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Diffstat (limited to 'docs/manual/customize-outside-br.txt')
| -rw-r--r-- | docs/manual/customize-outside-br.txt | 90 |
1 files changed, 29 insertions, 61 deletions
diff --git a/docs/manual/customize-outside-br.txt b/docs/manual/customize-outside-br.txt index f80ba7044..5fe7b6005 100644 --- a/docs/manual/customize-outside-br.txt +++ b/docs/manual/customize-outside-br.txt @@ -1,30 +1,25 @@ // -*- mode:doc -*- ; [[outside-br-custom]] -=== Keeping customizations outside Buildroot +=== Keeping customizations outside of Buildroot -The Buildroot community recommends and encourages upstreaming to the -official Buildroot version the packages and board support that are -written by developers. However, it is sometimes not possible or -desirable because some of these packages or board support are highly -specific or proprietary. +As already briefly mentioned in xref:customize-dir-structure[], you can +place project-specific customizations in two locations: -In this case, Buildroot users are offered two choices: + * directly within the Buildroot tree, typically maintaining them using + branches in a version control system so that upgrading to a newer + Buildroot release is easy. - * They can add their packages, board support and configuration files - directly within the Buildroot tree, and maintain them by using - branches in a version control system. - - * They can use the +BR2_EXTERNAL+ mechanism, which allows to keep - package recipes, board support and configuration files outside of - the Buildroot tree, while still having them nicely integrated in - the build logic. The following paragraphs give details on how to - use +BR2_EXTERNAL+. + * outside of the Buildroot tree, using the +BR2_EXTERNAL+ mechanism. + This mechanism allows to keep package recipes, board support and + configuration files outside of the Buildroot tree, while still + having them nicely integrated in the build logic. This section + explains how to use +BR2_EXTERNAL+. +BR2_EXTERNAL+ is an environment variable that can be used to point to a directory that contains Buildroot customizations. It can be passed to any Buildroot +make+ invocation. It is automatically saved in the -hidden +.br-external+ file in the output directory. By doing this, +hidden +.br-external+ file in the output directory. Thanks to this, there is no need to pass +BR2_EXTERNAL+ at every +make+ invocation. It can however be changed at any time by passing a new value, and can be removed by passing an empty value. @@ -32,7 +27,7 @@ removed by passing an empty value. *Note:* the +BR2_EXTERNAL+ path can be either an absolute or a relative path, but if it's passed as a relative path, it is important to note that it is interpreted relative to the main Buildroot source directory, *not* -the Buildroot output directory. +to the Buildroot output directory. Some examples: @@ -40,7 +35,7 @@ Some examples: buildroot/ $ make BR2_EXTERNAL=/path/to/foobar menuconfig ----- -Starting from now on, external definitions from the +/path/to/foobar+ +From now on, external definitions from the +/path/to/foobar+ directory will be used: ----- @@ -60,7 +55,7 @@ Or disable the usage of external definitions: buildroot/ $ make BR2_EXTERNAL= xconfig ----- -+BR2_EXTERNAL+ then allows three different things: ++BR2_EXTERNAL+ allows three different things: * One can store all the board-specific configuration files there, such as the kernel configuration, the root filesystem overlay, or @@ -72,63 +67,36 @@ Or disable the usage of external definitions: filesystem overlay), or the +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+ Buildroot option to +$(BR2_EXTERNAL)/board/<boardname>/kernel.config+ (to specify the - location of the kernel configuration file). To achieve this, it is - recommended but not mandatory, to store those details in - directories called +board/<boardname>/+ under +BR2_EXTERNAL+. This - matches the directory structure used within Buildroot. + location of the kernel configuration file). * One can store package recipes (i.e. +Config.in+ and +<packagename>.mk+), or even custom configuration options and make - logic. Buildroot automatically includes +BR2_EXTERNAL/Config.in+ to + logic. Buildroot automatically includes +$(BR2_EXTERNAL)/Config.in+ to make it appear in the top-level configuration menu, and includes - +BR2_EXTERNAL/external.mk+ with the rest of the makefile logic. + +$(BR2_EXTERNAL)/external.mk+ with the rest of the makefile logic. Providing those two files is mandatory, but they can be empty. + The main usage of this is to store package recipes. The recommended - way to do this is to write a +BR2_EXTERNAL/Config.in+ that looks - like: + way to do this is to write a +$(BR2_EXTERNAL)/Config.in+ file that + looks like: + ------ -source "$BR2_EXTERNAL/package/package1/Config.in" -source "$BR2_EXTERNAL/package/package2/Config.in" +source "$BR2_EXTERNAL/package/<boardname>/package1/Config.in" +source "$BR2_EXTERNAL/package/<boardname>/package2/Config.in" ------ + -Then, have a +BR2_EXTERNAL/external.mk+ file that looks like: +Then, have a +$(BR2_EXTERNAL)/external.mk+ file that looks like: + ------ -include $(sort $(wildcard $(BR2_EXTERNAL)/package/*/*.mk)) +include $(sort $(wildcard $(BR2_EXTERNAL)/package/*/*/*.mk)) ------ + -And then in +BR2_EXTERNAL/package/package1+ and - +BR2_EXTERNAL/package/package2+ create normal Buildroot package - recipes, as explained in xref:adding-packages[]. +And then in +$(BR2_EXTERNAL)/package/<boardname>/package1+ and + +$(BR2_EXTERNAL)/package/<boardname>/package2+ create normal Buildroot + package recipes, as explained in xref:adding-packages[]. * One can store Buildroot defconfigs in the +configs+ subdirectory of - +BR2_EXTERNAL+. Buildroot will automatically show them in the + +$(BR2_EXTERNAL)+. Buildroot will automatically show them in the output of +make help+ and allow them to be loaded with the normal +make <name>_defconfig+ command. They will be visible under the - +User-provided configs:+' label in the 'make help' output. - -In the end, a typical +BR2_EXTERNAL+ directory organization would -generally be: - ------ -$(BR2_EXTERNAL)/ -+-- Config.in -+-- external.mk -+-- board/ -| +-- <boardname>/ -| +-- linux.config -| +-- overlay/ -| +-- etc/ -| +-- <some file> -+-- configs/ -| +-- <boardname>_defconfig -+-- package/ - +-- package1/ - | +-- Config.in - | +-- package1.mk - +-- package2/ - +-- Config.in - +-- package2.mk ------- + +User-provided configs+' label in the 'make help' output. |