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
35 menu "Processor type and features"
38 prompt "Subarchitecture Type"
44 Choose this option if your computer is a standard PC or compatible.
49 Select this for an AMD Elan processor.
51 Do not use this option for K6/Athlon/Opteron processors!
53 If unsure, choose "PC-compatible" instead.
58 Voyager is a MCA based 32 way capable SMP architecture proprietary
59 to NCR Corp. Machine classes 345x/35xx/4100/51xx are voyager based.
63 If you do not specifically know you have a Voyager based machine,
64 say N here otherwise the kernel you build will not be bootable.
67 bool "NUMAQ (IBM/Sequent)"
71 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
72 multiquad box. This changes the way that processors are bootstrapped,
73 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
74 You will need a new lynxer.elf file to flash your firmware with - send
75 email to <Martin.Bligh@us.ibm.com>.
78 bool "Summit/EXA (IBM x440)"
81 This option is needed for IBM systems that use the Summit/EXA chipset.
82 In particular, it is needed for the x440.
84 If you don't have one of these computers, you should say N here.
87 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
90 This option is needed for the systems that have more than 8 CPUs
91 and if the system is not of any sub-arch type above.
93 If you don't have such a system, you should say N here.
96 bool "SGI 320/540 (Visual Workstation)"
98 The SGI Visual Workstation series is an IA32-based workstation
99 based on SGI systems chips with some legacy PC hardware attached.
101 Say Y here to create a kernel to run on the SGI 320 or 540.
103 A kernel compiled for the Visual Workstation will not run on PCs
104 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
106 config X86_GENERICARCH
107 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
110 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
111 It is intended for a generic binary kernel.
114 bool "Support for Unisys ES7000 IA32 series"
117 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
118 supposed to run on an IA32-based Unisys ES7000 system.
119 Only choose this option if you have such a system, otherwise you
127 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
129 config X86_SUMMIT_NUMA
132 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
134 config X86_CYCLONE_TIMER
137 depends on X86_SUMMIT || X86_GENERICARCH
139 config ES7000_CLUSTERED_APIC
142 depends on SMP && X86_ES7000 && MPENTIUMIII
147 prompt "Processor family"
153 This is the processor type of your CPU. This information is used for
154 optimizing purposes. In order to compile a kernel that can run on
155 all x86 CPU types (albeit not optimally fast), you can specify
158 The kernel will not necessarily run on earlier architectures than
159 the one you have chosen, e.g. a Pentium optimized kernel will run on
160 a PPro, but not necessarily on a i486.
162 Here are the settings recommended for greatest speed:
163 - "386" for the AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI
164 486DLC/DLC2, UMC 486SX-S and NexGen Nx586. Only "386" kernels
165 will run on a 386 class machine.
166 - "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or
167 SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
168 - "586" for generic Pentium CPUs lacking the TSC
169 (time stamp counter) register.
170 - "Pentium-Classic" for the Intel Pentium.
171 - "Pentium-MMX" for the Intel Pentium MMX.
172 - "Pentium-Pro" for the Intel Pentium Pro.
173 - "Pentium-II" for the Intel Pentium II or pre-Coppermine Celeron.
174 - "Pentium-III" for the Intel Pentium III or Coppermine Celeron.
175 - "Pentium-4" for the Intel Pentium 4 or P4-based Celeron.
176 - "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
177 - "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
178 - "Crusoe" for the Transmeta Crusoe series.
179 - "Winchip-C6" for original IDT Winchip.
180 - "Winchip-2" for IDT Winchip 2.
181 - "Winchip-2A" for IDT Winchips with 3dNow! capabilities.
182 - "CyrixIII/VIA C3" for VIA Cyrix III or VIA C3.
183 - "VIA C3-2 for VIA C3-2 "Nehemiah" (model 9 and above).
185 If you don't know what to do, choose "386".
190 Select this for a 486 series processor, either Intel or one of the
191 compatible processors from AMD, Cyrix, IBM, or Intel. Includes DX,
192 DX2, and DX4 variants; also SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or
196 bool "586/K5/5x86/6x86/6x86MX"
198 Select this for an 586 or 686 series processor such as the AMD K5,
199 the Intel 5x86 or 6x86, or the Intel 6x86MX. This choice does not
200 assume the RDTSC (Read Time Stamp Counter) instruction.
203 bool "Pentium-Classic"
205 Select this for a Pentium Classic processor with the RDTSC (Read
206 Time Stamp Counter) instruction for benchmarking.
211 Select this for a Pentium with the MMX graphics/multimedia
212 extended instructions.
217 Select this for Intel Pentium Pro chips. This enables the use of
218 Pentium Pro extended instructions, and disables the init-time guard
219 against the f00f bug found in earlier Pentiums.
222 bool "Pentium-II/Celeron(pre-Coppermine)"
224 Select this for Intel chips based on the Pentium-II and
225 pre-Coppermine Celeron core. This option enables an unaligned
226 copy optimization, compiles the kernel with optimization flags
227 tailored for the chip, and applies any applicable Pentium Pro
231 bool "Pentium-III/Celeron(Coppermine)/Pentium-III Xeon"
233 Select this for Intel chips based on the Pentium-III and
234 Celeron-Coppermine core. This option enables use of some
235 extended prefetch instructions in addition to the Pentium II
241 Select this for Intel Pentium M (not Pentium-4 M)
245 bool "Pentium-4/Celeron(P4-based)/Pentium-4 M/Xeon"
247 Select this for Intel Pentium 4 chips. This includes the
248 Pentium 4, P4-based Celeron and Xeon, and Pentium-4 M
249 (not Pentium M) chips. This option enables compile flags
250 optimized for the chip, uses the correct cache shift, and
251 applies any applicable Pentium III optimizations.
