Linux kernel configuration

1 development environment

Host: Ubuntu16.04

Development Board: Mini2440

Kernel version: 2.6.34.7

2 Download and Unzip

Download linux-2.6.34.7.tar.bz2 and Unzip:

TAR-AXVF linux-2.6.34.7.tar.bz2

3 Default configuration

Enter the kernel source top directory to execute:

Make Defconfig

The output is as follows:

[email protected]:~/mini2440/kernels/linux-2.6.34.7$ make Defconfig HOSTCC scripts/basic/fixdep HOSTCC scripts/ Basic/docproc HOSTCC scripts/basic/hash hostcc scripts/kconfig/conf.oscripts/kconfig/conf.c:in function ' conf_sym ': s      Cripts/kconfig/conf.c:159:6: warning:variable ' type ' set but not used [-wunused-but-set-variable] int type; ^scripts/kconfig/conf.c:in function ' Conf_choice ': scripts/kconfig/conf.c:231:6: warning:variable ' type ' set but not      used [-wunused-but-set-variable] int type; ^scripts/kconfig/conf.c:307:9: warning:ignoring return value of ' fgets ', declared with attribute Warn_unused_result [-wu         Nused-result] Fgets (line, N, stdin); ^scripts/kconfig/conf.c:in function ' Conf_askvalue ': scripts/kconfig/conf.c:105:8: warning:ignoring return value of '        Fgets ', declared with attribute Warn_unused_result [-wunused-result] fgets (line, N, stdin); ^ HOSTCC SCRIPTS/KCONFIG/KXGETTEXT.O SHIPPED scripts/kconfig/zconf.tab.c SHIPPEDSCRIPTS/KCONFIG/LEX.ZCONF.C SHIPPED scripts/kconfig/zconf.hash.c HOSTCC scripts/kconfig/zconf.tab.o HOSTLD scripts/k config/conf*** Default configuration is based on ' I386_defconfig ' # # Configuration written to. config#

According to the last 4 lines of the above output information, the kernel is configured for the x86 schema by default, and the . configis generated according to I386_defconfig (the source does not have this file, is only created when configured). Find i386_deconfigwith the Find command:

Use vim to open the . config and i386_defconfig, respectively, to find that their contents are basically the same, and compare them by using the diff Command:

by visible,. config is not exactly the same as I386_defconfig , makedefconfig is not simply arch/x86/configs/i386_ Defconfig Copy to . config.

3.1 Default Schema

The above default configuration is for x86 architecture , then how to start the ARM architecture default configuration? The answer is to specify the value of the ARCH variable for the top-level Makefile , specifying cross-compile toolchain prefix :

ARCH        = armcross_compile   ? = arm-linux-

Then execute Make defconfig, the target is ARM ArchitectureThe

[email protected]:~/mini2440/kernels/linux-2.6.34.7$ make Defconfig HOSTCC scripts/basic/fixdep HOSTCC scripts/ Basic/docproc HOSTCC scripts/basic/hash hostcc scripts/kconfig/conf.oscripts/kconfig/conf.c:in function ' conf_sym ': s      Cripts/kconfig/conf.c:159:6: warning:variable ' type ' set but not used [-wunused-but-set-variable] int type; ^scripts/kconfig/conf.c:in function ' Conf_choice ': scripts/kconfig/conf.c:231:6: warning:variable ' type ' set but not      used [-wunused-but-set-variable] int type; ^scripts/kconfig/conf.c:307:9: warning:ignoring return value of ' fgets ', declared with attribute Warn_unused_result [-wu         Nused-result] Fgets (line, N, stdin); ^scripts/kconfig/conf.c:in function ' Conf_askvalue ': scripts/kconfig/conf.c:105:8: warning:ignoring return value of '        Fgets ', declared with attribute Warn_unused_result [-wunused-result] fgets (line, N, stdin); ^ HOSTCC SCRIPTS/KCONFIG/KXGETTEXT.O SHIPPED scripts/kconfig/zconf.tab.c SHIPPEDSCRIPTS/KCONFIG/LEX.ZCONF.C SHIPPED scripts/kconfig/zconf.hash.c HOSTCC scripts/kconfig/zconf.tab.o HOSTLD scripts/k config/conf*** Default configuration is based on ' Versatile_defconfig ' # # Configuration written to. config#

The above information shows that the default configuration is generated according to versatile_defconfig . config, using Find lookup versatile_defconfig ：

Use diff to compare versatile_defconfig with . config:

By visible,versatile_defconfig and . config are still not exactly the same.

3.2 configuration file. config

From the above, the configuration information is mainly stored in the . config file of the kernel source top directory, and the first part of the . config of thearm architecture is as follows:

# # automatically generated make Config:don ' t edit# Linux kernel version:2.6.34.7# Tue may 11:30:25 2016#CONFIG_ARM=YC onfig_sys_supports_apm_emulation=yconfig_generic_time=yconfig_generic_clockevents=yconfig_have_proc_cpu= yconfig_generic_hardirqs=yconfig_stacktrace_support=yconfig_have_latencytop_support=yconfig_lockdep_support= Yconfig_trace_irqflags_support=yconfig_hardirqs_sw_resend=yconfig_generic_irq_probe=yconfig_rwsem_generic_ Spinlock=yconfig_generic_hweight=yconfig_generic_calibrate_delay=yconfig_need_dma_map_state=yconfig_generic_ hardirqs_no__do_irq=yconfig_vectors_base=0xffff0000config_defconfig_list= "/lib/modules/$UNAME _release/.config" Config_constructors=y

According to the above information in line 2nd, the contents of the. config file are generated automatically by Make config (in fact, I386_defconfig is also the 2nd line), do not manually modify.

