[coreboot] [PATCH] v3: missing 640k-1024k mem hole for i440bxemulation

Marc Jones Marc.Jones at AMD.com
Thu Mar 20 17:23:36 CET 2008

ron minnich wrote:
> On Wed, Mar 19, 2008 at 7:39 PM, Carl-Daniel Hailfinger
> <c-d.hailfinger.devel.2006 at gmx.net> wrote:
>> i440bxemulation is missing the 640k-1024k mem hole.
>>  geodelx has the hole.
> Right, but should it have the hole or not?  I mean, is this a
> mainboard that can get away without it? I'd like to kill that memory
> hole.
> thanks
> ron
The reason the hole is in Geode is because of the "legacy" memory 
descriptor setup (opposed to MTRRs as Intel and K8). It could be changed 
by setting r/w in the swisscheese descriptor or by removeing the 
swisscheese and extending the low memory descriptor.

coreboot doesn't do any legacy shadowing stuff, so the legacy area 
doesn't need to be saved or described. I don't know if the OS (linux) 
will take advantage of that or not. It may still skip the hole just to 
be safe or they might use the MTRRs the BIOS set.


Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones at amd.com

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