Messages in this thread | | | Date | Tue, 17 Aug 2010 09:05:20 +0200 | From | Borislav Petkov <> | Subject | Re: [Patch] Skip cpu_calibrate for kernel running under hypervisors. |
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From: "H. Peter Anvin" <hpa@zytor.com> Date: Mon, Aug 16, 2010 at 11:30:48PM -0700
> On 08/16/2010 10:51 PM, Alok Kataria wrote: > >> > >> I'm somewhat reluctant to take this one, since it assumes all the > >> hypervisors act the same. This seems rather inherently wrong. In fact, > >> the whole statement is fishy as heck... instead of being dependent on > >> AMD and so on, > > > > The check about being on AMD is something that was already there. > > > > I know it was... and calibrate_cpu() seems to be an AMD-specific > function, but that's rather crappy. I'm thinking that perhaps we should > make it an x86_init function, then the AMD CPU detection can install it > and the vmware hypervisor detection can uninstall it.
Btw, can we revisit this AMD-specific issue? IIUC, Alok you're seeing a mismatch between the calibrated TSC value and the cpu frequency even on cpus which have the CONSTANT_TSC bit set, i.e. their TSC is counting with P0 frequency. Can you please elaborate more on what systems you're seeing this (cpu family, chipset, etc)?
Thanks.
-- Regards/Gruss, Boris.
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