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From: Yazen Ghannam <yazen.ghannam@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Vishal Badole <Vishal.Badole@amd.com>,
	tony.luck@intel.com, linux-edac@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] EDAC/amd64: Mask UMC chip select to the four implemented selects
Date: Mon, 28 Sep 2026 16:03:34 -0400	[thread overview]
Message-ID: <20260928200334.GD2289128@yaz-khff2.amd.com> (raw)
In-Reply-To: <20260928192045.GAarq-DbwF6-q79hXC@fat_crate.local>

On Mon, Sep 28, 2026 at 12:20:45PM -0700, Borislav Petkov wrote:
> On Mon, Sep 28, 2026 at 10:38:21AM -0400, Yazen Ghannam wrote:
> > I didn't consider this a necessary fix. But it'd be good to have it to
> > avoid noise from reports.
> 
> I didn't either but what is Vishal doing to trigger this:
> 
> "Since only four csrows are allocated, a syndrome with bit 2 set decodes
> to an out-of-range csrow and trips:
> 
>   EDAC MC0: INTERNAL ERROR: csrow value is out of range (5 >= 4)"
> 
> Vishal?
> 
> From reading the commit message, I still have no clue how that happens and
> what are we fixing here.
> 

There are a couple of cases that trip this.

1) Newer hardware where 'bit 2' is redefined. For example, it could mean
'sub-channel' or something else relevant. In that case, a real error
would be decoded incorrectly.

2) Some hardware error injection methods that use arbitrary values. This
is like the 'error simulation' we do in the mce-inject module where we
can write something to the registers.

So the patch is a fix for #2 today, and it is a preemptive fix for #1.

Thanks,
Yazen

      reply	other threads:[~2026-09-28 20:03 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-25 17:26 [PATCH 0/2] EDAC/amd64: Consolidate Family 1Ah setup and fix UMC csrow decode Vishal Badole
2026-09-25 17:26 ` [PATCH 1/2] EDAC/amd64: Set zn_regs_v2 for all Family 1Ah models Vishal Badole
2026-09-28 14:21   ` Yazen Ghannam
2026-09-28 16:08     ` Badole, Vishal
2026-09-25 17:26 ` [PATCH 2/2] EDAC/amd64: Mask UMC chip select to the four implemented selects Vishal Badole
2026-09-25 18:14   ` Borislav Petkov
2026-09-28 14:38     ` Yazen Ghannam
2026-09-28 16:09       ` Badole, Vishal
2026-09-28 19:20       ` Borislav Petkov
2026-09-28 20:03         ` Yazen Ghannam [this message]

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