5e84b8b73c
The new skeleton of the manual as it has been thought:
1. About Buildroot:
Presentation of Buildroot
2. Starting up:
Everything to quickly and easily start working with Buildroot
3. Working with Buildroot
Basics to make your work fitting your needs
4. Troubleshooting
5. Going further in Buildroot's innards
Explaination of how buildroot is organised, how it works, etc
6. Developer Guidelines
7. Getting involved
8. Contibuting to Buildroot
9. Legal notice
10. Appendix
It is easy to distinguish two parts in this plan:
- Sections 1 to 4 mainly address people starting with Buildroot
- Sections 5 to 10 are more focused on how to develop Buildroot itself
Most of the existing sections have just been moved in the hierarchy,
few were split and dispatch in, what i think was the relevant section,
and numerous others have been created.
Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
62 lines
2.5 KiB
Plaintext
62 lines
2.5 KiB
Plaintext
// -*- mode:doc; -*-
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How Buildroot works
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-------------------
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As mentioned above, Buildroot is basically a set of Makefiles that
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download, configure, and compile software with the correct options. It
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also includes patches for various software packages - mainly the ones
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involved in the cross-compilation tool chain (+gcc+, +binutils+ and
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+uClibc+).
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There is basically one Makefile per software package, and they are
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named with the +.mk+ extension. Makefiles are split into three main
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sections:
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* *toolchain* (in the +toolchain/+ directory) contains the Makefiles
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and associated files for all software related to the
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cross-compilation toolchain: +binutils+, +gcc+, +gdb+,
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+kernel-headers+ and +uClibc+.
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* *package* (in the +package/+ directory) contains the Makefiles and
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associated files for all user-space tools that Buildroot can compile
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and add to the target root filesystem. There is one sub-directory
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per tool.
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* *target* (in the +target+ directory) contains the Makefiles and
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associated files for software related to the generation of the
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target root filesystem image. Four types of filesystems are
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supported: ext2, jffs2, cramfs and squashfs. For each of them there
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is a sub-directory with the required files. There is also a
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+default/+ directory that contains the target filesystem skeleton.
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Each directory contains at least 2 files:
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* +something.mk+ is the Makefile that downloads, configures,
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compiles and installs the package +something+.
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* +Config.in+ is a part of the configuration tool
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description file. It describes the options related to the
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package.
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The main Makefile performs the following steps (once the
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configuration is done):
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* Create all the output directories: +staging+, +target+, +build+,
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+stamps+, etc. in the output directory (+output/+ by default,
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another value can be specified using +O=+)
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* Generate all the targets listed in the +BASE_TARGETS+ variable. When
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an internal toolchain is used, this means generating the
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cross-compilation toolchain. When an external toolchain is used,
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this means checking the features of the external toolchain and
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importing it into the Buildroot environment.
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* Generate all the targets listed in the +TARGETS+ variable. This
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variable is filled by all the individual components'
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Makefiles. Generating these targets will trigger the compilation of
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the userspace packages (libraries, programs), the kernel, the
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bootloader and the generation of the root filesystem images,
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depending on the configuration.
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