254 bool "K6/K6-II/K6-III"
256 Select this for an AMD K6-family processor. Enables use of
257 some extended instructions, and passes appropriate optimization
261 bool "Athlon/Duron/K7"
263 Select this for an AMD Athlon K7-family processor. Enables use of
264 some extended instructions, and passes appropriate optimization
268 bool "Opteron/Athlon64/Hammer/K8"
270 Select this for an AMD Opteron or Athlon64 Hammer-family processor. Enables
271 use of some extended instructions, and passes appropriate optimization
277 Select this for a Transmeta Crusoe processor. Treats the processor
278 like a 586 with TSC, and sets some GCC optimization flags (like a
279 Pentium Pro with no alignment requirements).
284 Select this for an IDT Winchip C6 chip. Linux and GCC
285 treat this chip as a 586TSC with some extended instructions
286 and alignment requirements.
291 Select this for an IDT Winchip-2. Linux and GCC
292 treat this chip as a 586TSC with some extended instructions
293 and alignment requirements.
296 bool "Winchip-2A/Winchip-3"
298 Select this for an IDT Winchip-2A or 3. Linux and GCC
299 treat this chip as a 586TSC with some extended instructions
300 and alignment reqirements. Also enable out of order memory
301 stores for this CPU, which can increase performance of some
305 bool "CyrixIII/VIA-C3"
307 Select this for a Cyrix III or C3 chip. Presently Linux and GCC
308 treat this chip as a generic 586. Whilst the CPU is 686 class,
309 it lacks the cmov extension which gcc assumes is present when
311 Note that Nehemiah (Model 9) and above will not boot with this
312 kernel due to them lacking the 3DNow! instructions used in earlier
313 incarnations of the CPU.
316 bool "VIA C3-2 (Nehemiah)"
318 Select this for a VIA C3 "Nehemiah". Selecting this enables usage
319 of SSE and tells gcc to treat the CPU as a 686.
320 Note, this kernel will not boot on older (pre model 9) C3s.
325 bool "Generic x86 support"
327 Instead of just including optimizations for the selected
328 x86 variant (e.g. PII, Crusoe or Athlon), include some more
329 generic optimizations as well. This will make the kernel
330 perform better on x86 CPUs other than that selected.
332 This is really intended for distributors who need more
333 generic optimizations.
338 # Define implied options from the CPU selection here
350 config X86_L1_CACHE_SHIFT
352 default "7" if MPENTIUM4 || X86_GENERIC
353 default "4" if X86_ELAN || M486 || M386
354 default "5" if MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCRUSOE || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2
355 default "6" if MK7 || MK8 || MPENTIUMM
357 config RWSEM_GENERIC_SPINLOCK
362 config RWSEM_XCHGADD_ALGORITHM
367 config X86_PPRO_FENCE
369 depends on M686 || M586MMX || M586TSC || M586 || M486 || M386
374 depends on M586MMX || M586TSC || M586 || M486 || M386
377 config X86_WP_WORKS_OK
397 config X86_ALIGNMENT_16
399 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2
404 depends on MK7 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || MK8
407 config X86_INTEL_USERCOPY
409 depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK8 || MK7
412 config X86_USE_PPRO_CHECKSUM
414 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC3_2
419 depends on MCYRIXIII || MK7
424 depends on (MWINCHIP3D || MWINCHIP2 || MWINCHIPC6) && MTRR
428 bool "4 GB kernel-space and 4 GB user-space virtual memory support"
430 This option is only useful for systems that have more than 1 GB
433 The default kernel VM layout leaves 1 GB of virtual memory for
434 kernel-space mappings, and 3 GB of VM for user-space applications.
435 This option ups both the kernel-space VM and the user-space VM to
438 The cost of this option is additional TLB flushes done at
439 system-entry points that transition from user-mode into kernel-mode.
440 I.e. system calls and page faults, and IRQs that interrupt user-mode
441 code. There's also additional overhead to kernel operations that copy
442 memory to/from user-space. The overhead from this is hard to tell and
443 depends on the workload - it can be anything from no visible overhead
444 to 20-30% overhead. A good rule of thumb is to count with a runtime
447 The upside is the much increased kernel-space VM, which more than
448 quadruples the maximum amount of RAM supported. Kernels compiled with
449 this option boot on 64GB of RAM and still have more than 3.1 GB of
450 'lowmem' left. Another bonus is that highmem IO bouncing decreases,
451 if used with drivers that still use bounce-buffers.
453 There's also a 33% increase in user-space VM size - database
454 applications might see a boost from this.
456 But the cost of the TLB flushes and the runtime overhead has to be
457 weighed against the bonuses offered by the larger VM spaces. The
458 dividing line depends on the actual workload - there might be 4 GB
459 systems that benefit from this option. Systems with less than 4 GB
460 of RAM will rarely see a benefit from this option - but it's not
461 out of question, the exact circumstances have to be considered.
