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From:   Koba Ko <koba.ko@canonical.com>
Date:   Fri, 7 Jul 2023 01:40:40 +0800
Message-ID: <CAJB-X+X_KW=T4WOe2AS3SFFQKjt7VcQRFUCGYFcjipi5-aXdrw@mail.gmail.com>
Subject: Re: [PATCH v2] EDAC/i10nm: shift exponent is negative
To:     "Zhuo, Qiuxu" <qiuxu.zhuo@intel.com>
Cc:     "Luck, Tony" <tony.luck@intel.com>,
        Kai-Heng Feng <kai.heng.feng@canonical.com>,
        Markus Elfring <Markus.Elfring@web.de>,
        "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
        "kernel-janitors@vger.kernel.org" <kernel-janitors@vger.kernel.org>,
        Borislav Petkov <bp@alien8.de>,
        James Morse <james.morse@arm.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Robert Richter <rric@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Thu, Jul 6, 2023 at 10:12=E2=80=AFPM Zhuo, Qiuxu <qiuxu.zhuo@intel.com> =
wrote:
>
> > From: Luck, Tony <tony.luck@intel.com>
> > Sent: Wednesday, July 5, 2023 11:22 PM
> > ...
> > Subject: RE: [PATCH v2] EDAC/i10nm: shift exponent is negative
> >
> > >> # head /proc/cpuinfo
> >
> > This shows your system is the workstation version of Sapphire rapids. I=
 don't
> > think we did any validation of the EDAC driver against this model.
>
> No, we didn't do any validation of the EDAC on Sapphires Rapids workstati=
ons.
> From the link below, we know this is a Sapphire Rapids workstation with o=
nly 2 memory controllers.
> https://www.intel.com/content/www/us/en/products/sku/233480/intel-xeon-w3=
2435-processor-22-5m-cache-3-10-ghz/specifications.html
>
> We only did validation on the Sapphire Rapids servers which were with 4 m=
emory controllers per socket before.
>
> > > # dmidecode -t 17
> >
> > You have just one 16GB DIMM, and EDAC found that. So despite the messy
> > warnings, EDAC should be working for you.
> >
> > > # lspci
> >
> > I didn't dig into this. Qiuxu - can you compare this against a server S=
apphire
> > rapids?
> > Maybe it has some clues so the EDAC driver will know not to look for no=
n-
> > existent memory controllers.
>
> This Sapphire Rapids workstation had 2 memory controllers but appeared
> 4 memory controller PCIe devices from the log:
>
>     0000:fe:0c.0 1101: 8086:324a
>     0000:fe:0d.0 1101: 8086:324a // absent mc fooling the driver, should =
not appear
>     0000:fe:0e.0 1101: 8086:324a
>     0000:fe:0f.0 1101: 8086:324a // absent mc fooling the driver, should =
not appear
>
> By observing that the MMIO registers of these absent
> memory controllers consistently hold the value of ~0.
> We may identify a memory controller as absent by checking
> if its MMIO register "mcmtr" =3D=3D ~0 in all its channels.
>
> I made a patch below to skip all these absent memory controllers
> https://lore.kernel.org/linux-edac/20230706134216.37044-1-qiuxu.zhuo@inte=
l.com/T/#u
> @Koba Ko, could you please verify the patch from the link above on your w=
orkstation? Thanks!

Here's dmesg patched(Ref. 1). didn't find the previous message,
`EDAC DEBUG: skx_get_dimm_attr: bad ranks =3D 3 (raw=3D0xffffffff)`

Ref. 1, https://drive.google.com/drive/folders/1xym9JgZZgaJ3EqtP4ccRcVeQYoJ=
KmVlp?usp=3Dsharing

>
> BTW,
> Kai-Heng Feng also found the same issue before:
> https://lore.kernel.org/linux-edac/CAAd53p41Ku1m1rapeqb1xtD+kKuk+BaUW=3Dd=
umuoF0ZO3GhFjFA@mail.gmail.com/T/#m5de16dce60a8c836ec235868c7c16e3fefad0cc2
>
> - Qiuxu