linux-kernel - RE: [PATCH 0/2] PCI/AER: Consistently use

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Message-ID: <ab363e80d45e4c3d91770c1b1010d1ce@AcuMS.aculab.com>
Date:   Fri, 16 Nov 2018 12:37:00 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Alexandru Gagniuc' <mr.nuke.me@...il.com>,
        "helgaas@...gle.com" <helgaas@...gle.com>
CC:     "austin_bolen@...l.com" <austin_bolen@...l.com>,
        "alex_gagniuc@...lteam.com" <alex_gagniuc@...lteam.com>,
        "keith.busch@...el.com" <keith.busch@...el.com>,
        "Shyam_Iyer@...l.com" <Shyam_Iyer@...l.com>,
        "lukas@...ner.de" <lukas@...ner.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Russell Currey <ruscur@...sell.cc>,
        Sam Bobroff <sbobroff@...ux.ibm.com>,
        Oliver O'Halloran <oohall@...il.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: RE: [PATCH 0/2] PCI/AER: Consistently use _OSC to determine who owns
 AER

From: Alexandru Gagniuc
> Sent: 15 November 2018 23:16
...
> I've asked around a few people at Dell and they unanimously agree that
> _OSC is the correct way to determine ownership of AER.

This is all very well, but we have systems (they might be Dell ones)
where failure of a PCIe link (even when all the drivers are removed)
causes an NMI - and crashes the kernel.

There are other systems which have AER registers available for
some of the PCIe devices, but the BIOS ignores them and _OSC
doesn't let the kernel take control.
In this case the AER registers can contain useful information
after a read returns ~0u.
It would be useful to be able to get this information without
having to grovel through all the PCIe config space.

	David

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