2 # For a description of the syntax of this configuration file,
3 # see Documentation/kbuild/kconfig-language.txt.
6 mainmenu "Linux Kernel Configuration"
12 This is Linux's home port. Linux was originally native to the Intel
13 386, and runs on all the later x86 processors including the Intel
14 486, 586, Pentiums, and various instruction-set-compatible chips by
15 AMD, Cyrix, and others.
17 config SEMAPHORE_SLEEPERS
32 config GENERIC_ISA_DMA
40 config ARCH_MAY_HAVE_PC_FDC
46 menu "Processor type and features"
49 prompt "Subarchitecture Type"
55 Choose this option if your computer is a standard PC or compatible.
60 Select this for an AMD Elan processor.
62 Do not use this option for K6/Athlon/Opteron processors!
64 If unsure, choose "PC-compatible" instead.
69 Voyager is an MCA-based 32-way capable SMP architecture proprietary
70 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
74 If you do not specifically know you have a Voyager based machine,
75 say N here, otherwise the kernel you build will not be bootable.
78 bool "NUMAQ (IBM/Sequent)"
81 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
82 multiquad box. This changes the way that processors are bootstrapped,
83 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
84 You will need a new lynxer.elf file to flash your firmware with - send
85 email to <Martin.Bligh@us.ibm.com>.
88 bool "Summit/EXA (IBM x440)"
91 This option is needed for IBM systems that use the Summit/EXA chipset.
92 In particular, it is needed for the x440.
94 If you don't have one of these computers, you should say N here.
97 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
100 This option is needed for the systems that have more than 8 CPUs
101 and if the system is not of any sub-arch type above.
103 If you don't have such a system, you should say N here.
106 bool "SGI 320/540 (Visual Workstation)"
108 The SGI Visual Workstation series is an IA32-based workstation
109 based on SGI systems chips with some legacy PC hardware attached.
111 Say Y here to create a kernel to run on the SGI 320 or 540.
113 A kernel compiled for the Visual Workstation will not run on PCs
114 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
116 config X86_GENERICARCH
117 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
120 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
121 It is intended for a generic binary kernel.
124 bool "Support for Unisys ES7000 IA32 series"
127 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
128 supposed to run on an IA32-based Unisys ES7000 system.
129 Only choose this option if you have such a system, otherwise you
137 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
139 config X86_SUMMIT_NUMA
142 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
144 config X86_CYCLONE_TIMER
147 depends on X86_SUMMIT || X86_GENERICARCH
149 config ES7000_CLUSTERED_APIC
152 depends on SMP && X86_ES7000 && MPENTIUMIII
157 prompt "Processor family"
163 This is the processor type of your CPU. This information is used for
164 optimizing purposes. In order to compile a kernel that can run on
165 all x86 CPU types (albeit not optimally fast), you can specify
168 The kernel will not necessarily run on earlier architectures than
169 the one you have chosen, e.g. a Pentium optimized kernel will run on
170 a PPro, but not necessarily on a i486.
172 Here are the settings recommended for greatest speed:
173 - "386" for the AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI
174 486DLC/DLC2, UMC 486SX-S and NexGen Nx586. Only "386" kernels
175 will run on a 386 class machine.
176 - "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or
177 SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
178 - "586" for generic Pentium CPUs lacking the TSC
179 (time stamp counter) register.
180 - "Pentium-Classic" for the Intel Pentium.
181 - "Pentium-MMX" for the Intel Pentium MMX.
182 - "Pentium-Pro" for the Intel Pentium Pro.
183 - "Pentium-II" for the Intel Pentium II or pre-Coppermine Celeron.
184 - "Pentium-III" for the Intel Pentium III or Coppermine Celeron.
185 - "Pentium-4" for the Intel Pentium 4 or P4-based Celeron.
186 - "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
187 - "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
188 - "Crusoe" for the Transmeta Crusoe series.
189 - "Efficeon" for the Transmeta Efficeon series.
190 - "Winchip-C6" for original IDT Winchip.
191 - "Winchip-2" for IDT Winchip 2.
192 - "Winchip-2A" for IDT Winchips with 3dNow! capabilities.
193 - "GeodeGX1" for Geode GX1 (Cyrix MediaGX).
194 - "CyrixIII/VIA C3" for VIA Cyrix III or VIA C3.
195 - "VIA C3-2 for VIA C3-2 "Nehemiah" (model 9 and above).
