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php爱好者> php文档>5.Processor type and features

5.Processor type and features

时间：2006-04-18 来源：kevinislinuxer

Processor type and features
1. Subarchitecture Type
  1. PC-compatible X86_PC

Choose this option if your computer is a standard PC or compatible.

标准的PC或兼容机选择此选项。

AMD Elan X86_ELAN

Select this for an AMD Elan processor.

Do not use this option for K6/Athlon/Opteron processors!

If unsure, choose "PC-compatible" instead.

此选项为 AMD Elan 处理器设置，K6/Athlon/Opteron不用这个选项。如不确定选择PC-compatible

Voyager (NCR)

Voyager is an MCA-based 32-way capable SMP architecture proprietary

to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.

*** WARNING ***

If you do not specifically know you have a Voyager based machine,

say N here, otherwise the kernel you build will not be bootable.

如果你不能明确的知道你的机器基于Voyager就不要选这个选项。

NUMAQ (IBM/Sequent)

This option is used for getting Linux to run on a (IBM/Sequent) NUMA

multiquad box. This changes the way that processors are bootstrapped,

and uses Clustered Logical APIC addressing mode instead of Flat Logical.

You will need a new lynxer.elf file to flash your firmware with - send

email to <[email protected]>.

此选项可以让linux运行在（IBM/Sequent）NUMA上，不过你需要刷新一下固件，可以给下面的地址发email <[email protected]>

SGI 320/540 (Visual Workstation)

The SGI Visual Workstation series is an IA32-based workstation

based on SGI systems chips with some legacy PC hardware attached.

Say Y here to create a kernel to run on the SGI 320 or 540.

A kernel compiled for the Visual Workstation will not run on PCs

and vice versa. See <file:Documentation/sgi-visws.txt> for details.

此选项为SGI320或540虚拟机创建内核，但该内核不能用于PC，反之亦然，详情请看文件：Documentation/sgi-visws.txt

Processor family

CPU 选型

在此选项选择你的CPU类型，可以起到优化作用，为了编译在所有x86 CPU上都能运行的内核，你可以选386。你编译的内核不一定适用于比你的CPU早一些的架构，比如你为Pentium编译的内核也许能运行在Pentium pro上，但不一定能运行在486上。下面是可以达到最佳速度的推荐设置：

--选386的包括：386 AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI

486DLC/DLC2, UMC 486SX-S 及 NexGen Nx586

--选486的包括：AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S

--586 ：一般的没有TSC注册的Pentium CPU

--Pentium-class：Intel Pentium

.............

如果你不知道这些是什么东西，就选386。

This is the processor type of your CPU. This information is used for

optimizing purposes. In order to compile a kernel that can run on

all x86 CPU types (albeit not optimally fast), you can specify

"386" here.

The kernel will not necessarily run on earlier architectures than

the one you have chosen, e.g. a Pentium optimized kernel will run on

a PPro, but not necessarily on a i486.

Here are the settings recommended for greatest speed:

- "386" for the AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI

486DLC/DLC2, UMC 486SX-S and NexGen Nx586. Only "386" kernels

will run on a 386 class machine.

- "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or

SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.

- "586" for generic Pentium CPUs lacking the TSC

(time stamp counter) register.

- "Pentium-Classic" for the Intel Pentium.

- "Pentium-MMX" for the Intel Pentium MMX.

- "Pentium-Pro" for the Intel Pentium Pro.

- "Pentium-II" for the Intel Pentium II or pre-Coppermine Celeron.

- "Pentium-III" for the Intel Pentium III or Coppermine Celeron.

- "Pentium-4" for the Intel Pentium 4 or P4-based Celeron.

- "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).

- "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).

- "Crusoe" for the Transmeta Crusoe series.

- "Efficeon" for the Transmeta Efficeon series.

- "Winchip-C6" for original IDT Winchip.

- "Winchip-2" for IDT Winchip 2.

- "Winchip-2A" for IDT Winchips with 3dNow! capabilities.

- "GeodeGX1" for Geode GX1 (Cyrix MediaGX).

- "Geode GX/LX" For AMD Geode GX and LX processors.

- "CyrixIII/VIA C3" for VIA Cyrix III or VIA C3.

- "VIA C3-2 for VIA C3-2 "Nehemiah" (model 9 and above).

If you don't know what to do, choose "386".

