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Date: Mon, 30 Aug 2010 15:11:56 +0200
From: Jes Sorensen <Jes.Sorensen@redhat.com>
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Subject: [Qemu-devel] Re: [PATCH v3] Do not try loading option ROM for
 hotplug PCI device in pc-0.11 compat mode
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: qemu-devel@nongnu.org

On 08/30/10 15:00, Anthony Liguori wrote:
> On 08/30/2010 03:16 AM, Jes.Sorensen@redhat.com wrote:
>> From: Jes Sorensen<Jes.Sorensen@redhat.com>
>>
>> pc-0.11 and older uses fw_cfg to provide option ROMs. As fw_cfg is setup
>> at init time, it is not possible to load an option ROM for a hotplug
>> device when running in compat mode.
>>
>> v2: Alex Williamson pointed out that one can get to qdev directly from
>> pci_dev, so no need to pass it down.
>>
>> v3: Braces
>>    
> 
> What's the specific bug?  The devices themselves have a check for
> hotplug which inhibits rom addition during hotplug so either there's a
> device missing this check or if we're going to go this route, we ought
> to remove those checks in the other devices.

If you run in -M pc-0.11 or older option ROMs are provided via fw_cfg,
which means QEMU is unable to load it after boot time if you try to
hot-plug a new network device via the monitor. Instead it decides to
exit with an error.

My patch makes QEMU not try to load the option ROM in this case, which
IMHO is a reasonable workaround. It means you can't PXE from the
hot-plugged device, but at least QEMU doesn't exit out on you.

Cheers,
Jes