197 If you don't know what to do, choose "386".
202 Select this for a 486 series processor, either Intel or one of the
203 compatible processors from AMD, Cyrix, IBM, or Intel. Includes DX,
204 DX2, and DX4 variants; also SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or
208 bool "586/K5/5x86/6x86/6x86MX"
210 Select this for an 586 or 686 series processor such as the AMD K5,
211 the Cyrix 5x86, 6x86 and 6x86MX. This choice does not
212 assume the RDTSC (Read Time Stamp Counter) instruction.
215 bool "Pentium-Classic"
217 Select this for a Pentium Classic processor with the RDTSC (Read
218 Time Stamp Counter) instruction for benchmarking.
223 Select this for a Pentium with the MMX graphics/multimedia
224 extended instructions.
229 Select this for Intel Pentium Pro chips. This enables the use of
230 Pentium Pro extended instructions, and disables the init-time guard
231 against the f00f bug found in earlier Pentiums.
234 bool "Pentium-II/Celeron(pre-Coppermine)"
236 Select this for Intel chips based on the Pentium-II and
237 pre-Coppermine Celeron core. This option enables an unaligned
238 copy optimization, compiles the kernel with optimization flags
239 tailored for the chip, and applies any applicable Pentium Pro
243 bool "Pentium-III/Celeron(Coppermine)/Pentium-III Xeon"
245 Select this for Intel chips based on the Pentium-III and
246 Celeron-Coppermine core. This option enables use of some
247 extended prefetch instructions in addition to the Pentium II
253 Select this for Intel Pentium M (not Pentium-4 M)
257 bool "Pentium-4/Celeron(P4-based)/Pentium-4 M/Xeon"
259 Select this for Intel Pentium 4 chips. This includes the
260 Pentium 4, P4-based Celeron and Xeon, and Pentium-4 M
261 (not Pentium M) chips. This option enables compile flags
262 optimized for the chip, uses the correct cache shift, and
263 applies any applicable Pentium III optimizations.
266 bool "K6/K6-II/K6-III"
268 Select this for an AMD K6-family processor. Enables use of
269 some extended instructions, and passes appropriate optimization
273 bool "Athlon/Duron/K7"
275 Select this for an AMD Athlon K7-family processor. Enables use of
276 some extended instructions, and passes appropriate optimization
280 bool "Opteron/Athlon64/Hammer/K8"
282 Select this for an AMD Opteron or Athlon64 Hammer-family processor. Enables
283 use of some extended instructions, and passes appropriate optimization
289 Select this for a Transmeta Crusoe processor. Treats the processor
290 like a 586 with TSC, and sets some GCC optimization flags (like a
291 Pentium Pro with no alignment requirements).
296 Select this for a Transmeta Efficeon processor.
301 Select this for an IDT Winchip C6 chip. Linux and GCC
302 treat this chip as a 586TSC with some extended instructions
303 and alignment requirements.
308 Select this for an IDT Winchip-2. Linux and GCC
309 treat this chip as a 586TSC with some extended instructions
310 and alignment requirements.
313 bool "Winchip-2A/Winchip-3"
315 Select this for an IDT Winchip-2A or 3. Linux and GCC
316 treat this chip as a 586TSC with some extended instructions
317 and alignment reqirements. Also enable out of order memory
318 stores for this CPU, which can increase performance of some
324 Select this for a Geode GX1 (Cyrix MediaGX) chip.
327 bool "CyrixIII/VIA-C3"
329 Select this for a Cyrix III or C3 chip. Presently Linux and GCC
330 treat this chip as a generic 586. Whilst the CPU is 686 class,
331 it lacks the cmov extension which gcc assumes is present when
333 Note that Nehemiah (Model 9) and above will not boot with this
334 kernel due to them lacking the 3DNow! instructions used in earlier
335 incarnations of the CPU.
338 bool "VIA C3-2 (Nehemiah)"
340 Select this for a VIA C3 "Nehemiah". Selecting this enables usage
341 of SSE and tells gcc to treat the CPU as a 686.
342 Note, this kernel will not boot on older (pre model 9) C3s.
347 bool "Generic x86 support"
349 Instead of just including optimizations for the selected
350 x86 variant (e.g. PII, Crusoe or Athlon), include some more
351 generic optimizations as well. This will make the kernel
352 perform better on x86 CPUs other than that selected.
354 This is really intended for distributors who need more
355 generic optimizations.