Line 6th specifies that the arm schema is used, and all the remaining configuration items are prefixed with config_ .

3.3 Other default configuration files

According to reference [1], in the kernel source Arch directory has Alpha,x86,arm and other subdirectories, respectively, corresponding to the corresponding architecture:

The arm directory contains boot,common,configs,include , and the supported arm chip subdirectories for the kernel:

The configs directory contains the default profiles for each arm chip (including the 3.1-bar versatile_defconfig):

According to reference [1], to use the configuration files for these platforms, you can only copy them to the top-level directory and rename them to . config:

CD LINUX-2.6.34.7CP arch/arm/configs/mini2440_defconfig. config

4 Interactive Configuration

Enter the kernel source top directory to execute:

Make Config

The output is as follows:

[email protected]:~/mini2440/kernels/linux-2.6.34.7$ make config HOSTCC scripts/basic/fixdep HOSTCC scripts/ Basic/docproc HOSTCC scripts/basic/hash hostcc scripts/kconfig/conf.oscripts/kconfig/conf.c:in function ' conf_sym ': s      Cripts/kconfig/conf.c:159:6: warning:variable ' type ' set but not used [-wunused-but-set-variable] int type; ^scripts/kconfig/conf.c:in function ' Conf_choice ': scripts/kconfig/conf.c:231:6: warning:variable ' type ' set but not      used [-wunused-but-set-variable] int type; ^scripts/kconfig/conf.c:307:9: warning:ignoring return value of ' fgets ', declared with attribute Warn_unused_result [-wu         Nused-result] Fgets (line, N, stdin); ^scripts/kconfig/conf.c:in function ' Conf_askvalue ': scripts/kconfig/conf.c:105:8: warning:ignoring return value of '        Fgets ', declared with attribute Warn_unused_result [-wunused-result] fgets (line, N, stdin); ^ HOSTCC SCRIPTS/KCONFIG/KXGETTEXT.O SHIPPED scripts/kconfig/zconf.tab.c SHIPPED SCRIPTS/KCONFIG/LEX.ZCONF.C SHIPPED scripts/kconfig/zconf.hash.c HOSTCC scripts/kconfig/zconf.tab.o HOSTLD Scripts/kcon fig/confscripts/kconfig/conf arch/x86/kconfig## using defaults found in/boot/config-3.16.0-30-generic#/boot/ Config-3.16.0-30-generic:1264:warning:symbol value ' m ' Invalid for net_dsa/boot/config-3.16.0-30-generic:1680: Warning:symbol value ' m ' Invalid for Mtd_cmdline_parts/boot/config-3.16.0-30-generic:2418:warning:symbol value ' m ' Invalid for Net_dsa_mv88e6xxx/boot/config-3.16.0-30-generic:2419:warning:symbol value ' m ' Invalid for Net_dsa_ Mv88e6060/boot/config-3.16.0-30-generic:2421:warning:symbol value ' m ' Invalid for net_dsa_mv88e6131/boot/ Config-3.16.0-30-generic:2422:warning:symbol value ' m ' Invalid for net_dsa_mv88e6123_61_65/boot/ Config-3.16.0-30-generic:2861:warning:symbol value ' m ' Invalid for iwl4965/boot/config-3.16.0-30-generic:3783: Warning:symbol value ' m ' Invalid for Gpio_ucb1400/boot/config-3.16.0-30-generic:4259:warning:symbol value ' m ' invalID for Regulator_88pm8607/boot/config-3.16.0-30-generic:4318:warning:symbol value ' m ' Invalid for regulator_twl4030/ Boot/config-3.16.0-30-generic:5396:warning:symbol value ' m ' Invalid for snd_hda_codec_realtek/boot/ Config-3.16.0-30-generic:5397:warning:symbol value ' m ' Invalid for snd_hda_codec_analog/boot/ Config-3.16.0-30-generic:5398:warning:symbol value ' m ' Invalid for snd_hda_codec_sigmatel/boot/ Config-3.16.0-30-generic:5399:warning:symbol value ' m ' Invalid for snd_hda_codec_via/boot/config-3.16.0-30-generic : 5402:warning:symbol value ' m ' Invalid for Snd_hda_codec_cirrus/boot/config-3.16.0-30-generic:5403:warning:symbol Value ' m ' Invalid for Snd_hda_codec_conexant/boot/config-3.16.0-30-generic:5404:warning:symbol value ' m ' Invalid for Snd_hda_codec_ca0110/boot/config-3.16.0-30-generic:5407:warning:symbol value ' m ' Invalid for snd_hda_codec_cmedia/ Boot/config-3.16.0-30-generic:5408:warning:symbol value ' m ' Invalid for snd_hda_codec_si3054/boot/ config-3.16.0-30-generic:5409:Warning:symbol value ' m ' Invalid for Snd_hda_generic/boot/config-3.16.0-30-generic:7288:warning:symbol value ' m ' Invalid for Nfs_v3/boot/config-3.16.0-30-generic:7290:warning:symbol value ' m ' Invalid for nfs_v4** Linux Kernel Configu ration*** General setup*prompt for development and/or incomplete code/drivers (experimental) [n/y/?] (NEW)

As indicated in the last 1 lines above, the user is required to confirm whether Prompt for development and/or incomplete code/drivers (experimental), so it is InteractiveConfiguration, users need to know the kernel very much, the operation is more cumbersome.

5 Menu Configuration

Make Menuconfig

6 emptying the configuration

To remove the above configuration values, do the following:

Make Mrproper

Note: MakeDistcean cannot replace the above command!

Resources

[1] cross-compiling Linux kernel for ARM

Linux kernel configuration