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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:22:56 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:22:56 +0000 |
commit | 3f472a4e5ca21e3ddb13737473e636b2b11a408a (patch) | |
tree | 7db1ab317884b9f6e04b6e13737c1679879cb97a /debian/README.maintainers | |
parent | Adding upstream version 13.2.0. (diff) | |
download | gcc-13-debian.tar.xz gcc-13-debian.zip |
Adding debian version 13.2.0-10.debian/13.2.0-10debian
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'debian/README.maintainers')
-rw-r--r-- | debian/README.maintainers | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/debian/README.maintainers b/debian/README.maintainers new file mode 100644 index 0000000..9240455 --- /dev/null +++ b/debian/README.maintainers @@ -0,0 +1,190 @@ +-*- Outline -*- + +Read this file if you are a Debian Developer or would like to become +one, or if you would like to create your own binary packages of GCC. + +* Overview + +From the GCC sources, Debian currently builds 3 source packages and +almost 100 binary packages, using a single set of build scripts. The +3 source packages are: + +gcc-x.y: C, C++, Fortran, Objective-C and Objective-C++, plus many + common libraries like libssp and libgcc. +gnat-x.y: Ada. + +The way we do this is quite peculiar, so listen up :) + +When we build from the gcc-x.y source package, we produce, among many +others, a gcc-x.y-source binary package that contains the pristine +upstream tarball and some Debian-specific patches. Any user can then +install this package on their Debian system, and will have the full +souces in /usr/src/gcc-x.y/gcc-<timestamp>.tar.bz2, along with the +Makefile snippets that unpack and patch them. + +The intended use for this package is twofold: (a) allow users to build +their own cross-compilers, and (b) build the other packages like +gnat-x.y. + +- gcc-x.y requires only a C compiler to build and produces C, C++, + Fortran, Go and Objective-C compilers and libraries. It also + produces the binary package gcc-x.y-source containing all the + sources and patches in a tarball. + +- gnat-x.y build-depends on gcc-x.y-source and an Ada compiler. It + does not even have an .orig.tar.bz2 package; it is a Debian native + package. + +The benefits of this split are many: + +- bootstrapping a subset of languages is much faster than + bootstrapping all languages and libraries (which can take a full + week on slow architectures like mips or arm) + +- the language maintainers don't have to wait for each other + +- for new ports, the absence of a port of, say, gnat-x.y does not + block the porting of gcc-x.y. + +gcc-x.y-source is also intended for interested users to build +cross-compiler packages. Debian cannot provide all possible +cross-compiler packages (i.e. all possible host, target, language and +library combinations), so instead tries to facilitate building them. + +* The build sequence + +As for all other Debian packages, you build GCC by calling +debian/rules. + +The first thing debian/rules does it to look at the top-most entry in +debian/changelog: this tells it which source package it is building. +For example, if the first entry in debian/changelog reads: + +gnat-6 (6.2.0-1) unstable; urgency=low + + * Upload as gnat-6. + + -- Ludovic Brenta <lbrenta@debian.org> Tue, 26 Jun 2007 00:26:42 +0200 + +then, debian/rules will build only the gnat binary packages. + +The second step is to build debian/control from debian/control.m4 and +a complex set of rules specified in debian/rules.conf. The resulting +control file contains only the binary packages to be built. + +The third step is to select which patches to apply (this is done in +debian/rules.defs), and then to apply the selected patches (see +debian/rules.patch). The result of this step is a generated +debian/patches/series file for use by quilt. + +The fourth step is to unpack the GCC source tarball. This tarball is +either in the build directory (when building gcc-x.y), or in +/usr/src/gcc-x.y/gcc-x.y.z.tar.xz (when building the other source +packages). + +The fifth step is to apply all patches to the unpacked sources with +quilt. + +The sixth step is to create a "build" directory, cd into it, call +../src/configure, and bootstrap the compiler and libraries selected. +This is in debian/rules2. + +The seventh step is to call "make install" in the build directory: +this installs the compiler and libraries into debian/tmp +(i.e. debian/tmp/usr/bin/gcc, etc.) + +The eighth step is to run the GCC test suite. This actually takes at +least as much time as bootstrapping, and you can disable it by setting +WITHOUT_CHECK to "yes" in the environment. + +The ninth step is to build the binary packages, i.e. the .debs. This +is done by a set of language- and architecture-dependent Makefile +snippets in the debian/rules.d/ directory, which move files from the +debian/tmp tree to the debian/<package> trees. + +* Making your own packages + +In this example, we will build our own gnat-x.y package. + +1) Install gcc-x.y-source, which contains the real sources: + +# aptitude install gcc-x.y-source + +2) Create a build directory: + +$ mkdir gnat-x.y-x.y.z; cd gnat-x.y-x.y.z + +3) Checkout from Subversion: + +$ svn checkout svn://svn.debian.org/gcccvs/branches/sid/gcc-x.y/debian + +4) Edit the debian/changelog file, adding a new entry at the top that + starts with "gnat-x.y". + +5) Generate the debian/control file, adjusted for gnat: + +$ debian/rules control + +8) Build: + +$ dpkg-buildpackage + +* Hints + +You need a powerful machine to build GCC. The larger, the better. +The build scripts take advantage of as many CPU threads as are +available in your box (for example: 2 threads on a dual-core amd64; 4 +threads on a dual-core POWER5; 32 threads on an 8-core UltraSPARC T1, +etc.). + +If you have 2 GB or more of physical RAM, you can achieve maximum +performance by building in a tmpfs, like this: + +1) as root, create the new tmpfs: + +# mount -t tmpfs -o size=1280m none /home/lbrenta/src/debian/ram + +By default, the tmpfs will be limited to half your physical RAM. The +beauty of it is that it only consumes as much physical RAM as +necessary to hold the files in it; deleting files frees up RAM. + +2) As your regular user, create the working directory in the tmpfs + +$ cp --archive ~/src/debian/gcc-x.y-x.y.z ~/src/debian/ram + +3) Build in there. On my dual-core, 2 GHz amd64, it takes 34 minutes + to build gnat, and the tmpfs takes 992 MiB of physical RAM but + exceeds 1 GiB during the build. + +Note that the build process uses a lot of temporary files. Your $TEMP +directory should therefore also be in a ram disk. You can achieve +that either by mounting it as tmpfs, or by setting TEMP to point to +~/src/debian/ram. + +Also note that each thread in your processor(s) will run a compiler in +it and use up RAM. Therefore your physical memory should be: + +Physical_RAM >= 1.2 + 0.4 * Threads (in GiB) + +(this is an estimate; your mileage may vary). If you have less +physical RAM than recommended, reduce the number of threads allocated +to the build process, or do not use a tmpfs to build. + +* Patching GCC + +Debian applies a large number of patches to GCC as part of the build +process. It uses quilt but the necessary debian/patches/series is not +part of the packaging scripts; instead, "debian/rules patch" generates +this file by looking at debian/control (which is itself generated!), +debian/changelog and other files. Then it applies all the patches. +At this point, you can use quilt as usual: + +$ cd ~/src/debian/gcc-x.y +$ export QUILT_PATCHES=$PWD/debian/patches +$ quilt series + +If you add new patches, remember to add them to the version control +system too. + +-- +Ludovic Brenta, 2012-04-02. |