yocto编译内核驱动

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0. 内核模块编译方法

(1) 基于内核树在源码外编译模块

(2) 内核源码内编译模块

1. 基于内核树在源码外编译模块

(0) 使能构建环境

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source oe-init-build-env

使能之后，会进入build目录下

(1) 创建自定义meta层

在yocto的构建目录下，创建一个新的meta层

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bitbake-layers create-layer ../../meta-hello

(2) 添加层到构建环境

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bitbake-layers add-layer ../../meta-hello 
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yocto/poky/build$ bitbake-layers show-layers
NOTE: Starting bitbake server...
layer                 path                                                                    priority
========================================================================================================
core                  /home/ll/Free/yocto/poky/meta                                           5
yocto                 /home/ll/Free/yocto/poky/meta-poky                                      5
yoctobsp              /home/ll/Free/yocto/poky/meta-yocto-bsp                                 5
meta-hello            /home/ll/Free/yocto/meta-hello                                          6

(3) 添加驱动代码模块

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yocto$ ls
meta-arm  meta-hello  meta-openembedded  meta-renesas  meta-ros  meta-ros-publisher  poky
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$ mkdir -p meta-hello/recipes-kernel/hello/files

将 hello_drv.c和 Makefile添加到该目录下

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hello_drv.c
  
  1 #include <linux/kernel.h>
  2 #include <linux/module.h>
  3
  4 static int __init hello_drv_init(void)
  5 {
  6     pr_info("hello world drv!\r\n");
  7     return 0;
  8 }
  9
 10 static void __exit hello_drv_exit(void)
 11 {
 12     pr_info("good bye drv!\r\n");
 13 }
 14
 15 module_init(hello_drv_init);
 16 module_exit(hello_drv_exit);
 17 MODULE_LICENSE("GPL");hello_drv.c
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Makefile

  1 obj-m := hello_drv.o
  2
  3 all:
  4     $(MAKE) -C $(KERNEL_SRC) M=$(PWD) modules
  5
  6 modules_install:
  7     $(MAKE) -C $(KERNEL_SRC) M=$(PWD) modules_install
  8
  9 clean:
 10     $(MAKE) -C $(KERNEL_SRC) M=$(PWD) clean

在 meta-hello/recipes-kernel/hello目录下创建 hello.bb文件

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hello.bb

  1 SUMMARY = "Example of how to build a Linux Kernel Module"
  2 DESCRIPTION = "${SUMMARY}"
  3
  4 LICENSE = "GPL-2.0-only"
  5 LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/GPL-2.0-only;md5=801f80980d171dd6425610833a22dbe6"
  6
  7 inherit module
  8
  9 SRC_URI = "file://hello_drv.c \
 10            file://Makefile"
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 12 S = "${WORKDIR}"
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 14 UNPACKDIR = "${S}"
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 16 RPROVIDES:${PN} += "kernel-module-hello"

meta-hello目录架构

(4) 在目标镜像中包含驱动模块

在 meta/conf/machine/qemux86-64.conf文件下添加驱动模块

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MACHINE_EXTRA_RRECOMMENDS = "kernel-module-snd-ens1370 kernel-module-snd-rawmidi kernel-module-hello"

(5) 构建镜像

（0）确保 meta-hello的内容被包含

通过 local.conf 向 image 安装列表添加你的 package

在 build/conf/local.conf 中加入：

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IMAGE_INSTALL_append = " hello"
（1）编译镜像
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yocto/poky/build$ bitbake core-image-minimal
（2）编译完成

2. 内核源码内编译

(0) 使能构建环境

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source oe-init-build-env

使能之后，会进入build目录下

(1) 查找内核源码

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bitbake -s | grep linux

(2) 提取内核源码

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devtool modify linux-yocto-dev

(3) 添加hello_drv模块

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hello_drv.c

  1 #include <linux/kernel.h>
  2 #include <linux/module.h>
  3
  4 static int __init hello_drv_init(void)
  5 {
  6     pr_info("hello world drv!\r\n");
  7     return 0;
  8 }
  9
 10 static void __exit hello_drv_exit(void)
 11 {
 12     pr_info("good bye drv!\r\n");
 13 }
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 15 module_init(hello_drv_init);
 16 module_exit(hello_drv_exit);
 17 MODULE_LICENSE("GPL");
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Makefile
  1 obj-$(CONFIG_HELLO_DRV) += hello_drv.o
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Kconfig
  1 config HELLO_DRV
  2     tristate "Create a hello world drv module"
  3     default n
  4     help
  5         This is a module to print hello world drv

