Re: [Patch v3 3/3] UefiCpuPkg/MpInitLib: Load uCode once for each core.

["Dong, Eric" <eric.dong@intel.com>]

Hi Laszlo & Ray,

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Tuesday, July 17, 2018 10:07 PM
> To: Ni, Ruiyu <ruiyu.ni@intel.com>; Dong, Eric <eric.dong@intel.com>
> Cc: edk2-devel@lists.01.org
> Subject: Re: [edk2] [Patch v3 3/3] UefiCpuPkg/MpInitLib: Load uCode once for
> each core.
> 
> On 07/17/18 12:02, Ni, Ruiyu wrote:
> > On 7/16/2018 11:08 AM, Eric Dong wrote:
> >> GetProcessorLocationByApicId (GetInitialApicId (), NULL, NULL,
> >> &ThreadId);
> >> +  if (ThreadId != 0) {
> >> +    //
> >> +    // Skip loading microcode if it is not the first thread in one core.
> >> +    //
> >> +    return;
> >> +  }
> >> +
> >
> > Eric,
> > Is it possible that Thread#0 is disabled while Thread#1 is enabled? It
> > may cause the certain core with no uCode applied.
> >
> 
> I thought of this (superficially) but I figured the code would run anyway at
> CpuMpPei / CpuDxe startup only, at which point no logical processors could
> have been disabled yet -- programmatically, through the MP PPI / protocol. Is
> there any other reason why ThreadId=0 could be missing?
> 

Yes, I think at this point, all the threads should at the ready state.  The only case I can image is that the hardware has broken and the core can't be wake up.  But I think in this case, the core should can't work, not only thread 0 can't work.  What do you think?

> (I plan to check the rest of the series later.)
> 
> Thanks
> Laszlo