Subject: Re: The radeon framebuffer device panics init (on i386)
To: Michael Lorenz <>
From: Vincent <>
List: tech-kern
Date: 12/23/2006 22:13:04
According to Michael Lorenz:

>>> Hmm, so you r display does provide EDID data after all. I didn't see 
>>> any EDID stuff in your dmesg output but since the default mode used 
>>> by radeonfb is the same as what your display reports that doesn't 
>>> matter for now.
>> It is supposed to do so?
> Yes. And at least on my iBook it works just fine. To my surprise I might 
> add.

Well, there is obviously something more seriously wrong.

>> I think Xorg scans all the PCI bus, detects overlaps, and decides to 
>> map the video BIOS in a hole.
> Maybe - when X is up you can have a look with pcictl if there's 
> something else than 0x00000000 in the ROM BAR - somehow I doubt it. In 
> fact I think there's no dedicated video BIOS ROM and video BIOS is part 
> of the main BIOS.

No, there is nothing else, because I precisely dumped the BIOS under X.

"Expansion ROM Base Address: 0x00000000"

Anyhow, a ROM BAR should be ROM itself, no?

> What you could do is:
> - - find a safe address range for the ROM BAR ( usually you'll need 64kB 
> or 128kB )
> - - use pcitweak to set the address and enable the ROM
> - - write a little program that mmap()s the ROM via /dev/mem ( just open 
> /dev/mem for reading, use the address you picked as offset for mmap() ) 
> and see what's there. If you get SIGBUS, SIGSEGV or bogus data ( like 
> all 0x00000000 or 0xffffffff ) then there's likely no ROM.

Somehow, X seems to find something when launch, so I guess there is a 
piece of ROM somewhere. I'll try to tinker the way you indicated.

> Hmm, maybe it makes sense to have radeonfb look at the 'traditional' 
> physical address of the video BIOS and cross fingers.

Which is?

>> I've not tested CRT output yet, will do that now.
> That would at least tell us if radeonfb doesn't feed the panel the right 
> way or if there's something more fundamental wrong.

The CRT output does not work either. At least my TV screen stays blank.

I'll keep you posted.
Thanks again