[virt-tools-list] Emulating raspberry pi (arm1136-r2) in virt-manager?

[Martin Kletzander]

On 02/14/2013 09:01 PM, Cole Robinson wrote:
> On 02/14/2013 09:26 AM, Simon Lambourn wrote:
>> Hi,  I'm sure I am not the only person to want to do this:
>>
>> I can emulate raspberry pi using their disk image using raw qemu-system-arm,
>> but I cannot find the right CPU machine type in virt-manager.  Has anyone
>> found how to do this, or can someone offer advice please?
>>
>> The command I have used to start the raspberry pi emulation (on Ubuntu 12.10) is
>>
>> qemu-system-arm -kernel kernel-qemu -cpu arm1136-r2 -m 192 -M versatilepb
>> -no-reboot -serial stdio -append "root=/dev/sda2 panic=1" -hda
>> debian6-17-02-2012.img
>>
>> I downloaded the debian6...img file from the raspberry pi site. This all works
>> fine but I would like to set up a VM definition in virt-manager if possible.
>> In the dialog to create a new virtual machine I selected "import existing OS
>> image" and then on screen 4 "customise configuration before install", virt
>> type=qemu and architecture = arm.   Then I press Finish to customise the
>> configuration.    In Overview I select Machine type = versatilepb (and in Disk
>> type I select disk bus=IDE and storage format=Raw, but I'm not sure this is
>> important).
>>
>> However I can't find where or how to enter the cpu type - on the processor
>> page I have tried setting Model (under configuration) to arm1136, 1136,
>> arm1136-r2 and none of these are accepted by qemu. If I leave the Model type
>> blank I get a different error (HDA full duplex not supported by this binary).
>>
> 
> libvirt + qemu-system-arm don't play together too well at the moment. I don't
> think you will be able to do what you want to do without some qemu wrapper
> script. There's some hints here:
> 
> https://fedoraproject.org/wiki/Architectures/ARM/HowToQemu#Using_QEMU_with_libvirt
> 
> The plan is to make this all 'just work' in libvirt + virt-manager, but no
> time table yet.
> 
> - Cole
> 

Just confirming what Cole said; we tried to achieve something similar
few days ago.  The thing is, though, that libvirt supports mainly
emulating PCs in QEMU.  There are many things that aren't very easily
fixable.  Completely different devices must be specified in some
scenarios and some QEMU versions even expect different parameters when
running arm emulation (for the same options as the PC emulation).
Controllers are different, there is no PCI bus, but libvirt
automatically adds that and many many more things.

As suggested, the best way to make it work is try to make it "just work"
and don't expect too much.  There are many wrappers on the interwebz you
can use, two of them are in the link above.

Either you know that already or you'll learn that when reading the first
howto, but to briefly explain how that works; there is '<emulator>'
element in libvirt's domain XML and that says what binary (script)
should be used to run that particular machines.  You can create your
script, put it there and just make sure in the script that you mangle
the command-line enough so QEMU will start when you exec() it at the
end.  The less you change it, the more you may get out of it (networking
and such).

My 0.02$,
Martin