上层目录

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Makefile
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Kconfig

(4) 执行menuconfig，将新添加的驱动模块勾选上

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$ bitbake virtual/kernel -c menuconfig
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Device Drivers --> Character devices --> <*> Create a hello world drv module

(5) 单独编译linux内核，确保添加的驱动模块没有问题

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$ devtool build linux-yocto-dev

(6) 编译整个image

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$ devtool build-image core-image-sato
NOTE: Starting bitbake server...
Loading cache: 100% |#############################################################################################################################################################################| Time: 0:00:04
Loaded 7290 entries from dependency cache.
Parsing recipes: 100% |###########################################################################################################################################################################| Time: 0:00:10
Parsing of 4778 .bb files complete (4777 cached, 1 parsed). 7291 targets, 321 skipped, 1 masked, 0 errors.
WARNING: Skipping recipe linux-yocto-dev as it doesn't produce a package with the same name
WARNING: No recipes in workspace, building image core-image-sato unmodified
NOTE: Reconnecting to bitbake server...
Loading cache: 100% |#############################################################################################################################################################################| Time: 0:00:05
Loaded 7290 entries from dependency cache.
Parsing recipes: 100% |###########################################################################################################################################################################| Time: 0:00:08
Parsing of 4778 .bb files complete (4777 cached, 1 parsed). 7291 targets, 321 skipped, 1 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies

Build Configuration:
BB_VERSION           = "2.12.0"
BUILD_SYS            = "x86_64-linux"
NATIVELSBSTRING      = "universal"
TARGET_SYS           = "aarch64-poky-linux"
MACHINE              = "radxa-zero-3e"
DISTRO               = "poky"
DISTRO_VERSION       = "5.2.1"
TUNE_FEATURES        = "aarch64 crypto cortexa55"
TARGET_FPU           = ""
DISTRO_NAME          = "Poky (Yocto Project Reference Distro)"
ROS_DISTRO           = "humble"
ROS_VERSION          = "2"
ROS_PYTHON_VERSION   = "3"
meta
meta-poky
meta-yocto-bsp
meta-testlayer
meta-hellmodlayer    = "my-walnascar:ee0d8d8a61d8e22a3dd00c32cde58ee6e8ec458f"
meta-arm-toolchain
meta-arm             = "walnascar:c63ce2117ed9ad720c61a1e2df5d381ca1ac54a2"
meta-rockchip        = "walnascar:d5b97e3d82a866272f7235b7c3904bc1b85eb4c0"
meta-oe
meta-python          = "walnascar:2169c9afcc0945045bea49f58011080942d4ddb4"
meta-ros-common
meta-ros2
meta-ros2-humble     = "master:5fefe7f3c9e733321cb1786539a8c9c7571294cf"
workspace            = "my-walnascar:ee0d8d8a61d8e22a3dd00c32cde58ee6e8ec458f"

WARNING: /home/root1/Work/yocto/poky/meta/recipes-kernel/linux/linux-yocto-dev.bb:do_compile is tainted from a forced run                                                                         | ETA:  0:00:01
Sstate summary: Wanted 26 Local 13 Mirrors 0 Missed 13 Current 6897 (50% match, 99% complete)###################################################################################                  | ETA:  0:00:01
Removing 13 stale sstate objects for arch radxa_zero_3e: 100% |###################################################################################################################################| Time: 0:00:00
NOTE: Executing Tasks
NOTE: Tasks Summary: Attempted 13952 tasks of which 13931 didn't need to be rerun and all succeeded.

Summary: There was 1 WARNING message.
INFO: Successfully built core-image-sato. You can find output files in /home/root1/Work/yocto/poky/build/tmp/deploy/images/radxa-zero-3e

(7) 制作补丁

（0）查看代码差异
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$ git status
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$ git add
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$ git commit -m "xxx xxx xxx"

提交修改的代码

（1）创建layer目录
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$ bitbake-layers create-layer ../meta-hellodrvlayer
（2）添加layer目录
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$ bitbake-layers add-layer ../meta-hellodrvlayer

制作补丁，并指定到layer文件夹

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$ devtool finish linux-yocto-dev ../meta-hellodrvlayer

(8) 构建镜像

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bitbake core-image-sato