360 # Define implied options from the CPU selection here
372 config X86_L1_CACHE_SHIFT
374 default "7" if MPENTIUM4 || X86_GENERIC
375 default "4" if X86_ELAN || M486 || M386
376 default "5" if MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCRUSOE || MEFFICEON || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2 || MGEODEGX1
377 default "6" if MK7 || MK8 || MPENTIUMM
379 config RWSEM_GENERIC_SPINLOCK
384 config RWSEM_XCHGADD_ALGORITHM
389 config GENERIC_CALIBRATE_DELAY
393 config X86_PPRO_FENCE
395 depends on M686 || M586MMX || M586TSC || M586 || M486 || M386 || MGEODEGX1
400 depends on M586MMX || M586TSC || M586 || M486 || M386
403 config X86_WP_WORKS_OK
423 config X86_ALIGNMENT_16
425 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1
430 depends on MK7 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || MK8 || MEFFICEON
433 config X86_INTEL_USERCOPY
435 depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK8 || MK7 || MEFFICEON
438 config X86_USE_PPRO_CHECKSUM
440 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC3_2 || MEFFICEON
445 depends on MCYRIXIII || MK7
450 depends on (MWINCHIP3D || MWINCHIP2 || MWINCHIPC6) && MTRR
454 bool "HPET Timer Support"
456 This enables the use of the HPET for the kernel's internal timer.
457 HPET is the next generation timer replacing legacy 8254s.
458 You can safely choose Y here. However, HPET will only be
459 activated if the platform and the BIOS support this feature.
460 Otherwise the 8254 will be used for timing services.
462 Choose N to continue using the legacy 8254 timer.
464 config HPET_EMULATE_RTC
466 depends on HPET_TIMER && RTC=y
470 bool "Symmetric multi-processing support"
472 This enables support for systems with more than one CPU. If you have
473 a system with only one CPU, like most personal computers, say N. If
474 you have a system with more than one CPU, say Y.
476 If you say N here, the kernel will run on single and multiprocessor
477 machines, but will use only one CPU of a multiprocessor machine. If
478 you say Y here, the kernel will run on many, but not all,
479 singleprocessor machines. On a singleprocessor machine, the kernel
480 will run faster if you say N here.
482 Note that if you say Y here and choose architecture "586" or
483 "Pentium" under "Processor family", the kernel will not work on 486
484 architectures. Similarly, multiprocessor kernels for the "PPro"
485 architecture may not work on all Pentium based boards.
487 People using multiprocessor machines who say Y here should also say
488 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
489 Management" code will be disabled if you say Y here.
491 See also the <file:Documentation/smp.txt>,
492 <file:Documentation/i386/IO-APIC.txt>,
493 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
494 <http://www.tldp.org/docs.html#howto>.
496 If you don't know what to do here, say N.
499 int "Maximum number of CPUs (2-255)"
502 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
505 This allows you to specify the maximum number of CPUs which this
506 kernel will support. The maximum supported value is 255 and the
507 minimum value which makes sense is 2.
509 This is purely to save memory - each supported CPU adds
510 approximately eight kilobytes to the kernel image.
513 bool "SMT (Hyperthreading) scheduler support"
517 SMT scheduler support improves the CPU scheduler's decision making
518 when dealing with Intel Pentium 4 chips with HyperThreading at a
519 cost of slightly increased overhead in some places. If unsure say
522 source "kernel/Kconfig.preempt"
525 bool "Local APIC support on uniprocessors"
526 depends on !SMP && !(X86_VISWS || X86_VOYAGER)
528 A local APIC (Advanced Programmable Interrupt Controller) is an
529 integrated interrupt controller in the CPU. If you have a single-CPU
530 system which has a processor with a local APIC, you can say Y here to
531 enable and use it. If you say Y here even though your machine doesn't
532 have a local APIC, then the kernel will still run with no slowdown at
533 all. The local APIC supports CPU-generated self-interrupts (timer,
534 performance counters), and the NMI watchdog which detects hard
538 bool "IO-APIC support on uniprocessors"
539 depends on X86_UP_APIC
541 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
542 SMP-capable replacement for PC-style interrupt controllers. Most
543 SMP systems and many recent uniprocessor systems have one.
545 If you have a single-CPU system with an IO-APIC, you can say Y here
546 to use it. If you say Y here even though your machine doesn't have
547 an IO-APIC, then the kernel will still run with no slowdown at all.
549 config X86_LOCAL_APIC
551 depends on X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER)
556 depends on X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER))
559 config X86_VISWS_APIC
566 depends on (MWINCHIP3D || MWINCHIP2 || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2 || MGEODEGX1) && !X86_NUMAQ
570 bool "Machine Check Exception"
571 depends on !X86_VOYAGER
573 Machine Check Exception support allows the processor to notify the
574 kernel if it detects a problem (e.g. overheating, component failure).
575 The action the kernel takes depends on the severity of the problem,
576 ranging from a warning message on the console, to halting the machine.
