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Date:   Tue, 30 May 2023 18:05:48 +0200
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Subject: Re: [PATCH v2] ACPI: APEI: EINJ: EINJV2 support added
Content-Language: en-US
To:     "Luck, Tony" <tony.luck@intel.com>,
        Piyush Malgujar <pmalgujar@marvell.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
        "Williams, Dan J" <dan.j.williams@intel.com>,
        "xueshuai@linux.alibaba.com" <xueshuai@linux.alibaba.com>,
        "benjamin.cheatham@amd.com" <benjamin.cheatham@amd.com>,
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        "jannadurai@marvell.com" <jannadurai@marvell.com>,
        "cchavva@marvell.com" <cchavva@marvell.com>
References: <20230504133224.2669-1-pmalgujar@marvell.com>
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From:   "Wilczynski, Michal" <michal.wilczynski@intel.com>
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On 5/9/2023 8:35 PM, Luck, Tony wrote:
>> If a platform supports einj v2, then the einj directory wont be needed, as per spec,
>> if a non-zero Error Type value is set by EINJV2_SET_ERROR_TYPE, then any Error Type
>> value set by (einj case) SET_ERROR_TYPE_WITH_ADDRESS and/or SET_ERROR_TYPE will be
>> ignored. So based on einjv2 is supported or not, we can have either einjv2 or einj 
>> directory with the related params files in it respectively. 
>> Kindly let us know your thoughts.
> Piyush,
>
> There are a lot of validation tests built on top of the EINJ v1 Linux interface and interest
> in keeping them working rather than forcing a giant "change everything" when the first
> EINJ V2 system arrives.
>
> BIOS team here thinks that the EINJ V2 spec change is (or can be) incremental.
> Platform firmware can choose to continue supporting EINJ V1 while also providing
> EINJ V2 actions.
>
> So Linux should be prepared to handle:
>
> 1) Legacy systems with just the V1 interface.
>
> 2) Incremental systems that have both V1 and V2 interfaces.
>
> 3) Future looking systems that only have the V2 interface.
>
> -Tony

Hi all,

It seems to me like backwards compatibility has been a big priority historically for Linux.
I guess with debugfs we get more leeway to change things, however this interface seems
to be present for a very long time and seems to be entrenched enough to keep backwards
compatibility.


Piyush,
Did you make any progress on the solution ? I can offer some help if you don't have BW to work
on this.


Good video on the topic :)
Link: https://www.youtube.com/watch?v=Nn-SGblUhi4&ab_channel=FelipeContreras

>
>