Re: [Qemu-devel] Using iPXE with older qemu releases?

[Stefan Hajnoczi]

On Tue, Sep 27, 2011 at 6:50 PM, Kenton Cabiness
<address@hidden> wrote:
> Stefan,
>
> On 9/27/2011 2:23 AM, Stefan Hajnoczi wrote:
>>
>> On Mon, Sep 26, 2011 at 02:22:21PM -0500, Kenton Cabiness wrote:
>>>
>>> Is there a way to point an older qemu release (currently running
>>> qemu-kvm-0.12.1.2-2.16) to iPXE products?
>>>
>>> We have built iPXE and installed the files and tested by changing
>>> the symbolic links in /usr/share/qemu-kvm (RH6.1 system) to point to
>>> the iPXE files.  We would like to package the files in an RPM for
>>> installation on several machines, but since the links are owned by
>>> the qemu-kvm package, we cant have the iPXE package overwrite them.
>>>
>>> Is there a command line argument to qemu to point to a different
>>> directory for iPXE?  I've been looking through the code but can't
>>> find what tells qemu where to pick up the files.
>>
>> Try -device virtio-net-pci,romfile=/path/to/ipxe.rom,... as part of your
>> command-line.  If you have trouble getting this working, please post
>> your full command-line.
>>
>> Alternatively use -option-rom /path/to/ipxe.rom.  Either method should
>> work.
>
> Thanks for the reply.  Unfortunately, neither of these works for us.  We are
> using libvirt to configure and start up our VMs and it doesn't support the
> romfile= option (we've got a fairly robust configuration with 16 NICs using
> bridges, so I don't really want to try configuring everything manually and
> wouldn't fly with our project anyway).
>
> The -option-rom method works somewhat (we are using it to load sgabios, so I
> know the arguments are being recognized).   The value doesn't seem to
> override the default path for the romfile for the NIC.  If I remove the gpxe
> rom file from the default directory (or make it 0 length), then it fires off
> the iPXE PXEboot almost immediately (much faster than normal), but it can't
> communicate with the external DHCP server.  If I let it fail a couple of
> times and then reset the VM, then it launches iPXE and everything works
> correctly, so I'd say that something isn't getting initialized correctly if
> the load of the default romfile fails.

This almost sounds like there is a secondary problem with network
connectivity.  You could try booting an ipxe.iso instead of ROM just
to make sure that iPXE works reliably.

One thing that comes to mind is bridges with STP and forwarding delay
enabled, where the link is down for several seconds before traffic is
allowed.  This can cause a network bootloader to time out, may explain
why you need to let it fail a couple of times.

Stefan