463 config X86_SWITCH_PAGETABLES
466 config X86_4G_VM_LAYOUT
469 config X86_UACCESS_INDIRECT
472 config X86_HIGH_ENTRY
476 bool "HPET Timer Support"
478 This enables the use of the HPET for the kernel's internal timer.
479 HPET is the next generation timer replacing legacy 8254s.
480 You can safely choose Y here. However, HPET will only be
481 activated if the platform and the BIOS support this feature.
482 Otherwise the 8254 will be used for timing services.
484 Choose N to continue using the legacy 8254 timer.
486 config HPET_EMULATE_RTC
487 bool "Provide RTC interrupt"
488 depends on HPET_TIMER && RTC=y
491 bool "Symmetric multi-processing support"
493 This enables support for systems with more than one CPU. If you have
494 a system with only one CPU, like most personal computers, say N. If
495 you have a system with more than one CPU, say Y.
497 If you say N here, the kernel will run on single and multiprocessor
498 machines, but will use only one CPU of a multiprocessor machine. If
499 you say Y here, the kernel will run on many, but not all,
500 singleprocessor machines. On a singleprocessor machine, the kernel
501 will run faster if you say N here.
503 Note that if you say Y here and choose architecture "586" or
504 "Pentium" under "Processor family", the kernel will not work on 486
505 architectures. Similarly, multiprocessor kernels for the "PPro"
506 architecture may not work on all Pentium based boards.
508 People using multiprocessor machines who say Y here should also say
509 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
510 Management" code will be disabled if you say Y here.
512 See also the <file:Documentation/smp.txt>,
513 <file:Documentation/i386/IO-APIC.txt>,
514 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
515 <http://www.tldp.org/docs.html#howto>.
517 If you don't know what to do here, say N.
520 int "Maximum number of CPUs (2-255)"
523 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
526 This allows you to specify the maximum number of CPUs which this
527 kernel will support. The maximum supported value is 255 and the
528 minimum value which makes sense is 2.
530 This is purely to save memory - each supported CPU adds
531 approximately eight kilobytes to the kernel image.
534 bool "SMT (Hyperthreading) scheduler support"
538 SMT scheduler support improves the CPU scheduler's decision making
539 when dealing with Intel Pentium 4 chips with HyperThreading at a
540 cost of slightly increased overhead in some places. If unsure say
544 bool "Preemptible Kernel"
546 This option reduces the latency of the kernel when reacting to
547 real-time or interactive events by allowing a low priority process to
548 be preempted even if it is in kernel mode executing a system call.
549 This allows applications to run more reliably even when the system is
552 Say Y here if you are building a kernel for a desktop, embedded
553 or real-time system. Say N if you are unsure.
555 config PREEMPT_VOLUNTARY
556 bool "Voluntary Kernel Preemption"
560 This option reduces the latency of the kernel by adding more
561 "explicit preemption points" to the kernel code. These new
562 preemption points have been selected to minimize the maximum
563 latency of rescheduling, providing faster application reactions.
565 Say Y here if you are building a kernel for a desktop system.
566 Say N if you are unsure.
569 bool "Local APIC support on uniprocessors" if !SMP
570 depends on !(X86_VISWS || X86_VOYAGER)
572 A local APIC (Advanced Programmable Interrupt Controller) is an
573 integrated interrupt controller in the CPU. If you have a single-CPU
574 system which has a processor with a local APIC, you can say Y here to
575 enable and use it. If you say Y here even though your machine doesn't
576 have a local APIC, then the kernel will still run with no slowdown at
577 all. The local APIC supports CPU-generated self-interrupts (timer,
578 performance counters), and the NMI watchdog which detects hard
581 If you have a system with several CPUs, you do not need to say Y
582 here: the local APIC will be used automatically.
585 bool "IO-APIC support on uniprocessors"
586 depends on !SMP && X86_UP_APIC
588 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
589 SMP-capable replacement for PC-style interrupt controllers. Most
590 SMP systems and a small number of uniprocessor systems have one.
591 If you have a single-CPU system with an IO-APIC, you can say Y here
592 to use it. If you say Y here even though your machine doesn't have
593 an IO-APIC, then the kernel will still run with no slowdown at all.
595 If you have a system with several CPUs, you do not need to say Y
596 here: the IO-APIC will be used automatically.
598 config X86_LOCAL_APIC
600 depends on !SMP && X86_UP_APIC
605 depends on !SMP && X86_UP_IOAPIC
610 depends on (MWINCHIP3D || MWINCHIP2 || MCRUSOE || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2) && !X86_NUMAQ
614 bool "Machine Check Exception"
615 depends on !X86_VOYAGER
617 Machine Check Exception support allows the processor to notify the
618 kernel if it detects a problem (e.g. overheating, component failure).
619 The action the kernel takes depends on the severity of the problem,
620 ranging from a warning message on the console, to halting the machine.
