GB" here. This
707 selection turns Intel PAE (Physical Address Extension) mode on.
708 PAE implements 3-level paging on IA32 processors. PAE is fully
709 supported by Linux, PAE mode is implemented on all recent Intel
710 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
711 then the kernel will not boot on CPUs that don't support PAE!
713 The actual amount of total physical memory will either be
714 auto detected or can be forced by using a kernel command line option
715 such as "mem=256M". (Try "man bootparam" or see the documentation of
716 your boot loader (lilo or loadlin) about how to pass options to the
717 kernel at boot time.)
719 If unsure, say "off".
723 depends on !X86_NUMAQ
725 Select this if you have a 32-bit processor and between 1 and 4
726 gigabytes of physical RAM.
730 depends on !M386 && !M486
733 Select this if you have a 32-bit processor and more than 4
734 gigabytes of physical RAM.
739 depends on EXPERIMENTAL
740 prompt "Memory split" if EMBEDDED
744 Select the desired split between kernel and user memory.
746 If the address range available to the kernel is less than the
747 physical memory installed, the remaining memory will be available
748 as "high memory". Accessing high memory is a little more costly
749 than low memory, as it needs to be mapped into the kernel first.
750 Note that increasing the kernel address space limits the range
751 available to user programs, making the address space there
752 tighter. Selecting anything other than the default 3G/1G split
753 will also likely make your kernel incompatible with binary-only
756 If you are not absolutely sure what you are doing, leave this
760 bool "3G/1G user/kernel split"
761 config VMSPLIT_3G_OPT
763 bool "3G/1G user/kernel split (for full 1G low memory)"
765 bool "2G/2G user/kernel split"
766 config VMSPLIT_2G_OPT
768 bool "2G/2G user/kernel split (for full 2G low memory)"
770 bool "1G/3G user/kernel split"
775 default 0xB0000000 if VMSPLIT_3G_OPT
776 default 0x80000000 if VMSPLIT_2G
777 default 0x78000000 if VMSPLIT_2G_OPT
778 default 0x40000000 if VMSPLIT_1G
784 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
788 prompt "PAE (Physical Address Extension) Support"
789 depends on X86_32 && !HIGHMEM4G
790 select RESOURCES_64BIT
792 PAE is required for NX support, and furthermore enables
793 larger swapspace support for non-overcommit purposes. It
794 has the cost of more pagetable lookup overhead, and also
795 consumes more pagetable space per process.
797 # Common NUMA Features
799 bool "Numa Memory Allocation and Scheduler Support (EXPERIMENTAL)"
801 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT || X86_GENERICARCH) && ACPI) && EXPERIMENTAL)
803 default y if (X86_NUMAQ || X86_SUMMIT)
805 Enable NUMA (Non Uniform Memory Access) support.
806 The kernel will try to allocate memory used by a CPU on the
807 local memory controller of the CPU and add some more
808 NUMA awareness to the kernel.
810 For i386 this is currently highly experimental and should be only
811 used for kernel development. It might also cause boot failures.
812 For x86_64 this is recommended on all multiprocessor Opteron systems.
813 If the system is EM64T, you should say N unless your system is
816 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
817 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
821 prompt "Old style AMD Opteron NUMA detection"
822 depends on X86_64 && NUMA && PCI
824 Enable K8 NUMA node topology detection. You should say Y here if
825 you have a multi processor AMD K8 system. This uses an old
826 method to read the NUMA configuration directly from the builtin
827 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
828 instead, which also takes priority if both are compiled in.
830 config X86_64_ACPI_NUMA
832 prompt "ACPI NUMA detection"
833 depends on X86_64 && NUMA && ACPI && PCI
836 Enable ACPI SRAT based node topology detection.
839 bool "NUMA emulation"
840 depends on X86_64 && NUMA
842 Enable NUMA emulation. A flat machine will be split
843 into virtual nodes when booted with "numa=fake=N", where N is the
844 number of nodes. This is only useful for debugging.
