PBS is the Platform Build System. It is a set of scripts that automatically builds a defined set of software packages that can be installed in a root filesystem or as an initial ramdisk.
PBS builds everything from source. To do this, it downloads software tarballs from the internet and runs the contained build system to configure, build and install each package.
Note: For a quickstart with step by step guidance please see this HowTo.
The source tree contains the following directories:
- Documentation: This should be your starting point.
- arch: Architecture-specific definitions.
- checksums: Checksum files to verify downloaded files against.
- configs: Platform configuration files.
- download: Destination directory for downloaded files.
- packages: Package build scripts.
- platforms: Platform build scripts.
- scripts: PBS-related scripts and makefiles.
- support: Miscellaneous support files.
- toolchains: Cross-compilation toolchains (deprecated).
In order to keep this tree clean, platforms should be built in separate build directories. Typically, such a build directory would reside below the build subdirectory in the source tree. We recommend to use the following scheme.
build/<platform>
By passing the path (absolute or relative) to the build directory in the "O" (output) variable, the PBS will know where to put temporary files.
A platform is a collection of packages and some additional files and scripts to complete the filesystem. For more informations please see: Platforms
A package is any software component that can be built in an automated way. For more informations please see: Packages
To build a platform you need a toolchain. PBS Stage 1 is able to provide toolchains for various architectures. See its README for details.
But you can also use an external toolchain, for instance a toolchain provided by your distribution. To use such a toolchain you have to update your pbs.mk file. See User-configuration for more details.
The recommended way to setup and configure a platform is to use a platform defconfig. These files are located under /configs. These defconfigs contain the toolchain to use, the kernel configuration and a packages selections for this package for this platform.
$ make O=<build directory> PLATFORM=<platform-vendor> <platform>_defconfig
If you like to change a the platform settings or create a new platform this can be done with the following command:
$ make O=<build directory> menuconfig
When this command executes, it shows a dialog where the target hardware can be configured and individual packages be selected for later inclusion in the root filesystem.
PBS uses Kconfig to allow easy selection of software packages that are to be built. Based on this configuration it generates a dependency list to make sure that packets are built in the correct order.
Build a platform is done with the following command:
$ make O=<build directory>
Where is the directory where you already ran the menuconfig command or used a default platform configuration.
Once the build is completed, you need to generate the target filesystem. The most common targets are:
$ fakeroot make O=<build directory> initrd
(outputs <build directory>/uImage, uboot image)
and
$ fakeroot make O=<build directory> rootfs
(outputs <build directory>/rootfs.img, compressed squashfs)
This will pack all relevant files into a single compressed file, to be used by the bootloader or later by the kernel. This process will exclude all development and documentation files from the target filesystem to save space.
NOTE: If you set INITRD_MOUNT_TMPFS=y or ROOTFS_MOUNT_TMPFS=y you will need superuser permissions (sudo).
For more details regarding the build process please refer to:
General requirements:
-
automake, autoconf, gcc, make, quilt, bash, fakeroot
-
ncurses-devel (menuconfig)
-
expat-devel (build-tools/dbus)
-
zlib-devel (build-tools/glib)
-
libffi-devel (build-tools/glib)
-
libpng-devel (build-tools/gdk-pixbuf)
-
perl-XML-Simple (build-tools/icon-naming-utils)
- Ubuntu: libxml-simple-perl
Programs used to generate documentation during package creation:
- texinfo
- xmlto
Libraries and tools required during platform setup:
- gperf (core/udev - uclibc toolchain)
- luadoc (wm/awesome)
- ImageMagick (wm/awesome)
- Ubuntu: imagemagick
- docbook-utils (net/tunctl)