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

[David Woodhouse]

On Fri, 2013-02-08 at 18:37 -0500, Kevin O'Connor wrote:
> 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.

In my current builds, datalow_base is 0xd2800. datalow_start is 0xe1800,
and datalow_end is 0xe2071.

I didn't think we ever really went as low as datalow_base; that's just
the segment base, while all the offsets were higher?

If we really need writeable RAM all the way down to datalow_base, then
that's a problem; OVMF isn't currently giving us that.

> > 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.

Note the MaxRomAddr bit:
http://sourceforge.net/mailarchive/forum.php?thread_name=50FD7290.9060003%40redhat.com&forum_name=edk2-devel

-- 
dwmw2

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