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

[Anthony Liguori]

Alexander Graf wrote:
> 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" <address@hidden>:
> > >
> > >     
> > >       
> > > > 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?
>   

For starters, option roms run in real mode when you only have 1MB of 
addressable memory :-)

> > > 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.
>   

For 0.12, we just need to fail gracefully (meaning stop loading option 
roms when we run out of room).  It's not a regression compared to 0.11.

Regards,

Anthony Liguori