Messages in this thread | | | Date | Sat, 14 Jul 2018 07:08:28 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH 38/39] x86/mm/pti: Add Warning when booting on a PCID capable CPU |
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On Fri, Jul 13, 2018 at 11:59:44AM -0700, Andy Lutomirski wrote: > On Wed, Jul 11, 2018 at 4:29 AM, Joerg Roedel <joro@8bytes.org> wrote: > > From: Joerg Roedel <jroedel@suse.de> > > > > Warn the user in case the performance can be significantly > > improved by switching to a 64-bit kernel. > > ... > > > +#ifdef CONFIG_X86_32 > > + if (boot_cpu_has(X86_FEATURE_PCID)) { > > I'm a bit confused. Wouldn't the setup_clear_cpu_cap() call in > early_identify_cpu() prevent this from working?
Right you are, I don't have a PCID capable system at hand for testing, so I didn't catch this...
> Boris, do we have a straightforward way to ask "does the CPU advertise > this feature in CPUID regardless of whether we have it enabled right > now"?
I guess we need to call cpuid again.
Regards,
Joerg
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