848 default "6" if X86_64
849 default "4" if X86_NUMAQ
851 depends on NEED_MULTIPLE_NODES
853 config HAVE_ARCH_BOOTMEM_NODE
855 depends on X86_32 && NUMA
857 config ARCH_HAVE_MEMORY_PRESENT
859 depends on X86_32 && DISCONTIGMEM
861 config NEED_NODE_MEMMAP_SIZE
863 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
865 config HAVE_ARCH_ALLOC_REMAP
867 depends on X86_32 && NUMA
869 config ARCH_FLATMEM_ENABLE
871 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && X86_PC
873 config ARCH_DISCONTIGMEM_ENABLE
875 depends on NUMA && X86_32
877 config ARCH_DISCONTIGMEM_DEFAULT
879 depends on NUMA && X86_32
881 config ARCH_SPARSEMEM_DEFAULT
885 config ARCH_SPARSEMEM_ENABLE
887 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC)
888 select SPARSEMEM_STATIC if X86_32
889 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
891 config ARCH_SELECT_MEMORY_MODEL
893 depends on ARCH_SPARSEMEM_ENABLE
895 config ARCH_MEMORY_PROBE
897 depends on MEMORY_HOTPLUG
902 bool "Allocate 3rd-level pagetables from highmem"
903 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
905 The VM uses one page table entry for each page of physical memory.
906 For systems with a lot of RAM, this can be wasteful of precious
907 low memory. Setting this option will put user-space page table
908 entries in high memory.
910 config MATH_EMULATION
912 prompt "Math emulation" if X86_32
914 Linux can emulate a math coprocessor (used for floating point
915 operations) if you don't have one. 486DX and Pentium processors have
916 a math coprocessor built in, 486SX and 386 do not, unless you added
917 a 487DX or 387, respectively. (The messages during boot time can
918 give you some hints here ["man dmesg"].) Everyone needs either a
919 coprocessor or this emulation.
921 If you don't have a math coprocessor, you need to say Y here; if you
922 say Y here even though you have a coprocessor, the coprocessor will
923 be used nevertheless. (This behavior can be changed with the kernel
924 command line option "no387", which comes handy if your coprocessor
925 is broken. Try "man bootparam" or see the documentation of your boot
926 loader (lilo or loadlin) about how to pass options to the kernel at
927 boot time.) This means that it is a good idea to say Y here if you
928 intend to use this kernel on different machines.
930 More information about the internals of the Linux math coprocessor
931 emulation can be found in <file:arch/x86/math-emu/README>.
933 If you are not sure, say Y; apart from resulting in a 66 KB bigger
934 kernel, it won't hurt.
937 bool "MTRR (Memory Type Range Register) support"
939 On Intel P6 family processors (Pentium Pro, Pentium II and later)
940 the Memory Type Range Registers (MTRRs) may be used to control
941 processor access to memory ranges. This is most useful if you have
942 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
943 allows bus write transfers to be combined into a larger transfer
944 before bursting over the PCI/AGP bus. This can increase performance
945 of image write operations 2.5 times or more. Saying Y here creates a
946 /proc/mtrr file which may be used to manipulate your processor's
947 MTRRs. Typically the X server should use this.
949 This code has a reasonably generic interface so that similar
950 control registers on other processors can be easily supported
953 The Cyrix 6x86, 6x86MX and M II processors have Address Range
954 Registers (ARRs) which provide a similar functionality to MTRRs. For
955 these, the ARRs are used to emulate the MTRRs.
956 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
957 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
958 write-combining. All of these processors are supported by this code
959 and it makes sense to say Y here if you have one of them.
961 Saying Y here also fixes a problem with buggy SMP BIOSes which only
962 set the MTRRs for the boot CPU and not for the secondary CPUs. This
963 can lead to all sorts of problems, so it's good to say Y here.
