Re: Access to PCI Expansion ROMs on PPC

On Sun, 2007-11-25 at 08:30 -0500, Jon Smirl wrote:

quoted

The two cards with x86 firmware return 0xFF for those two readb()
instructions, while the X1900 with OF returns 0x00 for the readb().

Could one of the more knowledgeable folk for PPC intricacies suggest

why

quoted

those readb calls are returning the wrong data?

I don't know PPC at this low of level but it may be a problem with non
word-aligned access to memory. I thought readb() was supposed to work
on all archs and alignment issues are handled inside readb(). Also,
the readw() may have an endian bug.

Ugh ? Read be reads -bytes- ! Can you tell me how the hell can a byte
access be non-aligned ?

BenH, has source code for an x86 emulator that will run on PPC. That
will let you run the ROMs. The original plan was for the kernel to
generate a uevent that would have triggered the x86 emulator to run.

Progress along that path was blocked by the X developers. The X server
contains code for enabling the PCI ROM and reading it from user space.
I wanted to move this code out of X and into the kernel.

Because the path was blocked things like the PCI ROM API were never
throughly tested. It works most of the time but the occasional problem
is still turning up. Once we identify the PPC problem we can fix it in
the kernel.

Nobody blocked anything, you are free to develop an emulator triggered
by a uevent, nobody prevented you from doing so.

Now, regarding that user problem, this it totally unrelated as it's a
"mac" card.

It's possible that it's one of these radeons that disable ROM access via
a register in which case a quirk is needed to re-enable it.

Ben.