LiveCD customization and qemu(dapper)

[Tristan Wibberley]

Reza Roboubi wrote:

> 1.)  qemu says:
> warning: could not open /dev/net/tun: no virtual network emulation
> 
> I'm running breezy, one Ethernet card, dhcp configured, pretty simple.
> Running as non-privileged user.
> 
> Not quite sure how to set up the qemu network.

You can use -net user and there is also a command for port forwarding to
the virtual machine. This is a simple and straightforward way to do it.

> 3.)  faster qemu alternatives?  I found
> UML, Xen, OpenVZ, Mac on Linux, and Linux Vserver on
> wikipedia.
> 
> What do you think?

I think the only one of those that might be a qemu alternative is Mac on
Linux. The others are all completely different. If you use the qemu
kernel module, you can get host-equivalent guest hardware emulation at
near native speed (only ring 0 code is dynamically translated). With the
latest development kqemu and qemu cvs, you can get (currently) buggy
semi-virtualisation like I think VirtualPC and VMWare do. This technique
will work with most modern operating systems and most kernel mode
drivers, but will fail for some OSs - but it will fail a few percent
faster. I think qemu is in a class all of its own.

Xen is currently the astonishing performer, but that requires a
recompiled kernel.

> I had trouble figuring out how to boot an iso using UML; it appeared
> that the client (and host?) might need recompiles.  Is that true?

The client kernel must be recompiled. A UML host is a different
architecture to i386 PC, so you can't use the i386 PC kernel.

It's a shame that kqemu isn't included like the nvidia module is, can it
be added to the restricted repository for dapper and qemu compiled with
support? (requires permission from the developer) - its a bit late, I
know, but there isn't much that can be done about bugs in kqemu but
remove the package anyway, and it seems to be very reliable. Needs a
kqemu group too (should make first user a member of that group) and a
udev permissions rule KERNEL="kqemu", GROUP="kqemu", MODE="0660" - oh,
and a line in /etc/modules "kqemu major=0"

-- 
Tristan Wibberley