Select this for a 486 series processor, either Intel or one of the

compatible processors from AMD, Cyrix, IBM, or Intel. Includes DX,

DX2, and DX4 variants; also SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or

U5S.

586/K5/5x86/6x86/6x86MX

Select this for an 586 or 686 series processor such as the AMD K5,

the Cyrix 5x86, 6x86 and 6x86MX. This choice does not

assume the RDTSC (Read Time Stamp Counter) instruction.

Pentium-Classic

Select this for a Pentium Classic processor with the RDTSC (Read

Time Stamp Counter) instruction for benchmarking.

Pentium-MMX

Select this for a Pentium with the MMX graphics/multimedia

extended instructions.

Pentium-Pro

Select this for Intel Pentium Pro chips. This enables the use of

Pentium Pro extended instructions, and disables the init-time guard

against the f00f bug found in earlier Pentiums.

Pentium-II/Celeron(pre-Coppermine)

Select this for Intel chips based on the Pentium-II and

pre-Coppermine Celeron core. This option enables an unaligned

copy optimization, compiles the kernel with optimization flags

tailored for the chip, and applies any applicable Pentium Pro

optimizations.

Pentium-III/Celeron(Coppermine)/Pentium-III Xeon

Select this for Intel chips based on the Pentium-III and

Celeron-Coppermine core. This option enables use of some

extended prefetch instructions in addition to the Pentium II

extensions.

Pentium M

Select this for Intel Pentium M (not Pentium-4 M)

notebook chips.

Pentium-4/Celeron(P4-based)/Pentium-4 M/Xeon

Select this for Intel Pentium 4 chips. This includes the

Pentium 4, P4-based Celeron and Xeon, and Pentium-4 M

(not Pentium M) chips. This option enables compile flags

optimized for the chip, uses the correct cache shift, and

applies any applicable Pentium III optimizations.

K6/K6-II/K6-III

Select this for an AMD K6-family processor. Enables use of

some extended instructions, and passes appropriate optimization

flags to GCC.

Athlon/Duron/K7

Select this for an AMD Athlon K7-family processor. Enables use of

some extended instructions, and passes appropriate optimization

flags to GCC.

Opteron/Athlon64/Hammer/K8

Select this for an AMD Opteron or Athlon64 Hammer-family processor. Enables

use of some extended instructions, and passes appropriate optimization

flags to GCC.

Crusoe

Select this for a Transmeta Crusoe processor. Treats the processor

like a 586 with TSC, and sets some GCC optimization flags (like a

Pentium Pro with no alignment requirements).

Efficeo

Select this for a Transmeta Efficeon processor.

Winchip-C6

Select this for an IDT Winchip C6 chip. Linux and GCC

treat this chip as a 586TSC with some extended instructions

and alignment requirements.

Winchip-2

Select this for an IDT Winchip-2. Linux and GCC

treat this chip as a 586TSC with some extended instructions

and alignment requirements.

Winchip-2A/Winchip-3

Select this for an IDT Winchip-2A or 3. Linux and GCC

treat this chip as a 586TSC with some extended instructions

and alignment reqirements. Also enable out of order memory

stores for this CPU, which can increase performance of some

operations.

GeodeGX1

Select this for a Geode GX1 (Cyrix MediaGX) chip.

Geode GX/LX

Select this for AMD Geode GX and LX processors.

CyrixIII/VIA-C3

Select this for a Cyrix III or C3 chip. Presently Linux and GCC

treat this chip as a generic 586. Whilst the CPU is 686 class,

it lacks the cmov extension which gcc assumes is present when

generating 686 code.

Note that Nehemiah (Model 9) and above will not boot with this

kernel due to them lacking the 3DNow! instructions used in earlier

incarnations of the CPU.

VIA C3-2 (Nehemiah)

Select this for a VIA C3 "Nehemiah". Selecting this enables usage

of SSE and tells gcc to treat the CPU as a 686.

Note, this kernel will not boot on older (pre model 9) C3s.

Generic x86 support

Instead of just including optimizations for the selected

x86 variant (e.g. PII, Crusoe or Athlon), include some more

generic optimizations as well. This will make the kernel

perform better on x86 CPUs other than that selected.

This is really intended for distributors who need more

generic optimizations.

