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This guide explains how to build and set up
a DDE-based network card driver
with Debian GNU/Hurd,
if your (wired) network card
is not supported by the old in-kernel drivers shipped with gnumach.

This guide assumes that you have
an installation of Debian GNU/Linux on the same machine,
which helps in fetching the required packages
in absence of working networking in the Hurd.
The whole process is much more cumbersome otherwise.
It also assumes that apart from networking,
your Hurd system is already installed and operational.


We start by booting into Debian GNU/Linux,
so we can download everything we will need for building DDE.

Once there, first mount the Hurd partition (as root):

	$ mount /dev/hdd1 /mnt -t ext2 # assuming your Hurd partition is hdd1 -- replace with whatever matches your setup

Prepare apt offline configuration so we can get necessary packages:

	$ cd /mnt/etc/apt

	$ echo "deb http://ftp.debian-ports.org/debian unreleased main" >> sources.list # if you don't have sources.list set up yet on the Hurd system

	$ echo "deb-src http://ftp.debian-ports.org/debian unreleased main" >> sources.list

	$ echo "deb http://ftp.uk.debian.org/debian unstable main" >> sources.list

	$ echo "deb-src http://ftp.uk.debian.org/debian unstable main" >> sources.list

	$ wget http://www.gnu.org/software/hurd/hurd/running/debian/DebianAptOffline/apt.conf.offline

Download the packages for offline installation:

	$ cd /mnt

	$ apt-get -c etc/apt/apt.conf.offline update

	$ apt-get -c etc/apt/apt.conf.offline build-dep hurd gnumach

	$ apt-get -c etc/apt/apt.conf.offline install git-core build-essential libpciaccess-dev libpcap0.8-dev

Get DDE code:

	$ cd /mnt/home/me # assuming your user name on the Hurd system is "me"

	$ mkdir dde && cd dde

	$ git clone git://git.sv.gnu.org/hurd/incubator.git -b dde hurd

	$ git clone git://git.sv.gnu.org/hurd/gnumach.git -b master-user_level_drivers

Now comes the tricky part:
you need to find out
whether there is already a driver for your card
in the DDE source tree,
and otherwise get the driver code
from the official Linux source tree.

For this, you have to find out which Linux driver
is responsible for your network card.
In this guide we will use the forcedeth driver
(for Nvidia nForce chipsets) as example.
We check whether there is already a `dde_forcedeth` directory
in the newly cloned `hurd_dde` tree.
If there isn't, we have to find and download
the right source file from Linux:

Point a (JavaScript-capable) web browser at

	http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.29.y.git;a=tree;f=drivers/net;hb=HEAD

(Note: you **have** to use 2.6.29,
as this is the version DDE is currently based on.)

Find the right file to download
(forcedeth.c in this example);
then hit the "raw" link,
and save the resulting file (page) to /mnt/home/me/dde

(If you happen to need one of the few drivers
that consist of more than one source file,
the process will be more complicated,
and can't be covered in this guide...)


Now everything should be in place,
so we can boot into Hurd to do the actual work.

Once there, install the packages previously downloaded (again as root):

	$ apt-get build-dep hurd gnumach

	$ apt-get install git-core build-essential libpciaccess-dev libpcap0.8-dev

Make sure we can build stuff as normal user:

	$ chown -R me ~me/dde

Now you can log in with the normal user account to build stuff.

Build a DDE-enabled Mach:

	$ cd ~me/dde/gnumach

	$ autoreconf -i && ./configure --enable-kdb --enable-device-drivers=none --enable-lpr --enable-floppy --enable-ide

	$ make


If not already present in DDE,
we need to prepare the driver for the network card:

	$ cd ~me/dde/hurd

	$ cp -r dde_pcnet32 dde_forcedeth # using pcnet32 as template

	$ cd dde_forcedeth

	$ rm pcnet32.c # don't want the actual pcnet32 code here...

	$ cp ~me/dde/forcedeth.c . # ...but rather the forcedeth code

	$ sed -i 's/pcnet32/forcedeth/g' Makefile # adapt Makefile accordingly

	$ sed -i 's/pcnet32/forcedeth/g' .gitignore

	$ sed -i 's:-lhurd-slab:../libhurd-slab/libhurd-slab.a:' Makefile # fix up build system... XXX I guess this part is obsolete

	$ sed -i 's:-I/include:-I..:' Makefile # same

	$ nano forcedeth.c # Near the top of the file, there will be many #include lines. After the last one, add this:

    #include <ddekit/timer.h>

	$ cd ..

Commit the new driver with git.
This will be helpful if we update the DDE code later;
as well as for creating a patch for later reuse
and/or upstream submission:

	$ git add dde_forcedeth

	$ git commit -a -m 'Add forcedeth driver'


Having prepared the driver,
we can now build the necessary Hurd and DDE bits:

	$ autoreconf -i && ./configure

	$ mkdir -p hurd/include/ddekit # workaround for a buildsystem bug... XXX I'm pretty sure this is not necessary anymore

	$ make libddekit libmachdev devnode pfinet # Hurd components

	$ cd libdde_linux26 # common DDE driver code -- uses a different Makefile system than the Hurd components!

	$ make

	$ cd ../dde_forcedeth # actual driver

	$ make

Install the various built components to their final destinations (as root):

	$ cd ~me/dde/

	$ cp gnumach/gnumach /boot/gnumach_dde

	$ mkdir /hurd/dde

	$ cp hurd/devnode/devnode hurd/pfinet/pfinet hurd/dde_forcedeth/dde_forcedeth /hurd/dde


Now everything should be ready.
Before we can use the driver,
we have to boot with the newly built gnumach_dde
instead of the standard kernel.
(Adapt your grub configuration;
or manually edit the entry
in the boottime grub menu while testing.)

Once there, set up the translators for the driver (as root):

	$ settrans -c /dev/forcedeth /hurd/dde/forcedeth

	$ settrans -c /dev/eth0 /hurd/dde/devnode -M /dev/forcedeth eth0

Finally, we can set up the actual network translator,
using something like:

	$ settrans -c /servers/socket/2 /hurd/dde/pfinet -i /dev/eth0 -a 192.168.1.194 -g 192.168.1.254 -m 255.255.255.0 

For the exact syntax,
see the normal network setup documentation.
The only differences here
are the different location of the pfinet binary,
and the different syntax for the -i option.