linux-kernel - RE: [PATCH v2] ACPI: APEI: EINJ: EINJV2 support added

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Date:   Thu, 4 May 2023 21:00:51 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Piyush Malgujar <pmalgujar@...vell.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "xueshuai@...ux.alibaba.com" <xueshuai@...ux.alibaba.com>,
        "benjamin.cheatham@....com" <benjamin.cheatham@....com>,
        "bp@...en8.de" <bp@...en8.de>,
        "james.morse@....com" <james.morse@....com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "rafael@...nel.org" <rafael@...nel.org>
CC:     "jannadurai@...vell.com" <jannadurai@...vell.com>,
        "cchavva@...vell.com" <cchavva@...vell.com>
Subject: RE: [PATCH v2] ACPI: APEI: EINJ: EINJV2 support added

> +An error injection example::
> +
> +  # cd /sys/kernel/debug/apei/einj
> +  # cat available_error_type         # See which errors can be injected
> +  0x00000001 EINJV2 Processor Error
> +  0x00000002 EINJV2 Memory Error
> +  0x00000004 EINJV2 PCI Express Error
> +  # echo 0x2 > error_type
> +  # echo 0x5 > flags
> +  # echo 0x12345000 > param1
> +  # echo 0x2 > param5
> +  # echo 1 > error_inject
>
> Is the expectation that platforms that implement EINJV2 will not include legacy
> EINJ support?

I spoke to some BIOS folks here. They said that the ACPI 6.5 change is an
extension to the action table with new opcodes for GET/SET when EINJV2
is supported. The legacy actions are not deprecated. So platform firmware could
support both old and new injection formats.

So I'm going to double down on this:

> Maybe it would be better to change the top-level directory to:
>
>	/sys/kernel/debug/apei/einjv2

and say this isn't a "maybe". The EINJV2 interface files should go
in a new directory. The old files should continue to work (assuming
firmware still enumerates the old available types).

Simplifying the interface for EINJV2 in the new directory is an option.
I think we should take it ... the "paramN" files that mean different
things for different injection types were an evolution rather than a design.

-Tony