这个选项提供了对X86系列CPU最大的兼容性，用来支持一些很少见的x86体系的CPU，它可能会降低一些系统性能。如果你的CPU能够在上面的列表中找到，就里就不用选了。

HPET Timer Support

This enables the use of the HPET for the kernel's internal timer.

HPET is the next generation timer replacing legacy 8254s.

You can safely choose Y here. However, HPET will only be

activated if the platform and the BIOS support this feature.

Otherwise the 8254 will be used for timing services.

Choose N to continue using the legacy 8254 timer.

这也是一个新的特性，HPET是intel制定的新的用以代替传统的8254(PIT)中断定时器与RTC的定时器，全称叫作高精度事件定时器。如果你有一台较新的机器就选它吧，一般它是一个安全的选项，即使你的硬件不支持HPET也不会造成问题，因为它会自动用8254替换。

Symmetric multi-processing support

This enables support for systems with more than one CPU. If you have

a system with only one CPU, like most personal computers, say N. If

you have a system with more than one CPU, say Y.

If you say N here, the kernel will run on single and multiprocessor

machines, but will use only one CPU of a multiprocessor machine. If

you say Y here, the kernel will run on many, but not all,

singleprocessor machines. On a singleprocessor machine, the kernel

will run faster if you say N here.

Note that if you say Y here and choose architecture "586" or

"Pentium" under "Processor family", the kernel will not work on 486

architectures. Similarly, multiprocessor kernels for the "PPro"

architecture may not work on all Pentium based boards.

People using multiprocessor machines who say Y here should also say

Y to "Enhanced Real Time Clock Support", below. The "Advanced Power

Management" code will be disabled if you say Y here.

See also the <file:Documentation/smp.txt>,

<file:Documentation/i386/IO-APIC.txt>,

<file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at

<http://www.tldp.org/docs.html#howto>.

If you don't know what to do here, say N.

此选项支持多CPU，如果你的机器只有一个CPU，就选N，如果有多个就选Y。如果选N，编译出的内核可以运行在单CPU和多CPU的机器上，但多CPU的机器也将只用一个CPU，如果选Y，很多但内核机器也能运行，但不是所有的都行。如果机器是但CPU，选N的话内核会快一些。注意，如果此处选Y，而且在"Processor family"里选择了586或Pentium，内核在486机器上浆不能运行。

在这选Y的用户，在下面的选项Enhanced Real Time Clock Support也该选Y，但Advanced Power Management（高级电源管理）会被禁用。详细信息在以下文件，Documentation目录下的smp.txt，IO-APIC.txt，nmi_watchdog.txt，以及http://www.tldp.org/docs.html#howto，。

如果你不知道怎么做，选N。

Preemption Model
1. No Forced Preemption (Server)

This is the traditional Linux preemption model, geared towards

throughput. It will still provide good latencies most of the

time, but there are no guarantees and occasional longer delays

are possible.

Select this option if you are building a kernel for a server or

scientific/computation system, or if you want to maximize the

raw processing power of the kernel, irrespective of scheduling

latencies.

这就是可抢先式内核。也就是说被一些优先级很高的程序可以先与一些低优先级的程序执行，即使这些程序是在核心态下执行(这实际上仍然不是真正的抢先式内核)。从而减少内核潜伏期，提高系统的响应。

如果你是为服务器或用于科学计算的计算机构建内核，那就选这个选项。

Voluntary Kernel Preemption (Desktop)

This option reduces the latency of the kernel by adding more

"explicit preemption points" to the kernel code. These new

preemption points have been selected to reduce the maximum

latency of rescheduling, providing faster application reactions,

at the cost of slighly lower throughput.

This allows reaction to interactive events by allowing a

low priority process to voluntarily preempt itself even if it

is in kernel mode executing a system call. This allows

applications to run more 'smoothly' even when the system is

under load.

Select this if you are building a kernel for a desktop system.

如果你是为个人桌面系统构建内核，选这个选项。

Preemptible Kernel (Low-Latency Desktop)

This option reduces the latency of the kernel by making

all kernel code (that is not executing in a critical section)

preemptible. This allows reaction to interactive events by

permitting a low priority process to be preempted involuntarily

even if it is in kernel mode executing a system call and would

otherwise not be about to reach a natural preemption point.

This allows applications to run more 'smoothly' even when the

system is under load, at the cost of slighly lower throughput

and a slight runtime overhead to kernel code.

