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Subject: Re: [PATCH 0/2] PCI/AER: Consistently use _OSC to determine who owns
 AER
To:     Keith Busch <keith.busch@intel.com>,
        Tyler Baicar <baicar.tyler@gmail.com>
Cc:     mr.nuke.me@gmail.com, helgaas@google.com, austin_bolen@dell.com,
        alex_gagniuc@dellteam.com, Shyam_Iyer@dell.com, lukas@wunner.de,
        bhelgaas@google.com, rjw@rjwysocki.net, lenb@kernel.org,
        ruscur@russell.cc, sbobroff@linux.ibm.com, oohall@gmail.com,
        linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linuxppc-dev@lists.ozlabs.org
References: <20181115231605.24352-1-mr.nuke.me@gmail.com>
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 <20181119165318.GB26595@localhost.localdomain>
From:   Sinan Kaya <okaya@kernel.org>
Message-ID: <74f2c527-0890-5e14-5e2d-48934a42dae6@kernel.org>
Date:   Mon, 19 Nov 2018 12:32:42 -0500
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On 11/19/2018 11:53 AM, Keith Busch wrote:
> On Mon, Nov 19, 2018 at 11:53:05AM -0500, Tyler Baicar wrote:
>> On Thu, Nov 15, 2018 at 8:49 PM Sinan Kaya <okaya@kernel.org> wrote:
>>>
>>> On 11/15/2018 3:16 PM, Alexandru Gagniuc wrote:
>>>> I've asked around a few people at Dell and they unanimously agree that
>>>> _OSC is the correct way to determine ownership of AER. In linux, we
>>>> use the result of _OSC to enable AER services, but we use HEST to
>>>> determine AER ownership. That's inconsistent. This series drops the
>>>> use of HEST in favor of _OSC.
>>>>
>>>> [1]https://lkml.org/lkml/2018/11/15/62
>>>
>>> This change breaks the existing systems that rely on the HEST table
>>> telling the operating system about firmware first presence.
>>>
>>> Besides, HEST table has much more granularity about which PCI component
>>> needs firmware such as global/device/switch.
>>>
>>> You should probably circulate these ideas for wider consumption in UEFI
>>> forum as UEFI owns the HEST table definition.
>>
>> I agree with Sinan, this will break existing systems, and the granularity of the
>> HEST definition is more useful than the single bit in _OSC.
> 
> But we're not using HEST as a fine grain control. We disable native AER
> handling if *any* device has FF set in HEST, and that just forces people
> to use pcie_ports=native to get around that.
> 

I don't see *any* in the code.  aer_hest_parse() does the HEST table parsing.
It switches to firmware first mode if global flag in HEST is set. Otherwise
for each BDF in device, hest_match_pci() is used to do a cross-matching against
HEST table contents.

Am I missing something?