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AMD Errata: RDSEED failure on AMD Zen 5 Processors
- jcalvinowens 1y agoSee also: https://lore.kernel.org/lkml/20251103142800.GFaQi78AgT-qjY30r3@fat_crate.local/T/#ma8f142e006ef9bd61341f7b20bd92ae8063da281 https://lore.kernel.org/lkml/20251103142800.GFaQi78AgT-qjY30...
- rasz 1y agoagain? https://arstechnica.com/gadgets/2019/10/how-a-months-old-amd-microcode-bug-destroyed-my-weekend/ https://arstechnica.com/gadgets/2019/10/how-a-months-old-amd... ZEN seems to have suspiciously a lot of those rdrand "bugs"
- hulitu 1y agoCIA and NSA really need access to your data. /s
- jcalvinowens 1y agoI wrote a silly little testcase: https://gist.github.com/jcalvinowens/06530e6fc86f3b2c97a702745b20752d https://gist.github.com/jcalvinowens/06530e6fc86f3b2c97a7027... ...but both affected znver5 machines I have "pass", so clearly there's more to it than AMD is telling us. You should be able to get away with "-march=znver5 -mno-rdrnd -mno-rdseed" in CFLAGS if you care.
- jcalvinowens 1y agoOh, actually the original report was very specific: https://lore.kernel.org/all/20251018024010.4112396-1-gourry@gourry.net/ https://lore.kernel.org/all/20251018024010.4112396-1-gourry@...
- meltyness 1y agoIt's funny to me that the patch threads attempting to fix a concern with the CPU from the OS both immediately derail into "oh no, you broke something!!1" the CPU is assumed to work, despite Linux being designed with portability, theres not really a programming interface to cleanly disable arbitrary features, I guess we just screw with it until it seems to work OK and no one is yelling. Granted, Linux isnt a product, and a patch in a thread is unlikely to impact anyone