[coreboot] Fwd: SimNOW VGA int 1a

ron minnich rminnich at gmail.com
Thu Oct 16 23:44:30 CEST 2008

On Thu, Oct 16, 2008 at 2:35 PM, Carl-Daniel Hailfinger
<c-d.hailfinger.devel.2006 at gmx.net> wrote:

> Please help me understand this better. Is this a bug of real hardware, a
> bug of an emulator or an intended design feature?
> Depending on what it is, we could employ various ways to fix it.

it's one of the few bugs in the pci design.

You write ffffffff to a register. it reads back as the moving bits +
non moving bits. But at that point, until you change it, that's also
the address it will decode.

In this case, sadly, we set a bar to ffffffff, to set its size, and it
reads back ff000000, which gives us moving and non moving. Oh but ...
it also decodes that address, top 16m of addrss space, -> no more ROM.

hardware does this? yeah, probably.


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