Re: [PATCH] UefiCpuPkg/MtrrLib: Add flag to skip disabling MTRRs prior to MTRR change.

["Duran, Leo" <leo.duran@amd.com>]

> -----Original Message-----
> From: Ni, Ruiyu <ruiyu.ni@Intel.com>
> Sent: Thursday, September 13, 2018 11:44 PM
> To: Duran, Leo <leo.duran@amd.com>; Laszlo Ersek <lersek@redhat.com>;
> edk2-devel@lists.01.org
> Cc: Dong, Eric <eric.dong@intel.com>
> Subject: Re: [edk2] [PATCH] UefiCpuPkg/MtrrLib: Add flag to skip disabling
> MTRRs prior to MTRR change.
> 
> On 9/14/2018 3:31 AM, Duran, Leo wrote:
> >
> >
> >> -----Original Message-----
> >> From: Ni, Ruiyu <ruiyu.ni@intel.com>
> >> Sent: Wednesday, September 12, 2018 9:39 PM
> >> To: Duran, Leo <leo.duran@amd.com>; Laszlo Ersek
> <lersek@redhat.com>;
> >> edk2-devel@lists.01.org
> >> Cc: Dong, Eric <eric.dong@intel.com>
> >> Subject: RE: [PATCH] UefiCpuPkg/MtrrLib: Add flag to skip disabling
> >> MTRRs prior to MTRR change.
> >>
> >> Leo,
> >> Sorry I was in leave yesterday so didn't see the mail.
> >> Which MSRs are shared? Only the
> MSR_IA32_MTRR_DEF_TYPE_REGISTER?
> >> Or all the MSRs that configures the CPU MTRR setting?
> >>
> >
> > Hi Ray,
> > The MTTR config MSRs are also shared by threads within a core.
> >
> 
> Hi Leo,
> Do you think that fixing the caller is more proper?

Hi Ray,
Actually,
The proposed PCD is the simplest solution, as that works for us and does not change the existing (default) flow.

That is,
I'd prefer making a decision about the PCD in platform-specific code, rather than introducing complex detection and heuristics at the caller level in EDK2 (just for AMD).

So, please approve the PCD.

Thanks,
Leo

> 
> >> I also agree with Laszlo's comments to fix the caller if all MSRs
> >> relating to MTRR are shared.
> >> That will be to fix MpInitLib and CpuDxe driver.
> >>
> >> Thanks/Ray
> >>