[Qemu-devel] Missing PCI network device ROM bar on ARM

[Qemu-devel] Missing PCI network device ROM bar on ARM

[Pavel Hrdina]

Hi,

So there was made a decision that default ROM bars for network devices shouldn't
be packaged for ARM architecture.  Based on this thorough explanation [1] it
makes sense that it's useless.  However it leads to a small issue with starting
a guest on ARM hosts with PCI network device, if there are no ROM files included
it will fail with error message:

    -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:10:e9:80,bus=pci.2,addr=0x1:
    failed to find romfile "efi-virtio.rom"

there is also a bug [2].

It was originally created against virt-manager, but I've moved it to libvirt
temporally because I don't think that this should be a job for virt-manager to
workaround this ugly behavior of QEMU, because all other layers using libvirt
would have to do the same workaround.  However I also thing that it isn't a job
for libvirt too, because if you don't specify anything about using or not using
a ROM bar (you just don't care about it) the QEMU process should start without
any error.  This means that the default behavior should be based on the fact
whether there is or isn't a required ROM file to load.

So I would like to start a discussion where would be the best place to fix this.

Pavel

[1] <http://lists.nongnu.org/archive/html/qemu-devel/2016-05/msg02083.html>
[2] <https://bugzilla.redhat.com/show_bug.cgi?id=1337510>

Re: [Qemu-devel] Missing PCI network device ROM bar on ARM

[Daniel P. Berrange]

On Fri, Jul 22, 2016 at 04:55:16PM +0200, Pavel Hrdina wrote:
> Hi,
> 
> So there was made a decision that default ROM bars for network devices shouldn't
> be packaged for ARM architecture.  Based on this thorough explanation [1] it

What do you mean by 'shouldn't be packaged for ARM architecture' ?  It sounds
like you are referring to the QEMU RPM packaging, which would sound like a
bogus decision, since you can run non-arm emulator binaries on the arm host
arch.

> makes sense that it's useless.  However it leads to a small issue with starting
> a guest on ARM hosts with PCI network device, if there are no ROM files included
> it will fail with error message:
> 
>     -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:10:e9:80,bus=pci.2,addr=0x1:
>     failed to find romfile "efi-virtio.rom"
> 
> there is also a bug [2].
> 
> It was originally created against virt-manager, but I've moved it to libvirt
> temporally because I don't think that this should be a job for virt-manager to
> workaround this ugly behavior of QEMU, because all other layers using libvirt
> would have to do the same workaround.  However I also thing that it isn't a job
> for libvirt too, because if you don't specify anything about using or not using
> a ROM bar (you just don't care about it) the QEMU process should start without
> any error.  This means that the default behavior should be based on the fact
> whether there is or isn't a required ROM file to load.
> 
> So I would like to start a discussion where would be the best place to fix this.

Regards,
Daniel
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Re: [Qemu-devel] Missing PCI network device ROM bar on ARM

[Pavel Hrdina]

On Fri, Jul 22, 2016 at 04:11:58PM +0100, Daniel P. Berrange wrote:
> On Fri, Jul 22, 2016 at 04:55:16PM +0200, Pavel Hrdina wrote:
> > Hi,
> > 
> > So there was made a decision that default ROM bars for network devices shouldn't
> > be packaged for ARM architecture.  Based on this thorough explanation [1] it
> 
> What do you mean by 'shouldn't be packaged for ARM architecture' ?  It sounds
> like you are referring to the QEMU RPM packaging, which would sound like a
> bogus decision, since you can run non-arm emulator binaries on the arm host
> arch.

After a discussion on IRC this isn't an upstream issue so please ignore it.

Thanks,
Pavel