621 Your processor must be a Pentium or newer to support this - check the
622 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
623 have a design flaw which leads to false MCE events - hence MCE is
624 disabled on all P5 processors, unless explicitly enabled with "mce"
625 as a boot argument. Similarly, if MCE is built in and creates a
626 problem on some new non-standard machine, you can boot with "nomce"
627 to disable it. MCE support simply ignores non-MCE processors like
628 the 386 and 486, so nearly everyone can say Y here.
630 config X86_MCE_NONFATAL
631 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
634 Enabling this feature starts a timer that triggers every 5 seconds which
635 will look at the machine check registers to see if anything happened.
636 Non-fatal problems automatically get corrected (but still logged).
637 Disable this if you don't want to see these messages.
638 Seeing the messages this option prints out may be indicative of dying hardware,
639 or out-of-spec (ie, overclocked) hardware.
640 This option only does something on certain CPUs.
641 (AMD Athlon/Duron and Intel Pentium 4)
643 config X86_MCE_P4THERMAL
644 bool "check for P4 thermal throttling interrupt."
645 depends on X86_MCE && (X86_UP_APIC || SMP)
647 Enabling this feature will cause a message to be printed when the P4
648 enters thermal throttling.
651 tristate "Toshiba Laptop support"
653 This adds a driver to safely access the System Management Mode of
654 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
655 not work on models with a Phoenix BIOS. The System Management Mode
656 is used to set the BIOS and power saving options on Toshiba portables.
658 For information on utilities to make use of this driver see the
659 Toshiba Linux utilities web site at:
660 <http://www.buzzard.org.uk/toshiba/>.
662 Say Y if you intend to run this kernel on a Toshiba portable.
666 tristate "Dell laptop support"
668 This adds a driver to safely access the System Management Mode
669 of the CPU on the Dell Inspiron 8000. The System Management Mode
670 is used to read cpu temperature and cooling fan status and to
671 control the fans on the I8K portables.
673 This driver has been tested only on the Inspiron 8000 but it may
674 also work with other Dell laptops. You can force loading on other
675 models by passing the parameter `force=1' to the module. Use at
678 For information on utilities to make use of this driver see the
679 I8K Linux utilities web site at:
680 <http://people.debian.org/~dz/i8k/>
682 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
686 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
688 If you say Y here and also to "/dev file system support" in the
689 'File systems' section, you will be able to update the microcode on
690 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
691 Pentium III, Pentium 4, Xeon etc. You will obviously need the
692 actual microcode binary data itself which is not shipped with the
695 For latest news and information on obtaining all the required
696 ingredients for this driver, check:
697 <http://www.urbanmyth.org/microcode/>.
699 To compile this driver as a module, choose M here: the
700 module will be called microcode.
703 tristate "/dev/cpu/*/msr - Model-specific register support"
705 This device gives privileged processes access to the x86
706 Model-Specific Registers (MSRs). It is a character device with
707 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
708 MSR accesses are directed to a specific CPU on multi-processor
712 tristate "/dev/cpu/*/cpuid - CPU information support"
714 This device gives processes access to the x86 CPUID instruction to
715 be executed on a specific processor. It is a character device
716 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
719 source "drivers/firmware/Kconfig"
722 prompt "High Memory Support"
728 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
729 However, the address space of 32-bit x86 processors is only 4
730 Gigabytes large. That means that, if you have a large amount of
731 physical memory, not all of it can be "permanently mapped" by the
732 kernel. The physical memory that's not permanently mapped is called
735 If you are compiling a kernel which will never run on a machine with
736 more than 1 Gigabyte total physical RAM, answer "off" here (default
737 choice and suitable for most users). This will result in a "3GB/1GB"
738 split: 3GB are mapped so that each process sees a 3GB virtual memory
739 space and the remaining part of the 4GB virtual memory space is used
740 by the kernel to permanently map as much physical memory as
743 If the machine has between 1 and 4 Gigabytes physical RAM, then
746 If more than 4 Gigabytes is used then answer "64GB" here. This
747 selection turns Intel PAE (Physical Address Extension) mode on.
748 PAE implements 3-level paging on IA32 processors. PAE is fully
749 supported by Linux, PAE mode is implemented on all recent Intel
750 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
751 then the kernel will not boot on CPUs that don't support PAE!
753 The actual amount of total physical memory will either be
754 auto detected or can be forced by using a kernel command line option
755 such as "mem=256M". (Try "man bootparam" or see the documentation of
756 your boot loader (lilo or loadlin) about how to pass options to the
757 kernel at boot time.)
759 If unsure, say "off".
764 Select this if you have a 32-bit processor and between 1 and 4
765 gigabytes of physical RAM.
770 Select this if you have a 32-bit processor and more than 4
771 gigabytes of physical RAM.
777 depends on HIGHMEM64G || HIGHMEM4G
782 depends on HIGHMEM64G
785 # Common NUMA Features
787 bool "Numa Memory Allocation and Scheduler Support"
788 depends on SMP && HIGHMEM64G && (X86_NUMAQ || X86_GENERICARCH || (X86_SUMMIT && ACPI))
790 default y if (X86_NUMAQ || X86_SUMMIT)
792 # Need comments to help the hapless user trying to turn on NUMA support
793 comment "NUMA (NUMA-Q) requires SMP, 64GB highmem support"
794 depends on X86_NUMAQ && (!HIGHMEM64G || !SMP)
796 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
797 depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)
804 config HAVE_ARCH_BOOTMEM_NODE
810 bool "Allocate 3rd-level pagetables from highmem"
811 depends on HIGHMEM4G || HIGHMEM64G
813 The VM uses one page table entry for each page of physical memory.
814 For systems with a lot of RAM, this can be wasteful of precious
815 low memory. Setting this option will put user-space page table
816 entries in high memory.
