# Building [[GNU_Mach|gnumach]] from Source

If you want to build the [[GNU_Mach|gnumach]] kernel yourself instead of just using a
pre-built binary, follow these instructions.

The unpacked source tree is around 20 MiB, and the build tree (with all drivers
enabled) is around 50 MiB.

## Getting the Source Code

You can either use the git repository (see <http://savannah.gnu.org/git/?group=hurd>),

    $ git clone git.savannah.gnu.org:/srv/git/hurd/gnumach.git

... or Debian sources, if you're using Debian. (See [here](http://packages.debian.net/source/unstable/gnumach).)

    $ apt-get source gnumach

Please see the Debian [[running/debian/FAQ]] before using `apt-get source`.

## On Debian Systems:

### Preparing for the Build

Building GNU Mach requires the *build-essential* and *fakeroot* packages, their
dependencies and additional packages that are specified by the source gnumach
package:

    # apt-get install build-essential fakeroot
    # apt-get build-dep gnumach

### Building and Installing ... Debian `.deb` files

Change into the directory with the downloaded / unpacked GNU Mach sources, e.g.

    $ cd gnumach-XXXXXXXX

Start the build process with

    $ dpkg-buildpackage -us -uc -b -rfakeroot

[[GNU_Mach|gnumach]] is now building.  To use the new kernel, you must install the
resulting `.deb` package which is located one directory above the build
directory and has a similar name as the build directory, e.g.

    # dpkg -i ../gnumach_XXXXXXXX-X_hurd-i386.deb

You can now reboot your computer and enjoy the new kernel.

## On non-Debian Systems:

### Preparing for the Build

Building GNU Mach requires a C compiler, a static 32 bit standard C library and
your favourite flavor of awk (gawk) and GNU make.

### Installing only the Header Files

First, you have to create the configuartion files:

    $ cd gnumach
    $ autoreconf --install

GNU Mach and its headers should be built in separate directories:

    $ cd ..
    $ mkdir gnumach-build-h
    $ cd gnumach-build-h

Find the path to your GNU Mach sources (`../gnumach`) and configure
it (the --host flag is needed for 64 bit systems):

    $ ../gnumach/configure --prefix= --host=i686-unknown-linux-gnu

Install the header files into e.g. `~/gnu/include/`:

    $ make DESTDIR=~/gnu install-data

### Building and Installing

Building GNU Mach requires you to have the Mach Interface Generator
installed.  See [[building_MIG|mig/gnu_mig/building]] about how to do that, then come
back here.

GNU Mach should be built in a separate directory:

    $ cd ..
    $ mkdir gnumach-build
    $ cd gnumach-build

Find the path to your GNU Mach sources (`../gnumach`) and configure
it:

    $ ../gnumach/configure

If you are building on a 64 bit system, do the following instead:

    $ CPP='gcc -m32 -E -x c -undef -ansi' CC='gcc -m32' LD='ld -melf_i386'
    $ ../gnumach/configure --host=i686-unknown-linux-gnu

Build the kernel image:

    $ make gnumach.gz

Optionally run the (tiny) test suite:

    $ make check

You can then install and use `gnumach.gz`.

[TODO.]