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.
28 config GENERIC_ISA_DMA
38 menu "Processor type and features"
41 prompt "Subarchitecture Type"
47 Choose this option if your computer is a standard PC or compatible.
52 Select this for an AMD Elan processor.
54 Do not use this option for K6/Athlon/Opteron processors!
56 If unsure, choose "PC-compatible" instead.
61 Voyager is an MCA-based 32-way capable SMP architecture proprietary
62 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
66 If you do not specifically know you have a Voyager based machine,
67 say N here, otherwise the kernel you build will not be bootable.
70 bool "NUMAQ (IBM/Sequent)"
74 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
75 multiquad box. This changes the way that processors are bootstrapped,
76 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
77 You will need a new lynxer.elf file to flash your firmware with - send
78 email to <Martin.Bligh@us.ibm.com>.
81 bool "Summit/EXA (IBM x440)"
84 This option is needed for IBM systems that use the Summit/EXA chipset.
85 In particular, it is needed for the x440.
87 If you don't have one of these computers, you should say N here.
90 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
93 This option is needed for the systems that have more than 8 CPUs
94 and if the system is not of any sub-arch type above.
96 If you don't have such a system, you should say N here.
99 bool "SGI 320/540 (Visual Workstation)"
101 The SGI Visual Workstation series is an IA32-based workstation
102 based on SGI systems chips with some legacy PC hardware attached.
104 Say Y here to create a kernel to run on the SGI 320 or 540.
106 A kernel compiled for the Visual Workstation will not run on PCs
107 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
109 config X86_GENERICARCH
110 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
113 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
114 It is intended for a generic binary kernel.
117 bool "Support for Unisys ES7000 IA32 series"
120 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
121 supposed to run on an IA32-based Unisys ES7000 system.
122 Only choose this option if you have such a system, otherwise you
130 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
132 config X86_SUMMIT_NUMA
135 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
137 config X86_CYCLONE_TIMER
140 depends on X86_SUMMIT || X86_GENERICARCH
142 config ES7000_CLUSTERED_APIC
145 depends on SMP && X86_ES7000 && MPENTIUMIII
150 prompt "Processor family"
156 This is the processor type of your CPU. This information is used for
157 optimizing purposes. In order to compile a kernel that can run on
158 all x86 CPU types (albeit not optimally fast), you can specify
161 The kernel will not necessarily run on earlier architectures than
162 the one you have chosen, e.g. a Pentium optimized kernel will run on
163 a PPro, but not necessarily on a i486.
165 Here are the settings recommended for greatest speed:
166 - "386" for the AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI
167 486DLC/DLC2, UMC 486SX-S and NexGen Nx586. Only "386" kernels
168 will run on a 386 class machine.
169 - "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or
170 SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
171 - "586" for generic Pentium CPUs lacking the TSC
172 (time stamp counter) register.
173 - "Pentium-Classic" for the Intel Pentium.
174 - "Pentium-MMX" for the Intel Pentium MMX.
175 - "Pentium-Pro" for the Intel Pentium Pro.
176 - "Pentium-II" for the Intel Pentium II or pre-Coppermine Celeron.
177 - "Pentium-III" for the Intel Pentium III or Coppermine Celeron.
178 - "Pentium-4" for the Intel Pentium 4 or P4-based Celeron.
179 - "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
180 - "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
181 - "Crusoe" for the Transmeta Crusoe series.
182 - "Efficeon" for the Transmeta Efficeon series.
183 - "Winchip-C6" for original IDT Winchip.
184 - "Winchip-2" for IDT Winchip 2.
185 - "Winchip-2A" for IDT Winchips with 3dNow! capabilities.
186 - "CyrixIII/VIA C3" for VIA Cyrix III or VIA C3.
187 - "VIA C3-2 for VIA C3-2 "Nehemiah" (model 9 and above).
189 If you don't know what to do, choose "386".
194 Select this for a 486 series processor, either Intel or one of the
195 compatible processors from AMD, Cyrix, IBM, or Intel. Includes DX,
196 DX2, and DX4 variants; also SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or
200 bool "586/K5/5x86/6x86/6x86MX"
202 Select this for an 586 or 686 series processor such as the AMD K5,
203 the Cyrix 5x86, 6x86 and 6x86MX. This choice does not
204 assume the RDTSC (Read Time Stamp Counter) instruction.
