From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6D9F8CD98D2 for ; Fri, 12 Jun 2026 18:38:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=LrNLo7Ew0vkv5/2r20/RtbigqwQYa7RBbYfUHsMbkTE=; b=M6LdUFDhZvhXntgGGbGt45GxeR PGDO1au+3ip9XsWE1ZKBj7L26C5boiMgqSpb9K4CicD4WQ+Qo1mU0ZlSS4qckoyVscS6I/5cf+lcD fNXj6ZbcgfalLfXzNGC/LfhJdytDBTsxp5pMVw131Aqgw7mgUAm0WOIKUwsM9AOkH9hf1v7KBjwyc VWtMVEBu17FhHiVLJXiiMmEPjrPevXT78Esrxcv62FGKYsP9KpIAuwBo5GWYPRFgukAsAdKrRxB38 GryOY6byZWn7RtveRApllplfS8kehdTcFmQY+eKZosINSNk3498VysfHv7/y8qxtCZHdFd4LCLrIo EylQ8NSg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wY6mD-0000000BPlv-0ODZ; Fri, 12 Jun 2026 18:38:45 +0000 Received: from mail-qv1-xf2c.google.com ([2607:f8b0:4864:20::f2c]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wY6mA-0000000BPla-0AgP for kexec@lists.infradead.org; Fri, 12 Jun 2026 18:38:43 +0000 Received: by mail-qv1-xf2c.google.com with SMTP id 6a1803df08f44-8ccf6a63a45so16650786d6.3 for ; Fri, 12 Jun 2026 11:38:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; t=1781289520; x=1781894320; darn=lists.infradead.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=LrNLo7Ew0vkv5/2r20/RtbigqwQYa7RBbYfUHsMbkTE=; b=KBQfJzGbbO4VDYh+ND++0+M4leu1lj2RlZOY0sRCFx+RMfQs/GZpvFUU+X22JMwY0O dEorCtavsLk8Kew46tKWyJERu7uUm5g+GzIEJs/Lyeya8TmFWrgzfJKr1Pl83BIVc9mc Fun0my4w3cQhlyo8aYv43vPNF9zwOsRYbfLHILmfw+EkT5uIW1mhWMRXflt90wN7gV7t tfPm/M8jj5GTwyLsE+wBH1SdKEBHhWBEWnW6ZmwNNDEnw0eY3JNK5pIN64Rs45x6x3lt Y67Qp1+kgcM4IG5soPgsEYpx0fYR1onE9UQuBKmFfyEaUeldqpcDuPJTLCJhTqz9QxCm CN5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781289520; x=1781894320; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=LrNLo7Ew0vkv5/2r20/RtbigqwQYa7RBbYfUHsMbkTE=; b=Pi8X/axt6hV1WhZGLmrq+ZYIy+981a3AuAFsrMy4UyyskgWRM7/INBnSSbEblXhJP0 lFgDcO5oVGtVQf26ZqGYAgBDvoCVIKxv8eckYgRMBzBv3OKDZcPqSDEm0Ofl1TMclPYu dpTasVuWQ80TRJs3tcZ5drIj6lp2z/OPhJSFSa/7tDr41zxReA12KJ+TIB1uinifKksp OyzKUhvSfo+OFjyNi1VL91mI/ar8QGNdaKWuiBd8npX8/+VOJKd5M1BoDBQU+TztUA95 UjjtsapWUyHovkhOyQzvu819t3zXxVy0AWxQoPYSoXz3M+Zyr0cglT2WDqodiVL4D5tl KiOA== X-Forwarded-Encrypted: i=1; AFNElJ/DYMjBKQFyzZcCnQIpUw5v6FFt4BnDrWMZ8Tbqv/lapE407zcGopI6WMozYrNWoomy2Kpd1w==@lists.infradead.org X-Gm-Message-State: AOJu0Yy0bZ7kmI2JQmX1uVzzrX9VjxsquPObwmMUoMGTGBmKwJ3Vr4s3 hPwibgyYL2cP72zW85J2cAn6n9YqqdVX56jpakYou2M9qUfdBXNbxRbs9BE6Jaymlcg= X-Gm-Gg: Acq92OH2AIHtfj/VXDqQKJlu9P3v7iEOU0hHBf7IBgLBYzjImjKDsQFpDnqwzvdW1eE VGKKPYy24mahtEJgRaDANT6axxr0SyFhCvdL/7pTRYxClnb5i8On9o621TwZeRYfOtpkL5zMqIf lFL8ksJyGUkPco7CU+suE1cHaY04ToDJKqwed6Set5eGQPZ2scbGwWrHQn5oFq4hYoS3ImUGXPG HcojlggIH48iD68cPtQMgUEJgNtIiNH4sGqajVSIAQMF5jt2HwJskvmJTxRqaoQJuwIPQgs/QSt vAr6lVGpee5LUwEA8xCk6yw9ZAvb70nRs5TdrqgAw06OI1VBWePa0U145qxkLgsjhQ0dT3IhpJt IMf24njy6iLYumd2+7KLMu5VakqbQB5mIV4qbuwXOiPBQWEr621JTMOA9hV8gjeKh70GGKoNbdD rqdFbhmF5/gnXxiAN1z6Yo0Gg8Pwsnbsf/TcEpqJFxbLlZJf4Cwj0= X-Received: by 2002:a05:620a:3703:b0:914:c82c:79fe with SMTP id af79cd13be357-9161bd3547cmr582475285a.27.1781289520113; Fri, 12 Jun 2026 11:38:40 -0700 (PDT) Received: from plex ([71.181.43.54]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9161a03d6fcsm272063885a.35.2026.06.12.11.38.