Messages in this thread | | | Subject | Re: [PATCH 00/31 v2] PTI support for x86_32 | From | Andrew Cooper <> | Date | Fri, 9 Feb 2018 21:28:08 +0000 |
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On 09/02/2018 21:09, Pavel Machek wrote: > On Fri 2018-02-09 17:47:43, Andy Lutomirski wrote: >> PCID bit set in CPUID should print a big fat warning like "WARNING: >> you are using 32-bit PTI on a 64-bit PCID-capable CPU. Your >> performance will increase dramatically if you switch to a 64-bit >> kernel." > Hardware supports PCID even on 32-bit kernels, no?
Attempting to set CR4.PCIDE is disallowed outside of long mode. It is strictly a 64bit-only feature.
~Andrew
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