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