buildrootschalter/docs/manual/customize-configuration.txt
Thomas De Schampheleire 75de9ac6f2 manual/user guide/customization: rework section on storing configuration
This patch promotes the sections on Buildroot configuration and the
configuration of other components to top-level sections, to match the
overview in the introduction of the chapter. The introduction of the
original section is removed as it does not bring additional info anymore.

Some rewording is done as well.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
2014-09-21 19:41:12 +02:00

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// -*- mode:doc; -*-
// vim: set syntax=asciidoc:
[[customize-store-buildroot-config]]
=== Storing the Buildroot configuration
The Buildroot configuration can be stored using the 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+. If you want to save it in another place, change the
+BR2_DEFCONFIG+ option in the Buildroot configuration itself, or call
make with +make savedefconfig BR2_DEFCONFIG=<path-to-defconfig>+.
The recommended place to store this defconfig is
+configs/<boardname>_defconfig+. If you follow this recommendation, the
configuration will be listed in +make help+ and can be set again by
running +make <boardname>_defconfig+.
Alternatively, you can copy the file to any other place and rebuild with
+make defconfig BR2_DEFCONFIG=<path-to-defconfig-file>+.
[[customize-store-package-config]]
=== Storing the configuration of other components
The configuration files for BusyBox, the Linux kernel, Barebox and
uClibc should be stored as well if changed. For each of these
components, a Buildroot configuration option exists to point to an input
configuration file, e.g. +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+. To store
their configuration, set these configuration options to a path where you
want to save the configuration files, and then use the helper targets
described below to actually store the configuration.
As explained in xref:customize-dir-structure[], the recommended path to
store these configuration files is
+board/<company>/<boardname>/foo.config+.
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 at91bootstrap3, no helper exists so you have to copy the config
file manually to +BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_CONFIG_FILE+.