On Thu, 2007-08-30 at 08:40 -0400, Timothy Normand Miller wrote:
> Time to disassemble someone's BIOS code and find out?  :)

Just for the sake of trying, I attempted to extract the BIOS of one of
my nVidia cards, but I failed. `lspci -v' says the following:

> [virtual] Expansion ROM at d7ee0000 [disabled] [size=128K]

I suspect that the `[disabled]' string is key to the failure, and with
my new-found knowledge of PCI along with `lpsci -x', I can tell that the
ROM decode is disabled, but then the question arrives how to tell the
kernel how to enable it.

I can't imagine that the kernel will enjoy me writing directly into the
config space (although it is allowed through sysfs). I would have
thought that the kernel would enable it for me if I tried to
cat /sys/bus/pci/.../rom, but it didn't (instead cat got EINVAL from
read()). I can't find any other reliable mechanism to enable the ROM.

So, is it safe to just write the address mentioned in lspci into the
config space or will my machine crash and die if I try? Has anyone
tried?

As an aside, isn't it weird that the kernel keeps the address allocated
if the decode isn't enabled? If the address space is allocated, why
*not* decode it?

Fredrik Tolf


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