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jun 2026 11:38:39 -0700 (PDT) Date: Fri, 12 Jun 2026 18:38:38 +0000 From: Pasha Tatashin To: =?utf-8?B?TWljaGHFgiBDxYJhcGnFhHNraQ==?= Subject: Re: [PATCH v2] pstore: add a KHO backend Message-ID: References: <20260605121040.1177072-1-mclapinski@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260612_113842_100026_2F0A2306 X-CRM114-Status: GOOD ( 25.92 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tony Luck , Pasha Tatashin , Kees Cook , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Alexander Graf , Mike Rapoport , Pratyush Yadav Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 06-12 19:57, Michał Cłapiński wrote: > On Fri, Jun 12, 2026 at 7:21 PM Pasha Tatashin > wrote: > > > > On 06-12 17:42, Mike Rapoport wrote: > > > Hi, > > > > > > On Fri, Jun 05, 2026 at 02:10:40PM +0200, Michal Clapinski wrote: > > > > Up to this point to preserve late shutdown logs in memory, users had to > > > > predefine a memory region using ramoops. This commit changes this by > > > > preserving a buffer using kexec-handover. > > > > > > > > pstore_kho supports preserving only 1 dmesg buffer. > > > > It gets replaced with the new buffer on every kexec, so the user has to > > > > copy the file out of pstore after every kexec. > > > > There is no erase() support. > > > > > > Sorry I didn't jump at v1. > > > > > > pstore does not really need a KHO backend. It can use ram backend with > > > reserve_mem and reserve_mem can be preserved with KHO already. > > > > I just tested it, and it works well, I think it would be fine for > > Google's requirements: > > > > CONFIG_PSTORE=y > > CONFIG_PSTORE_RAM=y > > CONFIG_PSTORE_CONSOLE=y > > Is it common to write to this console? I think what I typically see in > the console are error logs that are also in dmesg, so if I preserve > console logs and dmesg I just have 2 files where one is a subset of > lines from the other. We need either your KHO backend, or the following patch: https://lore.kernel.org/all/20260612172623.1218280-1-pasha.tatashin@soleen.com/ We need all dmesg messages. Pasha > > > With the following parameters: > > 'reserve_mem=2M:2M:dmesg_buffer ramoops.mem_name=dmesg_buffer ramoops.max_reason=5 ramoops.console_size=2097152 ramoops.record_size=0 ramoops.ftrace_size=0 ramoops.pmsg_size=0' > > > > KHO preserves pstore properly. However, we need one patch that would > > allow for ramoops console to capture the output even when quiet is > > provided. > > > > Pasha