linux-kernel - Re: [PATCH 12/21] EDAC, ghes: Add support for legacy API counters

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Date:   Wed, 12 Jun 2019 18:41:06 +0000
From:   Robert Richter <rrichter@...vell.com>
To:     James Morse <james.morse@....com>
CC:     Borislav Petkov <bp@...en8.de>, Tony Luck <tony.luck@...el.com>,
        "Mauro Carvalho Chehab" <mchehab@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 12/21] EDAC, ghes: Add support for legacy API counters

On 29.05.19 16:13:02, James Morse wrote:
> On 29/05/2019 09:44, Robert Richter wrote:
> > The ghes driver is not able yet to count legacy API counters in sysfs,
> > e.g.:
> > 
> >  /sys/devices/system/edac/mc/mc0/csrow2/ce_count
> >  /sys/devices/system/edac/mc/mc0/csrow2/ch0_ce_count
> >  /sys/devices/system/edac/mc/mc0/csrow2/ch1_ce_count
> > 
> > Make counting csrows/channels generic so that the ghes driver can use
> > it too.
> 
> What for?

With EDAC_LEGACY_SYSFS enabled those counters are exposed to sysfs,
but the numbers are wrong (all zero).

> Is this for an arm64 system? Surely we don't have any systems that used to work with these
> legacy counters. Aren't they legacy because we want new software to stop using them!

The option is to support legacy userland. If we want to provide a
similar "user experience" as for x86 the counters should be correct.
Of course it is not a real mapping to csrows, but it makes that i/f
work.

In any case, this patch cleans up code as old API's counter code is
isolated and moved to common code. Making the counter's work for ghes
is actually a side-effect here. The cleanup is a prerequisit for
follow on patches.

-Robert

> 
> 
> Thanks,
> 
> James