AM2RD790

Please read this before running sensors-detect on this board.

On May 2nd, 2008, we have had one report that running sensors-detect on a Sapphire AM2RD790  killed the user's CPU. Apparently there is a memory voltage controller on the SMBus which went mad when probed by sensors-detect. Many thanks to Achim Gottinger for his help in investigating this issue.

Since then, we have addressed the problem both in sensors-detect and on the kernel front:

• In sensors-detect, we have added a heuristic to detect the memory voltage controller in question, and more generally any device using the same, unusual access protocol. When such a device is found, the I2C/SMBus address in question is skipped. The new code went in SVN on May 11th, 2008, and will ship in lm-sensors 3.0.2 (and 2.10.7).
• As not everybody will be using a safe version of sensors-detect immediately, and as other tools and kernel drivers could cause the same problem, the only safe way to address the problem was in the kernel. So the i2c-piix4 kernel driver has been  modified to no longer attach to the SMBus on the Sapphire AM2RD790 motherboard and its DFI sibling. The change went in kernel 2.6.26-rc2, and will be included in kernel 2.6.25.4 as well. Hardware monitoring on this board is implemented by the Super-I/O chip, so you don't need the SMBus for that.

As a summary:

• If you are running a 2.6.25.4 or later kernel, you can use sensors-detect, and more generally lm-sensors, on this motherboard safely.
• If you are running an older kernel, but you are using lm-sensors 3.0.2 or later, running sensors-detect should be safe. Nevertheless, it is strongly advised that you skip SMBus probing.
• If you are running an older kernel, and an older version of lm-sensors, then do not run sensors-detect. Simply load the it87 hardware monitoring driver, that's the one you need.

Other motherboards affected by this problem:

• DFI Lanparty NF4 Expert (different bus driver)
• DFI Lanparty UT 790FX