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Packaging for kernel-wedge
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This is kernel-wedge, an industrial strength kernel splitting tool. It is used to generate kernel module udebs for the debian installer. To use kernel-wedge, you need a source package, which will become the "source" for the generated udebs. Your source package will be very simple, looking something like this: debian/copyright debian/changelog debian/rules debian/control.stub kernel-versions modules/<arch>/* exclude-packages package-list The second group of files may be placed in a subdirectory, in which case the environment variable $KW_CONFIG_DIR must be set to the subdirectory name. Let's get the easy files out of the way. The changelog is a changelog, like any other, as is the copyright. The debian/rules can be something as simple as this: #!/usr/bin/make -f include /usr/share/kernel-wedge/generic-rules Or you can use the kernel-wedge command directly in your own rules file. Run it for some semblance of usage help. debian/control.stub is the top of a control file. Something like this: Source: linux-kernel-di-i386 Section: debian-installer Priority: optional Maintainer: Debian Install System Team <email@example.com> Build-Depends: kernel-wedge The rest of the control file will be generated for you. The kernel-versions file lists the kernel versions to produce packages for. There are 6 whitespace separated fields per line, and it looks something like this: # arch version flavour installedname suffix build-depends i386 2.4.25-1 386 2.4.25-1-386 - kernel-image-2.4.25-1-386, kernel-pcmcia-modules-2.4.25-1-386 i386 2.4.24 speakup 2.4.24-speakup - kernel-image-2.4.24-speakup In this case we are building two different flavours of i386 kernels. We could just as easily be building kernels for different architectures. The version is the kernel version, or can be "-", in which case a version must be specified when running the gen-control and install-files commands. The installedname column gives the directory/filename that the kernel and modules are installed using in the kernel .deb. If it is "-", it's generated from the version and flavor. The suffix column is either y, - or -$suffix; if it is y then the kernel image inside the udeb will include the version and flavour in its name, if it is -$suffix then it will include this. (So will the System.map). The build-depends are the package that is split up by kernel-wedge. If it's "-", kernel-wedge is being used inside the kernel's source package. Finally, you need a modules/<arch> directory, or directories. These are used to list the modules that go in a kernel. For example, for i386, we want to have some nic drivers, so we create a modules/i386/nic-modules listing them: # My short list of nic modules. 8139too e100 natsemi ne2k-pci tulip winbond-840 3c59x Suppose we want a different set of modules in the speakup flavored kernel. Then create a modules/<arch>-<flavor>/nic-modules instead, it will be used by preference. One udeb will be created for each modules list file, containing the listed modules. The names of the files should match the names of the various modules listed in the package-list file in the default-configuration directory. The default-configuration directory is specified by the environment variable $KW_DEFCONFIG_DIR. You will also want a special modules list file for the kernel-image udeb. If you need to include no modules with your kernel, it can be an empty file. but you should have a modules/<arch>/kernel. kernel-wedge will copy the listed modules into each package. If a listed module does not exist, it will fail by default. Sometimes you might want to make a module be included but it's not fatal for it not to be available. To indicate this, follow the module with a space and a "?". Module list files can also include other module lists by reference. This works similar to cpp includes, and can be used to include module lists distributed as part of kernel-wedge, or others. For example: # kernel-wedge's standard set of cdrom modules #include <cdrom-core-modules> # my own list #include "../../includes/cdrom-modules" The <name> syntax includes a file from the modules subdirectory of the default-configuration directory. A final capability of the module list files is the ability to include a module list and then override parts of it. Follow a module name with " -" to remove it from the list if it was previously listed, as by an include: # kernel-wedge's standard set of cdrom modules #include <cdrom-core-modules> # but not this one sr_mod - The udebs are named with the version of the kernel in their package name, since that can be useful during kernel transitions. The string -di is appended to prevent any posible collisions in names with real debs. A few other, optional files: The package-list file can be used to override and/or suppliment values from kernel-wedge's own /usr/share/kernel-wedge/package-list file. New packages can be defined in this file using the same format, or partial entries can be used to override a field or fields of a previously defined package. For example: # This file is used to build up the control file. The kernel version and # "-di" are appended to the package names. Section can be left out. So can # architecture, which is derived from the files in the modules directory. # It overwrites specifications from /usr/share/kernel-wedge/package-list. Package: fat-modules Priority: standard Package: nic-modules Depends: kernel-image, nic-shared-modules, core-modules, firewire-core-modules Package: other-modules Depends: kernel-image Description: some other modules I like to have in the installer Note that dependencies that are not built are omitted from the control file generated by the union of the package-list files. If you don't want that to happen for a particular dependency, follow it by a "!" Depends: some-third-party-module! The exclude-packages file is an optional file that lists any udebs (by full package name) that would normally be built, but that you want to skip. Building: Once you have your source package set up, run: kernel-wedge gen-control > debian/control You only need to do this once. Then build it like any other package. Be amazed at the sheer quantities of udebs that are spit out with no effort. Note that you will have to have the kernels listed as build dependencies installed normally; but see "kernel-wedge help build-all" for an alternative. Misc other info: The "kernel-wedge copy-modules" command does the actual copying of modules to the temp dirs that are used to build the package. It is complicated by the need to make sure that all of a module's dependencies are included in its package, or in a package on which it depends. If necessary, extra modules will be added to a package to make sure the dependencies are satisfied. The dependency information from modules.dep is compared with the output of the "kernel-wedge gen-deps" command, which extracts dependency information from package-lists, and formats it in a form used by tsort. If any additional modules are needed to meet dependencies of modules in the udebs, they will automatically be added. Since that might result in modules being copied to multiple udebs, the "kernel-wedge find-dups" command is used to scan for duplicates of modules. When you have duplicates, you need to find (or make) a package that both packages depend on, and move the duplicate modules to it. Alternatively, as a quick hack you can just touch a file named ignore-dups in the root of your package and duplicate modules will stop being a fatal error. SOURCEDIR can be set to a directory containing a tree of kernel modules and kernel image, and it will be used instead of the usual tree. That directory will need to have a modules.dep file already generated for this to work though -- but the modules.dep can even be copied from another system and it'll work. This can be useful if you cannot install the required kernel-image package, or are cross-compiling.