577 Your processor must be a Pentium or newer to support this - check the
578 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
579 have a design flaw which leads to false MCE events - hence MCE is
580 disabled on all P5 processors, unless explicitly enabled with "mce"
581 as a boot argument. Similarly, if MCE is built in and creates a
582 problem on some new non-standard machine, you can boot with "nomce"
583 to disable it. MCE support simply ignores non-MCE processors like
584 the 386 and 486, so nearly everyone can say Y here.
586 config X86_MCE_NONFATAL
587 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
590 Enabling this feature starts a timer that triggers every 5 seconds which
591 will look at the machine check registers to see if anything happened.
592 Non-fatal problems automatically get corrected (but still logged).
593 Disable this if you don't want to see these messages.
594 Seeing the messages this option prints out may be indicative of dying hardware,
595 or out-of-spec (ie, overclocked) hardware.
596 This option only does something on certain CPUs.
597 (AMD Athlon/Duron and Intel Pentium 4)
599 config X86_MCE_P4THERMAL
600 bool "check for P4 thermal throttling interrupt."
601 depends on X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
603 Enabling this feature will cause a message to be printed when the P4
604 enters thermal throttling.
607 tristate "Toshiba Laptop support"
609 This adds a driver to safely access the System Management Mode of
610 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
611 not work on models with a Phoenix BIOS. The System Management Mode
612 is used to set the BIOS and power saving options on Toshiba portables.
614 For information on utilities to make use of this driver see the
615 Toshiba Linux utilities web site at:
616 <http://www.buzzard.org.uk/toshiba/>.
618 Say Y if you intend to run this kernel on a Toshiba portable.
622 tristate "Dell laptop support"
624 This adds a driver to safely access the System Management Mode
625 of the CPU on the Dell Inspiron 8000. The System Management Mode
626 is used to read cpu temperature and cooling fan status and to
627 control the fans on the I8K portables.
629 This driver has been tested only on the Inspiron 8000 but it may
630 also work with other Dell laptops. You can force loading on other
631 models by passing the parameter `force=1' to the module. Use at
634 For information on utilities to make use of this driver see the
635 I8K Linux utilities web site at:
636 <http://people.debian.org/~dz/i8k/>
638 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
641 config X86_REBOOTFIXUPS
642 bool "Enable X86 board specific fixups for reboot"
646 This enables chipset and/or board specific fixups to be done
647 in order to get reboot to work correctly. This is only needed on
648 some combinations of hardware and BIOS. The symptom, for which
649 this config is intended, is when reboot ends with a stalled/hung
652 Currently, the only fixup is for the Geode GX1/CS5530A/TROM2.1.
655 Say Y if you want to enable the fixup. Currently, it's safe to
656 enable this option even if you don't need it.
660 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
662 If you say Y here and also to "/dev file system support" in the
663 'File systems' section, you will be able to update the microcode on
664 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
665 Pentium III, Pentium 4, Xeon etc. You will obviously need the
666 actual microcode binary data itself which is not shipped with the
669 For latest news and information on obtaining all the required
670 ingredients for this driver, check:
671 <http://www.urbanmyth.org/microcode/>.
673 To compile this driver as a module, choose M here: the
674 module will be called microcode.
677 tristate "/dev/cpu/*/msr - Model-specific register support"
679 This device gives privileged processes access to the x86
680 Model-Specific Registers (MSRs). It is a character device with
681 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
682 MSR accesses are directed to a specific CPU on multi-processor
686 tristate "/dev/cpu/*/cpuid - CPU information support"
688 This device gives processes access to the x86 CPUID instruction to
689 be executed on a specific processor. It is a character device
690 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
693 source "drivers/firmware/Kconfig"
696 prompt "High Memory Support"
702 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
703 However, the address space of 32-bit x86 processors is only 4
704 Gigabytes large. That means that, if you have a large amount of
705 physical memory, not all of it can be "permanently mapped" by the
706 kernel. The physical memory that's not permanently mapped is called
709 If you are compiling a kernel which will never run on a machine with
710 more than 1 Gigabyte total physical RAM, answer "off" here (default
711 choice and suitable for most users). This will result in a "3GB/1GB"
712 split: 3GB are mapped so that each process sees a 3GB virtual memory
713 space and the remaining part of the 4GB virtual memory space is used
714 by the kernel to permanently map as much physical memory as
717 If the machine has between 1 and 4 Gigabytes physical RAM, then
720 If more than 4 Gigabytes is used then answer "64GB" here. This
721 selection turns Intel PAE (Physical Address Extension) mode on.
722 PAE implements 3-level paging on IA32 processors. PAE is fully
723 supported by Linux, PAE mode is implemented on all recent Intel
724 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
725 then the kernel will not boot on CPUs that don't support PAE!
