[SeaBIOS] Proper support for PCI-based option rom loading (was Re: [Qemu-devel] Re: qdev property bug?)

Kevin OConnor kevin at koconnor.net
Wed Dec 16 00:54:13 CET 2009

On Tue, Dec 15, 2009 at 12:35 PM, Anthony Liguori <anthony at codemonkey.ws>wrote:

> Avi Kivity wrote:
>> bochs bios required all 128kB, so this is probably a leftover.
> This is apparently well defined in the PIIX spec.  There is a bit of a
> difference between the lower half and upper half of the BIOS region though
> and I expect this is part of what the problem is.  FYI, the following patch
> works.  Surprisingly, we only need to restore the 0xe8000..0xe8fff region.
>  Still trying to understand what's happening.
SeaBIOS is currently using over 64K of space.  So, it is extending into the
and thus needs to have the e-segment copied properly (I missed that in my
earlier email).

SeaBIOS is only extending a few K into the e-segment, so only that part
needs to
be saved and restored.

Should SeaBIOS options be trimmed so that it fit under 64K, then the build
create only a 64K rom.  However, since it is larger than 64K, it pads itself
to 128K.  As
mentioned before, SeaBIOS can still copy roms into the unused parts of the
as it knows which parts of the e-segment it is using.

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