Notes

./lanuch 最终的操作是

cd sdk_3921/buildroot-dist # 进入buildroot目录
make BR2_EXTERNAL=sdk_3921/platform/ O=sdk3921/out/rts3923_fpga/ rts3923_fpga_defconfig

local.mk # BR2_PACKAGE_OVERRIDE_FILE 在platform/configs中定义
external.mk
    include common.mk
    	include package/*/*/*.mk
    	include package/*/*.mk
    include package/*/*/src.mki
    include package/*/*/gen.mki
    include post_pkg.mk

platform/local.mk: 指定自定义源码位置

在local.mk中还定义了：

make rr: Reconstruct rootfs

make rp: Rebuild external packages

Managing the build and the configuration

Out of tree build

在buildroot Makefile中有

ifeq ($(O),$(CURDIR)/output)
CONFIG_DIR := $(CURDIR)
NEED_WRAPPER =
else
CONFIG_DIR := $(O)
NEED_WRAPPER = y
endif

可以看出，如果O != buildroot_dist/output, CONFIG_DIR = sdk3921/out/rts3923_fpga/

在CONFIG_DIR目录下，保存着.config配置文件。

Other building tips

Cleaning all the build output, but keeping the configuration file(删除build/):

make clean

Cleaning everything, including the configuration file, and downloaded file if at the default location (相当于删除了build/和.config一系列配置文件，需要重新make menuconfig):

make distclean

Buildroot source and build trees

Build tree

  • output/对应BASE_DIR
  • output/build/对应BUILD_DIR
  • output/host/对应HOST_DIR
    • Contains both the tools built for the host (cross-compiler, etc.) and the sysroot of the toolchain
    • Host tools are directly in host/
    • The sysroot is in host/<tuple>/sysroot/usrE.g: arm-unknown-linux-gnueabihf
    • Variable for the sysroot: STAGING_DIR. ouput目录下的staging目录也是软连接到这的
  • output/target/对应TARGET_DIR
    • Used to generate the final root filesystem images in images/
  • output/image/对应BINARIES_DIR

Managing the Linux kernel configuration

  • make linux-update-config, to save a full config file
  • make linux-update-defconfig, to save a minimal defconfig

Root filesystem in Buildroot

copy rootfs overlays->execute post-build scripts->execute post-image scripts

platform/board/rts3923/rootfs_overlay

platform/board/rts3923/post_build.sh

platform/board/rts3923/post_image.sh

Advanced topics

BR2_EXTERNAL

Ipcam sdk在make的时候指定

make BR2_EXTERNAL=sdk_3921/platform/ O=sdk3921/out/rts3923_fpga/ rts3923_fpga_defconfig

Each external directory must contain:

  • external.desc, which provides a name and description. The $BR2_EXTERNAL_<NAME>_PATH variable is available, where NAME is defined in external.desc.
  • Config.in, configuration options that will be included in menuconfig（在menuconfig external options里）
  • external.mk, will be included in the make logic

make <pkg>-dirclean, completely remove the package source code directory. The next make invocation will fully rebuild this package. 相当于直接删除build/<pkg>

make <pkg>-rebuild, force to re-execute the build and installation steps of the package.

make <pkg>-reconfigure, force to re-execute the configure, build and installation steps of the package.

legacy

添加自己的软件包

添加package/Config.in入口

config BR2_PACKAGE_HELLOWORLD
bool "helloworld"
help
  This is a demo to add myown(fuzidage) package.

配置APP对应的Config.in和mk文件

在package中新增目录helloworld，并在里面添加Config.in和helloworld.mk Config.in

config BR2_PACKAGE_HELLOWORLD
bool "helloworld"
help
  This is a demo to add myown(fuzidage) package.

helloworld.mk

HELLOWORLD_VERSION:= 1.0.0
HELLOWORLD_SITE:= $(BR2_EXTERNAL)/source/ipcam/helloworld
HELLOWORLD_SITE_METHOD:=local
HELLOWORLD_INSTALL_TARGET:=YES

$(eval $(cmake-package))

如何重新编译软件包

经过第一次完整编译后，如果我们需要对源码包重新配置，我们不能直接在buildroot上的根目录下直接make，buildroot是不知道你已经对源码进行重新配置，它只会将第一次编译出来的文件，再次打包成根文件系统镜像文件。

那么可以通过以下2种方式重新编译：

1. 直接删除源码包,然后make all

例如我们要重新编译helloworld，那么可以直接删除output/build/helloworld目录，那么当你make的时候，就会自动从dl文件夹下，解压缩源码包，并重新安装。这种效率偏低

2. 进行xxx-rebuild,然后make all

也是以helloworld为例子，我们直接输入make helloworld-rebuild，即可对build/helloworld/目录进行重新编译，然后还要进行make all(或者make helloworld)

Config.in 语法

用Kconfig语言编写，用来配置packages

必须以BR2_PACKAGE_<PACKAGE>开头

Config.in 是层级结构package/<pkg>/Config.in都被包含在package/Config.in

menuconfig中层级目录由menu来嵌套定义

menu "Base System"
source "$BR2_EXTERNAL_platform_PATH/package/example/Config.in"
source "$BR2_EXTERNAL_platform_PATH/package/fstools/Config.in"
endmenu

menu "Test Package"
source "$BR2_EXTERNAL_platform_PATH/package/foobar/Config.in"
endmenu

// Test Package在Base System下一级目录
menu "Base System"
menu "Test Package"
endmenu
endmenu

if/endif

choice/endchoice

select、depends on

select是一种自动依赖，如果A select B，只要A被enable，B就会被enable，而且不可unselected

depends on是一种用户定义的依赖，如果A depends on B, A只有在B被enable后才可见

  • make \<pkg\>-show-depend: 查看pkg依赖的包
  • make \<pkg\>-show-rdepend: 查看依赖pkg的包

.mk文件

xxx_SITE_METHOD = local
xxx_SITE = 本地源码库地址

xxx_SITE_METHOD = remote
xxx_SITE = 远程URL

Packages可以被安装到不同目录：

  • target目录：$(TARGET_DIR)
  • staging目录：$(STAGING_DIR)
  • images目录：$(BINARIES_DIR)

分别由三个变量决定：

  • <pkg>_INSTALL_TARGET , defaults to YES. If YES, then <pkg>_INSTALL_TARGET_CMDS will be called
  • <pkg>_INSTALL_STAGING , defaults to NO. If YES, then <pkg>_INSTALL_STAGING_CMDS will be called
  • <pkg>_INSTALL_IMAGES , defaults to NO. If YES, then <pkg>_INSTALL_IMAGES_CMDS will be called

  • Application Package一般只要安装到target
  • Shared library动态库必须安装到target与staging
  • header-based library和static-only library静态库只安装到staging
  • bootloader和linux要安装到images

Config.in文件不规定编译顺序，.mk文件中的<pkg>_DEPENDENCIES可以规定编译顺序，<pkg>_DEPENDENCIES后面的软件包先编译。

参考