Re: [Qemu-devel] 128Kb bios size and older machines?

[Ian Campbell]

On Thu, 2014-02-06 at 17:08 +0400, Michael Tokarev wrote:
> 06.02.2014 12:50, Gerd Hoffmann wrote:
> > On Do, 2014-02-06 at 12:28 +0400, Michael Tokarev wrote:
> >> Since the "small" (128Kb) seabios is now built without
> >> support of xen, does that mean that xen will be unable
> >> to use qemu with -M 1.7 and before?  Does it _ever_ use
> >> -M option like this?
> > 
> > As far I know xen has its own seabios builds anyway as they
> > have to add hvmloader to the mix.  Thats why it has been
> > turned off in the upstream blob builds, nobody will use these
> > with xen anyway.
> 
> Thank you Gerd for the answer.  Ian, can you give some light
> here, what is still missing in seabios for xen?  Because,
> well, ..

Nothing is missing in seabios.

The above patch is a fix to Xen not SeaBIOS, which lets it work
correctly regardless of the size of the seabios binary.

There is no need to do anything other than apply that fix to the Xen
packages (perhaps by upgrading to 4.3.1) AFAIK.

> > Not sure how all that is organized in the debian xen/seabios packages.
> 
> .. debian uses upstream seabios directly with xen now, not
> the one which comes from xen repository.
> 
> (And yes I know about
>   
> http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=5f2875739beef3a75c7a7e8579b6cbcb464e61b3
> which talks about >128kb bios size.  This is actually exactly
> the same issue which I'm trying to address now, from a few PoVs:
> qemu now builds/uses stripped-down bios for older (pre-2.0) machine
> types, and that stripped-down version does not include Xen bits
> in order to fit in 128Kb, because with xen it doesn't fit anymore.
> Maybe we should start building special xen variant of seabios --
> stripped down but WITH xen.  Oh well.)

Why is this stripped down SeaBIOS needed?

Is there some reason the Xen build can't pickup the non-stripped down
(post-2.0) SeaBIOS?

Ian.