Checklist for uploaders ======================= There is a checklist in the kernel-team.git repository; see . Updating the upstream source ============================ In addition to the build-dependencies, you will need the rsync package installed. 1) Run: ./debian/bin/genorig.py where is a local or remote git repository with the upstream release tag in it. If you do not have a local repository, use the appropriate one of: * https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git * https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git * git://kernel.ubuntu.com/ubuntu/linux.git This will produce ../orig/linux_.orig.tar.xz (e.g. linux_3.5~rc1.orig.tar.xz). It involves deleting files for DFSG compliance, as listed in the Files-Excluded field in debian/copyright. 2) Run: make -f debian/rules orig This will apply the main quilt series to the upstream source, which will usually fail due to conflicts with upstream changes. You need to resolve those by dropping or refreshing patches. Recording updates in the changelog ---------------------------------- Upstream commits that we already cherry-picked and included in a previous package upload should not be mentioned, since they don't make any difference to the package. Any other commits that fix a Debian bug report and/or a security issue with a CVE ID should always be listed, along with the (Closes: #nnnnnn) and/or (CVE-yyyy-nnnn) reference. Aside from those general rules: * For an upstream release candidate, don't attempt to list the changes * For a stable release by Linus, refer to the summary at kernelnewbies.org, e.g. https://kernelnewbies.org/Linux_4.5 * For a stable update, refer to the changelog on kernel.org, e.g. https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.5.1, and list all changes that are relevant to our package and that fix bugs that we would consider 'important' or higher severity - The script debian/bin/stable-update updates the changelog version and inserts the list of changes. It doesn't attempt to filter out irrelevant or unimportant changes. - If you have time, please delete irrelevant changes such as: + Fixes for architectures not supported by the package + Fixes for drivers that aren't enabled in any of our configurations + Build fixes for configurations that we don't use + Fixes for lockdep false positives If you have time, please add bracketted prefixes to the upstream change list as described below under "Changelog conventions". Applying patches to the Debian kernel tree ========================================== The Debian kernel packaging uses the quilt patch system, but with multiple series to allow for featuresets. Patches are stored below debian/patches, loosely sorted in bugfix/, features/ and debian/. Patches are in the standard kernel patch format (unified diff to be applied with patch -p1) and generally have DEP-3 headers. For each optional featureset there is an additional patch directory debian/patches-. If you want to generate a source tree with all patches applied, run make -f debian/rules source The resulting source can be found below debian/build. Changelog conventions ===================== If a change only affects some architectures, flavours or featuresets, this should be noted with a bracketted prefix on the changelog line: * [] Change to featureset * [] Change that affects Debian architecture * [,...] Change that affects Debian architectures , , ... * [/] Change that affects kernel flavour on Debian architecture * [/{,...}] Change that affects kernel flavours , , ... on Debian architecture You can use wildcards to cover multiple values, e.g. 'arm*' for armel, armhf and arm64 architectures. Also 'x86' is used to cover the Debian architectures amd64, i386 and x32. Kernel config files =================== Each kernel configuration file is constructed dynamically from a number of files under debian/config and (if it exists) debian/config.local. They are read in the following order, such that files later on the list can override settings from earlier files. Files in debian/config.local can also override settings from the corresponding file in debian/config. 1. Common: - Default filename: config - Filename list: [build.config] 2. Per kernel architecture: - Default filename: kernelarch-/config - Filename list: [kernelarch.build.config] 3. Per Debian architecture: - Default filename: /config - Filename list: [kernelarch.debianarch.build.config] 4. Per Debian architecture and flavour: - Default filename: /config. - Filename list: [kernelarch.debianarch.flavour.build.config] 5. Per featureset: - Default filename: featureset-/config - Filename list: [featureset.build.config] 6. Per Debian architecture and featureset: - Default filename: //config - Filename list: [kernelarch.debianarch.featureset.build.config] 7. Per Debian architecture, featureset, and flavour: - Default filename: //config. - Filename list: [kernelarch.debianarch.featureset.flavour.build.config] You can check the final list of configuration files by reading debian/rules.gen. Each binary-arch____image rule passes the list to debian/rules.real as the KCONFIG variable. These files should be kept in order using the kconfigeditor2 utility from . With this source package as your working directory, run: debian/rules source .../kernel-team/utils/kconfigeditor2/process.py . This will also warn about any symbols that no longer exist, or cannot be explicitly configured. Control file ============ The master control file debian/control must be generated before the package is uploaded. debian/rules contains various targets to facilitate this task: debian/control Generates the control file by invoking the debian/bin/gencontrol.py script, which combines the templates from the templates directory and architecture-specific defines.toml file to produce