727 The actual amount of total physical memory will either be
728 auto detected or can be forced by using a kernel command line option
729 such as "mem=256M". (Try "man bootparam" or see the documentation of
730 your boot loader (lilo or loadlin) about how to pass options to the
731 kernel at boot time.)
733 If unsure, say "off".
738 Select this if you have a 32-bit processor and between 1 and 4
739 gigabytes of physical RAM.
744 Select this if you have a 32-bit processor and more than 4
745 gigabytes of physical RAM.
751 depends on HIGHMEM64G || HIGHMEM4G
756 depends on HIGHMEM64G
759 # Common NUMA Features
761 bool "Numa Memory Allocation and Scheduler Support"
762 depends on SMP && HIGHMEM64G && (X86_NUMAQ || X86_GENERICARCH || (X86_SUMMIT && ACPI))
764 default y if (X86_NUMAQ || X86_SUMMIT)
765 select SPARSEMEM_STATIC
767 # Need comments to help the hapless user trying to turn on NUMA support
768 comment "NUMA (NUMA-Q) requires SMP, 64GB highmem support"
769 depends on X86_NUMAQ && (!HIGHMEM64G || !SMP)
771 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
772 depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)
774 config HAVE_ARCH_BOOTMEM_NODE
779 config ARCH_HAVE_MEMORY_PRESENT
781 depends on DISCONTIGMEM
784 config NEED_NODE_MEMMAP_SIZE
786 depends on DISCONTIGMEM || SPARSEMEM
789 config HAVE_ARCH_ALLOC_REMAP
794 config ARCH_DISCONTIGMEM_ENABLE
798 config ARCH_DISCONTIGMEM_DEFAULT
802 config ARCH_SPARSEMEM_ENABLE
806 config ARCH_SELECT_MEMORY_MODEL
808 depends on ARCH_SPARSEMEM_ENABLE
812 config HAVE_ARCH_EARLY_PFN_TO_NID
818 bool "Allocate 3rd-level pagetables from highmem"
819 depends on HIGHMEM4G || HIGHMEM64G
821 The VM uses one page table entry for each page of physical memory.
822 For systems with a lot of RAM, this can be wasteful of precious
823 low memory. Setting this option will put user-space page table
824 entries in high memory.
826 config MATH_EMULATION
827 bool "Math emulation"
829 Linux can emulate a math coprocessor (used for floating point
830 operations) if you don't have one. 486DX and Pentium processors have
831 a math coprocessor built in, 486SX and 386 do not, unless you added
832 a 487DX or 387, respectively. (The messages during boot time can
833 give you some hints here ["man dmesg"].) Everyone needs either a
834 coprocessor or this emulation.
836 If you don't have a math coprocessor, you need to say Y here; if you
837 say Y here even though you have a coprocessor, the coprocessor will
838 be used nevertheless. (This behavior can be changed with the kernel
839 command line option "no387", which comes handy if your coprocessor
840 is broken. Try "man bootparam" or see the documentation of your boot
841 loader (lilo or loadlin) about how to pass options to the kernel at
842 boot time.) This means that it is a good idea to say Y here if you
843 intend to use this kernel on different machines.
845 More information about the internals of the Linux math coprocessor
846 emulation can be found in <file:arch/i386/math-emu/README>.
848 If you are not sure, say Y; apart from resulting in a 66 KB bigger
849 kernel, it won't hurt.
852 bool "MTRR (Memory Type Range Register) support"
854 On Intel P6 family processors (Pentium Pro, Pentium II and later)
855 the Memory Type Range Registers (MTRRs) may be used to control
856 processor access to memory ranges. This is most useful if you have
857 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
858 allows bus write transfers to be combined into a larger transfer
859 before bursting over the PCI/AGP bus. This can increase performance
860 of image write operations 2.5 times or more. Saying Y here creates a
861 /proc/mtrr file which may be used to manipulate your processor's
862 MTRRs. Typically the X server should use this.
864 This code has a reasonably generic interface so that similar
865 control registers on other processors can be easily supported
868 The Cyrix 6x86, 6x86MX and M II processors have Address Range
869 Registers (ARRs) which provide a similar functionality to MTRRs. For
870 these, the ARRs are used to emulate the MTRRs.
871 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
872 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
873 write-combining. All of these processors are supported by this code
874 and it makes sense to say Y here if you have one of them.
876 Saying Y here also fixes a problem with buggy SMP BIOSes which only
877 set the MTRRs for the boot CPU and not for the secondary CPUs. This
878 can lead to all sorts of problems, so it's good to say Y here.
880 You can safely say Y even if your machine doesn't have MTRRs, you'll
881 just add about 9 KB to your kernel.