207 bool "Pentium-Classic"
209 Select this for a Pentium Classic processor with the RDTSC (Read
210 Time Stamp Counter) instruction for benchmarking.
215 Select this for a Pentium with the MMX graphics/multimedia
216 extended instructions.
221 Select this for Intel Pentium Pro chips. This enables the use of
222 Pentium Pro extended instructions, and disables the init-time guard
223 against the f00f bug found in earlier Pentiums.
226 bool "Pentium-II/Celeron(pre-Coppermine)"
228 Select this for Intel chips based on the Pentium-II and
229 pre-Coppermine Celeron core. This option enables an unaligned
230 copy optimization, compiles the kernel with optimization flags
231 tailored for the chip, and applies any applicable Pentium Pro
235 bool "Pentium-III/Celeron(Coppermine)/Pentium-III Xeon"
237 Select this for Intel chips based on the Pentium-III and
238 Celeron-Coppermine core. This option enables use of some
239 extended prefetch instructions in addition to the Pentium II
245 Select this for Intel Pentium M (not Pentium-4 M)
249 bool "Pentium-4/Celeron(P4-based)/Pentium-4 M/Xeon"
251 Select this for Intel Pentium 4 chips. This includes the
252 Pentium 4, P4-based Celeron and Xeon, and Pentium-4 M
253 (not Pentium M) chips. This option enables compile flags
254 optimized for the chip, uses the correct cache shift, and
255 applies any applicable Pentium III optimizations.
258 bool "K6/K6-II/K6-III"
260 Select this for an AMD K6-family processor. Enables use of
261 some extended instructions, and passes appropriate optimization
265 bool "Athlon/Duron/K7"
267 Select this for an AMD Athlon K7-family processor. Enables use of
268 some extended instructions, and passes appropriate optimization
272 bool "Opteron/Athlon64/Hammer/K8"
274 Select this for an AMD Opteron or Athlon64 Hammer-family processor. Enables
275 use of some extended instructions, and passes appropriate optimization
281 Select this for a Transmeta Crusoe processor. Treats the processor
282 like a 586 with TSC, and sets some GCC optimization flags (like a
283 Pentium Pro with no alignment requirements).
288 Select this for a Transmeta Efficeon processor.
293 Select this for an IDT Winchip C6 chip. Linux and GCC
294 treat this chip as a 586TSC with some extended instructions
295 and alignment requirements.
300 Select this for an IDT Winchip-2. Linux and GCC
301 treat this chip as a 586TSC with some extended instructions
302 and alignment requirements.
305 bool "Winchip-2A/Winchip-3"
307 Select this for an IDT Winchip-2A or 3. Linux and GCC
308 treat this chip as a 586TSC with some extended instructions
309 and alignment reqirements. Also enable out of order memory
310 stores for this CPU, which can increase performance of some
314 bool "CyrixIII/VIA-C3"
316 Select this for a Cyrix III or C3 chip. Presently Linux and GCC
317 treat this chip as a generic 586. Whilst the CPU is 686 class,
318 it lacks the cmov extension which gcc assumes is present when
320 Note that Nehemiah (Model 9) and above will not boot with this
321 kernel due to them lacking the 3DNow! instructions used in earlier
322 incarnations of the CPU.
325 bool "VIA C3-2 (Nehemiah)"
327 Select this for a VIA C3 "Nehemiah". Selecting this enables usage
328 of SSE and tells gcc to treat the CPU as a 686.
329 Note, this kernel will not boot on older (pre model 9) C3s.
334 bool "Generic x86 support"
336 Instead of just including optimizations for the selected
337 x86 variant (e.g. PII, Crusoe or Athlon), include some more
338 generic optimizations as well. This will make the kernel
339 perform better on x86 CPUs other than that selected.
341 This is really intended for distributors who need more
342 generic optimizations.
347 # Define implied options from the CPU selection here
359 config X86_L1_CACHE_SHIFT
361 default "7" if MPENTIUM4 || X86_GENERIC
362 default "4" if X86_ELAN || M486 || M386
363 default "5" if MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCRUSOE || MEFFICEON || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2
364 default "6" if MK7 || MK8 || MPENTIUMM
366 config RWSEM_GENERIC_SPINLOCK
371 config RWSEM_XCHGADD_ALGORITHM
376 config GENERIC_CALIBRATE_DELAY
380 config X86_PPRO_FENCE
382 depends on M686 || M586MMX || M586TSC || M586 || M486 || M386
387 depends on M586MMX || M586TSC || M586 || M486 || M386
390 config X86_WP_WORKS_OK
410 config X86_ALIGNMENT_16
412 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2
417 depends on MK7 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || MK8 || MEFFICEON
420 config X86_INTEL_USERCOPY
422 depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK8 || MK7 || MEFFICEON
425 config X86_USE_PPRO_CHECKSUM
427 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC3_2 || MEFFICEON
432 depends on MCYRIXIII || MK7
437 depends on (MWINCHIP3D || MWINCHIP2 || MWINCHIPC6) && MTRR
441 bool "HPET Timer Support"
