From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3zmQBZ32cvzF0lW for ; Wed, 21 Feb 2018 15:54:30 +1100 (AEDT) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w1L4sRRf066999 for ; Tue, 20 Feb 2018 23:54:28 -0500 Received: from e38.co.us.ibm.com (e38.co.us.ibm.com [32.97.110.159]) by mx0a-001b2d01.pphosted.com with ESMTP id 2g901yudu4-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 20 Feb 2018 23:54:26 -0500 Received: from localhost by e38.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 20 Feb 2018 21:54:25 -0700 From: Stewart Smith To: Balbir Singh , linuxppc-dev@lists.ozlabs.org Cc: npiggin@gmail.com Subject: Re: [RFC] powerpc/powernv/mce: Don't silently restart the machine In-Reply-To: <20180221010111.30517-1-bsingharora@gmail.com> References: <20180221010111.30517-1-bsingharora@gmail.com> Date: Wed, 21 Feb 2018 15:54:20 +1100 MIME-Version: 1.0 Content-Type: text/plain Message-Id: <87vaeruemb.fsf@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Balbir Singh writes: > On MCE the current code will restart the machine with > ppc_md.restart(). This case was extremely unlikely since > prior to that a skiboot call is made and that resulted in > a checkstop for analysis. > > With newer skiboots, on P9 we don't checkstop the box by > default, instead we return back to the kernel to extract > useful information at the time of the MCE. While we still > get this information, this patch converts the restart to > a panic(), so that if configured a dump can be taken and > we can track and probably debug the potential issue causing > the MCE. I agree with the patch, although I'd be nervous stating that skiboot is going to keep this behaviour. In *theory* we should only ever get a platform error when there's actually something that isn't the kernel's fault. Like any firmware promise though, it's slightly less reliable than one from a politician. I'd say that in this case deferring to policy on what to do in event of panic() is the right thing. -- Stewart Smith OPAL Architect, IBM.