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Diffstat (limited to 'HACKING')
| -rw-r--r-- | HACKING | 119 |
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diff --git a/HACKING b/HACKING new file mode 100644 index 0000000000..500d2e3bf0 --- /dev/null +++ b/HACKING @@ -0,0 +1,119 @@ +-*- mode: org; coding: utf-8; -*- + +#+TITLE: Hacking Guix and its incredible distro + +Copyright © 2012 Ludovic Courtès <ludo@gnu.org> + + Copying and distribution of this file, with or without modification, + are permitted in any medium without royalty provided the copyright + notice and this notice are preserved. + + +* Porting the Guix distro on a new platform + +** Introduction + +Unlike Make or similar build tools, Guix requires absolutely /all/ the +dependencies of a build process to be specified. + +For a user-land software distribution, that means that the process that +builds GCC (then used to build all other programs) must itself be +specified; and the process to build the C library to build that GCC; and +the process to build the GCC to build that library; and... See the +problem? Chicken-and-egg. + +To break that cycle, the distro starts from a set of pre-built +binaries–usually referred to as “bootstrap binaries.” These include +statically-linked versions of Guile, GCC, Coreutils, Make, Grep, sed, +etc., and the GNU C Library. + +This section describes how to build those bootstrap binaries when +porting to a new platform. + +** When the platform is supported by Nixpkgs + +In that case, the easiest thing is to bootstrap the distro using +binaries from Nixpkgs. + +To do that, you need to comment out the definitions of +‘%bootstrap-guile’ and ‘%bootstrap-inputs’ in distro/packages/base.scm +to force the use of Nixpkgs derivations. For instance, when porting to +‘i686-linux’, you should redefine these variables along these lines: + +#+BEGIN_SRC scheme + (define %bootstrap-guile + (nixpkgs-derivation "guile" "i686-linux")) + + (define %bootstrap-inputs + (compile-time-value + `(("libc" ,(nixpkgs-derivation "glibc" "i686-linux")) + ,@(map (lambda (name) + (list name (nixpkgs-derivation name "i686-linux"))) + '("gnutar" "gzip" "bzip2" "xz" "patch" + "coreutils" "gnused" "gnugrep" "bash" + "gawk" ; used by `config.status' + "gcc" "binutils"))))) +#+END_SRC + +That should allow the distro to be bootstrapped. + +Then, the tarballs containing the initial binaries of Guile, Coreutils, +GCC, libc, etc. need to be built. To that end, run the following +commands: + +#+BEGIN_SRC sh + ./pre-inst-env guix-build \ + -e '(@@ (distro packages base) %guile-bootstrap-tarball)' \ + --system=i686-linux + + ./pre-inst-env guix-build \ + -e '(@@ (distro packages base) %bootstrap-binaries-tarball)' \ + --system=i686-linux + + ./pre-inst-env guix-build \ + -e '(@@ (distro packages base) %binutils-bootstrap-tarball)' \ + --system=i686-linux + + ./pre-inst-env guix-build \ + -e '(@@ (distro packages base) %glibc-bootstrap-tarball)' \ + --system=i686-linux + + ./pre-inst-env guix-build \ + -e '(@@ (distro packages base) %gcc-bootstrap-tarball)' \ + --system=i686-linux + +#+END_SRC + +These should build tarballs containing statically-linked tools usable on +that system. + +In the source tree, you need to install binaries for ‘mkdir’, ‘bash’, +‘tar’, and ‘xz’ under ‘distro/packages/bootstrap/i686-linux’. These +binaries can be extracted from the static-binaries tarball built above. + +A rule for +‘distro/packages/bootstrap/i686-linux/guile-bootstrap-2.0.6.tar.xz’ +needs to be added in ‘Makefile.am’, with the appropriate hexadecimal +vrepresentation of its SHA256 hash. + +You may then revert your changes to ‘base.scm’. For the variables +‘%bootstrap-coreutils&co’, ‘%bootstrap-binutils’, ‘%bootstrap-glibc’, +and ‘%bootstrap-gcc’, the expected SHA256 of the corresponding tarballs +for ‘i686-linux’ (built above) must be added. + +This should be enough to bootstrap the distro without resorting to +Nixpkgs. + +** When the platform is *not* supported by Nixpkgs + +In that case, the bootstrap binaries should be built using whatever +tools are available on the target platform. That is, the tarballs and +binaries show above must first be built manually, using the available +tools. + +They should have the same properties as those built by the Guix recipes +shown above. For example, all the binaries (except for glibc) must be +statically-linked; the bootstrap Guile must be relocatable (see patch in +the Guix distro); the static-binaries tarball must contain the same +programs (Coreutils, Grep, sed, Awk, etc.); and so on. + |