This page discusses things for Unix systems, there is a separate page for Microsoft Windows systems.

Readily Available Images

To try out the Hurd you can use the image of the Debian GNU/Hurd:

Official Debian GNU/Hurd QEMU image

(!) Note that the following are unofficial images: they have been prepared by volunteers and may not have been tested extensively.

Disk image with a short intro on translators. Just start it with 'qemu disk_image.img'. It should work without any of the configuration below. If you want to know what you can do with it, please have a look at its wikipage. And when you use it, please tell me your experience with it! - ArneBab

What is Needed to create a QEMU image

First thing is to install QEMU.
A grub boot disk for the floppy disk image needed for booting. The 0.97 version works fine. I downloaded it and renamed to floppy.img. Alternatively, the Debian grub-disk package (up till version 0.97-28) is fine as well.
You will need a Debian/Hurd installation CD. K16 works fine.

Installing Debian/Hurd with QEMU

First off you will need to create a disk image using qemu-img. I have set mine to 2 gigabytes, although you should be able to get away with less(Currently, the maximum disk image size one can create with QEMU is 4.5G).

$ qemu-img create hd0.img 2G

Next you will want to start up QEMU and begin the installation process. The first time you run it you will want to use the -boot d option to boot off the cdrom.

$ qemu -hda hd0.img -cdrom debian-K16-hurd-i386-CD1.iso -fda floppy.img  -boot d

Now at his point do the regular install using hd0 as your harddrive. Partition it and install the base system. Once you have finished installing the base system select the reboot option as this will ensure the disk is properly un-mounted. When the Debian CD menu comes up again simply close QEMU.

Now run your image with floppy booting (-boot a) and finish the install (./native-install .. etc).

Important: Older versions on gnumach needed that the -M isapc was passed to qemu. This is not needed anymore.

Also see another text about how to create an image for the GNU system.

Transferring Files

Mounting Disk Image on Host

You may wish to mount your disk image on your host system to transfer files. To do this you will first need to find the offset of the partition you wish to mount.

# fdisk -ul hd0.img
...
128 heads, 63 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes

   Device Boot      Start         End      Blocks   Id  System
hd0.img1   *          63     3515903     1757920+  83  Linux
hd0.img2         3515904     4193279      338688   82  Linux swap / Solaris

Now take the number of sectors for the beginning of the partition and multiply it by the sector size. My partition starts at sector 63 and I have a sector size of 512 therefor my offset is 32256.

# mount -o loop,offset=32256 hd0.img /mnt/diskimage

Having QEMU create virtual FAT disk images

Manual.

QEMU has a facility to create FAT file systems on-the-fly:

qemu [...] -hdc fat:[somewhere]

The Hurd fatfs translator currently is read-only, but for testing executables (etc.) that is enough. And it is much easier than loop-mounting the file systems images. (Also you don't need `root' rights.)

However, note that there is a bug in fatfs: GNU Savannah bug #25961.

Networking in QEMU

Some further notes about networking and home hints about sharing files.

Internet Access

If you just want to access the internet from within QEMU, you can setup pfinet for QEMU's user-networking:

# settrans -afgp /servers/socket/2 /hurd/pfinet -i eth0 -a 10.0.2.15 -g 10.0.2.2 -m 255.255.255.0
# echo "nameserver 10.0.2.3" > /etc/resolv.conf

Outgoing internet connections should just work then.

If you want to connect from the host system to the Hurd system running in QEMU, you need to setup something more advanced, like bridged networking.

Bridged Networking

What is Needed

Your Linux kernel will need 802.1d Ethernet Bridging support and TUN/TAP device driver support.
You will need to install bridge-utils.

Setting Up the Host Bridge

You need to setup a bridge on the host first. This assumes eth0 is down. I have modified my hosts network startup scripts to automatically setup a bridge, you may want to do this also.

# brctl addbr br0
# ifconfig eth0 0.0.0.0 promisc up
# brctl addif br0 eth0

At this point you will need to setup br0 as you would normally eth0 (dhcpcd br0 for example).

The qemu-ifup Script

This script gets called when QEMU starts and will attach the tun device to the bridge. QEMU will look for this file at /etc/qemu-ifup and that is where I keep mine.

#!/bin/sh
sudo ifconfig $1 0.0.0.0 promisc up
sudo brctl addif br0 $1

Setting up the Network in the Hurd

Now it is time to start-up your QEMU Hurd system and get networking going in there.

Important: Remember you may need to use the -M isapc or -isa flag if using an older version of the gnumach package.

$ qemu -hda hd0.img -cdrom debian-K9-hurd-i386-CD1.iso -fda floppy.img -boot a -net nic -net tap

Once you have logged in as root run the pfinet translator with values that apply to your network. Think of your QEMU client as another computer in your network.

# settrans -fgap /servers/socket/2 /hurd/pfinet -i eth0 -a xxx.xxx.xxx.xxx -g xxx.xxx.xxx.xxx -m xxx.xxx.xxx.xxx

That should do it! Do not forget to edit/update /etc/resolv.conf to get DNS working.

TODO

IRC, #hurd, 2007-07-04.

<azeem-uni> so, is there a way to use a Debian GNU/Hurd partition (/dev/hda6) with qemu directly?
<tschwinge> Don't dare to do that, please.
<tschwinge> It will lead to inconsistencies.
<tschwinge> Because the Linux kernel thinks that it has complete control over the disk, or something.
<tschwinge> In theory you could run something like ``-hda /dev/hda'', having GRUB installed on there to offer you to boot your Hurd system from hda6 and that will even work, but then don't get the idea to stop qemu, mount that partition on your Linux system and restart qemu.  That's where I got lots of inconsistencies then, afterwards.
<azeem-uni> it's probably the same problem as having that partition mounted, suspending to disk, booting into it in the Hurd, and resume Linux
<neal> right
<tschwinge> That's a different problem.
<tschwinge> Then the partitoon is still mounted.
<neal> no, I think it is basically the same problem
<tschwinge> The file system stuff is cached in the kernel.
<neal> you have data that has not been written to disk yet
<tschwinge> Right.
<neal> and neither is prepared for the resource to be shared
<tschwinge> In the azeem-uni scenarion the data is on the file system layer and in my scenarion it's some disk block caching inside the Linux kernel, I guess.
<azeem-uni> anyway, do you guys think if I use -hda /dev/hda and tell Grub to boot off /dev/hda6, that the rest of hda should be fine, right?
<azeem-uni> maybe adding -snapshot makes it totally safe
<neal> azeem: Should be fine.
<tschwinge> Yes.

The problem is actually that the linux block cache doesn't make any consistency between /dev/hda and /dev/hda6, so if you give /dev/hda to qemu, qemu writings won't be consistent with mounting /dev/hda6 in linux. You can give /dev/hda6 directly to qemu and it will be fine.