the debian/control file. Note that this target is intentionally made to fail with a non-zero exit code to make sure that it is never run during an automatic build. orig Populate the current directory with all files from the unpacked upstream tarball in ../orig/linux_${ver} and apply the Debian quilt patch stack. clean-generated Clean up all auto-generated files inside the ./debian directory maintainerclean What clean-generated does and additionally also cleans up all files other than the ./debian and ./.git directories. The following variables are substituted into the templates: @version@ Upstream kernel version, for example 2.6.11. @arch@ The Debian arch name, such as powerpc or i386. @flavour@ The build flavour, such as 686 or k7-smp. @class@ The CPU/architecture class; displayed in synopsis. It should be fairly short, as the synopsis is supposed to be <80 chars. It should be in the form "foo class", and will show up in the description as "foo class machines". @longclass@ The CPU/architecture class; displayed in the extended description. The same rules apply as in @class@. If this is unset, it will default to @class@. @desc@ (Potentially) multi-line verbiage that's appended to -image descriptions. Normally, the arch-specific contents should be controlled by adjusting the corresponding defines.toml file. Build-dependencies that relate to specific binary packages can be specified in a Build-Depends field in the template for that binary package. gencontrol.py will append the value to the source package's Build-Depends-Arch or Build-Depends-Indep field, as appropriate. It will also use the binary package's Architecture and Build-Profile as the architecture-qualification and/or restriction for each build- dependency that doesn't already have them. TODO: - Patches applied to the upstream source - How to define a flavour - More detail on generation of debian/control and configs Running tests ============= linux supports autopkgtest and should be able to run most of the kernel's self-tests on any architecture where kexec is supported, but it has higher resource requirements than most packages: - A VM with plenty of disk space (10GB is enough), RAM (1GB is probably enough) and at least 2 CPUs - The temporary directory for adt-virt-qemu (-o option) will need several GB of space, so a tmpfs may not be suitable Note that if you tell adt-run to use an 'unbuilt tree' (i.e. an unpacked source package) it does not exclude VCS directories such as .git. Either use a packed source package or copy the working tree elsewhere excluding .git. Example invocation: adt-run -B ../linux-image-4.2.0-rc6-amd64_4.2~rc6-1~exp2_amd64.deb \ ../linux_4.2~rc6-1~exp2.dsc \ --timeout-test=1200 \ --- adt-virt-qemu /var/cache/autopkgtest/adt-sid.img -o /var/tmp -c 2 Build profiles ============== Several build profiles are understood and supported: - nodoc: Exclude most documentation - noudeb: Exclude installer udeb packages - pkg.linux.notools: Exclude userland tool packages (linux-kbuild-, linux-perf, etc.) - pkg.linux.mintools: Build minimal set of userland tool packages (linux-kbuild-) - pkg.linux.nokernel: Exclude kernel image and header packages - pkg.linux.nokerneldbg: Exclude kernel debug packages - pkg.linux.nokerneldbginfo: Build kernel without debug symbols (also disables BTF) - pkg.linux.nosource: Exclude source binary package (linux-source-) - cross: Needed when cross-building. - nopython: Disable Python bindings. This currently disables building the linux-perf- package, as the perf program embeds Python. - pkg.linux.nometa: Exclude most meta-packages. The linux-headers-*-all* packages can still be built. - pkg.linux.quick: Perform a limited build that should provide good coverage yet be quick enough for use in CI. Build rules =========== The Debian build rules are split across multiple makefiles: - debian/rules: Standard top-level makefile for Debian package build. - debian/rules.gen: Intermediate makefile between debian/rules and debian/rules.real. This is generated by gencontrol.py based on the configuration under debian/config. - debian/rules.real: Makefile for building a single kernel flavour or other group of binary packages. - debian/rules.d: Makefiles for building userland code from specific source directories. The directory structure mirrors the kernel source directories. debian/rules.real uses the "make-tools" to invoke these makefiles. All builds *must* be done out-of-tree in a subdirectory of debian/build, so that the output files do not end up in the linux-source- binary package. Currently kernel builds use debian/build/build___, userland code uses debian/build/build-tools/ and documentation uses debian/build/build-doc. Code signing ============ The kernel image and modules may be signed after building, to support a Secure Boot or Trusted Boot policy. In Debian, this is performed by a "code signing service" that is separate from the normal package build process. The initial package build generates binary packages named linux-image--signed-template, that contain a source package template and metadata about the files to be signed. The code signing service will download this and the linux-image packages to be signed. It will add detached signatures to the source package, then upload it (without ever running debian/rules). The source package template is generated by debian/bin/gencontrol_signed.py and debian/rules.real with files from debian/signing_templates and debian/templates. To test changes to these: 1. Build the linux source package. 2. Generate the signed source package by running the script "debian-test-sign" from the kernel-team.git repository. It is also possible to set up a development configuration of the official code signing service, but this is more complicated. 3. Build the signed source package.