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Wed, 17 Nov 2021 14:47:38 +0000 Received: from b03ledav006.gho.boulder.ibm.com (b03ledav006.gho.boulder.ibm.com [9.17.130.237]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1AHElb0b25493844 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Nov 2021 14:47:37 GMT Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ED28AC6057; Wed, 17 Nov 2021 14:47:36 +0000 (GMT) Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BD1BCC6067; Wed, 17 Nov 2021 14:47:36 +0000 (GMT) Received: from localhost (unknown [9.211.102.167]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Wed, 17 Nov 2021 14:47:36 +0000 (GMT) From: Nathan Lynch To: Michael Ellerman , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] powerpc/pseries: delete scanlog In-Reply-To: <877dd7m5jd.fsf@mpe.ellerman.id.au> References: <20210920173203.1800475-1-nathanl@linux.ibm.com> <87sfvvijjw.fsf@linux.ibm.com> <877dd7m5jd.fsf@mpe.ellerman.id.au> Date: Wed, 17 Nov 2021 08:47:36 -0600 Message-ID: <87mtm2j0tz.fsf@linux.ibm.com> Content-Type: text/plain; charset=utf-8 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: hfOOVuoSe-mZImfzP5xzbhpbktMGfSnt X-Proofpoint-ORIG-GUID: hfOOVuoSe-mZImfzP5xzbhpbktMGfSnt Content-Transfer-Encoding: quoted-printable X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-17_05,2021-11-17_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 adultscore=0 clxscore=1015 mlxlogscore=999 lowpriorityscore=0 bulkscore=0 spamscore=0 phishscore=0 impostorscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111170073 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tyreld@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Michael Ellerman writes: > Nathan Lynch writes: >> Nathan Lynch writes: >>> Remove the pseries scanlog driver. >>> >>> This code supports functions from Power4-era servers that are not prese= nt >>> on targets currently supported by arch/powerpc. System manuals from this >>> time have this description: >>> >>> Scan Dump data is a set of chip data that the service processor gathe= rs >>> after a system malfunction. It consists of chip scan rings, chip trace >>> arrays, and Scan COM (SCOM) registers. This data is stored in the >>> scan-log partition of the system=E2=80=99s Nonvolatile Random Access >>> Memory (NVRAM). >>> >>> PowerVM partition firmware development doesn't recognize the associated >>> function call or property, and they don't see any references to them in >>> their codebase. It seems to have been specific to non-virtualized >>> pseries. >> >> Just bumping this to see if there are any objections. > > Not an objection, I like nothing better than dropping old unused cruft, > but are we sure it's safe to remove the proc file? > > I see that rtas_errd still looks for it, have you checked that it will > handle the absence of the file gracefully and continue doing whatever > else it does? Uhh. I will stop forgetting to check ppc64_diag when making such changes. Thanks for pointing this out. > On further inspection it looks like the code that looks for it in > rtas_errd is #if 0'ed out (??), so maybe it's dead. Yes it seems so. From rtas_errd's main(): #if 0 /*=20 * Check to see if a new scanlog dump is available; if so, copy it to * the filesystem and associate the dump with the first error processed. */ check_scanlog_dump(); #endif And that's the only entry point into the code that collects the scanlog data. And that dead code appears to deal with the absence of /proc/ppc64/scan-log-dump gracefully. It has been like that since initial git import in 2013. > Anyway if you can test that rtas_errd still works that'd be good. I've verified that it starts normally and logs EPOW events associated with partition migration. > Presumably there's no other code that cares about the proc file. AFAIK this is right. powerpc-utils and librtas do not use it. librtas has a wrapper for the calling the associated RTAS function directly, but that's fine. I tried using GitHub's search to find instances of "scan-log-dump" that weren't from Linux or ppc64_diag (need to be logged in I think): https://github.com/search?q=3D%22scan-log-dump%22+-path%3Aarch%2Fpowerpc+-f= ilename%3Ascanlog.c+-extension%3Apatch&type=3DCode&ref=3Dadvsearch&l=3D&l=3D This hasn't yielded any unexpected users. There may be better search terms but that's what a few minutes of fiddling with it got me.