Mapping Video BIOS?

Greg 'groggy' Lehey grog at
Sat Jul 26 18:09:43 PDT 2003

On Saturday, 26 July 2003 at 18:44:43 -0600, M. Warner Losh wrote:
> In message: <20030727002138.GD45069 at>
>             "Greg 'groggy' Lehey" <grog at> writes:
>> On Saturday, 26 July 2003 at 11:27:06 -0600, M. Warner Losh wrote:
>>> In message: <20030726080217.GB45069 at>
>>>             "Greg 'groggy' Lehey" <grog at> writes:
>>>> machine doesn't have a serial port, so I can't apply a kernel debugger
>>>> to find out what's going on.
>>> Does it have a firewire port?
>> Yes.  How can I use that?
> If you have a second machine with firewire, then you can use the
> firewire port as your console.  Look at /usr/ports/devel/dcons.  It is
> one of the under-publicized cool features from Japan (Thanks
> Shimokawa-san!).

Ah, good stuff.  I'll have to check if it also works with gdb.
Unfortunately, this is my only machine with firewire.  I was wondering
if there were USB/conventional serial converters that I could use.

>> I had also expected that you could shed some light on the BIOS mapping
>> issue.  Since my last message I've become pretty sure that it must be
>> something to do with the chip set setup.  Is it possible that we're
>> not mapping the entire area 0xc0000 to 0xfffff?
> I'm not sure what you mean by this question.  Since OLDCARD works, and
> requires read/write access to that physical memory range, I doubt that
> it is unmapped.

I'm not sure at what level.  I suspect that something in the chipset
is turning off that area of memory, or mapping something else to it.
The dump from Microsoft shows that there's another BIOS at 0xcf000,
but what I have mapped in memory shows only 0xff up to address
0xd0000, where I find another BIOS signature:

0x28377fe0:     0xffffffff      0xffffffff      0xffffffff      0xffffffff
0x28377ff0:     0xffffffff      0xffffffff      0xffffffff      0xffffffff
0x28378000:     0xe80caa55      0x4ecb14c8      0x0000033b      0x00000000
0x28378010:     0x00000000      0x00200000      0x00600040      0x90c08b2e
0x28378020:     0x49444e55      0x0000ea16      0x0c9d0201      0xad100800

> It may be the case that we aren't setting things up so that XFree86
> can call the BIOS, but given that we used PCIBIOS before ACPI, it
> seems unlikely.

Well, this is a new laptop, so it's possible that something *is*
getting set up incorrectly.

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