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See this LWN story: https://lwn.net/Articles/940783/ https://lwn.net/Articles/940783/ on Linux, any cpus that don't have updated microcode will have AVX comple
by kzrdude 3y ago
See this LWN story: https://lwn.net/Articles/940783/ https://lwn.net/Articles/940783/
on Linux, any cpus that don't have updated microcode will have AVX completely disabled as a mitigation for this issue. That's rather harsh if you ask me and would be very noticeable. Now I'm interested in finding out if I can get updated microcode..
- kzrdude 3y agoMaybe that's not the default? Not entirely clear from the text.
- Bu9818 3y ago`[ 0.000000] microcode: updated early: 0x27 -> 0x28, date = 2019-11-12` I'm on haswell. Is there a list of what CPUs get updated microcode? Sad.
- starlevel003 3y agohaswell isn't vulnerable, it only affects skylake or later
- hansendc 3y agoThe AVX disable is only when you use "gather_data_sampling=force". The default is to leave AVX alone and proclaim the system to be vulnerable. From https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=553a5c03e90a https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin... : > Specifying "gather_data_sampling=force" will use the microcode mitigation when > available or disable AVX on affected systems where the microcode hasn't been > updated to include the mitigation. Disclaimer: I work on Linux at Intel. I probably wrote or tweaked the documentation and changelogs that are confusing folks.
- kzrdude 3y agoGreat, thanks for the clarification