一、概述
Linux 内核编译流程如下：
1、配置 Linux 内核。
2、编译 Linux 内核。
说明：进入 Linux 内核源码，使用 make help 参看相关配置。
二、make menuconfig 工作原理
1、menuconfig 它本身是一个软件，只提供图形界面配置的一些逻辑，并不负责提供内容。
2、menuconfig 是内核源码树的各目录下的 kconfig 提供的。
3、menuconfig 中所有选中配置项的相关值会保存到配置文件中（默认配置文件为 .config）。
4、在编译内核时，Makefile 根据相关配置项选择需要编译的源码。
三、Kconfig 语法
参考文档：Documentation/kbuild/kconfig-language.txt。
Linux 驱动开发 六十五：《kconfig-language.txt》翻译_lqonlylove的博客-CSDN博客
四、Linux 内核中 Kconfig 分析
1、顶层 Kconfig 内容
#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.txt.
#
mainmenu "Linux/$ARCH $KERNELVERSION Kernel Configuration"
config SRCARCH
string
option env="SRCARCH"
source "arch/$SRCARCH/Kconfig"
-
mainmenu：标题栏； -
config：定义配置项；-
string：数据类型； -
env：导入Kconfig的环境变量；
-
-
source：读取的配置文件位置。
2、arch/arm/Kconfig 内容
……
source "init/Kconfig" # 包含配置文件
source "kernel/Kconfig.freezer"
menu "System Type" # 定义配置菜单栏
config MMU # 在 System Type 下定义配置项
bool "MMU-based Paged Memory Management Support"
default y
help
Select if you want MMU-based virtualised addressing space
support by paged memory management. If unsure, say 'Y'.
#
# The "ARM system type" choice list is ordered alphabetically by option
# text. Please add new entries in the option alphabetic order.
#
choice
prompt "ARM system type"
default ARCH_VERSATILE if !MMU
default ARCH_MULTIPLATFORM if MMU
config ARCH_MULTIPLATFORM
bool "Allow multiple platforms to be selected"
depends on MMU
select ARCH_WANT_OPTIONAL_GPIOLIB
select ARM_HAS_SG_CHAIN
select ARM_PATCH_PHYS_VIRT
select AUTO_ZRELADDR
select CLKSRC_OF
select COMMON_CLK
select GENERIC_CLOCKEVENTS
select MIGHT_HAVE_PCI
select MULTI_IRQ_HANDLER
select SPARSE_IRQ
select USE_OF
……
config ARCH_VERSATILE
bool "ARM Ltd. Versatile family"
select ARCH_WANT_OPTIONAL_GPIOLIB
select ARM_AMBA
select ARM_TIMER_SP804
select ARM_VIC
select CLKDEV_LOOKUP
select GENERIC_CLOCKEVENTS
select HAVE_MACH_CLKDEV
select ICST
select PLAT_VERSATILE
select PLAT_VERSATILE_CLOCK
select PLAT_VERSATILE_SCHED_CLOCK
select VERSATILE_FPGA_IRQ
help
This enables support for ARM Ltd Versatile board.
……
menu "Multiple platform selection"
depends on ARCH_MULTIPLATFORM # Multiple platform selection 依赖 ARCH_MULTIPLATFORM 配置项
comment "CPU Core family selection"
……
#
# This is sorted alphabetically by mach-* pathname. However, plat-*
# Kconfigs may be included either alphabetically (according to the
# plat- suffix) or along side the corresponding mach-* source.
#
source "arch/arm/mach-mvebu/Kconfig"
……
menu "Bus support"
……
menu "Kernel Features"
menu "CPU Power Management"
source "drivers/cpufreq/Kconfig"
source "drivers/cpuidle/Kconfig"
endmenu
menu "Floating point emulation"
comment "At least one emulation must be selected"
endmenu
……
menu "Userspace binary formats"
source "fs/Kconfig.binfmt"
endmenu
menu "Power management options"
source "kernel/power/Kconfig"
endmenu
source "net/Kconfig"
source "drivers/Kconfig"
source "drivers/firmware/Kconfig"
source "fs/Kconfig"
source "arch/arm/Kconfig.debug"
source "security/Kconfig"
source "crypto/Kconfig"
if CRYPTO
source "arch/arm/crypto/Kconfig"
endif
source "lib/Kconfig"
source "arch/arm/kvm/Kconfig"
-
source：包含一个配置文件； -
menu：定义一个菜单项； -
choice：定义一个选项组； -
config：定义一个配置项； -
comment：定义一个注释；
3、其他配置文件
五、测试
1、添加菜单
为了方便测试，在顶层 Kconfig 下添加一个 bool 配置项，配置项内容如下：
menu "onlylove test"
endmenu
2、添加 bool 类型配置
menu "onlylove test"
config ONLYLOVE_TEST
bool "onlylove test Management Support"
endmenu
3、添加 tristate 类型配置
menu "onlylove test"
config ONLYLOVE_TEST
tristate "onlylove test Management Support"
endmenu
4、添加 string 类型配置
menu "onlylove test"
config ONLYLOVE_TEST
string "onlylove test Management Support"
endmenu
5、添加 hex 类型配置
menu "onlylove test"
config ONLYLOVE_TEST
hex "onlylove test Management Support"
endmenu
6、添加 int 类型值
menu "onlylove test"
config ONLYLOVE_TEST
int "onlylove test Management Support"
endmenu
7、查看配置是否生效
1、添加菜单和配置项
menu "onlylove test"
config ONLYLOVE_TEST
tristate "onlylove test Management Support"
endmenu
2、查看旧配置文件
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15$ cat .config | grep ONLYLOVE_TEST
