Eric W. Biederman
ebiederman at lnxi.com
Fri Apr 18 17:21:01 CEST 2003
Jim Garlick <garlick at llnl.gov> writes:
> Sounds very similar to a problem observed on the SuperMicro P4DPR/DPE which
> has the same winbond sensor chip. The solution was to tell lm_sensors to
> access the Winbond via ISA rather than I2C.
> I think there is also some code in the p4dpr/p4dpe linuxbios port to notice
> the memory initialization problem and work around it (e.g. wait a while
> and reset?) The details have faded but you might check the code.
So the details. On Intels ICH3 southbridge there is an smbus/i2c controller
that when it sees invalid on the bus it locks up. But it only sees invalid
data when you are actually using the bus. Using lm_sensors just increases
the probability that the smbus controller will lock up.
At which point a reboot will fail because SPD information cannot be
read over the smbus, leading the LinuxBIOS to think you have no RAM.
To the best of my knowledge there is no fix. This is just something
that needs to be avoided.
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