883 See <file:Documentation/mtrr.txt> for more information.
886 bool "Boot from EFI support (EXPERIMENTAL)"
890 This enables the the kernel to boot on EFI platforms using
891 system configuration information passed to it from the firmware.
892 This also enables the kernel to use any EFI runtime services that are
893 available (such as the EFI variable services).
895 This option is only useful on systems that have EFI firmware
896 and will result in a kernel image that is ~8k larger. In addition,
897 you must use the latest ELILO loader available at
898 <http://elilo.sourceforge.net> in order to take advantage of
899 kernel initialization using EFI information (neither GRUB nor LILO know
900 anything about EFI). However, even with this option, the resultant
901 kernel should continue to boot on existing non-EFI platforms.
904 bool "Enable kernel irq balancing"
905 depends on SMP && X86_IO_APIC
908 The default yes will allow the kernel to do irq load balancing.
909 Saying no will keep the kernel from doing irq load balancing.
913 depends on (SMP || PREEMPT) && X86_CMPXCHG
916 # turning this on wastes a bunch of space.
917 # Summit needs it only when NUMA is on
920 depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
924 bool "Use register arguments (EXPERIMENTAL)"
925 depends on EXPERIMENTAL
928 Compile the kernel with -mregparm=3. This uses a different ABI
929 and passes the first three arguments of a function call in registers.
930 This will probably break binary only modules.
932 This feature is only enabled for gcc-3.0 and later - earlier compilers
933 generate incorrect output with certain kernel constructs when
937 bool "Enable seccomp to safely compute untrusted bytecode"
941 This kernel feature is useful for number crunching applications
942 that may need to compute untrusted bytecode during their
943 execution. By using pipes or other transports made available to
944 the process as file descriptors supporting the read/write
945 syscalls, it's possible to isolate those applications in
946 their own address space using seccomp. Once seccomp is
947 enabled via /proc/<pid>/seccomp, it cannot be disabled
948 and the task is only allowed to execute a few safe syscalls
949 defined by each seccomp mode.
951 If unsure, say Y. Only embedded should say N here.
953 source kernel/Kconfig.hz
955 config PHYSICAL_START
956 hex "Physical address where the kernel is loaded" if EMBEDDED
959 This gives the physical address where the kernel is loaded.
960 Primarily used in the case of kexec on panic where the
961 fail safe kernel needs to run at a different address than
964 Don't change this unless you know what you are doing.
967 bool "kexec system call (EXPERIMENTAL)"
968 depends on EXPERIMENTAL
970 kexec is a system call that implements the ability to shutdown your
971 current kernel, and to start another kernel. It is like a reboot
972 but it is indepedent of the system firmware. And like a reboot
973 you can start any kernel with it, not just Linux.
975 The name comes from the similiarity to the exec system call.
977 It is an ongoing process to be certain the hardware in a machine
978 is properly shutdown, so do not be surprised if this code does not
979 initially work for you. It may help to enable device hotplugging
980 support. As of this writing the exact hardware interface is
981 strongly in flux, so no good recommendation can be made.
984 bool "kernel crash dumps (EXPERIMENTAL)"
986 depends on EXPERIMENTAL
989 Generate crash dump after being started by kexec.
993 menu "Power management options (ACPI, APM)"
994 depends on !X86_VOYAGER
996 source kernel/power/Kconfig
998 source "drivers/acpi/Kconfig"
1000 menu "APM (Advanced Power Management) BIOS Support"
1001 depends on PM && !X86_VISWS
1004 tristate "APM (Advanced Power Management) BIOS support"
1007 APM is a BIOS specification for saving power using several different
1008 techniques. This is mostly useful for battery powered laptops with
1009 APM compliant BIOSes. If you say Y here, the system time will be
1010 reset after a RESUME operation, the /proc/apm device will provide
1011 battery status information, and user-space programs will receive
1012 notification of APM "events" (e.g. battery status change).
1014 If you select "Y" here, you can disable actual use of the APM
1015 BIOS by passing the "apm=off" option to the kernel at boot time.
1017 Note that the APM support is almost completely disabled for
1018 machines with more than one CPU.
1020 In order to use APM, you will need supporting software. For location
1021 and more information, read <file:Documentation/pm.txt> and the
1022 Battery Powered Linux mini-HOWTO, available from
1023 <http://www.tldp.org/docs.html#howto>.
1025 This driver does not spin down disk drives (see the hdparm(8)
1026 manpage ("man 8 hdparm") for that), and it doesn't turn off
1027 VESA-compliant "green" monitors.
1029 This driver does not support the TI 4000M TravelMate and the ACER
1030 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1031 desktop machines also don't have compliant BIOSes, and this driver
1032 may cause those machines to panic during the boot phase.
