linux-kernel - Re: [PATCH 3/3] ghes_edac: add platform check to enable ghes

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Message-ID: <20170719055235.GD26030@nazgul.tnic>
Date:   Wed, 19 Jul 2017 07:52:35 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Kani, Toshimitsu" <toshi.kani@....com>
Cc:     "tony.luck@...el.com" <tony.luck@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "srinivas.pandruvada@...ux.intel.com" 
        <srinivas.pandruvada@...ux.intel.com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>
Subject: Re: [PATCH 3/3] ghes_edac: add platform check to enable ghes_edac

On Tue, Jul 18, 2017 at 09:20:44PM +0000, Kani, Toshimitsu wrote:
> I agree that 'osc_sb_apei_support_acked' should be checked when
> enabling ghes_edac.  I do not know the details of existing issues, but
> it sounds unlikely that this will address all of them since bugs can be
> everywhere.

No, see below.

> For instance, ghes_edac relies on DMI/SMBIOS info, unlike
> other EDAC drivers, which can be buggy regardless of this _OSC info.

That's the problem with firmware. You can't really fix it and it is
buggy as hell.

> I agree that making ghes_edac as a normal module is a good thing, but I
> do not think it's going to solve this issue.

Of course it will - if the firmware says it wants to look at the errors
first, then it gets to do so. This is the whole handling of hardware
errors in the firmware deal. I admit, sometimes it makes sense because
the firmware has the most intimate knowledge of the platform and, in
a perfect world, we won't ever need to have platform-specific EDAC
drivers.

But, we don't live in a perfect world. And the vendor execution of the
whole firmware-error-handling deal is an abomination at best.

So, if we realize that the firmware is buggy, we can use a platform list
to blacklist it (^hint hint^) and have a parameter to disable ghes_edac
from loading.

But we'll deal with that when we get to cross that bridge. Right now,
I'd like to do the loading spec-conform and not fiddle with white-,
black-, or any-other-color lists.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--