Messages in this thread |  | | | Date | Thu, 25 Sep 2008 11:46:42 -0700 | | From | "H. Peter Anvin" <> | | Subject | Re: [Bug #11382] e1000e: 2.6.27-rc1 corrupts EEPROM/NVM | |
Jiri Kosina wrote:
> > Yes, I think that xorg/xorg i915 driver/libdrm/GEM/whatever are the
> biggest suspect currently, according to the data that has been gathered so
> far.> > Still, what confuses me a little bit -- the EEPROM of the card is set to
> all 0xff, once the corruption happens. Isn't that a quite a coincidence,
> that bytes representing "nothing" in this context are used?
>
Typical card EEPROMs are serial - either I2C or SPI. I believe the
Intel cards use SPI EEPROMs, but I'm not sure.
[Disclaimer: I don't actually know SPI all that well; I know I2C better.
However, I'm pretty sure the following argument does apply to both.]
Consider a corruption which turns a read command into a write command --
often just a single bit difference. Now, the EEPROM will expect data in
to write, but nothing will be driving the data line, so it will
typically be a 1. As the host tries to read, it will therefore fill the
EEPROM with all ones.
-hpa
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