linux-kernel - Re: [PATCH v2 8/8] x86/MCE/AMD Support new memory interleaving modes during address translation

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Date:   Tue, 29 Sep 2020 08:21:17 -0500
From:   Yazen Ghannam <yazen.ghannam@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        tony.luck@...el.com, x86@...nel.org,
        Smita.KoralahalliChannabasappa@....com
Subject: Re: [PATCH v2 8/8] x86/MCE/AMD Support new memory interleaving modes
 during address translation

On Mon, Sep 28, 2020 at 08:14:07PM +0200, Borislav Petkov wrote:
> On Mon, Sep 28, 2020 at 10:53:50AM -0500, Yazen Ghannam wrote:
> 
> > I agree that the translation code is implementation-specific and applies
> > only to DRAM ECC errors, so it make sense to have it in amd64_edac. The
> > only issue is getting the address translation to earlier notifiers. I
> > think we can add a new one in amd64_edac to run before others. Maybe this
> > can be a new priority class like MCE_PRIO_PREPROCESS, or something like
> > that for notifiers that fixup the MCE data.
> 
> Well, I'm not sure you need notifiers here - you wanna call
> mce_usable_address() and in it, it should do the address conversion
> calculation to give you a physical address which you can feed to
> memory_failure etc.
> 
> Now, mce_usable_address() is core code and we can make core code call
> into a module but that is yucky. So *that* is your reason for keeping it
> where it is.
>

Okay, we'll keep the code where it is. I'll work on another set to call
the address translation with mce_usable_address().

> Looking at its size:
> 
> $ readelf -s vmlinux | grep umc_normaddr_to
>   2864: ffffffff817d8ae5   168 FUNC    LOCAL  DEFAULT    1 umc_normaddr_to_[...]
>  91866: ffffffff81030e00  1127 FUNC    GLOBAL DEFAULT    1 umc_normaddr_to_[...]
> 
> that's something like ~1.3K and if you split it and do some
> experimenting, you might get it even slimmer. Not that ~1.3K is that
> huge for current standards but we should always aim at not bloating the
> fat guy our kernel already is.
>

Okay, I'll keep an eye on this and try to slim it down.

Thanks,
Yazen