443 This enables the use of the HPET for the kernel's internal timer.
444 HPET is the next generation timer replacing legacy 8254s.
445 You can safely choose Y here. However, HPET will only be
446 activated if the platform and the BIOS support this feature.
447 Otherwise the 8254 will be used for timing services.
449 Choose N to continue using the legacy 8254 timer.
451 config HPET_EMULATE_RTC
452 bool "Provide RTC interrupt"
453 depends on HPET_TIMER && RTC=y
456 bool "Symmetric multi-processing support"
458 This enables support for systems with more than one CPU. If you have
459 a system with only one CPU, like most personal computers, say N. If
460 you have a system with more than one CPU, say Y.
462 If you say N here, the kernel will run on single and multiprocessor
463 machines, but will use only one CPU of a multiprocessor machine. If
464 you say Y here, the kernel will run on many, but not all,
465 singleprocessor machines. On a singleprocessor machine, the kernel
466 will run faster if you say N here.
468 Note that if you say Y here and choose architecture "586" or
469 "Pentium" under "Processor family", the kernel will not work on 486
470 architectures. Similarly, multiprocessor kernels for the "PPro"
471 architecture may not work on all Pentium based boards.
473 People using multiprocessor machines who say Y here should also say
474 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
475 Management" code will be disabled if you say Y here.
477 See also the <file:Documentation/smp.txt>,
478 <file:Documentation/i386/IO-APIC.txt>,
479 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
480 <http://www.tldp.org/docs.html#howto>.
482 If you don't know what to do here, say N.
485 int "Maximum number of CPUs (2-255)"
488 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
491 This allows you to specify the maximum number of CPUs which this
492 kernel will support. The maximum supported value is 255 and the
493 minimum value which makes sense is 2.
495 This is purely to save memory - each supported CPU adds
496 approximately eight kilobytes to the kernel image.
499 bool "SMT (Hyperthreading) scheduler support"
503 SMT scheduler support improves the CPU scheduler's decision making
504 when dealing with Intel Pentium 4 chips with HyperThreading at a
505 cost of slightly increased overhead in some places. If unsure say
509 bool "Preemptible Kernel"
511 This option reduces the latency of the kernel when reacting to
512 real-time or interactive events by allowing a low priority process to
513 be preempted even if it is in kernel mode executing a system call.
514 This allows applications to run more reliably even when the system is
517 Say Y here if you are building a kernel for a desktop, embedded
518 or real-time system. Say N if you are unsure.
521 bool "Preempt The Big Kernel Lock"
525 This option reduces the latency of the kernel by making the
526 big kernel lock preemptible.
528 Say Y here if you are building a kernel for a desktop system.
529 Say N if you are unsure.
532 bool "Local APIC support on uniprocessors" if !SMP
533 depends on !(X86_VISWS || X86_VOYAGER)
535 A local APIC (Advanced Programmable Interrupt Controller) is an
536 integrated interrupt controller in the CPU. If you have a single-CPU
537 system which has a processor with a local APIC, you can say Y here to
538 enable and use it. If you say Y here even though your machine doesn't
539 have a local APIC, then the kernel will still run with no slowdown at
540 all. The local APIC supports CPU-generated self-interrupts (timer,
541 performance counters), and the NMI watchdog which detects hard
544 If you have a system with several CPUs, you do not need to say Y
545 here: the local APIC will be used automatically.
548 bool "IO-APIC support on uniprocessors"
549 depends on !SMP && X86_UP_APIC
551 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
552 SMP-capable replacement for PC-style interrupt controllers. Most
553 SMP systems and a small number of uniprocessor systems have one.
554 If you have a single-CPU system with an IO-APIC, you can say Y here
555 to use it. If you say Y here even though your machine doesn't have
556 an IO-APIC, then the kernel will still run with no slowdown at all.
558 If you have a system with several CPUs, you do not need to say Y
559 here: the IO-APIC will be used automatically.
