diff options
| -rw-r--r-- | hurd/building/cross-compiling.mdwn | 87 |
1 files changed, 75 insertions, 12 deletions
diff --git a/hurd/building/cross-compiling.mdwn b/hurd/building/cross-compiling.mdwn index 8c8d0625..edde4400 100644 --- a/hurd/building/cross-compiling.mdwn +++ b/hurd/building/cross-compiling.mdwn @@ -18,16 +18,12 @@ For now, find the shell scripts at ## Using -Read through it. Understand it. Then use it. +Read through it. Understand it. Only then use it by following the next steps. /!\ Be made aware that -- while it is of course possible to build a working -cross-compiler -- this is not trivial to do. You'll have to patch several of -the source packages. See the corresponding Debian unstable source packages -about which Hurd-specific patches exist and check which of them are not yet in -the upstream source packages. Not all of the patches from the Debian packages -are needed for getting a functional tool chain, though. Applying patches is -definitely needed for the glibc, Hurd and GCC source packages, as there are a -bunch of outstanding patches that are needed for getting a functional build. +cross-compiler -- this is not trivial to do. You'll have to patch source +packages. See the following list about needed patches, which have not yet been +installed in the upstream repositories. ### Supported Versions of Source Packages @@ -66,10 +62,6 @@ guarantee is given. Always the preferred version is listed first. TODO. patches: libiberty (?!), config. - For building recent version of GCC (e.g., the upcoming 4.3) you'll need to - have development packages of GMP and MPFR (for the *build* system) - installed. - --> * `src/gnumach`: [GNU Mach](http://hurd.gnu.org/) @@ -138,6 +130,77 @@ guarantee is given. Always the preferred version is listed first. --> +### Preparation + +Unpack the tarballs if you downloaded any. + +Create a directory where the cross build shall be rooted in and a `src` +subdirectory in there. Then create symbolic links for every of the above +packages: from `src/PACKAGE` to where you stored or unpacked it. If you don't +intend to build several cross compilers or use the source trees otherwise, you +can also directly store the source trees in `src/`. The source trees can be +shared between multiple cross build trees since the packages' build systems are +supposed not to modify the files in the source trees. Not all packages adhere +to that, but they fail to do so only for pre-processed documentation, etc. + +Either make sure that `cross-gnu-env` and `cross-gnu` are found in `$PATH` +(`~/bin/`, for example) or alternatively remember to use their full paths in +the following. + +The system you're running the script on (the *build* system) needs to have a +basic compiling environment installed, i.e., a C compiler with the basic +libraries and `make`. You might also need `flex` and `bison`. For building +recent version of GCC (e.g., the upcoming 4.3, which is not yet supported) +you'll need to have development packages of GMP and MPFR installed. + + +### Setting Up the Environment + +Do this every time you intend to use the cross compiler: + + $ ROOT=to/the/cross/build/root + $ . cross-gnu-env + +This will set several environment variables, which are later used by (a) the +`cross-gnu` script and (b) by you, the user of the cross compiler. `$TARGET` +will be set by the script, `$PATH` will be adjusted, etc. See the +`cross-gnu-env` file for all environment variables that are set, as well as +their default values. `$ROOT` will be made an absolute path if it isn't +already. + +Later, you'll be able to do things like `../configure --host="$TARGET"` and the +cross compiler will be found automatically. + + +### Creating the Cross Build Environment + +After setting up the environemt, just run `cross-gnu` and watch the messages +flow by. In the end you should see a message: *[...]/cross-gnu: Everything +should be in place now.* + + +### Staying Up-To-Date + +You can re-run `cross-gnu` to rebuild the parts of the sources that have +changed since the last run. This will save a lot of time compared to starting +from scratch again. Also, it is especially useful if you aren't working with +unpacked tarballs, but on CVS's branches or want to quickly get a new tool +chain with patches you applied to the source trees. However: do *not* use this +technique when doing major changes to the source trees, like switching from GCC +4.0 to GCC 4.1. + + +#### Comment + +Unfortunately the GNU Automake build system (which is used by GNU Mach's +`gnumach-1-branch`) will overwrite installed files (header files in this case +here), even if they didn't change. And because all packages' build systems are +using dependency tracking, a lot of files will be rebuilt each time `cross-gnu` +is re-run, even if the files themselves didn't change. Talk to [[tschwinge]] +if you want to work on fixing that -- it is already clear what needs to be +done, it just hasn't been done yet. + + # References * <http://lists.gnu.org/archive/html/bug-hurd/2004-09/msg00030.html> |