1034 Generally, if you don't have a battery in your machine, there isn't
1035 much point in using this driver and you should say N. If you get
1036 random kernel OOPSes or reboots that don't seem to be related to
1037 anything, try disabling/enabling this option (or disabling/enabling
1040 Some other things you should try when experiencing seemingly random,
1043 1) make sure that you have enough swap space and that it is
1045 2) pass the "no-hlt" option to the kernel
1046 3) switch on floating point emulation in the kernel and pass
1047 the "no387" option to the kernel
1048 4) pass the "floppy=nodma" option to the kernel
1049 5) pass the "mem=4M" option to the kernel (thereby disabling
1050 all but the first 4 MB of RAM)
1051 6) make sure that the CPU is not over clocked.
1052 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1053 8) disable the cache from your BIOS settings
1054 9) install a fan for the video card or exchange video RAM
1055 10) install a better fan for the CPU
1056 11) exchange RAM chips
1057 12) exchange the motherboard.
1059 To compile this driver as a module, choose M here: the
1060 module will be called apm.
1062 config APM_IGNORE_USER_SUSPEND
1063 bool "Ignore USER SUSPEND"
1066 This option will ignore USER SUSPEND requests. On machines with a
1067 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1068 series notebooks, it is necessary to say Y because of a BIOS bug.
1070 config APM_DO_ENABLE
1071 bool "Enable PM at boot time"
1074 Enable APM features at boot time. From page 36 of the APM BIOS
1075 specification: "When disabled, the APM BIOS does not automatically
1076 power manage devices, enter the Standby State, enter the Suspend
1077 State, or take power saving steps in response to CPU Idle calls."
1078 This driver will make CPU Idle calls when Linux is idle (unless this
1079 feature is turned off -- see "Do CPU IDLE calls", below). This
1080 should always save battery power, but more complicated APM features
1081 will be dependent on your BIOS implementation. You may need to turn
1082 this option off if your computer hangs at boot time when using APM
1083 support, or if it beeps continuously instead of suspending. Turn
1084 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1085 T400CDT. This is off by default since most machines do fine without
1089 bool "Make CPU Idle calls when idle"
1092 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1093 On some machines, this can activate improved power savings, such as
1094 a slowed CPU clock rate, when the machine is idle. These idle calls
1095 are made after the idle loop has run for some length of time (e.g.,
1096 333 mS). On some machines, this will cause a hang at boot time or
1097 whenever the CPU becomes idle. (On machines with more than one CPU,
1098 this option does nothing.)
1100 config APM_DISPLAY_BLANK
1101 bool "Enable console blanking using APM"
1104 Enable console blanking using the APM. Some laptops can use this to
1105 turn off the LCD backlight when the screen blanker of the Linux
1106 virtual console blanks the screen. Note that this is only used by
1107 the virtual console screen blanker, and won't turn off the backlight
1108 when using the X Window system. This also doesn't have anything to
1109 do with your VESA-compliant power-saving monitor. Further, this
1110 option doesn't work for all laptops -- it might not turn off your
1111 backlight at all, or it might print a lot of errors to the console,
1112 especially if you are using gpm.
1114 config APM_RTC_IS_GMT
1115 bool "RTC stores time in GMT"
1118 Say Y here if your RTC (Real Time Clock a.k.a. hardware clock)
1119 stores the time in GMT (Greenwich Mean Time). Say N if your RTC
1122 It is in fact recommended to store GMT in your RTC, because then you
1123 don't have to worry about daylight savings time changes. The only
1124 reason not to use GMT in your RTC is if you also run a broken OS
1125 that doesn't understand GMT.
1127 config APM_ALLOW_INTS
1128 bool "Allow interrupts during APM BIOS calls"
1131 Normally we disable external interrupts while we are making calls to
1132 the APM BIOS as a measure to lessen the effects of a badly behaving
1133 BIOS implementation. The BIOS should reenable interrupts if it
1134 needs to. Unfortunately, some BIOSes do not -- especially those in
1135 many of the newer IBM Thinkpads. If you experience hangs when you
1136 suspend, try setting this to Y. Otherwise, say N.
1138 config APM_REAL_MODE_POWER_OFF
1139 bool "Use real mode APM BIOS call to power off"
1142 Use real mode APM BIOS calls to switch off the computer. This is
1143 a work-around for a number of buggy BIOSes. Switch this option on if
1144 your computer crashes instead of powering off properly.
