linux-kernel - Re: [PATCH 1/3] x86/MCE, EDAC/mce_amd: Add support for new MCA

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Date:   Mon, 18 Jul 2022 10:57:19 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <yazen.ghannam@....com>
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        tony.luck@...el.com, x86@...nel.org,
        Smita.KoralahalliChannabasappa@....com
Subject: Re: [PATCH 1/3] x86/MCE, EDAC/mce_amd: Add support for new
 MCA_SYND{1,2} registers

On Mon, Jul 11, 2022 at 05:31:41PM +0000, Yazen Ghannam wrote:
> Is your concern specifically on growing/changing struct mce, or is it more
> about limiting info sent to userspace?

Well, both, kinda.

> If it's the former, then I've been thinking it would be good to introduce a
> new internal "struct mce_ext" that includes struct mce plus other things. This
> way struct mce can still be uapi, and things like mcelog can use it. And at
> the same time we can new data used in the kernel or shared through
> tracepoints.
> 
> /* Extended MCE structure */
> struct mce_ext {
> 	struct mce *m;
> 	/* new stuff here */
> };
> 
> What do you think?

The moment you make it part of a trace record, it practically becomes
ABI.

So we could have some opaque blob which is called vendor-specific data
and which is dumped raw to userspace, without any specification to its
format so that luserspace doesn't get any ideas...

Lemme talk to rostedt.

-- 
Regards/Gruss,
    Boris.

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