[SeaBIOS] [PATCH 0/5][RFC] Simultaneous multi-platform support

[Kevin O'Connor]

On Fri, Feb 08, 2013 at 11:25:39PM +0000, David Woodhouse wrote:
> On Fri, 2013-02-08 at 18:02 -0500, Kevin O'Connor wrote:
> > 
> > >I'm not sure it would even work for CSM, because it would
> > > probably be too big.
> > 
> > As an aside, is there a way to pass in the "init" sections to ovmf
> > such that they don't prevent option roms from using the space?  Also,
> > I briefly tried not padding bios.bin to a power of 2, but ovmf doesn't
> > seem to like that.
> 
> I've already proposed the UmbStart and UmbEnd fields which the CSM can
> use to mark the memory it needs to be writeable, and I've hard-coded
> that to 0xe0000-0xf0000 for the SeaBIOS CSM build. That 0xe0000 should
> actually be datalow_start, shouldn't it?

I think you'd want datalow_base.  Ideally SeaBIOS would update the
setting dynamically.

> We could happily declare that OVMF can place option ROMs up to UmbStart
> (== datalow_start) so when SeaBIOS relocates its own init code, the
> extra memory (below the memory it uses for its own purposes) can be
> reclaimed.
> 
> In fact I think my OVMF patch for the UmbStart,UmbEnd support already
> did that, didn't it?

That would work for SeaBIOS.  I missed that in your proposal.

-Kevin