lkml.org 
[lkml]   [2022]   [Aug]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 0/7] x86/topology: Improve CPUID.1F handling

* Zhang Rui <rui.zhang@intel.com> wrote:

> On Intel AlderLake-N platforms where there are Ecores only, the Ecore
> Module topology is enumerated via CPUID.1F Module level, which has not
> been supported by Linux kernel yet.
>
> This exposes two issues in current CPUID.1F handling code.
> 1. Linux interprets the Module id bits as package id and erroneously
> reports a multi module system as a multi-package system.
> 2. Linux excludes the unknown Module id bits from the core_id, and results
> in duplicate core_id’s shown in a package after the first issue solved.
>
> Plus that, a third problem is observed on Intel Hybrid ADL-S/P platforms.
> The return value of CPUID.1F SMT level EBX (number of siblings) differs on
> Pcore CPUs and Ecore CPUs, and results in inconsistent smp_num_siblings
> value based on the Pcore/Ecore CPU enumeration order. This could bring
> some potential issues although we have not observed any functionalities
> issues so far.
>
> Patch 1/7 and 2/7 fix the first two issues. And at the same time, it
> reveals a reality that the core_id could be sparse on platforms with
> CPUID.1F support.
> Patch 3/7 improves coretemp driver code to be able to handle sparse core
> id, which is the only driver that uses core_id as array index and run on
> platforms with CPUID.1F support.
>
> Patch 4/7 to 7/7 propose a fix for the third problem and update the
> related Documents.

Yeah, so patch 3/7 probably needs to come first - otherwise there's a
window for bisection breakage.

Thanks,

Ingo

\
 
 \ /
  Last update: 2022-08-13 12:45    [W:0.095 / U:0.444 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site