818 config MATH_EMULATION
819 bool "Math emulation"
821 Linux can emulate a math coprocessor (used for floating point
822 operations) if you don't have one. 486DX and Pentium processors have
823 a math coprocessor built in, 486SX and 386 do not, unless you added
824 a 487DX or 387, respectively. (The messages during boot time can
825 give you some hints here ["man dmesg"].) Everyone needs either a
826 coprocessor or this emulation.
828 If you don't have a math coprocessor, you need to say Y here; if you
829 say Y here even though you have a coprocessor, the coprocessor will
830 be used nevertheless. (This behavior can be changed with the kernel
831 command line option "no387", which comes handy if your coprocessor
832 is broken. Try "man bootparam" or see the documentation of your boot
833 loader (lilo or loadlin) about how to pass options to the kernel at
834 boot time.) This means that it is a good idea to say Y here if you
835 intend to use this kernel on different machines.
837 More information about the internals of the Linux math coprocessor
838 emulation can be found in <file:arch/i386/math-emu/README>.
840 If you are not sure, say Y; apart from resulting in a 66 KB bigger
841 kernel, it won't hurt.
844 bool "MTRR (Memory Type Range Register) support"
846 On Intel P6 family processors (Pentium Pro, Pentium II and later)
847 the Memory Type Range Registers (MTRRs) may be used to control
848 processor access to memory ranges. This is most useful if you have
849 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
850 allows bus write transfers to be combined into a larger transfer
851 before bursting over the PCI/AGP bus. This can increase performance
852 of image write operations 2.5 times or more. Saying Y here creates a
853 /proc/mtrr file which may be used to manipulate your processor's
854 MTRRs. Typically the X server should use this.
856 This code has a reasonably generic interface so that similar
857 control registers on other processors can be easily supported
860 The Cyrix 6x86, 6x86MX and M II processors have Address Range
861 Registers (ARRs) which provide a similar functionality to MTRRs. For
862 these, the ARRs are used to emulate the MTRRs.
863 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
864 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
865 write-combining. All of these processors are supported by this code
866 and it makes sense to say Y here if you have one of them.
868 Saying Y here also fixes a problem with buggy SMP BIOSes which only
869 set the MTRRs for the boot CPU and not for the secondary CPUs. This
870 can lead to all sorts of problems, so it's good to say Y here.
872 You can safely say Y even if your machine doesn't have MTRRs, you'll
873 just add about 9 KB to your kernel.
875 See <file:Documentation/mtrr.txt> for more information.
878 bool "Boot from EFI support (EXPERIMENTAL)"
883 This enables the the kernel to boot on EFI platforms using
884 system configuration information passed to it from the firmware.
885 This also enables the kernel to use any EFI runtime services that are
886 available (such as the EFI variable services).
888 This option is only useful on systems that have EFI firmware
889 and will result in a kernel image that is ~8k larger. In addition,
890 you must use the latest ELILO loader available at
891 <http://elilo.sourceforge.net> in order to take advantage of
892 kernel initialization using EFI information (neither GRUB nor LILO know
893 anything about EFI). However, even with this option, the resultant
894 kernel should continue to boot on existing non-EFI platforms.
897 bool "Enable kernel irq balancing"
898 depends on SMP && X86_IO_APIC
901 The default yes will allow the kernel to do irq load balancing.
902 Saying no will keep the kernel from doing irq load balancing.
906 depends on (SMP || PREEMPT) && X86_CMPXCHG
909 # turning this on wastes a bunch of space.
910 # Summit needs it only when NUMA is on
913 depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
917 bool "Use register arguments (EXPERIMENTAL)"
918 depends on EXPERIMENTAL
921 Compile the kernel with -mregparm=3. This uses an different ABI
922 and passes the first three arguments of a function call in registers.
923 This will probably break binary only modules.
925 This feature is only enabled for gcc-3.0 and later - earlier compilers
926 generate incorrect output with certain kernel constructs when
930 bool "Use separate IRQ stacks"
932 If you say Y here the kernel will use a separate IRQ stack on each
933 cpu to handle interrupts.
935 config STACK_SIZE_SHIFT
936 int "Kernel stack size (12 => 4KB, 13 => 8KB, 14 => 16KB)"
938 default 12 if IRQSTACKS
941 Select kernel stack size. 4KB stacks are best as they let
942 the system scale further. Use 8KB stacks if you have an
943 experimental kernel where a stack overlow with a 4KB stack
944 might occur. Use 16KB stacks if you want to safely support
945 Windows device drivers using either Linuxant or ndiswrapper.
948 int "Print stack trace when stack grows beyond specified bytes"
949 default 4096 if IRQSTACKS
952 The kernel will print a stack trace when the current stack exceeds
958 menu "Power management options (ACPI, APM)"
959 depends on !X86_VOYAGER
961 source kernel/power/Kconfig
963 source "drivers/acpi/Kconfig"
965 menu "APM (Advanced Power Management) BIOS Support"
969 tristate "APM (Advanced Power Management) BIOS support"
972 APM is a BIOS specification for saving power using several different
973 techniques. This is mostly useful for battery powered laptops with
974 APM compliant BIOSes. If you say Y here, the system time will be
975 reset after a RESUME operation, the /proc/apm device will provide
976 battery status information, and user-space programs will receive
977 notification of APM "events" (e.g. battery status change).
