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

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Date:   Mon, 19 Nov 2018 20:54:21 -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 11/19/2018 6:49 PM, Alex_Gagniuc@...lteam.com wrote:
> On 11/19/2018 02:33 PM, Sinan Kaya wrote:
>> However; table assumes governance about for which entities firmware first
>> should be enabled. There is no cross reference to _OSC or permission
>> negotiation like _OST.
> 
> Well, from an OSPM perspective, is FFS something that can be enabled or
> disabled? FFS seems to be static to OSPM, which would change the sort of
> assumptions we can reasonably make here.

IMO, it can be enabled/disabled in BIOS. I have seen this implementation before.
If the trigger is the presence of a statically compiled ACPI HEST table (as the
current code does); presence of FFS would be static from OSPM perspective.
BIOS could patch this table or hide it during boot.

If FFS were to be negotiated via _OSC as indirectly implied in this series, then
same BIOS could patch the ACPI table to return different values for the _OSC
return.

> 
> 
>>>> As I said in my previous email, the right place to talk about this is UEFI
>>>> forum.
>>>
>>> The way I would present the problem to he spec writers is that, although
>>> the spec appears to be consistent, we've seen firmware vendors that made
>>> the wrong assumptions about HEST/_OSC. Instead of describing AER
>>> ownership with _OSC, they attempted to do it with HEST. So we should add
>>> an implementation note, or clarification about this.
>>
>> I agree.
> 
> Cool. While the UEFI Secret Society debates, can we figure out if/how
> [patch 1/2] breaks those systems, or is it only [patch 2/2] of this
> series that we suspect?

I went back and looked at both patches. Both of them are removing references to
HEST table. I think both patches are impacted by this discussion.

> 
> Alex
>