linux-kernel - Re: [PATCH v3] x86/mce: Try printing all machine check banks known before panic

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Message-ID: <20141122094433.GA12152@pd.tnic>
Date:	Sat, 22 Nov 2014 10:44:33 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	rui wang <ruiv.wang@...il.com>
Cc:	"Luck, Tony" <tony.luck@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"gong.chen@...ux.intel.com" <gong.chen@...ux.intel.com>,
	"Wang, Rui Y" <rui.y.wang@...el.com>
Subject: Re: [PATCH v3] x86/mce: Try printing all machine check banks known
 before panic

On Sat, Nov 22, 2014 at 10:16:49AM +0800, rui wang wrote:
> I think both possibilities are valid. But experiments show that the
> error logs are not in the dmesg preserved by kdump in /var/crash/
> after panic and reboot, and not in the mcelog.entry[] array in the
> kernel. So they must be somewhere in user space memory. Even if we
> have serial console connected we still can't cache them. The
> difficulty is that there's no easy way to force a user space daemon to
> do something during panic.
> 
> The new banks_saved[] array acts like a safe guard when you pass
> something to someone else - to prevent it from getting lost in the
> interim.

... and instead of duplicating the mcelog functionality partially by
adding yet another array of struct mces, simply change mcelog to not
zero out its contents and dump the last 32 errors that passed through
there.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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