Select this if you are building a kernel for a desktop or

embedded system with latency requirements in the milliseconds

range.

如果你是为桌面系统或嵌入式系统（毫秒及潜伏请求），就选这个选项。

Local APIC support on uniprocessors

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.

IO-APIC support on uniprocessors

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.

单CPU的高级可编程中断控制器，即使你的CPU不支持，内核也不会因此减慢速度。不过我不知道这是干什么用的。

Machine Check Exception

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.

如果系统出现一些问题比如CPU过热，内核将会在屏幕上打印相关信息来提醒你。这个功能是需要硬件支持的。你可以查看/proc/cpuinfo看看是否有mce标志，有的话就选吧。如果你十分十分的不幸，选了它之后出现问题，可以在启动时加nomce参数来关闭它。

Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4

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 hardware,

or out-of-spec (ie, overclocked) hardware.

This option only does something on certain CPUs.

(AMD Athlon/Duron and Intel Pentium 4)

打开这个选项将会检查你机器上可能存在的问题，如果有一个非致命错误出现将会自动的修复并且记录，这可以帮助你查出程序出现问题的原因，是一个不错的选项。当然它只能用在AMD Athlon/Duron / Intel Pentium 4这类CPU上。如果你正好在用它们中的一个你就选吧。

check for P4 thermal throttling interrupt.

Enabling this feature will cause a message to be printed when the P4

enters thermal throttling.

如果打开此选项，当P4 CPU进入发热量抑制时会输出信息。

Toshiba Laptop support

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.

对东芝笔记本电脑的支持，提供一个驱动，可安全进入使用东芝BIOS的CPU的系统管理模式以进行BIOS和节能设置，对Phoenix BIOS 不适用。详情见网页：<http://www.buzzard.org.uk/toshiba/>

如果你的内核运行在东芝便携机器上就选这个选项。

Dell laptop support

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.

对DELL笔记本电脑的支持，与上面类似。此驱动仅在Inspiron8000上测试过，但是在DELL笔记本电脑上也许能行，风险自理。详情请见<http://people.debian.org/~dz/i8k/>，Inspiron8000用户可选，否则别选。

Enable X86 board specific fixups for reboot

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 GX1/CS5530A/TROM2.1.

combination.

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.

对于不能正常重启的修复，即使你不需要这项功能，选上也是安全的，不过目前它只能修复Geode GX1/CS5530A/TROM2.1。

/dev/cpu/microcode - Intel IA32 CPU microcode support

If you say Y here and also to "/dev file system support" in the

'File systems' section, 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.

是否支持Intel IA32架构的CPU（Xeon）？这个选项将让你可以更新Intel IA32系列处理器的微代码，当然你还必须在文件系统选项中选择devfs才能正常的使用它。如果你把它译为模块你还需要在modprobe.conf中加上这一行alias char-major-10-184 microcode 内核本身并不带有微代码的二进制文件，你可以到这个网址去得到新的信息http://www.urbanmyth.org/microcode/

/dev/cpu/*/msr - Model-specific register support

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.

是否打开Pentium CPU特殊功能寄存器的功能？这个选项桌面用户一般用不到，它主要用在Intel的嵌入式CPU中的，这个寄存器的作用也依赖与不同的CPU类型而有所不同，一般可以用来改变一些CPU原有物理结构的用途，但不同的CPU用途差别也很大。

/dev/cpu/*/cpuid - CPU information support

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.

是否打开记录Petium CPU相关信息功能？这会在/dev/cpu中建立一系列的设备文件，用以让过程去访问指定的CPU。一般不用选。

Firmware Drivers

Say Y or M here if you want to enable BIOS Enhanced Disk Drive

Services real mode BIOS calls to determine which disk

BIOS tries boot from. This information is then exported via sysfs.

This option is experimental and is known to fail to boot on some

obscure configurations. Most disk controller BIOS vendors do

not yet implement this feature.

此驱动处于试验阶段，现在大多数磁盘驱动器BIOS厂商不使用。

BIOS Enhanced Disk Drive calls determine boot disk (EXPERIMENTAL)

Say Y or M here if you want to enable BIOS Enhanced Disk Drive

Services real mode BIOS calls to determine which disk

BIOS tries boot from. This information is then exported via sysfs.

This option is experimental and is known to fail to boot on some

obscure configurations. Most disk controller BIOS vendors do

not yet implement this feature.