965 You can safely say Y even if your machine doesn't have MTRRs, you'll
966 just add about 9 KB to your kernel.
968 See <file:Documentation/mtrr.txt> for more information.
972 prompt "EFI runtime service support"
975 This enables the kernel to use EFI runtime services that are
976 available (such as the EFI variable services).
978 This option is only useful on systems that have EFI firmware.
979 In addition, you should use the latest ELILO loader available
980 at <http://elilo.sourceforge.net> in order to take advantage
981 of EFI runtime services. However, even with this option, the
982 resultant kernel should continue to boot on existing non-EFI
987 prompt "Enable kernel irq balancing"
988 depends on X86_32 && SMP && X86_IO_APIC
990 The default yes will allow the kernel to do irq load balancing.
991 Saying no will keep the kernel from doing irq load balancing.
993 # turning this on wastes a bunch of space.
994 # Summit needs it only when NUMA is on
997 depends on X86_32 && (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
1001 prompt "Enable seccomp to safely compute untrusted bytecode"
1004 This kernel feature is useful for number crunching applications
1005 that may need to compute untrusted bytecode during their
1006 execution. By using pipes or other transports made available to
1007 the process as file descriptors supporting the read/write
1008 syscalls, it's possible to isolate those applications in
1009 their own address space using seccomp. Once seccomp is
1010 enabled via /proc/<pid>/seccomp, it cannot be disabled
1011 and the task is only allowed to execute a few safe syscalls
1012 defined by each seccomp mode.
1014 If unsure, say Y. Only embedded should say N here.
1016 config CC_STACKPROTECTOR
1017 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1018 depends on X86_64 && EXPERIMENTAL
1020 This option turns on the -fstack-protector GCC feature. This
1021 feature puts, at the beginning of critical functions, a canary
1022 value on the stack just before the return address, and validates
1023 the value just before actually returning. Stack based buffer
1024 overflows (that need to overwrite this return address) now also
1025 overwrite the canary, which gets detected and the attack is then
1026 neutralized via a kernel panic.
1028 This feature requires gcc version 4.2 or above, or a distribution
1029 gcc with the feature backported. Older versions are automatically
1030 detected and for those versions, this configuration option is ignored.
1032 config CC_STACKPROTECTOR_ALL
1033 bool "Use stack-protector for all functions"
1034 depends on CC_STACKPROTECTOR
1036 Normally, GCC only inserts the canary value protection for
1037 functions that use large-ish on-stack buffers. By enabling
1038 this option, GCC will be asked to do this for ALL functions.
1040 source kernel/Kconfig.hz
1043 bool "kexec system call"
1045 kexec is a system call that implements the ability to shutdown your
1046 current kernel, and to start another kernel. It is like a reboot
1047 but it is independent of the system firmware. And like a reboot
1048 you can start any kernel with it, not just Linux.
1050 The name comes from the similarity to the exec system call.
1052 It is an ongoing process to be certain the hardware in a machine
1053 is properly shutdown, so do not be surprised if this code does not
1054 initially work for you. It may help to enable device hotplugging
1055 support. As of this writing the exact hardware interface is
1056 strongly in flux, so no good recommendation can be made.
1059 bool "kernel crash dumps (EXPERIMENTAL)"
1060 depends on EXPERIMENTAL
1061 depends on X86_64 || (X86_32 && HIGHMEM)
1063 Generate crash dump after being started by kexec.
1064 This should be normally only set in special crash dump kernels
1065 which are loaded in the main kernel with kexec-tools into
1066 a specially reserved region and then later executed after
1067 a crash by kdump/kexec. The crash dump kernel must be compiled
1068 to a memory address not used by the main kernel or BIOS using
1069 PHYSICAL_START, or it must be built as a relocatable image
1070 (CONFIG_RELOCATABLE=y).
