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diff --git a/docs/manual/customize-store.txt b/docs/manual/customize-store.txt new file mode 100644 index 000000000..b6e3d0813 --- /dev/null +++ b/docs/manual/customize-store.txt @@ -0,0 +1,160 @@ +// -*- mode:doc -*- + +[[customize-store]] +Storing the configuration +------------------------- + +When you have a buildroot configuration that you are satisfied with and +you want to share it with others, put it under revision control or move +on to a different buildroot project, you need to store the configuration +so it can be rebuilt later. The configuration that needs to be stored +consists of the buildroot configuration, the configuration files for +packages that you use (kernel, busybox, uClibc, ...), and your rootfs +modifications. + +Basics for storing the configuration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +[[customize-store-basics]] + +Buildroot configuration +^^^^^^^^^^^^^^^^^^^^^^^ + +For storing the buildroot configuration itself, buildroot offers the +following command: +make savedefconfig+ + +This strips the buildroot configuration down by removing configuration +options that are at their default value. The result is stored in a file +called +defconfig+. Copy this file to +foo_defconfig+ in the +configs+ +directory. The configuration can then be rebuilt by running ++make foo_defconfig+ + +Alternatively, you can copy the file to any other place and rebuild with ++make defconfig BR2_DEFCONFIG=<path-to-defconfig-file>+. + + +Other package configuration +^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The configuration files for busybox, the linux kernel, barebox, uClibc and +crosstool-NG should be stored as well if changed. For each of these, a +buildroot configuration option exists to point to an input configuration +file, e.g. +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+. To save their +configuration, set those configuration options to a path outside +your output directory, e.g. +board/<manufacturer>/<boardname>/linux.config+. +Then, copy the configuration files to that path. + +Make sure that you create a configuration file 'before' changing +the +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+ etc. options. Otherwise, +buildroot will try to access this config file, which doesn't exist +yet, and will fail. You can create the configuration file by running ++make linux-menuconfig+ etc. + +Buildroot provides a few helper targets to make the saving of +configuration files easier. + +* +make linux-update-defconfig+ saves the linux configuration to the + path specified by +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+. It + simplifies the config file by removing default values. However, + this only works with kernels starting from 2.6.33. For earlier + kernels, use +make linux-update-config+. +* +make busybox-update-config+ saves the busybox configuration to the + path specified by +BR2_PACKAGE_BUSYBOX_CONFIG+. +* +make uclibc-update-config+ saves the uClibc configuration to the + path specified by +BR2_UCLIBC_CONFIG+. +* +make barebox-update-defconfig+ saves the barebox configuration to the + path specified by +BR2_TARGET_BAREBOX_CUSTOM_CONFIG_FILE+. +* For crosstool-NG and at91bootstrap3, no helper exists so you + have to copy the config file manually to +BR2_TOOLCHAIN_CTNG_CONFIG+, + resp. +BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_CONFIG_FILE+. + + +Creating your own board support +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Creating your own board support in Buildroot allows users of a +particular hardware platform to easily build a system that is known to +work. + +To do so, you need to create a normal Buildroot configuration that +builds a basic system for the hardware: toolchain, kernel, bootloader, +filesystem and a simple Busybox-only userspace. No specific package +should be selected: the configuration should be as minimal as +possible, and should only build a working basic Busybox system for the +target platform. You can of course use more complicated configurations +for your internal projects, but the Buildroot project will only +integrate basic board configurations. This is because package +selections are highly application-specific. + +Once you have a known working configuration, run +make +savedefconfig+. This will generate a minimal +defconfig+ file at the +root of the Buildroot source tree. Move this file into the +configs/+ +directory, and rename it +<boardname>_defconfig+. + +It is recommended to use as much as possible upstream versions of the +Linux kernel and bootloaders, and to use as much as possible default +kernel and bootloader configurations. If they are incorrect for your +board, or no default exists, we encourage you to send fixes to the +corresponding upstream projects. + +However, in the mean time, you may want to store kernel or bootloader +configuration or patches specific to your target platform. To do so, +create a directory +board/<manufacturer>+ and a subdirectory ++board/<manufacturer>/<boardname>+. You can then store your patches +and configurations in these directories, and reference them from the main +Buildroot configuration. + + +Step-by-step instructions for storing configuration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +To store the configuration for a specific product, device or +application, it is advisable to use the same conventions as for the +board support: put the buildroot defconfig in the +configs+ directory, +and any other files in a subdirectory of the +boards+ directory. This +section gives step-by-step instructions about how to do that. Of course, +you can skip the steps that are not relevant for your use case. + +1. +make menuconfig+ to configure toolchain, packages and kernel. +1. +make linux-menuconfig+ to update the kernel config, similar for + other configuration. +1. +mkdir -p board/<manufacturer>/<boardname>+ +1. Set the following options to +board/<manufacturer>/<boardname>/<package>.config+ + (as far as they are relevant): + * +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+ + * +BR2_PACKAGE_BUSYBOX_CONFIG+ + * +BR2_TOOLCHAIN_CTNG_CONFIG+ + * +BR2_UCLIBC_CONFIG+ + * +BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_CONFIG_FILE+ + * +BR2_TARGET_BAREBOX_CUSTOM_CONFIG_FILE+ +1. Write the configuration files: + * +make linux-update-defconfig+ + * +make busybox-update-config+ + * +cp <output>/build/build-toolchain/.config board/<manufacturer>/<boardname>/ctng.config+ + * +make uclibc-update-config+ + * +cp <output>/build/at91bootstrap3-*/.config board/<manufacturer>/<boardname>/at91bootstrap3.config+ + * +make barebox-update-defconfig+ +1. Create +board/<manufacturer>/<boardname>/fs-overlay/+ and fill it + with additional files you need on your rootfs, e.g. + +board/<manufacturer>/<boardname>/fs-overlay/etc/inittab+. +1. Create a post-build script + +board/<manufacturer>/<boardname>/post-build.sh+. It should contain + the following command: ++ +------------ +rsync -a --exclude .empty --exclude '*~' ${0%/*}/fs-overlay $1 +------------ ++ +1. Set +BR2_ROOTFS_POST_BUILD_SCRIPT+ to +board/<manufacturer>/<boardname>/post-build.sh+ +1. If additional setuid permissions have to be set or device nodes have + to be created, create +board/<manufacturer>/<boardname>/device_table.txt+ + and add that path to +BR2_ROOTFS_DEVICE_TABLE+. +1. +make savedefconfig+ to save the buildroot configuration. +1. +cp defconfig configs/<boardname>_defconfig+ +1. To add patches to the linux build, set +BR2_LINUX_KERNEL_PATCH+ to + +board/<manufacturer>/<boardname>/patches/linux/+ and add your + patches in that directory. Each patch should be called + +linux-<num>-<description>.patch+. Similar for U-Boot, barebox, + at91bootstrap and at91bootstrap3. +1. If you need modifications to other packages, or if you need to add + packages, do that directly in the +packages/+ directory, following the + instructions in xref:adding-packages[]. |