kconfig

linux 内核源代码

# The code disables itself when not needed.
config GART_IOMMU
	bool "GART IOMMU support" if EMBEDDED
	default y
	select SWIOTLB
	select AGP
	depends on X86_64 && PCI
	help
	  Support for full DMA access of devices with 32bit memory access only
	  on systems with more than 3GB. This is usually needed for USB,
	  sound, many IDE/SATA chipsets and some other devices.
	  Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
	  based hardware IOMMU and a software bounce buffer based IOMMU used
	  on Intel systems and as fallback.
	  The code is only active when needed (enough memory and limited
	  device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
	  too.

config CALGARY_IOMMU
	bool "IBM Calgary IOMMU support"
	select SWIOTLB
	depends on X86_64 && PCI && EXPERIMENTAL
	help
	  Support for hardware IOMMUs in IBM's xSeries x366 and x460
	  systems. Needed to run systems with more than 3GB of memory
	  properly with 32-bit PCI devices that do not support DAC
	  (Double Address Cycle). Calgary also supports bus level
	  isolation, where all DMAs pass through the IOMMU.  This
	  prevents them from going anywhere except their intended
	  destination. This catches hard-to-find kernel bugs and
	  mis-behaving drivers and devices that do not use the DMA-API
	  properly to set up their DMA buffers.  The IOMMU can be
	  turned off at boot time with the iommu=off parameter.
	  Normally the kernel will make the right choice by itself.
	  If unsure, say Y.

config CALGARY_IOMMU_ENABLED_BY_DEFAULT
	bool "Should Calgary be enabled by default?"
	default y
	depends on CALGARY_IOMMU
	help
	  Should Calgary be enabled by default? if you choose 'y', Calgary
	  will be used (if it exists). If you choose 'n', Calgary will not be
	  used even if it exists. If you choose 'n' and would like to use
	  Calgary anyway, pass 'iommu=calgary' on the kernel command line.
	  If unsure, say Y.

# need this always selected by IOMMU for the VIA workaround
config SWIOTLB
	bool
	help
	  Support for software bounce buffers used on x86-64 systems
	  which don't have a hardware IOMMU (e.g. the current generation
	  of Intel's x86-64 CPUs). Using this PCI devices which can only
	  access 32-bits of memory can be used on systems with more than
	  3 GB of memory. If unsure, say Y.


config NR_CPUS
	int "Maximum number of CPUs (2-255)"
	range 2 255
	depends on SMP
	default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
	default "8"
	help
	  This allows you to specify the maximum number of CPUs which this
	  kernel will support.  The maximum supported value is 255 and the
	  minimum value which makes sense is 2.

	  This is purely to save memory - each supported CPU adds
	  approximately eight kilobytes to the kernel image.

config SCHED_SMT
	bool "SMT (Hyperthreading) scheduler support"
	depends on (X86_64 && SMP) || (X86_32 && X86_HT)
	help
	  SMT scheduler support improves the CPU scheduler's decision making
	  when dealing with Intel Pentium 4 chips with HyperThreading at a
	  cost of slightly increased overhead in some places. If unsure say
	  N here.

config SCHED_MC
	bool "Multi-core scheduler support"
	depends on (X86_64 && SMP) || (X86_32 && X86_HT)
	default y
	help
	  Multi-core scheduler support improves the CPU scheduler's decision
	  making when dealing with multi-core CPU chips at a cost of slightly
	  increased overhead in some places. If unsure say N here.

source "kernel/Kconfig.preempt"

config X86_UP_APIC
	bool "Local APIC support on uniprocessors"
	depends on X86_32 && !SMP && !(X86_VISWS || X86_VOYAGER || X86_GENERICARCH)
	help
	  A local APIC (Advanced Programmable Interrupt Controller) is an
	  integrated interrupt controller in the CPU. If you have a single-CPU
	  system which has a processor with a local APIC, you can say Y here to
	  enable and use it. If you say Y here even though your machine doesn't
	  have a local APIC, then the kernel will still run with no slowdown at
	  all. The local APIC supports CPU-generated self-interrupts (timer,
	  performance counters), and the NMI watchdog which detects hard
	  lockups.

config X86_UP_IOAPIC
	bool "IO-APIC support on uniprocessors"
	depends on X86_UP_APIC
	help
	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
	  SMP-capable replacement for PC-style interrupt controllers. Most
	  SMP systems and many recent uniprocessor systems have one.