1071 For more details see Documentation/kdump/kdump.txt
1073 config PHYSICAL_START
1074 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1075 default "0x1000000" if X86_NUMAQ
1076 default "0x200000" if X86_64
1079 This gives the physical address where the kernel is loaded.
1081 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1082 bzImage will decompress itself to above physical address and
1083 run from there. Otherwise, bzImage will run from the address where
1084 it has been loaded by the boot loader and will ignore above physical
1087 In normal kdump cases one does not have to set/change this option
1088 as now bzImage can be compiled as a completely relocatable image
1089 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1090 address. This option is mainly useful for the folks who don't want
1091 to use a bzImage for capturing the crash dump and want to use a
1092 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1093 to be specifically compiled to run from a specific memory area
1094 (normally a reserved region) and this option comes handy.
1096 So if you are using bzImage for capturing the crash dump, leave
1097 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1098 Otherwise if you plan to use vmlinux for capturing the crash dump
1099 change this value to start of the reserved region (Typically 16MB
1100 0x1000000). In other words, it can be set based on the "X" value as
1101 specified in the "crashkernel=YM@XM" command line boot parameter
1102 passed to the panic-ed kernel. Typically this parameter is set as
1103 crashkernel=64M@16M. Please take a look at
1104 Documentation/kdump/kdump.txt for more details about crash dumps.
1106 Usage of bzImage for capturing the crash dump is recommended as
1107 one does not have to build two kernels. Same kernel can be used
1108 as production kernel and capture kernel. Above option should have
1109 gone away after relocatable bzImage support is introduced. But it
1110 is present because there are users out there who continue to use
1111 vmlinux for dump capture. This option should go away down the
1114 Don't change this unless you know what you are doing.
1117 bool "Build a relocatable kernel (EXPERIMENTAL)"
1118 depends on EXPERIMENTAL
1120 This builds a kernel image that retains relocation information
1121 so it can be loaded someplace besides the default 1MB.
1122 The relocations tend to make the kernel binary about 10% larger,
1123 but are discarded at runtime.
1125 One use is for the kexec on panic case where the recovery kernel
1126 must live at a different physical address than the primary
1129 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1130 it has been loaded at and the compile time physical address
1131 (CONFIG_PHYSICAL_START) is ignored.
1133 config PHYSICAL_ALIGN
1135 prompt "Alignment value to which kernel should be aligned" if X86_32
1136 default "0x100000" if X86_32
1137 default "0x200000" if X86_64
1138 range 0x2000 0x400000
1140 This value puts the alignment restrictions on physical address
1141 where kernel is loaded and run from. Kernel is compiled for an
1142 address which meets above alignment restriction.
1144 If bootloader loads the kernel at a non-aligned address and
1145 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1146 address aligned to above value and run from there.
1148 If bootloader loads the kernel at a non-aligned address and
1149 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1150 load address and decompress itself to the address it has been
1151 compiled for and run from there. The address for which kernel is
1152 compiled already meets above alignment restrictions. Hence the
1153 end result is that kernel runs from a physical address meeting
1154 above alignment restrictions.
1156 Don't change this unless you know what you are doing.
1159 bool "Support for suspend on SMP and hot-pluggable CPUs (EXPERIMENTAL)"
1160 depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER
1162 Say Y here to experiment with turning CPUs off and on, and to
1163 enable suspend on SMP systems. CPUs can be controlled through
1164 /sys/devices/system/cpu.
1165 Say N if you want to disable CPU hotplug and don't need to
1170 prompt "Compat VDSO support"