1148 source "arch/i386/kernel/cpu/cpufreq/Kconfig"
1152 menu "Bus options (PCI, PCMCIA, EISA, MCA, ISA)"
1155 bool "PCI support" if !X86_VISWS
1156 depends on !X86_VOYAGER
1157 default y if X86_VISWS
1159 Find out whether you have a PCI motherboard. PCI is the name of a
1160 bus system, i.e. the way the CPU talks to the other stuff inside
1161 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1162 VESA. If you have PCI, say Y, otherwise N.
1164 The PCI-HOWTO, available from
1165 <http://www.tldp.org/docs.html#howto>, contains valuable
1166 information about which PCI hardware does work under Linux and which
1170 prompt "PCI access mode"
1171 depends on PCI && !X86_VISWS
1174 On PCI systems, the BIOS can be used to detect the PCI devices and
1175 determine their configuration. However, some old PCI motherboards
1176 have BIOS bugs and may crash if this is done. Also, some embedded
1177 PCI-based systems don't have any BIOS at all. Linux can also try to
1178 detect the PCI hardware directly without using the BIOS.
1180 With this option, you can specify how Linux should detect the
1181 PCI devices. If you choose "BIOS", the BIOS will be used,
1182 if you choose "Direct", the BIOS won't be used, and if you
1183 choose "MMConfig", then PCI Express MMCONFIG will be used.
1184 If you choose "Any", the kernel will try MMCONFIG, then the
1185 direct access method and falls back to the BIOS if that doesn't
1186 work. If unsure, go with the default, which is "Any".
1191 config PCI_GOMMCONFIG
1204 depends on !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1209 depends on PCI && ((PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1214 depends on PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1218 source "drivers/pci/pcie/Kconfig"
1220 source "drivers/pci/Kconfig"
1228 depends on !(X86_VOYAGER || X86_VISWS)
1230 Find out whether you have ISA slots on your motherboard. ISA is the
1231 name of a bus system, i.e. the way the CPU talks to the other stuff
1232 inside your box. Other bus systems are PCI, EISA, MicroChannel
1233 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1234 newer boards don't support it. If you have ISA, say Y, otherwise N.
1240 The Extended Industry Standard Architecture (EISA) bus was
1241 developed as an open alternative to the IBM MicroChannel bus.
1243 The EISA bus provided some of the features of the IBM MicroChannel
1244 bus while maintaining backward compatibility with cards made for
1245 the older ISA bus. The EISA bus saw limited use between 1988 and
1246 1995 when it was made obsolete by the PCI bus.
1248 Say Y here if you are building a kernel for an EISA-based machine.
1252 source "drivers/eisa/Kconfig"
1255 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1256 default y if X86_VOYAGER
1258 MicroChannel Architecture is found in some IBM PS/2 machines and
1259 laptops. It is a bus system similar to PCI or ISA. See
1260 <file:Documentation/mca.txt> (and especially the web page given
1261 there) before attempting to build an MCA bus kernel.
1263 source "drivers/mca/Kconfig"
1266 tristate "NatSemi SCx200 support"
1267 depends on !X86_VOYAGER
1269 This provides basic support for the National Semiconductor SCx200
1270 processor. Right now this is just a driver for the GPIO pins.
1272 If you don't know what to do here, say N.
1274 This support is also available as a module. If compiled as a
1275 module, it will be called scx200.
1278 bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
1279 depends on SMP && HOTPLUG && EXPERIMENTAL
1281 Say Y here to experiment with turning CPUs off and on. CPUs
1282 can be controlled through /sys/devices/system/cpu.
1286 source "drivers/pcmcia/Kconfig"
1288 source "drivers/pci/hotplug/Kconfig"
1292 menu "Executable file formats"
1294 source "fs/Kconfig.binfmt"
1298 source "net/Kconfig"
1300 source "drivers/Kconfig"
1304 source "arch/i386/oprofile/Kconfig"
1306 source "arch/i386/Kconfig.debug"
1308 source "security/Kconfig"
1310 source "crypto/Kconfig"
1312 source "lib/Kconfig"
1315 # Use the generic interrupt handling code in kernel/irq/:
1317 config GENERIC_HARDIRQS
1321 config GENERIC_IRQ_PROBE
1325 config GENERIC_PENDING_IRQ
1327 depends on GENERIC_HARDIRQS && SMP
1332 depends on SMP && !X86_VOYAGER
1337 depends on SMP && !(X86_VISWS || X86_VOYAGER)
1340 config X86_BIOS_REBOOT
1342 depends on !(X86_VISWS || X86_VOYAGER)
1345 config X86_TRAMPOLINE
1347 depends on X86_SMP || (X86_VOYAGER && SMP)
1352 depends on X86 && !EMBEDDED