	  If you have a single-CPU system with an IO-APIC, you can say Y here
	  to use it. If you say Y here even though your machine doesn't have
	  an IO-APIC, then the kernel will still run with no slowdown at all.

config X86_LOCAL_APIC
	bool
	depends on X86_64 || (X86_32 && (X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER) || X86_GENERICARCH))
	default y

config X86_IO_APIC
	bool
	depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER)) || X86_GENERICARCH))
	default y

config X86_VISWS_APIC
	bool
	depends on X86_32 && X86_VISWS
	default y

config X86_MCE
	bool "Machine Check Exception"
	depends on !X86_VOYAGER
	---help---
	  Machine Check Exception support allows the processor to notify the
	  kernel if it detects a problem (e.g. overheating, component failure).
	  The action the kernel takes depends on the severity of the problem,
	  ranging from a warning message on the console, to halting the machine.
	  Your processor must be a Pentium or newer to support this - check the
	  flags in /proc/cpuinfo for mce.  Note that some older Pentium systems
	  have a design flaw which leads to false MCE events - hence MCE is
	  disabled on all P5 processors, unless explicitly enabled with "mce"
	  as a boot argument.  Similarly, if MCE is built in and creates a
	  problem on some new non-standard machine, you can boot with "nomce"
	  to disable it.  MCE support simply ignores non-MCE processors like
	  the 386 and 486, so nearly everyone can say Y here.

config X86_MCE_INTEL
	bool "Intel MCE features"
	depends on X86_64 && X86_MCE && X86_LOCAL_APIC
	default y
	help
	   Additional support for intel specific MCE features such as
	   the thermal monitor.

config X86_MCE_AMD
	bool "AMD MCE features"
	depends on X86_64 && X86_MCE && X86_LOCAL_APIC
	default y
	help
	   Additional support for AMD specific MCE features such as
	   the DRAM Error Threshold.

config X86_MCE_NONFATAL
	tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
	depends on X86_32 && X86_MCE
	help
	  Enabling this feature starts a timer that triggers every 5 seconds which
	  will look at the machine check registers to see if anything happened.
	  Non-fatal problems automatically get corrected (but still logged).
	  Disable this if you don't want to see these messages.
	  Seeing the messages this option prints out may be indicative of dying
	  or out-of-spec (ie, overclocked) hardware.
	  This option only does something on certain CPUs.
	  (AMD Athlon/Duron and Intel Pentium 4)

config X86_MCE_P4THERMAL
	bool "check for P4 thermal throttling interrupt."
	depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
	help
	  Enabling this feature will cause a message to be printed when the P4
	  enters thermal throttling.

config VM86
	bool "Enable VM86 support" if EMBEDDED
	default y
	depends on X86_32
	help
          This option is required by programs like DOSEMU to run 16-bit legacy
	  code on X86 processors. It also may be needed by software like
          XFree86 to initialize some video cards via BIOS. Disabling this
          option saves about 6k.

config TOSHIBA
	tristate "Toshiba Laptop support"
	depends on X86_32
	---help---
	  This adds a driver to safely access the System Management Mode of
	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
	  not work on models with a Phoenix BIOS. The System Management Mode
	  is used to set the BIOS and power saving options on Toshiba portables.

	  For information on utilities to make use of this driver see the
	  Toshiba Linux utilities web site at:
	  <http://www.buzzard.org.uk/toshiba/>.

	  Say Y if you intend to run this kernel on a Toshiba portable.
	  Say N otherwise.

config I8K
	tristate "Dell laptop support"
	depends on X86_32
	---help---
	  This adds a driver to safely access the System Management Mode
	  of the CPU on the Dell Inspiron 8000. The System Management Mode
	  is used to read cpu temperature and cooling fan status and to
	  control the fans on the I8K portables.

	  This driver has been tested only on the Inspiron 8000 but it may
	  also work with other Dell laptops. You can force loading on other
	  models by passing the parameter `force=1' to the module. Use at
	  your own risk.

	  For information on utilities to make use of this driver see the
	  I8K Linux utilities web site at:
	  <http://people.debian.org/~dz/i8k/>

	  Say Y if you intend to run this kernel on a Dell Inspiron 8000.
	  Say N otherwise.

config X86_REBOOTFIXUPS
	bool "Enable X86 board specific fixups for reboot"
	depends on X86_32 && X86
	default n
	---help---
	  This enables chipset and/or board specific fixups to be done
	  in order to get reboot to work correctly. This is only needed on
	  some combinations of hardware and BIOS. The symptom, for which
	  this config is intended, is when reboot ends with a stalled/hung
	  system.

	  Currently, the only fixup is for the Geode machines using
	  CS5530A and CS5536 chipsets.

	  Say Y if you want to enable the fixup. Currently, it's safe to
	  enable this option even if you don't need it.
	  Say N otherwise.

config MICROCODE
	tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
	select FW_LOADER
	---help---
	  If you say Y here, you will be able to update the microcode on
	  Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
	  Pentium III, Pentium 4, Xeon etc.  You will obviously need the
	  actual microcode binary data itself which is not shipped with the
	  Linux kernel.