1171 depends on X86_32 || IA32_EMULATION
1173 Map the 32-bit VDSO to the predictable old-style address too.
1175 Say N here if you are running a sufficiently recent glibc
1176 version (2.3.3 or later), to remove the high-mapped
1177 VDSO mapping and to exclusively use the randomized VDSO.
1183 config ARCH_ENABLE_MEMORY_HOTPLUG
1185 depends on X86_64 || (X86_32 && HIGHMEM)
1187 config HAVE_ARCH_EARLY_PFN_TO_NID
1191 menu "Power management options"
1192 depends on !X86_VOYAGER
1194 config ARCH_HIBERNATION_HEADER
1196 depends on X86_64 && HIBERNATION
1198 source "kernel/power/Kconfig"
1200 source "drivers/acpi/Kconfig"
1203 tristate "APM (Advanced Power Management) BIOS support"
1204 depends on X86_32 && PM_SLEEP && !X86_VISWS
1206 APM is a BIOS specification for saving power using several different
1207 techniques. This is mostly useful for battery powered laptops with
1208 APM compliant BIOSes. If you say Y here, the system time will be
1209 reset after a RESUME operation, the /proc/apm device will provide
1210 battery status information, and user-space programs will receive
1211 notification of APM "events" (e.g. battery status change).
1213 If you select "Y" here, you can disable actual use of the APM
1214 BIOS by passing the "apm=off" option to the kernel at boot time.
1216 Note that the APM support is almost completely disabled for
1217 machines with more than one CPU.
1219 In order to use APM, you will need supporting software. For location
1220 and more information, read <file:Documentation/pm.txt> and the
1221 Battery Powered Linux mini-HOWTO, available from
1222 <http://www.tldp.org/docs.html#howto>.
1224 This driver does not spin down disk drives (see the hdparm(8)
1225 manpage ("man 8 hdparm") for that), and it doesn't turn off
1226 VESA-compliant "green" monitors.
1228 This driver does not support the TI 4000M TravelMate and the ACER
1229 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1230 desktop machines also don't have compliant BIOSes, and this driver
1231 may cause those machines to panic during the boot phase.
1233 Generally, if you don't have a battery in your machine, there isn't
1234 much point in using this driver and you should say N. If you get
1235 random kernel OOPSes or reboots that don't seem to be related to
1236 anything, try disabling/enabling this option (or disabling/enabling
1239 Some other things you should try when experiencing seemingly random,
1242 1) make sure that you have enough swap space and that it is
1244 2) pass the "no-hlt" option to the kernel
1245 3) switch on floating point emulation in the kernel and pass
1246 the "no387" option to the kernel
1247 4) pass the "floppy=nodma" option to the kernel
1248 5) pass the "mem=4M" option to the kernel (thereby disabling
1249 all but the first 4 MB of RAM)
1250 6) make sure that the CPU is not over clocked.
1251 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1252 8) disable the cache from your BIOS settings
1253 9) install a fan for the video card or exchange video RAM
1254 10) install a better fan for the CPU
1255 11) exchange RAM chips
1256 12) exchange the motherboard.
1258 To compile this driver as a module, choose M here: the
1259 module will be called apm.
1263 config APM_IGNORE_USER_SUSPEND
1264 bool "Ignore USER SUSPEND"
1266 This option will ignore USER SUSPEND requests. On machines with a
1267 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1268 series notebooks, it is necessary to say Y because of a BIOS bug.
1270 config APM_DO_ENABLE
1271 bool "Enable PM at boot time"
1273 Enable APM features at boot time. From page 36 of the APM BIOS
1274 specification: "When disabled, the APM BIOS does not automatically
1275 power manage devices, enter the Standby State, enter the Suspend
1276 State, or take power saving steps in response to CPU Idle calls."
1277 This driver will make CPU Idle calls when Linux is idle (unless this
1278 feature is turned off -- see "Do CPU IDLE calls", below). This
1279 should always save battery power, but more complicated APM features
1280 will be dependent on your BIOS implementation. You may need to turn
1281 this option off if your computer hangs at boot time when using APM
1282 support, or if it beeps continuously instead of suspending. Turn
1283 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1284 T400CDT. This is off by default since most machines do fine without
1288 bool "Make CPU Idle calls when idle"
1290 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1291 On some machines, this can activate improved power savings, such as
1292 a slowed CPU clock rate, when the machine is idle. These idle calls
1293 are made after the idle loop has run for some length of time (e.g.,
1294 333 mS). On some machines, this will cause a hang at boot time or
1295 whenever the CPU becomes idle. (On machines with more than one CPU,
1296 this option does nothing.)
