Re: Layerscape behavior when a UE is detected

From: York Sun <york.sun@nxp.com>
To: Tracy Smith <tlsmith3777@gmail.com>
Cc: "bp@alien8.de" <bp@alien8.de>,
	"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
	"util-linux@vger.kernel.org" <util-linux@vger.kernel.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: Layerscape behavior when a UE is detected
Date: Wed, 5 Dec 2018 22:57:18 +0000	[thread overview]
Message-ID: <AM0PR04MB39717D1017A161D54940486D9AA80@AM0PR04MB3971.eurprd04.prod.outlook.com> (raw)
In-Reply-To: CAChUvXNSGosbBbiBh-MF8FsnKpL3jMaS-fr_BzQAjEcPCWi7Ew@mail.gmail.com

On 12/5/18 2:54 PM, Tracy Smith wrote:
>>> Question 4) If so, will a panic ever be called if there is a hardware
>>> uncorrectable memory failure?
> 
>> No. It is up to upper layer of EDAC driver. Layerscape driver only reports CEs and UEs.
> 
> Just to be clear, the upper layer of the EDAC driver will or will not
> panic when a UE is detected on layerscape?
> 
> If there is no panic by the upper layer and no reset triggered by the
> layerscape CPLD or memory controller, what happens on layerscape when
> a UE is detected by the memory controller?
> 
> Forcing a UE by grounding a dataline caused a reset on layerscape
> after a few seconds, but no panic. It is unclear why it reset, but it
> appears as though a WDT was tripped. The UE was reported by EDAC and
> seen in the log.
> 
I can't help you on that. I never tried to force errors by grounding the
signals. You have read the driver. Do you see panic? The idea is to
report the error and let upper layer to decide what to do. Sometimes
limping forward is better than reset or panic. Again, it is not driver's
responsibility.

York