979 If you select "Y" here, you can disable actual use of the APM
980 BIOS by passing the "apm=off" option to the kernel at boot time.
982 Note that the APM support is almost completely disabled for
983 machines with more than one CPU.
985 In order to use APM, you will need supporting software. For location
986 and more information, read <file:Documentation/pm.txt> and the
987 Battery Powered Linux mini-HOWTO, available from
988 <http://www.tldp.org/docs.html#howto>.
990 This driver does not spin down disk drives (see the hdparm(8)
991 manpage ("man 8 hdparm") for that), and it doesn't turn off
992 VESA-compliant "green" monitors.
994 This driver does not support the TI 4000M TravelMate and the ACER
995 486/DX4/75 because they don't have compliant BIOSes. Many "green"
996 desktop machines also don't have compliant BIOSes, and this driver
997 may cause those machines to panic during the boot phase.
999 Generally, if you don't have a battery in your machine, there isn't
1000 much point in using this driver and you should say N. If you get
1001 random kernel OOPSes or reboots that don't seem to be related to
1002 anything, try disabling/enabling this option (or disabling/enabling
1005 Some other things you should try when experiencing seemingly random,
1008 1) make sure that you have enough swap space and that it is
1010 2) pass the "no-hlt" option to the kernel
1011 3) switch on floating point emulation in the kernel and pass
1012 the "no387" option to the kernel
1013 4) pass the "floppy=nodma" option to the kernel
1014 5) pass the "mem=4M" option to the kernel (thereby disabling
1015 all but the first 4 MB of RAM)
1016 6) make sure that the CPU is not over clocked.
1017 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1018 8) disable the cache from your BIOS settings
1019 9) install a fan for the video card or exchange video RAM
1020 10) install a better fan for the CPU
1021 11) exchange RAM chips
1022 12) exchange the motherboard.
1024 To compile this driver as a module, choose M here: the
1025 module will be called apm.
1027 config APM_IGNORE_USER_SUSPEND
1028 bool "Ignore USER SUSPEND"
1031 This option will ignore USER SUSPEND requests. On machines with a
1032 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1033 series notebooks, it is necessary to say Y because of a BIOS bug.
1035 config APM_DO_ENABLE
1036 bool "Enable PM at boot time"
1039 Enable APM features at boot time. From page 36 of the APM BIOS
1040 specification: "When disabled, the APM BIOS does not automatically
1041 power manage devices, enter the Standby State, enter the Suspend
1042 State, or take power saving steps in response to CPU Idle calls."
1043 This driver will make CPU Idle calls when Linux is idle (unless this
1044 feature is turned off -- see "Do CPU IDLE calls", below). This
1045 should always save battery power, but more complicated APM features
1046 will be dependent on your BIOS implementation. You may need to turn
1047 this option off if your computer hangs at boot time when using APM
1048 support, or if it beeps continuously instead of suspending. Turn
1049 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1050 T400CDT. This is off by default since most machines do fine without
1054 bool "Make CPU Idle calls when idle"
1057 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1058 On some machines, this can activate improved power savings, such as
1059 a slowed CPU clock rate, when the machine is idle. These idle calls
1060 are made after the idle loop has run for some length of time (e.g.,
1061 333 mS). On some machines, this will cause a hang at boot time or
1062 whenever the CPU becomes idle. (On machines with more than one CPU,
1063 this option does nothing.)
1065 config APM_DISPLAY_BLANK
1066 bool "Enable console blanking using APM"
1069 Enable console blanking using the APM. Some laptops can use this to
1070 turn off the LCD backlight when the screen blanker of the Linux
1071 virtual console blanks the screen. Note that this is only used by
1072 the virtual console screen blanker, and won't turn off the backlight
1073 when using the X Window system. This also doesn't have anything to
1074 do with your VESA-compliant power-saving monitor. Further, this
1075 option doesn't work for all laptops -- it might not turn off your
1076 backlight at all, or it might print a lot of errors to the console,
1077 especially if you are using gpm.
1079 config APM_RTC_IS_GMT
1080 bool "RTC stores time in GMT"
1083 Say Y here if your RTC (Real Time Clock a.k.a. hardware clock)
1084 stores the time in GMT (Greenwich Mean Time). Say N if your RTC
1087 It is in fact recommended to store GMT in your RTC, because then you
1088 don't have to worry about daylight savings time changes. The only
1089 reason not to use GMT in your RTC is if you also run a broken OS
1090 that doesn't understand GMT.
1092 config APM_ALLOW_INTS
1093 bool "Allow interrupts during APM BIOS calls"
1096 Normally we disable external interrupts while we are making calls to
1097 the APM BIOS as a measure to lessen the effects of a badly behaving
1098 BIOS implementation. The BIOS should reenable interrupts if it
1099 needs to. Unfortunately, some BIOSes do not -- especially those in
1100 many of the newer IBM Thinkpads. If you experience hangs when you
1101 suspend, try setting this to Y. Otherwise, say N.