561 config X86_LOCAL_APIC
563 depends on !SMP && X86_UP_APIC
568 depends on !SMP && X86_UP_IOAPIC
573 depends on (MWINCHIP3D || MWINCHIP2 || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2) && !X86_NUMAQ
577 bool "Machine Check Exception"
578 depends on !X86_VOYAGER
580 Machine Check Exception support allows the processor to notify the
581 kernel if it detects a problem (e.g. overheating, component failure).
582 The action the kernel takes depends on the severity of the problem,
583 ranging from a warning message on the console, to halting the machine.
584 Your processor must be a Pentium or newer to support this - check the
585 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
586 have a design flaw which leads to false MCE events - hence MCE is
587 disabled on all P5 processors, unless explicitly enabled with "mce"
588 as a boot argument. Similarly, if MCE is built in and creates a
589 problem on some new non-standard machine, you can boot with "nomce"
590 to disable it. MCE support simply ignores non-MCE processors like
591 the 386 and 486, so nearly everyone can say Y here.
593 config X86_MCE_NONFATAL
594 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
597 Enabling this feature starts a timer that triggers every 5 seconds which
598 will look at the machine check registers to see if anything happened.
599 Non-fatal problems automatically get corrected (but still logged).
600 Disable this if you don't want to see these messages.
601 Seeing the messages this option prints out may be indicative of dying hardware,
602 or out-of-spec (ie, overclocked) hardware.
603 This option only does something on certain CPUs.
604 (AMD Athlon/Duron and Intel Pentium 4)
606 config X86_MCE_P4THERMAL
607 bool "check for P4 thermal throttling interrupt."
608 depends on X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
610 Enabling this feature will cause a message to be printed when the P4
611 enters thermal throttling.
614 tristate "Toshiba Laptop support"
616 This adds a driver to safely access the System Management Mode of
617 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
618 not work on models with a Phoenix BIOS. The System Management Mode
619 is used to set the BIOS and power saving options on Toshiba portables.
621 For information on utilities to make use of this driver see the
622 Toshiba Linux utilities web site at:
623 <http://www.buzzard.org.uk/toshiba/>.
625 Say Y if you intend to run this kernel on a Toshiba portable.
629 tristate "Dell laptop support"
631 This adds a driver to safely access the System Management Mode
632 of the CPU on the Dell Inspiron 8000. The System Management Mode
633 is used to read cpu temperature and cooling fan status and to
634 control the fans on the I8K portables.
636 This driver has been tested only on the Inspiron 8000 but it may
637 also work with other Dell laptops. You can force loading on other
638 models by passing the parameter `force=1' to the module. Use at
641 For information on utilities to make use of this driver see the
642 I8K Linux utilities web site at:
643 <http://people.debian.org/~dz/i8k/>
645 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
649 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
651 If you say Y here and also to "/dev file system support" in the
652 'File systems' section, you will be able to update the microcode on
653 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
654 Pentium III, Pentium 4, Xeon etc. You will obviously need the
655 actual microcode binary data itself which is not shipped with the
658 For latest news and information on obtaining all the required
659 ingredients for this driver, check:
660 <http://www.urbanmyth.org/microcode/>.
662 To compile this driver as a module, choose M here: the
663 module will be called microcode.
666 tristate "/dev/cpu/*/msr - Model-specific register support"
668 This device gives privileged processes access to the x86
669 Model-Specific Registers (MSRs). It is a character device with
670 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
671 MSR accesses are directed to a specific CPU on multi-processor
675 tristate "/dev/cpu/*/cpuid - CPU information support"
677 This device gives processes access to the x86 CPUID instruction to
678 be executed on a specific processor. It is a character device
679 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
682 source "drivers/firmware/Kconfig"
685 prompt "High Memory Support"
691 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
692 However, the address space of 32-bit x86 processors is only 4
693 Gigabytes large. That means that, if you have a large amount of
694 physical memory, not all of it can be "permanently mapped" by the
695 kernel. The physical memory that's not permanently mapped is called
698 If you are compiling a kernel which will never run on a machine with
699 more than 1 Gigabyte total physical RAM, answer "off" here (default
700 choice and suitable for most users). This will result in a "3GB/1GB"
701 split: 3GB are mapped so that each process sees a 3GB virtual memory
702 space and the remaining part of the 4GB virtual memory space is used
703 by the kernel to permanently map as much physical memory as
706 If the machine has between 1 and 4 Gigabytes physical RAM, then
709 If more than 4 Gigabytes is used then answer "64GB" here. This
710 selection turns Intel PAE (Physical Address Extension) mode on.
