Re: [Qemu-devel] Re: qdev property bug?

[Anthony Liguori <anthony@codemonkey.ws>]

Sebastian Herbszt wrote:
> Anthony Liguori wrote:
>> Michael S. Tsirkin wrote:
>>>
>>> Further, we should error out when device is added.
>>> Doing this during boot is way too late, management
>>> won't be able to understand such errors and
>>> won't be able to recover.
>>>   
>>
>> I don't quite understand this.
>>
>> In 0.11, we never loaded option roms unless a user specified -boot 
>> n.  If a user specified -boot n and used more than one nic type, I'm 
>> fairly certain it would error out during start up because it would 
>> run out of option rom space.  Maybe it required three types of nics, 
>> but the point still remains.
>
> I think it used to be possible to have two different nic types and 
> only load
> one rom, e.g. -net nic,model=pcnet -net nic,model=e1000 -option-rom 
> e1000.rom
> Then use the boot menu to select the e1000 nic.

That's a super hack :-)  The fact that works is pure luck.

>> In 0.12, we always load the option rom for a PCI device.  An easy 
>> solution here would be to just gracefully handle the case where we 
>> ran out of option rom space and (silently) stop loading additional 
>> roms.  With respect to -boot n, it makes the behavior buggy (you 
>> cannot boot from the second nic) but my original point is that that 
>> is not a regression from 0.11.
>
> Even if i repeat myself [1] i suggest putting an option-rom loading 
> flag to the -net option:
> -net nic,model=e1000,rom=[on,off,e1000.bin]

Well it ought to be a qdev property and it ought to be applicable to 
every PCI device.

>> For 0.13, we should probably allow a user to suppress option rom 
>> loading for a given PCI device.  The limited space is a pretty good 
>> justification for that.
>
> The default behaviour should be not loading option-roms; users should 
> request those.

I disagree.  A user should not have to decide whether they want PXE boot 
or not when they create a VM.  The less decisions a user has to make up 
front the easier qemu is to use.

Regards,

Anthony Liguori