AMD shipped buggy Opterons?
AMD is scheduled to make a public statement today regarding a number of buggy
Opterons inadvertently shipped by the company, according to Reg
Hardware. The processors, which are said to be "perhaps no more than
3,000" 2.6GHz Opteron x52s and 2.8GHz Opteron x54s, reportedly have
faulty floating-point units that can cause data corruption. While AMD
has yet to reveal any details about the bug, Reg Hardware received the
following information from an AMD customer:
It is believed that the glitch is triggered when the affected chip's FPU
is made to loop through a series of memory-fetch, multiplication and
addition operations without any condition checks on the result of the
calculations. The loop has to run over and over again for long enough to
cause localised heating which - and here's the real problem - causes the
result of the operation to be recorded incorrectly, leading to data
To trigger the bug, the loop has to be run millions of time, the source
said, potentially for hours at a time, and no other operations being
introduced during the run.
Luckily, AMD is said to have determined that the bug can only be
reproduced in a synthetic benchmark. Reg Hardware's source echoed the
claim, saying "[t]he only thing I could think that would be coded this
way would be some type of strange cipher code."