Table of Contents

Terminology

Buildroot is the tool that we use to build the kernel, kernel modules, user tools, and root file system for our Linux RT machines.

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egumtow@aird-b50-srv01 /scratch/egumtow> mkdir buildroot
egumtow@aird-b50-srv01 /scratch/egumtow> cd buildroot
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot> mkdir buildroot-2019.08-2
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot> cd buildroot-2019.08-2
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2> mkdir host
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2> mkdir download
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2> git clone https://github.com/slaclab/buildroot-site.git site-top
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2> cd site-top
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/site-stop> git checkout origin/br-2019.08
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/site-stop> cd ..
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2> wget https://buildroot.org/downloads/buildroot-2019.08.tar.gz
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2> tar xzvf buildroot-2019.08.tar.gz
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2> mv buildroot-2019.08 buildroot-2019.08-2-x86_64
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2> cd buildroot-2019.08-2-x86_64/
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/buildroot-2019.08-2-x86_64> ln -s ../site-top site
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/buildroot-2019.08-2-x86_64> site/scripts/br-installconf.sh -a x86_64
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/buildroot-2019.08-2-x86_64> make
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/buildroot-2019.08-2-x86_64> ls -l output/images
total 58256
-rw-r--r-- 1 egumtow gu  3796944 Sep 19 16:36 bzImage
-rw-r--r-- 1 egumtow gu 62914560 Sep 19 16:36 rootfs.ext2
-rw-r--r-- 1 egumtow gu 17510981 Sep 19 16:36 rootfs.ext2.gz
drwxr-xr-x 2 egumtow gu     4096 Sep 19 16:34 syslinux/

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• make menuconfig - for configuration changes to buildroot
  • saved to .config
• make linux-menuconfig - for configuration changes to the kernel
  • saved to output/build/linux-<version>/.config
• make busybox-menuconfig - for changes to BusyBox
  • saved to output/build/busybox-<version>/.config

And then subsequently save them (your changes to the config) by running:outside buildroot.  The instructions in the git repo's README give instructions for "make" targets, but I've not had success, I think they don't work.  Instead, for now we can manually copy the config changes to the appropriate locations in the "site" directory.

• make savedefconfig
  • saved to site/br2-external/configs/<architecture>_defconfig
  make savedefconfig
• make linux-update-defconfig
  • saved to output/build/linux-<version>/defconfig
    • MANUALLY save to site/config/linux-<version>-<architecture>.config - note that <architecture> can be "common" if it applies to all architectures
• cp output/build/busybox-<version>/.config site/config/bb-<version>.config

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When you run the "save" commands you are saving the config files to the "site" directory where you will later push them to git.  They will be preserved in git so we don't make the same changes for  the next version of buildroot (artifacts).  The next time (maybe years later) we apply the SLAC customizations, we run the br-installconf.sh script and the changes are applied to buildroot (tool).

Under which config (buildroot, linux, busybox) a config option exists isn't always obvious until you find it.

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After you've made your config file changes and saved the configs, run "make clean" followed by "make".

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egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/buildroot-2019.08-2-x86_64> make clean
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/buildroot-2019.08-2-x86_64> cp output/build/busybox-1.31.0/.config site/config/bb-1.31.0.config
egumtow@aird-b50-srv01 /scratch/egumtow/buildroot/buildroot-2019.08-2/buildroot-2019.08-2-x86_64> make

SLAC properties

There is a SLAC-specific file in the file system skeleton (fs_skeleton).  The file system skeleton exists in the site directory.  The file is at /etc/SLAC_properties.  The syntax is

PROPERTY=value

One property per line.  This file can be read by human users or scripts to determine behavior.  For example, if HAVE_ROOT_PASSWORD is set, then scripts know that if they use "su" then a password is required - the implication being "su" can't be used during the boot process when humans are not involved.

Buildroot documentation

Buildroot has ample documentation.  Be careful that the version of the documentation matches the version your buildroot.  The documentation that you should read comes with the download of buildroot at docs/manual/manual.text.

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