1298 config APM_DISPLAY_BLANK
1299 bool "Enable console blanking using APM"
1301 Enable console blanking using the APM. Some laptops can use this to
1302 turn off the LCD backlight when the screen blanker of the Linux
1303 virtual console blanks the screen. Note that this is only used by
1304 the virtual console screen blanker, and won't turn off the backlight
1305 when using the X Window system. This also doesn't have anything to
1306 do with your VESA-compliant power-saving monitor. Further, this
1307 option doesn't work for all laptops -- it might not turn off your
1308 backlight at all, or it might print a lot of errors to the console,
1309 especially if you are using gpm.
1311 config APM_ALLOW_INTS
1312 bool "Allow interrupts during APM BIOS calls"
1314 Normally we disable external interrupts while we are making calls to
1315 the APM BIOS as a measure to lessen the effects of a badly behaving
1316 BIOS implementation. The BIOS should reenable interrupts if it
1317 needs to. Unfortunately, some BIOSes do not -- especially those in
1318 many of the newer IBM Thinkpads. If you experience hangs when you
1319 suspend, try setting this to Y. Otherwise, say N.
1321 config APM_REAL_MODE_POWER_OFF
1322 bool "Use real mode APM BIOS call to power off"
1324 Use real mode APM BIOS calls to switch off the computer. This is
1325 a work-around for a number of buggy BIOSes. Switch this option on if
1326 your computer crashes instead of powering off properly.
1330 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1332 source "drivers/cpuidle/Kconfig"
1337 menu "Bus options (PCI etc.)"
1340 bool "PCI support" if !X86_VISWS
1341 depends on !X86_VOYAGER
1342 default y if X86_VISWS
1343 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1345 Find out whether you have a PCI motherboard. PCI is the name of a
1346 bus system, i.e. the way the CPU talks to the other stuff inside
1347 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1348 VESA. If you have PCI, say Y, otherwise N.
1350 The PCI-HOWTO, available from
1351 <http://www.tldp.org/docs.html#howto>, contains valuable
1352 information about which PCI hardware does work under Linux and which
1356 prompt "PCI access mode"
1357 depends on X86_32 && PCI && !X86_VISWS
1360 On PCI systems, the BIOS can be used to detect the PCI devices and
1361 determine their configuration. However, some old PCI motherboards
1362 have BIOS bugs and may crash if this is done. Also, some embedded
1363 PCI-based systems don't have any BIOS at all. Linux can also try to
1364 detect the PCI hardware directly without using the BIOS.
1366 With this option, you can specify how Linux should detect the
1367 PCI devices. If you choose "BIOS", the BIOS will be used,
1368 if you choose "Direct", the BIOS won't be used, and if you
1369 choose "MMConfig", then PCI Express MMCONFIG will be used.
1370 If you choose "Any", the kernel will try MMCONFIG, then the
1371 direct access method and falls back to the BIOS if that doesn't
1372 work. If unsure, go with the default, which is "Any".
1377 config PCI_GOMMCONFIG
1390 depends on X86_32 && !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1392 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1395 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1399 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1406 bool "Support mmconfig PCI config space access"
1407 depends on X86_64 && PCI && ACPI
1410 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1411 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1413 DMA remapping (DMAR) devices support enables independent address
1414 translations for Direct Memory Access (DMA) from devices.
1415 These DMA remapping devices are reported via ACPI tables
1416 and include PCI device scope covered by these DMA
1421 prompt "Support for Graphics workaround"
1424 Current Graphics drivers tend to use physical address
1425 for DMA and avoid using DMA APIs. Setting this config
1426 option permits the IOMMU driver to set a unity map for
1427 all the OS-visible memory. Hence the driver can continue
1428 to use physical addresses for DMA.
