13562ddd2a
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Acked-by: Samuel Martin <s.martin49@gmail.com> Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
113 lines
4.4 KiB
Plaintext
113 lines
4.4 KiB
Plaintext
// -*- mode:doc; -*-
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Using Buildroot
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---------------
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Buildroot has a nice configuration tool similar to the one you can
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find in the http://www.kernel.org/[Linux kernel] or in
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http://www.busybox.net/[Busybox]. Note that you can *and should build
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everything as a normal user*. There is no need to be root to configure
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and use Buildroot. The first step is to run the configuration
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assistant:
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--------------------
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$ make menuconfig
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--------------------
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to run the curses-based configurator, or
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--------------------
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$ make xconfig
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--------------------
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or
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--------------------
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$ make gconfig
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--------------------
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to run the Qt or GTK-based configurators.
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All of these "make" commands will need to build a configuration
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utility (including the interface), so you may need to install
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"development" packages for relevant libraries used by the
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configuration utilities. Check xref:requirement[] to know what
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Buildroot needs, and specifically the xref:requirement-optional[optional requirements]
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to get the dependencies of your favorite interface.
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For each menu entry in the configuration tool, you can find associated
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help that describes the purpose of the entry.
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Once everything is configured, the configuration tool generates a
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+.config+ file that contains the description of your
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configuration. It will be used by the Makefiles to do what's needed.
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Let's go:
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--------------------
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$ make
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--------------------
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You *should never* use +make -jN+ with Buildroot: it does not support
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'top-level parallel make'. Instead, use the +BR2_JLEVEL+ option to
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tell Buildroot to run each package compilation with +make -jN+.
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The `make` command will generally perform the following steps:
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* download source files (as required);
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* configure, build and install the cross-compiling toolchain using the
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appropriate toolchain backend, or simply import an external toolchain;
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* build/install selected target packages;
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* build a kernel image, if selected;
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* build a bootloader image, if selected;
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* create a root filesystem in selected formats.
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Buildroot output is stored in a single directory, +output/+.
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This directory contains several subdirectories:
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* +images/+ where all the images (kernel image, bootloader and root
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filesystem images) are stored.
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* +build/+ where all the components except for the cross-compilation
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toolchain are built (this includes tools needed to run Buildroot on
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the host and packages compiled for the target). The +build/+
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directory contains one subdirectory for each of these components.
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* +staging/+ which contains a hierarchy similar to a root filesystem
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hierarchy. This directory contains the installation of the
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cross-compilation toolchain and all the userspace packages selected
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for the target. However, this directory is 'not' intended to be
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the root filesystem for the target: it contains a lot of development
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files, unstripped binaries and libraries that make it far too big
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for an embedded system. These development files are used to compile
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libraries and applications for the target that depend on other
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libraries.
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* +target/+ which contains 'almost' the complete root filesystem for
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the target: everything needed is present except the device files in
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+/dev/+ (Buildroot can't create them because Buildroot doesn't run
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as root and doesn't want to run as root). Also, it doesn't have the correct
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permissions (e.g. setuid for the busybox binary). Therefore, this directory
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*should not be used on your target*. Instead, you should use one of
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the images built in the +images/+ directory. If you need an
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extracted image of the root filesystem for booting over NFS, then
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use the tarball image generated in +images/+ and extract it as
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root. Compared to +staging/+, +target/+ contains only the files and
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libraries needed to run the selected target applications: the
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development files (headers, etc.) are not present, the binaries are
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stripped.
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* +host/+ contains the installation of tools compiled for the host
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that are needed for the proper execution of Buildroot, including the
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cross-compilation toolchain.
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* +toolchain/+ contains the build directories for the various
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components of the cross-compilation toolchain.
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These commands, +make menuconfig|gconfig|xconfig+ and +make+, are the
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basic ones that allow to easily and quickly generate images fitting
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your needs, with all the supports and applications you enabled.
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More details about the "make" command usage are given in
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xref:make-tips[].
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