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Have you got a reference for that statement? Because my interpretation of what has been said so far is that AMD deliberately chose not to allow speculative depe
by pja 9y ago
Have you got a reference for that statement? Because my interpretation of what has been said so far is that AMD deliberately chose not to allow speculative dependent loads that crossed privilege boundaries by enforcing permission checks on all reads whereas Intel chose to permit all loads & rely on the fixup at the retirement stage of the pipeline to enforce privilege boundaries.
Happy to be proven wrong however.
- thecompilr 9y agoI don't have hard evidence, but A) they are vulnerable to two out of the three attacks, which indicates they did not in fact consider speculative execution a danger B) it is hard to believe that if they researched the topic at AMD, they wouldn't find this vulnerability in Intel processors a long time ago
- jacksmith21006 9y agoThey did across priv boundaries which was the point.
- pja 9y agoI note in passing that the AMD processor manual is explicit that all reads are checked against the privilege bit before being issued. It’s this protection that means that AMD processors are not subject to meltdown. All CPU manufacturers appear to have been caught on the hop by Spectre (branch prediction history side channels).