711 PAE implements 3-level paging on IA32 processors. PAE is fully
712 supported by Linux, PAE mode is implemented on all recent Intel
713 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
714 then the kernel will not boot on CPUs that don't support PAE!
716 The actual amount of total physical memory will either be
717 auto detected or can be forced by using a kernel command line option
718 such as "mem=256M". (Try "man bootparam" or see the documentation of
719 your boot loader (lilo or loadlin) about how to pass options to the
720 kernel at boot time.)
722 If unsure, say "off".
727 Select this if you have a 32-bit processor and between 1 and 4
728 gigabytes of physical RAM.
733 Select this if you have a 32-bit processor and more than 4
734 gigabytes of physical RAM.
739 prompt "Memory Split User Space"
742 A different Userspace/Kernel split allows you to
743 utilize up to alsmost 3GB of RAM without the requirement
744 for HIGHMEM. It also increases the available lowmem.
747 bool "3.0GB/1.0GB Kernel (Default)"
749 This is the default split of 3GB userspace to 1GB kernel
750 space, which will result in about 860MB of lowmem.
753 bool "2.5GB/1.5GB Kernel"
755 This split provides 2.5GB userspace and 1.5GB kernel
756 space, which will result in about 1370MB of lowmem.
759 bool "2.0GB/2.0GB Kernel"
761 This split provides 2GB userspace and 2GB kernel
762 space, which will result in about 1880MB of lowmem.
765 bool "1.5GB/2.5GB Kernel"
767 This split provides 1.5GB userspace and 2.5GB kernel
768 space, which will result in about 2390MB of lowmem.
771 bool "1.0GB/3.0GB Kernel"
773 This split provides 1GB userspace and 3GB kernel
774 space, which will result in about 2900MB of lowmem.
780 depends on HIGHMEM64G || HIGHMEM4G
785 depends on HIGHMEM64G
788 # Common NUMA Features
790 bool "Numa Memory Allocation and Scheduler Support"
791 depends on SMP && HIGHMEM64G && (X86_NUMAQ || X86_GENERICARCH || (X86_SUMMIT && ACPI))
793 default y if (X86_NUMAQ || X86_SUMMIT)
795 # Need comments to help the hapless user trying to turn on NUMA support
796 comment "NUMA (NUMA-Q) requires SMP, 64GB highmem support"
797 depends on X86_NUMAQ && (!HIGHMEM64G || !SMP)
799 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
800 depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)
807 config HAVE_ARCH_BOOTMEM_NODE
813 bool "Allocate 3rd-level pagetables from highmem"
814 depends on HIGHMEM4G || HIGHMEM64G
816 The VM uses one page table entry for each page of physical memory.
817 For systems with a lot of RAM, this can be wasteful of precious
818 low memory. Setting this option will put user-space page table
819 entries in high memory.
821 config MATH_EMULATION
822 bool "Math emulation"
824 Linux can emulate a math coprocessor (used for floating point
825 operations) if you don't have one. 486DX and Pentium processors have
826 a math coprocessor built in, 486SX and 386 do not, unless you added
827 a 487DX or 387, respectively. (The messages during boot time can
828 give you some hints here ["man dmesg"].) Everyone needs either a
829 coprocessor or this emulation.
831 If you don't have a math coprocessor, you need to say Y here; if you
832 say Y here even though you have a coprocessor, the coprocessor will
833 be used nevertheless. (This behavior can be changed with the kernel
834 command line option "no387", which comes handy if your coprocessor
835 is broken. Try "man bootparam" or see the documentation of your boot
836 loader (lilo or loadlin) about how to pass options to the kernel at
837 boot time.) This means that it is a good idea to say Y here if you
838 intend to use this kernel on different machines.
840 More information about the internals of the Linux math coprocessor
841 emulation can be found in <file:arch/i386/math-emu/README>.
843 If you are not sure, say Y; apart from resulting in a 66 KB bigger
844 kernel, it won't hurt.