1430 config DMAR_FLOPPY_WA
1434 Floppy disk drivers are know to bypass DMA API calls
1435 thereby failing to work when IOMMU is enabled. This
1436 workaround will setup a 1:1 mapping for the first
1437 16M to make floppy (an ISA device) work.
1439 source "drivers/pci/pcie/Kconfig"
1441 source "drivers/pci/Kconfig"
1443 # x86_64 have no ISA slots, but do have ISA-style DMA.
1451 depends on !(X86_VOYAGER || X86_VISWS)
1453 Find out whether you have ISA slots on your motherboard. ISA is the
1454 name of a bus system, i.e. the way the CPU talks to the other stuff
1455 inside your box. Other bus systems are PCI, EISA, MicroChannel
1456 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1457 newer boards don't support it. If you have ISA, say Y, otherwise N.
1463 The Extended Industry Standard Architecture (EISA) bus was
1464 developed as an open alternative to the IBM MicroChannel bus.
1466 The EISA bus provided some of the features of the IBM MicroChannel
1467 bus while maintaining backward compatibility with cards made for
1468 the older ISA bus. The EISA bus saw limited use between 1988 and
1469 1995 when it was made obsolete by the PCI bus.
1471 Say Y here if you are building a kernel for an EISA-based machine.
1475 source "drivers/eisa/Kconfig"
1478 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1479 default y if X86_VOYAGER
1481 MicroChannel Architecture is found in some IBM PS/2 machines and
1482 laptops. It is a bus system similar to PCI or ISA. See
1483 <file:Documentation/mca.txt> (and especially the web page given
1484 there) before attempting to build an MCA bus kernel.
1486 source "drivers/mca/Kconfig"
1489 tristate "NatSemi SCx200 support"
1490 depends on !X86_VOYAGER
1492 This provides basic support for National Semiconductor's
1493 (now AMD's) Geode processors. The driver probes for the
1494 PCI-IDs of several on-chip devices, so its a good dependency
1495 for other scx200_* drivers.
1497 If compiled as a module, the driver is named scx200.
1499 config SCx200HR_TIMER
1500 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1501 depends on SCx200 && GENERIC_TIME
1504 This driver provides a clocksource built upon the on-chip
1505 27MHz high-resolution timer. Its also a workaround for
1506 NSC Geode SC-1100's buggy TSC, which loses time when the
1507 processor goes idle (as is done by the scheduler). The
1508 other workaround is idle=poll boot option.
1510 config GEODE_MFGPT_TIMER
1512 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1513 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1515 This driver provides a clock event source based on the MFGPT
1516 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1517 MFGPTs have a better resolution and max interval than the
1518 generic PIT, and are suitable for use as high-res timers.
1524 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1526 source "drivers/pcmcia/Kconfig"
1528 source "drivers/pci/hotplug/Kconfig"
1533 menu "Executable file formats / Emulations"
1535 source "fs/Kconfig.binfmt"
1537 config IA32_EMULATION
1538 bool "IA32 Emulation"
1540 select COMPAT_BINFMT_ELF
1542 Include code to run 32-bit programs under a 64-bit kernel. You should
1543 likely turn this on, unless you're 100% sure that you don't have any
1544 32-bit programs left.
1547 tristate "IA32 a.out support"
1548 depends on IA32_EMULATION
1550 Support old a.out binaries in the 32bit emulation.
1554 depends on IA32_EMULATION
1556 config COMPAT_FOR_U64_ALIGNMENT
1560 config SYSVIPC_COMPAT
1562 depends on X86_64 && COMPAT && SYSVIPC
1567 source "net/Kconfig"
1569 source "drivers/Kconfig"
1571 source "drivers/firmware/Kconfig"
1575 source "kernel/Kconfig.instrumentation"
1577 source "arch/x86/Kconfig.debug"
1579 source "security/Kconfig"
1581 source "crypto/Kconfig"
1583 source "lib/Kconfig"
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