On Wed, Jan 25, 2017 at 11:26:53AM -0600, Aaron Durbin via coreboot wrote:
On Wed, Jan 25, 2017 at 11:24 AM, Timothy Pearson tpearson@raptorengineering.com wrote:
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On 01/24/2017 10:55 PM, Taiidan@gmx.com wrote:
I know the 63xx has a very fatal NMI exploit, but according to the libreboot (oh no) website the 62xx works safely out of the box without microcode however I would like to confirm if this is actually true.
I looked at the errata .pdf from the AMD website but I didn't see anything that seemed significant.
As far as we have been able to determine it does, again with the caveat that this is without microcode _updates_, not without microcode. There is still the off chance that these CPUs ship with a backdoor inside the burnt microcode ROM that is patched out with an update. Unlike POWER and ARM we are solely dependent on the vendor being trustworthy enough to disclose issues in their errata document; outside of that, there is simply no feasible way to know for certain what bugs are lurking inside the CPU.
POWER and ARM parts can have microcode too. That's up to the implementation. I'm not sure how you can distinguish the difference. Because one posts an update vs others never indicating there is an update? Even if parts have no microcode, there's a possibility of backdoors baked into the silicon. In all situations one needs to trust the vendor.
I guess that "Reflections on Trusting Trust" by Ken Thompson (https://www.ece.cmu.edu/~ganger/712.fall02/papers/p761-thompson.pdf) is still (and will always be) relevant?
Bob
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Robert Wilkinson