847 bool "MTRR (Memory Type Range Register) support"
849 On Intel P6 family processors (Pentium Pro, Pentium II and later)
850 the Memory Type Range Registers (MTRRs) may be used to control
851 processor access to memory ranges. This is most useful if you have
852 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
853 allows bus write transfers to be combined into a larger transfer
854 before bursting over the PCI/AGP bus. This can increase performance
855 of image write operations 2.5 times or more. Saying Y here creates a
856 /proc/mtrr file which may be used to manipulate your processor's
857 MTRRs. Typically the X server should use this.
859 This code has a reasonably generic interface so that similar
860 control registers on other processors can be easily supported
863 The Cyrix 6x86, 6x86MX and M II processors have Address Range
864 Registers (ARRs) which provide a similar functionality to MTRRs. For
865 these, the ARRs are used to emulate the MTRRs.
866 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
867 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
868 write-combining. All of these processors are supported by this code
869 and it makes sense to say Y here if you have one of them.
871 Saying Y here also fixes a problem with buggy SMP BIOSes which only
872 set the MTRRs for the boot CPU and not for the secondary CPUs. This
873 can lead to all sorts of problems, so it's good to say Y here.
875 You can safely say Y even if your machine doesn't have MTRRs, you'll
876 just add about 9 KB to your kernel.
878 See <file:Documentation/mtrr.txt> for more information.
881 bool "Boot from EFI support (EXPERIMENTAL)"
885 This enables the the kernel to boot on EFI platforms using
886 system configuration information passed to it from the firmware.
887 This also enables the kernel to use any EFI runtime services that are
888 available (such as the EFI variable services).
890 This option is only useful on systems that have EFI firmware
891 and will result in a kernel image that is ~8k larger. In addition,
892 you must use the latest ELILO loader available at
893 <http://elilo.sourceforge.net> in order to take advantage of
894 kernel initialization using EFI information (neither GRUB nor LILO know
895 anything about EFI). However, even with this option, the resultant
896 kernel should continue to boot on existing non-EFI platforms.
899 bool "Enable kernel irq balancing"
900 depends on SMP && X86_IO_APIC
903 The default yes will allow the kernel to do irq load balancing.
904 Saying no will keep the kernel from doing irq load balancing.
908 depends on (SMP || PREEMPT) && X86_CMPXCHG
911 # turning this on wastes a bunch of space.
912 # Summit needs it only when NUMA is on
915 depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
919 bool "Use register arguments (EXPERIMENTAL)"
920 depends on EXPERIMENTAL
923 Compile the kernel with -mregparm=3. This uses a different ABI
924 and passes the first three arguments of a function call in registers.
925 This will probably break binary only modules.
927 This feature is only enabled for gcc-3.0 and later - earlier compilers
928 generate incorrect output with certain kernel constructs when
934 menu "Power management options (ACPI, APM)"
935 depends on !X86_VOYAGER
937 source kernel/power/Kconfig
939 source "drivers/acpi/Kconfig"
941 menu "APM (Advanced Power Management) BIOS Support"
942 depends on PM && !X86_VISWS
945 tristate "APM (Advanced Power Management) BIOS support"
948 APM is a BIOS specification for saving power using several different
949 techniques. This is mostly useful for battery powered laptops with
950 APM compliant BIOSes. If you say Y here, the system time will be
951 reset after a RESUME operation, the /proc/apm device will provide
952 battery status information, and user-space programs will receive
953 notification of APM "events" (e.g. battery status change).
955 If you select "Y" here, you can disable actual use of the APM
956 BIOS by passing the "apm=off" option to the kernel at boot time.
958 Note that the APM support is almost completely disabled for
959 machines with more than one CPU.
961 In order to use APM, you will need supporting software. For location
962 and more information, read <file:Documentation/pm.txt> and the
963 Battery Powered Linux mini-HOWTO, available from
964 <http://www.tldp.org/docs.html#howto>.
966 This driver does not spin down disk drives (see the hdparm(8)
967 manpage ("man 8 hdparm") for that), and it doesn't turn off
968 VESA-compliant "green" monitors.
970 This driver does not support the TI 4000M TravelMate and the ACER
971 486/DX4/75 because they don't have compliant BIOSes. Many "green"
972 desktop machines also don't have compliant BIOSes, and this driver
973 may cause those machines to panic during the boot phase.
975 Generally, if you don't have a battery in your machine, there isn't
976 much point in using this driver and you should say N. If you get
977 random kernel OOPSes or reboots that don't seem to be related to
978 anything, try disabling/enabling this option (or disabling/enabling
981 Some other things you should try when experiencing seemingly random,
984 1) make sure that you have enough swap space and that it is
986 2) pass the "no-hlt" option to the kernel
987 3) switch on floating point emulation in the kernel and pass
988 the "no387" option to the kernel
989 4) pass the "floppy=nodma" option to the kernel
990 5) pass the "mem=4M" option to the kernel (thereby disabling
991 all but the first 4 MB of RAM)
992 6) make sure that the CPU is not over clocked.
