Re: [RFC PATCH 1/2] EDAC/ghes: Add EDAC device for the CPU caches

Borislav Petkov
2021-01-18T18:38:35Z

On Fri, Jan 15, 2021 at 11:06:30AM +0000, Shiju Jose wrote:
> L2 cache corrected errors are detected occasionally on few of
> our ARM64 hardware boards. Though it is rare, the probability of
> the CPU cache errors frequently occurring can't be avoided.
> The earlier failure detection by monitoring the cache corrected
> errors for the frequent occurrences and taking preventive
> action could prevent more serious hardware faults.
>
> On Intel architectures, cache corrected errors are reported and
> the affected cores are offline in the architecture specific method.
> http://www.mcelog.org/cache.html
>
> However for the firmware-first error reporting, specifically on
> ARM64 architectures, there is no provision present for reporting
> the cache corrected error count to the user-space and taking
> preventive action such as offline the affected cores.

How hard was it to write that in your first submission? What do you
think would be the best way to persuade a patch reviewer/maintainer to
take a look at your submission?

> >Why a separate Kconfig item?
> CONFIG_EDAC_GHES_CPU_CACHE_ERROR is added to make this
> feature optional only for the platforms which need this and supported.
>
> >
> >> + depends on EDAC_GHES

depends on EDAC_GHES hardly expresses which platforms need it/support
it.

If anything, depends on ARM64.

> >Init stuff belongs into ghes_scan_system().
> >
> Did you mean calling ghes_edac_create_cpu_device() in the ghes_scan_system()?

I mean, all hardware discovery needs to happen in ghes_scan_system
- you don't need to call those from outside the driver, in
ghes_edac_register().

--
Regards/Gruss,
Boris.