From: <Alex_Gagniuc@Dellteam.com>
To: <okaya@kernel.org>, <mr.nuke.me@gmail.com>, <keith.busch@intel.com>
Cc: baicar.tyler@gmail.com, sbobroff@linux.ibm.com,
linux-pci@vger.kernel.org, rjw@rjwysocki.net,
linux-kernel@vger.kernel.org, Shyam.Iyer@dell.com,
linux-acpi@vger.kernel.org, lukas@wunner.de, oohall@gmail.com,
Austin.Bolen@dell.com, bhelgaas@google.com,
linuxppc-dev@lists.ozlabs.org, lenb@kernel.org
Subject: Re: [PATCH 0/2] PCI/AER: Consistently use _OSC to determine who owns AER
Date: Tue, 20 Nov 2018 20:44:46 +0000 [thread overview]
Message-ID: <e86f04ef8c054d61969862a6e7b72d0d@ausx13mps321.AMER.DELL.COM> (raw)
In-Reply-To: 3b18a9fa-7bdd-0fb4-285d-4efb454be50a@kernel.org
On 11/19/2018 07:54 PM, Sinan Kaya wrote:
> On 11/19/2018 6:49 PM, Alex_Gagniuc@Dellteam.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.
It is theoretically possible to have proprietary BIOS settings to
disable FFS. The platform vendors that I've spoken to do not offer this
option. Though even if, hypothetically, BIOS clears the FFS bit in HEST,
it won't stop it from commandeering the CPU and doing whatever it wants.
Although, I'm not quite sure why we'd want to negotiate FFS itself. FFS
is too big of a can of worms (goes far beyond AER error reporting), when
what we really care about is if OS can use a specific feature or not.
>> 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.
I'd prefer "sure" instead of "think". "I think it breaks some system I'm
not telling you about" doesn't help much in figuring out how not to
break said system(s). :)
Alex
next prev parent reply other threads:[~2018-11-20 20:47 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-15 23:16 [PATCH 0/2] PCI/AER: Consistently use _OSC to determine who owns AER Alexandru Gagniuc
2018-11-15 23:16 ` [PATCH 1/2] PCI/AER: Do not use APEI/HEST to disable AER services globally Alexandru Gagniuc
2018-11-15 23:16 ` [PATCH 2/2] PCI/AER: Determine AER ownership based on _OSC instead of HEST Alexandru Gagniuc
2018-11-15 23:43 ` Keith Busch
2018-11-16 1:49 ` [PATCH 0/2] PCI/AER: Consistently use _OSC to determine who owns AER Sinan Kaya
2018-11-19 16:53 ` Tyler Baicar
2018-11-19 16:53 ` Keith Busch
2018-11-19 17:32 ` Sinan Kaya
2018-11-19 17:36 ` Keith Busch
2018-11-19 17:42 ` Sinan Kaya
2018-11-19 17:41 ` Keith Busch
2018-11-19 17:56 ` Sinan Kaya
2018-11-19 18:10 ` Keith Busch
2018-11-19 18:24 ` Sinan Kaya
2018-11-19 19:11 ` Alex G.
2018-11-19 19:32 ` Sinan Kaya
2018-11-19 20:16 ` Alex_Gagniuc
2018-11-19 20:33 ` Sinan Kaya
2018-11-19 23:49 ` Alex_Gagniuc
2018-11-20 1:54 ` Sinan Kaya
2018-11-20 20:44 ` Alex_Gagniuc [this message]
2018-11-20 21:02 ` Sinan Kaya
2018-11-20 21:42 ` Keith Busch
2018-11-20 22:28 ` Sinan Kaya
2018-11-20 22:35 ` Alex G.
2018-11-20 21:46 ` Alex_Gagniuc
2018-11-20 22:08 ` Sinan Kaya
2018-11-20 22:36 ` Alex_Gagniuc
2018-11-27 18:22 ` Alex_Gagniuc
2018-11-27 18:32 ` Sinan Kaya
2018-11-27 18:46 ` Tyler Baicar
2018-11-16 12:37 ` David Laight
2019-03-05 23:16 ` Bjorn Helgaas
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