I am not a member of this list (I read occasionally via the public
archives) or an experienced kernel hacker but I do have a few
semi-informed thoughts on the 8256x NVM corruption issue. Take with
salt as necessary:
According to Intel's datasheet, these interfaces expose *writable* PCI
ID registers at NVM words 0x0A-0x0E. Fill the NVM with FFs and the
interface will probably respond with vendor ID : device ID FFFF:FFFF
during bus enumeration. The potential for these devices to disappear
off the PCI bus after NVM corruption means that unbricking damaged
devices could be nontrivial.
One possible recovery option would be see if a bricked interface still
responds to commands at the appropriate hardware address in the PCI
configuration space. Even if the device escapes enumeration because its
vendor ID and device ID are invalid, the hardware might be alive enough
to work with an NVM-reflash driver that ignored the PCI ID. In the best
case, getting a dead device back could just be a matter of setting up
MBARB by writing to the configuration space for bus 0 dev 25 fn 0 (for
ICH9) and reloading the NVM with a reasonable set of defaults.
Another recovery possibility would be to rewrite the NVM using the ICH's
SPI interface. The same flash chip serves both the BIOS and NIC. The
NVM might be rewritable through the ICH even if the NVM is too deeply
corrupted for the NIC to respond to reflash commands. This fix would be
complex, risky, and possibly motherboard specific, but should be able to
put most bricked 8256x NICs back together unless NVM corruption has
caused deeper damage.
Finally, given that one write to the wrong part of the NVM will turn one
of these NICs into a brick, memory mapping the NVM--even for the
briefest period--seems deeply imprudent. As long as the NVM is memory
mapped, all it takes to turn one of these NICs into a brick is for one
kernel mode bug to make one dword write to any of those registers. With
the current cost of ...