# CONFIG_ONLYLOVE_TEST is not set
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15$
3、选中 onlylove test Management Support 配置项
4、查看新配置文件
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15$ cat .config | grep ONLYLOVE_TEST
CONFIG_ONLYLOVE_TEST=m
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15$
六、向 Linux 内核中添加自己编写驱动
1、确定驱动所属类型
-
ICM-20608属于SPI设备。
2、找到对应Kconfig文件
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15/drivers/spi$ pwd
/home/onlylove/my/linux/linux-imx-4.1.15/drivers/spi
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15/drivers/spi$ ls -l Kconfig
-rw-rw-r-- 1 onlylove onlylove 20563 May 24 2019 Kconfig
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15/drivers/spi$
3、添加驱动文件
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15/drivers/spi$ pwd
/home/onlylove/my/linux/linux-imx-4.1.15/drivers/spi
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15/drivers/spi$ ls -l spi-icm2068.c
ls: cannot access 'spi-icm2068.c': No such file or directory
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15/drivers/spi$ cp -f ~/my/imx6ull_drive/13_icm20608_spi/spi-icm2068.c ./
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15/drivers/spi$ ls -l spi-icm2068.c
-rw-rw-r-- 1 onlylove onlylove 12758 Nov 13 00:25 spi-icm2068.c
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15/drivers/spi$
4、添加配置项
config ONLYLOVE_ICM20608
tristate "Icm20608 Device Support"
help
This supports user icm20608 device.
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15$ cat .config | grep ONLYLOVE_ICM20608
CONFIG_ONLYLOVE_ICM20608=y
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15$
5、添加Makefile编译项
obj-$(CONFIG_ONLYLOVE_ICM20608) += spi-icm2068.o
6、编译内核
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15$ make -j4
scripts/kconfig/conf --silentoldconfig Kconfig
CHK include/config/kernel.release
CHK include/generated/uapi/linux/version.h
CHK include/generated/utsrelease.h
make[1]: 'include/generated/mach-types.h' is up to date.
CHK include/generated/bounds.h
CHK include/generated/asm-offsets.h
CALL scripts/checksyscalls.sh
CHK include/generated/compile.h
CC drivers/spi/spi-icm2068.o
LD drivers/spi/built-in.o
LD drivers/built-in.o
LINK vmlinux
LD vmlinux.o
MODPOST vmlinux.o
GEN .version
CHK include/generated/compile.h
UPD include/generated/compile.h
CC init/version.o
LD init/built-in.o
KSYM .tmp_kallsyms1.o
KSYM .tmp_kallsyms2.o
LD vmlinux
SORTEX vmlinux
SYSMAP System.map
OBJCOPY arch/arm/boot/Image
Building modules, stage 2.
MODPOST 27 modules
Kernel: arch/arm/boot/Image is ready
LZO arch/arm/boot/compressed/piggy.lzo
AS arch/arm/boot/compressed/piggy.lzo.o
LD arch/arm/boot/compressed/vmlinux
OBJCOPY arch/arm/boot/zImage
Kernel: arch/arm/boot/zImage is ready
onlylove@ubuntu:~/my/linux/linux-imx-4.1.15$
日志 CC drivers/spi/spi-icm2068.o 表示 spi-icm2068 驱动编译成功。
7、驱动测试
1、Linux 启动日志
以上日志可以确定 icm20608 驱动加载成功。icm20608 设备 ID 读取成功。文章来源：https://www.toymoban.com/news/detail-409377.html
2、app程序调用icm20608驱动
# ls
icm20608_app
# ls -l /dev/icm20608
crw-rw---- 1 root root 10, 62 Jan 1 00:00 /dev/icm20608
#
# ./icm20608_app /dev/icm20608
data[0] = 6 data[1] = 13 data[2] = 0 data[3] = 43 data[4] = 6 data[5] = 2067
原始值:
gx = 6, gy = 13, gz = 0
ax = 43, ay = 6, az = 2067
temp = 1715
实际值:act gx = 0.37°/S, act gy = 0.79°/S, act gz = 0.00°/S
act ax = 0.02g, act ay = 0.00g, act az = 1.01g
act temp = 30.17°C
data[0] = 7 data[1] = 13 data[2] = 0 data[3] = 39 data[4] = 8 data[5] = 2063
原始值:
gx = 7, gy = 13, gz = 0
ax = 39, ay = 8, az = 2063
temp = 1708
实际值:act gx = 0.43°/S, act gy = 0.79°/S, act gz = 0.00°/S
act ax = 0.02g, act ay = 0.00g, act az = 1.01g
act temp = 30.15°C
data[0] = 8 data[1] = 12 data[2] = -1 data[3] = 43 data[4] = 11 data[5] = 2067
原始值:
gx = 8, gy = 12, gz = -1
ax = 43, ay = 11, az = 2067
temp = 1711
实际值:act gx = 0.49°/S, act gy = 0.73°/S, act gz = -0.06°/S
act ax = 0.02g, act ay = 0.01g, act az = 1.01g
act temp = 30.16°C
^C
#
数据读取成功。文章来源地址https://www.toymoban.com/news/detail-409377.html
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