BIOS update support for DELL systems via sysfs

Say m if you want to have the option of updating the BIOS for your

DELL system. Note you need a Dell OpenManage or Dell Update package (DUP)

supporting application to comunicate with the BIOS regarding the new

image for the image update to take effect.

See <file:Documentation/dell_rbu.txt> for more details on the driver.

Dell Systems Management Base Driver

The Dell Systems Management Base Driver provides a sysfs interface

for systems management software to perform System Management

Interrupts (SMIs) and Host Control Actions (system power cycle or

power off after OS shutdown) on certain Dell systems.

See <file:Documentation/dcdbas.txt> for more details on the driver

and the Dell systems on which Dell systems management software makes

use of this driver.

Say Y or M here to enable the driver for use by Dell systems

management software such as Dell OpenManage.

High Memory Support
1. off

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".

Linux可以在行x86系统上使用64G的物理内存，但32位x86处理器只支持4G，这意味着如果你有大容量的内存，不是所有的部分都能被内核永久映射，不能永久映射的物理内存被称为“high memory”

Select this if you have a 32-bit processor and between 1 and 4

gigabytes of physical RAM.

选此选项，如果你使用32位处理器，并拥有1~4G物理内存。

64GB

Select this if you have a 32-bit processor and more than 4

gigabytes of physical RAM.

选此选项，如果你使用32位处理器，并拥有大于4G物理内存。

Memory split

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!

如果你不是绝对清楚你在做什么，不要动这个选项。

3G/1G user/kernel split
3G/1G user/kernel split (for full 1G low memory)
2G/2G user/kernel split
1G/3G user/kernel split

Memory model

内存模式，对大多数用户而言，第一项是正确的选择，其他选项涉及内存热插拔。

Flat Memory

This option allows you to change some of the ways that

Linux manages its memory internally. Most users will

only have one option here: FLATMEM. This is normal

and a correct option.

Some users of more advanced features like NUMA and

memory hotplug may have different options here.

DISCONTIGMEM is an more mature, better tested system,

but is incompatible with memory hotplug and may suffer

decreased performance over SPARSEMEM. If unsure between

"Sparse Memory" and "Discontiguous Memory", choose

"Discontiguous Memory".

If unsure, choose this option (Flat Memory) over any other.

Sparse Memory

This will be the only option for some systems, including

memory hotplug systems. This is normal.

For many other systems, this will be an alternative to

"Discontiguous Memory". This option provides some potential

performance benefits, along with decreased code complexity,

but it is newer, and more experimental.

If unsure, choose "Discontiguous Memory" or "Flat Memory"

over this option.

Allocate 3rd-level pagetables from highmem

The VM uses one page table entry for each page of physical memory.

For systems with a lot of RAM, this can be wasteful of precious

low memory. Setting this option will put user-space page table

entries in high memory.

除非有几G的内存，否则选择这个是没有意义的。

Math emulation

Linux can emulate a math coprocessor (used for floating point

operations) if you don't have one. 486DX and Pentium processors have

a math coprocessor built in, 486SX and 386 do not, unless you added

a 487DX or 387, respectively. (The messages during boot time can

give you some hints here ["man dmesg"].) Everyone needs either a

coprocessor or this emulation.

If you don't have a math coprocessor, you need to say Y here; if you

say Y here even though you have a coprocessor, the coprocessor will

be used nevertheless. (This behavior can be changed with the kernel

command line option "no387", which comes handy if your coprocessor

is broken. 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.) This means that it is a good idea to say Y here if you

intend to use this kernel on different machines.

More information about the internals of the Linux math coprocessor

emulation can be found in <file:arch/i386/math-emu/README>.

If you are not sure, say Y; apart from resulting in a 66 KB bigger

kernel, it won't hurt.

核心模拟数学浮点运算器，协处理器是在386时代的宠儿，现在早已下岗。选择Y，内核会增大66k。

MTRR (Memory Type Range Register) support

On Intel P6 family processors (Pentium Pro, Pentium II and later)

the Memory Type Range Registers (MTRRs) may be used to control

processor access to memory ranges. This is most useful if you have

a video (VGA) card on a PCI or AGP bus. Enabling write-combining

allows bus write transfers to be combined into a larger transfer

before bursting over the PCI/AGP bus. This can increase performance

of image write operations 2.5 times or more. Saying Y here creates a

/proc/mtrr file which may be used to manipulate your processor's

MTRRs. Typically the X server should use this.

