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

[Alexander Graf <agraf@suse.de>]

Michael S. Tsirkin wrote:
> On Mon, Dec 14, 2009 at 12:55:28PM +0100, Alexander Graf wrote:
>   
>> Am 14.12.2009 um 11:59 schrieb "Michael S. Tsirkin" <mst@redhat.com>:
>>
>>     
>>> On Mon, Dec 14, 2009 at 11:16:34AM +0100, Gerd Hoffmann wrote:
>>>       
>>>> On 12/14/09 10:44, Michael S. Tsirkin wrote:
>>>>         
>>>>> No, it did not even start booting the kernel. Just gave me blank  
>>>>> screen.
>>>>>           
>>>> [ testing ]
>>>>
>>>> Oh.  That is something completely different.  A bug in the rom  
>>>> loader.
>>>> It fails to fit both e1000 (default nic) and virtio-net boot roms  
>>>> into
>>>> the option rom area and bails out (before loading seabios).  vl.c
>>>> doesn't check the return value and happily continues (without bios).
>>>> Which doesn't work out very well ...
>>>>
>>>> With two identical nics the (single) rom fits and qemu boots.
>>>>
>>>> Hmm.  Of course vl.c must be fixed to check the return value.
>>>>         
>>> Yes.
>>>
>>>       
>>>> Not sure how to deal with the rom size issue.  The gPXE roms look  
>>>> quit
>>>> big compared to the older roms we had.
>>>>         
>>> Hmm, it's a regression then ...
>>>       
>> How does real hw handle this? I'm pretty sure most servers these days  
>> use more option rom space than this. They usually have some onboard raid 
>> bios, external storage, on-board nic, pci nic, ...
>>     
>
> Real hardware might do several things I know about
> - option rom is typically small.
> - option rom is not loaded always (BIOS option), or not for all cards.
> There are might be other tricks.
>   

There are probably other tricks. I was booting up a machine that had
like 5 options roms going through their initialization that all weren't
exactly small.

>> So there must be some way to just have more option rom space.  
>>     
>
> What do you mean?
>   

Well, what's keeping us from having 5 MB of option roms?

>> Implementing anything else would just be a waste of time. It'd break  
>> again when ppl do device assignment.
>>
>> Alex
>>     
>
> We need some solution for 0.12 though IMO.
> This does not need to address device assignment,
> but it must be simple.
>   

Agreed. If there is a solution that gives us the chance to support an
arbitrary number of option roms that wouldn't take forever to implement,
I'd rather take that one though.

Alex