[SeaBIOS] [PATCH v2] Update EFI_COMPATIBILITY16_TABLE to match 0.98 spec update

David Woodhouse dwmw2 at infradead.org
Mon May 19 22:12:28 CEST 2014

On Fri, 2014-01-10 at 12:49 -0500, Kevin O'Connor wrote:
> On Fri, Dec 06, 2013 at 11:56:22AM +0000, David Woodhouse wrote:
> > We expect to use the space between the top of option ROMs and the bottom
> > of our own BIOS code as a stack. OVMF was previously marking the whole
> > region from 0xC0000 to 0xFFFFF read-only before invoking our Legacy16Boot
> > method. Read-only stack considered harmful.
> > 
> > Version 0.98 of the CSM spec adds the UmaAddress and UmaSize fields, which
> > allow the CSM to specify a memory region that needs to be writable.
> > 
> > There exists CONFIG_MALLOC_UPPERMEMORY which we could turn off to use
> > the 9-segment, but that isn't particularly useful for the CSM case
> > either because that memory isn't ours to play with until the final
> > Legacy16Boot call. There's a LowPmmMemory given to use by UEFI to play
> > with, but that's right in the *middle* of low memory and using that for
> > persistent allocations would be painful. So just require
> Hi David,
> Are you still looking at this?  If I recall correctly, you were going
> to run a test without CONFIG_MALLOC_UPPERMEMORY set.

That appears to make it boot OK, although I'm still not sure it's
*correct* to be using the 9-segment from the CSM before we've actually
been told to *boot*. Maybe we just get lucky. 

Do you want a version of the patch which doesn't add the dependency on


-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 5745 bytes
Desc: not available
URL: <http://www.seabios.org/pipermail/seabios/attachments/20140519/5f47bd1f/attachment.bin>

More information about the SeaBIOS mailing list