This code has a reasonably generic interface so that similar

control registers on other processors can be easily supported

as well:

The Cyrix 6x86, 6x86MX and M II processors have Address Range

Registers (ARRs) which provide a similar functionality to MTRRs. For

these, the ARRs are used to emulate the MTRRs.

The AMD K6-2 (stepping 8 and above) and K6-3 processors have two

MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing

write-combining. All of these processors are supported by this code

and it makes sense to say Y here if you have one of them.

Saying Y here also fixes a problem with buggy SMP BIOSes which only

set the MTRRs for the boot CPU and not for the secondary CPUs. This

can lead to all sorts of problems, so it's good to say Y here.

You can safely say Y even if your machine doesn't have MTRRs, you'll

just add about 9 KB to your kernel.

See <file:Documentation/mtrr.txt> for more information.

在PCI或者AGP总线众进行更快速的通讯。由于现在所有系统都将它们的显卡接在PCI或AGP总线上，你通常需要选择“MTRR”。无论如何，打开这个选项通常都是安全的——即使你的机器没有使用PCI或AGP总线的显卡。

Boot from EFI support (EXPERIMENTAL)

This enables the the kernel to boot on EFI platforms using

system configuration information passed to it from the firmware.

This also enables the kernel to use any EFI runtime services that are

available (such as the EFI variable services).

This option is only useful on systems that have EFI firmware

and will result in a kernel image that is ~8k larger. In addition,

you must use the latest ELILO loader available at

<http://elilo.sourceforge.net> in order to take advantage of

kernel initialization using EFI information (neither GRUB nor LILO know

anything about EFI). However, even with this option, the resultant

kernel should continue to boot on existing non-EFI platforms.

由于我使用的是GRUB，所以选上这个也没什么用，如果你打算使用EFI的功能，你可以到http://elilo.sourceforge.net看看。此选项在测试阶段。

Use register arguments (EXPERIMENTAL)

Compile the kernel with -mregparm=3. This uses a different ABI

and passes the first three arguments of a function call in registers.

This will probably break binary only modules.

Enable seccomp to safely compute untrusted bytecode

This kernel feature is useful for number crunching applications

that may need to compute untrusted bytecode during their

execution. By using pipes or other transports made available to

the process as file descriptors supporting the read/write

syscalls, it's possible to isolate those applications in

their own address space using seccomp. Once seccomp is

enabled via /proc/<pid>/seccomp, it cannot be disabled

and the task is only allowed to execute a few safe syscalls

defined by each seccomp mode.

If unsure, say Y. Only embedded should say N here.

不懂，如不确定，选Y。

Timer frequency

Allows the configuration of the timer frequency. It is customary

to have the timer interrupt run at 1000 HZ but 100 HZ may be more

beneficial for servers and NUMA systems that do not need to have

a fast response for user interaction and that may experience bus

contention and cacheline bounces as a result of timer interrupts.

Note that the timer interrupt occurs on each processor in an SMP

environment leading to NR_CPUS * HZ number of timer interrupts

per second.

计时器频率，某些应用不需要对用户交互的太快的反应而可以使用较低频率，选项1为服务器的典型频率，选项3为桌面用户的选择，2位两者的折中。

100 HZ

100 HZ is a typical choice for servers, SMP and NUMA systems

with lots of processors that may show reduced performance if

too many timer interrupts are occurring.

250 HZ

250 HZ is a good compromise choice allowing server performance

while also showing good interactive responsiveness even

on SMP and NUMA systems.

1000 HZ

1000 HZ is the preferred choice for desktop systems and other

systems requiring fast interactive responses to events.

kexec system call (EXPERIMENTAL)

kexec is a system call that implements the ability to shutdown your

current kernel, and to start another kernel. It is like a reboot

but it is indepedent of the system firmware. And like a reboot

you can start any kernel with it, not just Linux.

The name comes from the similiarity to the exec system call.

It is an ongoing process to be certain the hardware in a machine

is properly shutdown, so do not be surprised if this code does not

initially work for you. It may help to enable device hotplugging

support. As of this writing the exact hardware interface is

strongly in flux, so no good recommendation can be made.

kernel crash dumps (EXPERIMENTAL)

Generate crash dump after being started by kexec.