	  For latest news and information on obtaining all the required
	  ingredients for this driver, check:
	  <http://www.urbanmyth.org/microcode/>.

	  To compile this driver as a module, choose M here: the
	  module will be called microcode.

config MICROCODE_OLD_INTERFACE
	bool
	depends on MICROCODE
	default y

config X86_MSR
	tristate "/dev/cpu/*/msr - Model-specific register support"
	help
	  This device gives privileged processes access to the x86
	  Model-Specific Registers (MSRs).  It is a character device with
	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
	  MSR accesses are directed to a specific CPU on multi-processor
	  systems.

config X86_CPUID
	tristate "/dev/cpu/*/cpuid - CPU information support"
	help
	  This device gives processes access to the x86 CPUID instruction to
	  be executed on a specific processor.  It is a character device
	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
	  /dev/cpu/31/cpuid.

choice
	prompt "High Memory Support"
	default HIGHMEM4G if !X86_NUMAQ
	default HIGHMEM64G if X86_NUMAQ
	depends on X86_32

config NOHIGHMEM
	bool "off"
	depends on !X86_NUMAQ
	---help---
	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
	  However, the address space of 32-bit x86 processors is only 4
	  Gigabytes large. That means that, if you have a large amount of
	  physical memory, not all of it can be "permanently mapped" by the
	  kernel. The physical memory that's not permanently mapped is called
	  "high memory".

	  If you are compiling a kernel which will never run on a machine with
	  more than 1 Gigabyte total physical RAM, answer "off" here (default
	  choice and suitable for most users). This will result in a "3GB/1GB"
	  split: 3GB are mapped so that each process sees a 3GB virtual memory
	  space and the remaining part of the 4GB virtual memory space is used
	  by the kernel to permanently map as much physical memory as
	  possible.

	  If the machine has between 1 and 4 Gigabytes physical RAM, then
	  answer "4GB" here.

	  If more than 4 Gigabytes is used then answer "64GB" here. This
	  selection turns Intel PAE (Physical Address Extension) mode on.
	  PAE implements 3-level paging on IA32 processors. PAE is fully
	  supported by Linux, PAE mode is implemented on all recent Intel
	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
	  then the kernel will not boot on CPUs that don't support PAE!

	  The actual amount of total physical memory will either be
	  auto detected or can be forced by using a kernel command line option
	  such as "mem=256M". (Try "man bootparam" or see the documentation of
	  your boot loader (lilo or loadlin) about how to pass options to the
	  kernel at boot time.)

	  If unsure, say "off".

config HIGHMEM4G
	bool "4GB"
	depends on !X86_NUMAQ
	help
	  Select this if you have a 32-bit processor and between 1 and 4
	  gigabytes of physical RAM.

config HIGHMEM64G
	bool "64GB"
	depends on !M386 && !M486
	select X86_PAE
	help
	  Select this if you have a 32-bit processor and more than 4
	  gigabytes of physical RAM.

endchoice

choice
	depends on EXPERIMENTAL
	prompt "Memory split" if EMBEDDED
	default VMSPLIT_3G
	depends on X86_32
	help
	  Select the desired split between kernel and user memory.

	  If the address range available to the kernel is less than the
	  physical memory installed, the remaining memory will be available
	  as "high memory". Accessing high memory is a little more costly
	  than low memory, as it needs to be mapped into the kernel first.
	  Note that increasing the kernel address space limits the range
	  available to user programs, making the address space there
	  tighter.  Selecting anything other than the default 3G/1G split
	  will also likely make your kernel incompatible with binary-only
	  kernel modules.

	  If you are not absolutely sure what you are doing, leave this
	  option alone!

	config VMSPLIT_3G
		bool "3G/1G user/kernel split"
	config VMSPLIT_3G_OPT
		depends on !X86_PAE
		bool "3G/1G user/kernel split (for full 1G low memory)"
	config VMSPLIT_2G
		bool "2G/2G user/kernel split"
	config VMSPLIT_2G_OPT
		depends on !X86_PAE
		bool "2G/2G user/kernel split (for full 2G low memory)"
	config VMSPLIT_1G
		bool "1G/3G user/kernel split"
endchoice

config PAGE_OFFSET
	hex
	default 0xB0000000 if VMSPLIT_3G_OPT
	default 0x80000000 if VMSPLIT_2G
	default 0x78000000 if VMSPLIT_2G_OPT
	default 0x40000000 if VMSPLIT_1G
	default 0xC0000000
	depends on X86_32

config HIGHMEM
	bool
	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
	default y

config X86_PAE
	bool "PAE (Physical Address Extension) Support"
	default n
	depends on X86_32 && !HIGHMEM4G
	select RESOURCES_64BIT
	help
	  PAE is required for NX support, and furthermore enables
	  larger swapspace support for non-overcommit purposes. It