993 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
994 8) disable the cache from your BIOS settings
995 9) install a fan for the video card or exchange video RAM
996 10) install a better fan for the CPU
997 11) exchange RAM chips
998 12) exchange the motherboard.
1000 To compile this driver as a module, choose M here: the
1001 module will be called apm.
1003 config APM_IGNORE_USER_SUSPEND
1004 bool "Ignore USER SUSPEND"
1007 This option will ignore USER SUSPEND requests. On machines with a
1008 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1009 series notebooks, it is necessary to say Y because of a BIOS bug.
1011 config APM_DO_ENABLE
1012 bool "Enable PM at boot time"
1015 Enable APM features at boot time. From page 36 of the APM BIOS
1016 specification: "When disabled, the APM BIOS does not automatically
1017 power manage devices, enter the Standby State, enter the Suspend
1018 State, or take power saving steps in response to CPU Idle calls."
1019 This driver will make CPU Idle calls when Linux is idle (unless this
1020 feature is turned off -- see "Do CPU IDLE calls", below). This
1021 should always save battery power, but more complicated APM features
1022 will be dependent on your BIOS implementation. You may need to turn
1023 this option off if your computer hangs at boot time when using APM
1024 support, or if it beeps continuously instead of suspending. Turn
1025 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1026 T400CDT. This is off by default since most machines do fine without
1030 bool "Make CPU Idle calls when idle"
1033 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1034 On some machines, this can activate improved power savings, such as
1035 a slowed CPU clock rate, when the machine is idle. These idle calls
1036 are made after the idle loop has run for some length of time (e.g.,
1037 333 mS). On some machines, this will cause a hang at boot time or
1038 whenever the CPU becomes idle. (On machines with more than one CPU,
1039 this option does nothing.)
1041 config APM_DISPLAY_BLANK
1042 bool "Enable console blanking using APM"
1045 Enable console blanking using the APM. Some laptops can use this to
1046 turn off the LCD backlight when the screen blanker of the Linux
1047 virtual console blanks the screen. Note that this is only used by
1048 the virtual console screen blanker, and won't turn off the backlight
1049 when using the X Window system. This also doesn't have anything to
1050 do with your VESA-compliant power-saving monitor. Further, this
1051 option doesn't work for all laptops -- it might not turn off your
1052 backlight at all, or it might print a lot of errors to the console,
1053 especially if you are using gpm.
1055 config APM_RTC_IS_GMT
1056 bool "RTC stores time in GMT"
1059 Say Y here if your RTC (Real Time Clock a.k.a. hardware clock)
1060 stores the time in GMT (Greenwich Mean Time). Say N if your RTC
1063 It is in fact recommended to store GMT in your RTC, because then you
1064 don't have to worry about daylight savings time changes. The only
1065 reason not to use GMT in your RTC is if you also run a broken OS
1066 that doesn't understand GMT.
1068 config APM_ALLOW_INTS
1069 bool "Allow interrupts during APM BIOS calls"
1072 Normally we disable external interrupts while we are making calls to
1073 the APM BIOS as a measure to lessen the effects of a badly behaving
1074 BIOS implementation. The BIOS should reenable interrupts if it
1075 needs to. Unfortunately, some BIOSes do not -- especially those in
1076 many of the newer IBM Thinkpads. If you experience hangs when you
1077 suspend, try setting this to Y. Otherwise, say N.
1079 config APM_REAL_MODE_POWER_OFF
1080 bool "Use real mode APM BIOS call to power off"
1083 Use real mode APM BIOS calls to switch off the computer. This is
1084 a work-around for a number of buggy BIOSes. Switch this option on if
1085 your computer crashes instead of powering off properly.
1089 source "arch/i386/kernel/cpu/cpufreq/Kconfig"
1093 menu "Bus options (PCI, PCMCIA, EISA, MCA, ISA)"
1095 config X86_VISWS_APIC
1097 depends on X86_VISWS
1100 config X86_LOCAL_APIC
1102 depends on (X86_VISWS || SMP) && !X86_VOYAGER
1107 depends on SMP && !(X86_VISWS || X86_VOYAGER)
1111 bool "PCI support" if !X86_VISWS
1112 depends on !X86_VOYAGER
1113 default y if X86_VISWS
1115 Find out whether you have a PCI motherboard. PCI is the name of a
1116 bus system, i.e. the way the CPU talks to the other stuff inside
1117 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1118 VESA. If you have PCI, say Y, otherwise N.
