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

[Kevin OConnor <kevin@koconnor.net>]

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On Tue, Dec 15, 2009 at 12:35 PM, Anthony Liguori <anthony@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
e-segment
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
would
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
e-segment,
as it knows which parts of the e-segment it is using.

-Kevin

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