Configuration Options

Configuration options are introduced by the keyword config that must be followed by a configuration symbol.

config <symbol>

<type-name> "Description" <attributes>

The type name indicates the option type. As mentioned earlier, the tristate type has one of the following states: y, n, or m. Additional option types include the following:

□ bool permits a Boolean query that returns either y or n — in other words, the entry may be selected or not.

□ string queries a string.

□ hex and integer read hexadecimal and decimal numbers respectively.

The following syntax can be used instead of the type name:

config <symbol> <type-name> prompt "Description"

In functional terms, this is identical to the previous, shorter alternative.

The choice element must be used with the following syntax if users are required to select one of a group of options:



config <symbol_1> <type-name> <attributes>

config <symbol_n> <type-name> <attributes>


Each configuration option has its own configuration symbol that has the value y if the option is selected or n if not. choice selections are usually indicated by radio buttons in the configuration front ends, as illustrated in Figure B-3.

The source code for the CPU selection shown in the figure looks like this (the help texts have been omitted to improve readability):

choice prompt "Processor family" default M686 if X86_32

config M3 8 6

bool "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.

config M48 6

bool "486"

config M586

bool "586/K5/5x86/6x86/6x86MX"

config M586TSC

bool "Pentium-Classic"

config M586MMX

bool "Pentium-MMX"

config M686

bool "Pentium-Pro"


bool "Pentium-II/Celeron(pre-Coppermine)

config MGEODE_LX

bool "Geode GX/LX"


bool "CyrixIII/VIA-C3"

config MVIAC3_2

bool "VIA C3-2 (Nehemiah)


Linux Kemel V2.6.24 Configuration

File Edit Option Help

Option n 64-bit kernel S General setup

G Enable loadable module support ® Enable the block layer (NEW)

□ F'aravidualized guest support (NEW) ® Power management options ® Bus options (PCI etc.)

Executable file formats / Emulations Networking ® Device Drivers

Firmware Drivers ® File systems

E Instrumentation Support ® Kernel hacking Security options B Cryptographic API Library routines


-IJUIVI/ochugi iiji-

O SummltfEXA (IGMX440)

O Support for other sub-arch SMP systems with more than 8 CPUs O SGI 320/540 (Visual Workstation) O Generic architecture (Summit, bigsmp. ES70Q0, default) O Support for Unisys ES7000 IA32 series EJ Single-depth WCHAN output (NEW) 8 Processorfamlly O 386 O 486

O 586iK5/5x86/6x86i6x86MX O Pentium-Classic QFentlum-MMX O Pentium-Pro

O Pentlum-ll/Celeron(p re-Coppermine) O Pentium-IWCeleron(Coppermlne)/Pentium-lll Xeon O Pentium M

® Pentium-4iCeleron(P4-based)/Pentium-4 M/olcierXeon



O Opteron/Athlon64/Hammer/K8

O Crusoe

O Efficeon



Processor type and features

Figure B-3: CPU selection with choice elements on IA-32.

Continue reading here: Attributes

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