1103 config APM_REAL_MODE_POWER_OFF
1104 bool "Use real mode APM BIOS call to power off"
1107 Use real mode APM BIOS calls to switch off the computer. This is
1108 a work-around for a number of buggy BIOSes. Switch this option on if
1109 your computer crashes instead of powering off properly.
1113 source "arch/i386/kernel/cpu/cpufreq/Kconfig"
1118 menu "Bus options (PCI, PCMCIA, EISA, MCA, ISA)"
1120 config X86_VISWS_APIC
1122 depends on X86_VISWS
1125 config X86_LOCAL_APIC
1127 depends on (X86_VISWS || SMP) && !X86_VOYAGER
1132 depends on SMP && !(X86_VISWS || X86_VOYAGER)
1136 bool "PCI support" if !X86_VISWS
1137 depends on !X86_VOYAGER
1138 default y if X86_VISWS
1140 Find out whether you have a PCI motherboard. PCI is the name of a
1141 bus system, i.e. the way the CPU talks to the other stuff inside
1142 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1143 VESA. If you have PCI, say Y, otherwise N.
1145 The PCI-HOWTO, available from
1146 <http://www.tldp.org/docs.html#howto>, contains valuable
1147 information about which PCI hardware does work under Linux and which
1151 prompt "PCI access mode"
1152 depends on PCI && !X86_VISWS
1155 On PCI systems, the BIOS can be used to detect the PCI devices and
1156 determine their configuration. However, some old PCI motherboards
1157 have BIOS bugs and may crash if this is done. Also, some embedded
1158 PCI-based systems don't have any BIOS at all. Linux can also try to
1159 detect the PCI hardware directly without using the BIOS.
1161 With this option, you can specify how Linux should detect the
1162 PCI devices. If you choose "BIOS", the BIOS will be used,
1163 if you choose "Direct", the BIOS won't be used, and if you
1164 choose "MMConfig", then PCI Express MMCONFIG will be used.
1165 If you choose "Any", the kernel will try MMCONFIG, then the
1166 direct access method and falls back to the BIOS if that doesn't
1167 work. If unsure, go with the default, which is "Any".
1172 config PCI_GOMMCONFIG
1185 depends on !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1190 depends on PCI && ((PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1195 depends on PCI && (PCI_GOMMCONFIG || PCI_GOANY)
1199 source "drivers/pci/Kconfig"
1203 depends on !(X86_VOYAGER || X86_VISWS)
1205 Find out whether you have ISA slots on your motherboard. ISA is the
1206 name of a bus system, i.e. the way the CPU talks to the other stuff
1207 inside your box. Other bus systems are PCI, EISA, MicroChannel
1208 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1209 newer boards don't support it. If you have ISA, say Y, otherwise N.
1215 The Extended Industry Standard Architecture (EISA) bus was
1216 developed as an open alternative to the IBM MicroChannel bus.
1218 The EISA bus provided some of the features of the IBM MicroChannel
1219 bus while maintaining backward compatibility with cards made for
1220 the older ISA bus. The EISA bus saw limited use between 1988 and
1221 1995 when it was made obsolete by the PCI bus.
1223 Say Y here if you are building a kernel for an EISA-based machine.
1227 source "drivers/eisa/Kconfig"
1231 depends on !(X86_VISWS || X86_VOYAGER)
1233 MicroChannel Architecture is found in some IBM PS/2 machines and
1234 laptops. It is a bus system similar to PCI or ISA. See
1235 <file:Documentation/mca.txt> (and especially the web page given
1236 there) before attempting to build an MCA bus kernel.
1239 depends on X86_VOYAGER
1240 default y if X86_VOYAGER
1242 source "drivers/mca/Kconfig"
1245 tristate "NatSemi SCx200 support"
1246 depends on !X86_VOYAGER
1248 This provides basic support for the National Semiconductor SCx200
1249 processor. Right now this is just a driver for the GPIO pins.
1251 If you don't know what to do here, say N.
1253 This support is also available as a module. If compiled as a
1254 module, it will be called scx200.
1256 source "drivers/pcmcia/Kconfig"
1258 source "drivers/pci/hotplug/Kconfig"
1263 menu "Executable file formats"
1265 source "fs/Kconfig.binfmt"
1269 source "drivers/Kconfig"
1273 source "arch/i386/oprofile/Kconfig"
1276 menu "Kernel hacking"
1279 tristate "Crash dump support (EXPERIMENTAL)"
1280 depends on EXPERIMENTAL
1283 Say Y here to enable saving an image of system memory when a panic
1284 or other error occurs. Dumps can also be forced with the SysRq+d
1285 key if MAGIC_SYSRQ is enabled.
