Running GoboLinux under QEMU

This article is potentially out of date!

You can find a more up-to-date approach here: https://gist.github.com/fyrak1s/fd58e1bcb3a9ead77588a83e087ed376. These resources are meant to be merged in the future.

We’ll illustrate how to:

  • create a disk image
  • boot an ISO image of Gobo under QEMU
  • install Gobo to a disk image on the host filesystem
  • reboot the newly installed guest
  • initialize networking
  • launch QEMU from a helper script

Create a disk image

This is where we will install our Linux system.

qemu-img create gobo.img 20G

Boot the installer

Here is the full command you can edit and paste into the terminal:

sudo qemu-system-x86_64 \
-cdrom GoboLinux-016.01-alpha-x86_64.iso \
-hda gobo.img \
-boot d \
-m 768 -enable-kvm -show-cursor -cpu host -daemonize \
-vga std -soundhw ac97 -rtc base=utc \
-usb -usbdevice tablet -device usb-mouse -vga std -clock unix

To test boot only the ISO, omit the -hda option.

Boot the disk image

After you’ve finished the installation, shutdown the guest OS and terminate QEMU. Start QEMU again, this time booting from the disk image:

sudo qemu-system-x86_64 \
-hda gobo.img \
-boot c \
-m 768 -enable-kvm -show-cursor -cpu host -daemonize \
-vga std -soundhw ac97 -rtc base=utc \
-usb -usbdevice tablet -device usb-mouse -vga std -clock unix

Networking under QEMU

QEMU provides a networking stack so that the guest OS running on this virtual machine can access the internet, or ssh to the host.

The only extra setup needed is to run Gobo’s DHCP client inside the guest.

dhcpcd

By default QEMU acts as a firewall and does not permit any incoming traffic. It also doesn’t support protocols other than TCP and UDP. This means that ping and other ICMP utilities won’t work.

Details can be found here.

Helper script

Qemust is a perl5 script you can use to start your QEMU processes. With most options defined in the script, the command line becomes much simpler.

To boot from an ISO and install to a disk image:

qemust --iso=GoboLinux-016.01-alpha-x86_64.iso --image=gobo.img

To boot from the disk image

qemust  --image=gobo.img

To test an ISO:

qemust --iso=GoboLinux-016.01-alpha-x86_64.iso

The script has some library dependencies. The most convenient way to install them (and any CPAN modules) is to use cpanminus (cpanm). So install cpanminus, then the dependencies:

cpan App::cpanminus
cpanm Getopt::Long::Descriptive

The script follows below. Edit the QEMU options to your liking, put the script in somewhere in your $PATH, and make it executable with something like chmod a+x ~/bin/qemust.

#!/usr/bin/env perl
use strict;
use warnings;

#   qemust - start QEMU

use 5.012;
use Getopt::Long::Descriptive;
my ($opt, $usage) = describe_options(
   '%c %o',
   [ 'iso=s',  "ISO file to boot" ],
   [ 'image=s',"OS disk image file" ],
   [ 'help',   "print usage message and exit" ],
   [ 'n',      "print QEMU startup command and exit" ],
 );
print($usage->text), exit if $opt->{help} or ! keys %$opt;

my $boot_drive = $opt->{iso} ? 'd' : 'c';

my @cmd = grep{! /^\s*$/} map{s/\s*#.*$//; $_} split "\n",<<"CMD";

sudo                 # run as root
qemu-system-x86_64   # for 64-bit CPUs
-enable-kvm          # faster virtualization
-show-cursor         #
-boot $boot_drive    # boot from DVD/CDROM if present
-m 768               # use memory 768MB
-cpu host            # same CPU model as host
-daemonize           # avoid race conditions when QEMU started by external program
-vga std             # probably -vga vmware would work, too
-soundhw ac97        # typical soundcard, -soundhw hda should also work
-rtc base=utc        # timer related
-usb                 # enable USB driver
-usbdevice tablet    # so QEMU can report mouse position without grabbing mouse
-device usb-mouse    #
-clock unix          #

CMD

push @cmd, "-cdrom $opt->{iso}" if $opt->{iso};
push @cmd, "-hda $opt->{image}" if $opt->{image};
my $cmd = join " \\\n",@cmd;
say $cmd;
system($cmd) unless $opt->{n};
__END__