[libvirt] OVMF exposure in libvirt

[Paolo Bonzini]

Il 18/07/2014 15:01, Michal Privoznik ha scritto:
> On 14.07.2014 16:12, Paolo Bonzini wrote:
>> Il 14/07/2014 11:27, Daniel P. Berrange ha scritto:
>>>       -drive file=img_1,if=pflash,format=raw,readonly \
>>>       -drive file=img_2,if=pflash,format=raw
>>
>> It's safer to add ",unit=0" and ",unit=1" too.
>>
>>> We already use <loader/> for specifying alternative BIOS blobs for
>>> the QEMU -bios arg. Since you say this obsoletes the -bios arg, I
>>> think it makes sense to use <loader/> for the read-only firmware
>>> image.
>>
>> It obsoletes the -bios argument, but it is not the same thing:
>>
>> 1) on some machines you can use "-drive if=pflash" for the nvram, but
>> not for the firmware
> 
> And how should the FW cmd line look like then?

You use -bios for the firmware, and -drive (without unit=1) for the nvram.

>>
>> 2) on some older versions of QEMU, "-drive if=pflash" will work only on
>> TCG or will not work at all so you cannot blindly replace it.
> 
> Whoa. How to detect this? I mean, how do detect both?

Do not bother.  Just assume that people know what they're doing.

Paolo

>>
>> What about:
>>
>>     <loader readonly='on|off' type='rom|flash'>...</loader>
>>     <nvram>...</nvram>
>>
>> where the mapping from <nvram> to -drive if=flash is partly
>> machine-dependent.  On x86, for example, <nvram> adds the ",unit=1"
>> sub-option and fails if the <loader> element is absent; it also fails if
>> <loader> has type='rom'.
>>
> 
> Makes sense.
> 
>>> For the variable storage, I'd probably suggest <nvram/> as the
>>> element name, since IIUC that's a fairly commonly used term for
>>> this concept.
>>
>> I like this.
>>
>>> Additionally it would be great if we'd be able to
>>> generate an empty nvram for a guest if the user doesn't specify it.
> 
> I'm not big fan of this. Pre-creating storage is something that should
> be done by mgmt applications (migration with non-shared storage is
> something different).
> 
>>
>> Laszlo has OVMF patches to "auto-format" an all-zero nvram file.
> 
> Great. Do they work automagically or does libvirt need to enable the
> formatting somehow (e.g. monitor command, cmd line argument, ...)?
> 
>>
>> Paolo
>