1287 config CRASH_DUMP_BLOCKDEV
1288 tristate "Crash dump block device driver"
1289 depends on CRASH_DUMP
1291 Say Y to allow saving crash dumps directly to a disk device.
1293 config CRASH_DUMP_NETDEV
1294 tristate "Crash dump network device driver"
1295 depends on CRASH_DUMP
1297 Say Y to allow saving crash dumps over a network device.
1299 config CRASH_DUMP_MEMDEV
1300 bool "Crash dump staged memory driver"
1301 depends on CRASH_DUMP
1303 Say Y to allow intermediate saving crash dumps in spare
1304 memory pages which would then be written out to disk
1307 config CRASH_DUMP_SOFTBOOT
1308 bool "Save crash dump across a soft reboot"
1309 depends on CRASH_DUMP_MEMDEV
1311 Say Y to allow a crash dump to be preserved in memory
1312 pages across a soft reboot and written out to disk
1313 thereafter. For this to work, CRASH_DUMP must be
1314 configured as part of the kernel (not as a module).
1316 config CRASH_DUMP_COMPRESS_RLE
1317 tristate "Crash dump RLE compression"
1318 depends on CRASH_DUMP
1320 Say Y to allow saving dumps with Run Length Encoding compression.
1322 config CRASH_DUMP_COMPRESS_GZIP
1323 tristate "Crash dump GZIP compression"
1326 depends on CRASH_DUMP
1328 Say Y to allow saving dumps with Gnu Zip compression.
1331 bool "Kernel debugging"
1333 Say Y here if you are developing drivers or trying to debug and
1334 identify kernel problems.
1337 bool "Early printk" if EMBEDDED
1340 Write kernel log output directly into the VGA buffer or to a serial
1343 This is useful for kernel debugging when your machine crashes very
1344 early before the console code is initialized. For normal operation
1345 it is not recommended because it looks ugly and doesn't cooperate
1346 with klogd/syslogd or the X server. You should normally N here,
1347 unless you want to debug such a crash.
1349 config DEBUG_STACKOVERFLOW
1350 bool "Check for stack overflows"
1351 depends on DEBUG_KERNEL
1353 config DEBUG_STACK_USAGE
1354 bool "Stack utilization instrumentation"
1355 depends on DEBUG_KERNEL
1357 Enables the display of the minimum amount of free stack which each
1358 task has ever had available in the sysrq-T and sysrq-P debug output.
1360 This option will slow down process creation somewhat.
1363 bool "Debug memory allocations"
1364 depends on DEBUG_KERNEL
1366 Say Y here to have the kernel do limited verification on memory
1367 allocation as well as poisoning memory on free to catch use of freed
1371 bool "Magic SysRq key"
1372 depends on DEBUG_KERNEL
1374 If you say Y here, you will have some control over the system even
1375 if the system crashes for example during kernel debugging (e.g., you
1376 will be able to flush the buffer cache to disk, reboot the system
1377 immediately or dump some status information). This is accomplished
1378 by pressing various keys while holding SysRq (Alt+PrintScreen). It
1379 also works on a serial console (on PC hardware at least), if you
1380 send a BREAK and then within 5 seconds a command keypress. The
1381 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
1382 unless you really know what this hack does.
1384 config DEBUG_SPINLOCK
1385 bool "Spinlock debugging"
1386 depends on DEBUG_KERNEL
1388 Say Y here and build SMP to catch missing spinlock initialization
1389 and certain other kinds of spinlock errors commonly made. This is
1390 best used in conjunction with the NMI watchdog so that spinlock
1391 deadlocks are also debuggable.
1393 config DEBUG_PAGEALLOC
1394 bool "Page alloc debugging"
1395 depends on DEBUG_KERNEL
1397 Unmap pages from the kernel linear mapping after free_pages().
1398 This results in a large slowdown, but helps to find certain types
1399 of memory corruptions.
1401 config DEBUG_HIGHMEM
1402 bool "Highmem debugging"
1403 depends on DEBUG_KERNEL && HIGHMEM
1405 This options enables addition error checking for high memory systems.
1406 Disable for production systems.
1409 bool "Compile the kernel with debug info"
1410 depends on DEBUG_KERNEL
1412 If you say Y here the resulting kernel image will include
1413 debugging info resulting in a larger kernel image.
1414 Say Y here only if you plan to use gdb to debug the kernel.
1415 If you don't debug the kernel, you can say N.
1417 config DEBUG_SPINLOCK_SLEEP
1418 bool "Sleep-inside-spinlock checking"
1420 If you say Y here, various routines which may sleep will become very
1421 noisy if they are called with a spinlock held.
1423 config FRAME_POINTER
1424 bool "Compile the kernel with frame pointers"
1426 If you say Y here the resulting kernel image will be slightly larger
1427 and slower, but it will give very useful debugging information.
1428 If you don't debug the kernel, you can say N, but we may not be able
1429 to solve problems without frame pointers.
1431 config X86_FIND_SMP_CONFIG
1433 depends on X86_LOCAL_APIC || X86_VOYAGER
1438 depends on X86_LOCAL_APIC && !X86_VISWS
1443 source "kernel/vserver/Kconfig"
1445 source "security/Kconfig"
1447 source "crypto/Kconfig"
1449 source "lib/Kconfig"
1453 depends on SMP && !X86_VOYAGER
1458 depends on SMP && !(X86_VISWS || X86_VOYAGER)
1461 config X86_BIOS_REBOOT
1463 depends on !(X86_VISWS || X86_VOYAGER)
1466 config X86_TRAMPOLINE
1468 depends on X86_SMP || (X86_VOYAGER && SMP)
1473 depends on X86 && !EMBEDDED
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