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New Ryzen FMA bug

Question asked by sirzooro on Jul 29, 2017
Latest reply on Aug 11, 2017 by rwd4ever

Hi all,

There is one more bug in Ryzen CPU, which still exists after BIOS update to version AGESA 1.0.0.6a. It affects Ryzen users of TN-Grid projects who want to use FMA app version. Apps without FMA instructions (AVX, SSE2) are fine. What is interesting, crash signature is always the same:

Privileged Instruction (0xc0000096) at address 0x00000000004f5458

I am author of this app, so I did some analysis and found that for some reason Ryzen loads instruction from incorrect address (in the middle of valid one). This invalid instruction is STI which is a privileged one, what causes crash.

More details are on TN-Grid project forum: http://gene.disi.unitn.it/test/forum_thread.php?id=167

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