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

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Message-ID: <bac2c78a-cd56-7287-e4fd-6042e9b3432c@kernel.org>
Date:   Tue, 20 Nov 2018 17:08:33 -0500
From:   Sinan Kaya <okaya@...nel.org>
To:     Alex_Gagniuc@...lteam.com, mr.nuke.me@...il.com,
        keith.busch@...el.com
Cc:     baicar.tyler@...il.com, Austin.Bolen@...l.com, Shyam.Iyer@...l.com,
        lukas@...ner.de, bhelgaas@...gle.com, rjw@...ysocki.net,
        lenb@...nel.org, ruscur@...sell.cc, sbobroff@...ux.ibm.com,
        oohall@...il.com, linux-pci@...r.kernel.org,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 0/2] PCI/AER: Consistently use _OSC to determine who owns
 AER

On 11/20/2018 4:46 PM, Alex_Gagniuc@...lteam.com wrote:
> Now, let's assume, for the sake of argument, that the firmware on those
> system's is broken, and it didn't intend to give the OS control of AER.
> OSPM checking HEST instead of _OSC is still wrong, according to the
> spec. Two wrongs don't make a right, they just don't crash.
> 
> I think the correct way is to identify those broken systems, and add
> quirks for them. Continuing to have inconsistent and over-complicated
> logic that is not spec compliant is not any better.

Remember that both _OSC and HEST are in the ACPI specification. I don't
think there is a consensus on what is "wrong".

There is certainly a need for spec clarification.

One version is:

"if HEST table is present, ignore _OSC"

or

Another version is:

"if HEST table is present, make sure that FW sets _OSC bit for AER to
false. Otherwise, warn like crazy that this BIOS is broken and needs
an update and can cause all sorts of trouble"

I can see both points of view. The second one can also be worked around
by an SMBIOS quirk too as you suggested. Counting the number of quirks
and random bug reports will be an interesting exercise / regression.

I followed the ASWG thread yesterday. There will be a meeting next week to
discuss this.

My preference is not to introduce new behavior/regression to the kernel.