1120 The PCI-HOWTO, available from
1121 <http://www.tldp.org/docs.html#howto>, contains valuable
1122 information about which PCI hardware does work under Linux and which
1126 prompt "PCI access mode"
1127 depends on PCI && !X86_VISWS
1130 On PCI systems, the BIOS can be used to detect the PCI devices and
1131 determine their configuration. However, some old PCI motherboards
1132 have BIOS bugs and may crash if this is done. Also, some embedded
1133 PCI-based systems don't have any BIOS at all. Linux can also try to
1134 detect the PCI hardware directly without using the BIOS.
1136 With this option, you can specify how Linux should detect the
1137 PCI devices. If you choose "BIOS", the BIOS will be used,
1138 if you choose "Direct", the BIOS won't be used, and if you
1139 choose "MMConfig", then PCI Express MMCONFIG will be used.
1140 If you choose "Any", the kernel will try MMCONFIG, then the
1141 direct access method and falls back to the BIOS if that doesn't
1142 work. If unsure, go with the default, which is "Any".
1147 config PCI_GOMMCONFIG
1160 depends on !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1165 depends on PCI && ((PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1170 depends on PCI && (PCI_GOMMCONFIG || (PCI_GOANY && ACPI))
1174 source "drivers/pci/pcie/Kconfig"
1176 source "drivers/pci/Kconfig"
1180 depends on !(X86_VOYAGER || X86_VISWS)
1182 Find out whether you have ISA slots on your motherboard. ISA is the
1183 name of a bus system, i.e. the way the CPU talks to the other stuff
1184 inside your box. Other bus systems are PCI, EISA, MicroChannel
1185 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1186 newer boards don't support it. If you have ISA, say Y, otherwise N.
1192 The Extended Industry Standard Architecture (EISA) bus was
1193 developed as an open alternative to the IBM MicroChannel bus.
1195 The EISA bus provided some of the features of the IBM MicroChannel
1196 bus while maintaining backward compatibility with cards made for
1197 the older ISA bus. The EISA bus saw limited use between 1988 and
1198 1995 when it was made obsolete by the PCI bus.
1200 Say Y here if you are building a kernel for an EISA-based machine.
1204 source "drivers/eisa/Kconfig"
1208 depends on !(X86_VISWS || X86_VOYAGER)
1210 MicroChannel Architecture is found in some IBM PS/2 machines and
1211 laptops. It is a bus system similar to PCI or ISA. See
1212 <file:Documentation/mca.txt> (and especially the web page given
1213 there) before attempting to build an MCA bus kernel.
1216 depends on X86_VOYAGER
1217 default y if X86_VOYAGER
1219 source "drivers/mca/Kconfig"
1222 tristate "NatSemi SCx200 support"
1223 depends on !X86_VOYAGER
1225 This provides basic support for the National Semiconductor SCx200
1226 processor. Right now this is just a driver for the GPIO pins.
1228 If you don't know what to do here, say N.
1230 This support is also available as a module. If compiled as a
1231 module, it will be called scx200.
1233 source "drivers/pcmcia/Kconfig"
1235 source "drivers/pci/hotplug/Kconfig"
1239 menu "Executable file formats"
1241 source "fs/Kconfig.binfmt"
1245 source "drivers/Kconfig"
1249 source "arch/i386/oprofile/Kconfig"
1251 source "arch/i386/Kconfig.debug"
1253 source "kernel/vserver/Kconfig"
1255 source "security/Kconfig"
1257 source "crypto/Kconfig"
1259 source "lib/Kconfig"
1262 # Use the generic interrupt handling code in kernel/irq/:
1264 config GENERIC_HARDIRQS
1268 config GENERIC_IRQ_PROBE
1274 depends on SMP && !X86_VOYAGER
1279 depends on SMP && !(X86_VISWS || X86_VOYAGER)
1282 config X86_BIOS_REBOOT
1284 depends on !(X86_VISWS || X86_VOYAGER)
1287 config X86_TRAMPOLINE
1289 depends on X86_SMP || (X86_VOYAGER && SMP)
1294 depends on X86 && !EMBEDDED