From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f179.google.com (mail-pf1-f179.google.com [209.85.210.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 022D4433A6 for ; Tue, 9 Apr 2024 22:41:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712702481; cv=none; b=FBA+QuAMlR17S/yc5rbeR5lP62icY44CPGBetJA7gM+AiQZTwGFMZOXR1RBFOeIOV6+t0zyONY1YY4757JDlq7nwTyIsunAMjKrRsmSXAwbxM29DFx1/Myc1qpoMFQz5Jv/hYOsJSFoWJxOxz7YUZ9s0G8rjt0jBGpibbMZDD+U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712702481; c=relaxed/simple; bh=3NhGzvOWJu8inKax2x217roNis9rN/Ham5KfaPA0/Q4=; h=Content-Type:From:Mime-Version:Subject:Date:Message-Id:References: Cc:In-Reply-To:To; b=mWIj0dmfklLTGwsoV2k3eFwCyWQdvCTcRK/DqAJBG5xqb84IJvWRdYLGAr13h1TPXCufKy+h7HHXIk3DK5AjNltO7y7VeEjld8lzIT2Eth1hfy0vyloAx0bnrewQoDOd08SOCX31DffCThYBFbPUJbMyO3ajD6BrAAUc9KBhkiU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org; spf=pass smtp.mailfrom=joelfernandes.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b=le6yobmN; arc=none smtp.client-ip=209.85.210.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=joelfernandes.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="le6yobmN" Received: by mail-pf1-f179.google.com with SMTP id d2e1a72fcca58-6ecf05fd12fso5127135b3a.2 for ; Tue, 09 Apr 2024 15:41:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1712702479; x=1713307279; darn=vger.kernel.org; h=to:in-reply-to:cc:references:message-id:date:subject:mime-version :from:content-transfer-encoding:from:to:cc:subject:date:message-id :reply-to; bh=3NhGzvOWJu8inKax2x217roNis9rN/Ham5KfaPA0/Q4=; b=le6yobmNKIk7IcTrMR7Yh1AwzfvsJdsn82Viz0c1EC3SmHM/Rx+55n58Ug4HFiHvP+ mvLXPVPbToE1zLeMe7C1+f/FOd9XTiMtbuVNSEvBLoed+MtHbbtgyIThSBoEWKXyGwVF K7zRAWYmoqkOjBvgpPSaPytSO9wvKW7kAwOeA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712702479; x=1713307279; h=to:in-reply-to:cc:references:message-id:date:subject:mime-version :from:content-transfer-encoding:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=3NhGzvOWJu8inKax2x217roNis9rN/Ham5KfaPA0/Q4=; b=Sv0b9Tw2ddHTASuApWZYTswSReN7a+DBdj/ACks1saQhzLr/NKvBDtoU1rAhgthR1x alghdP5r+rMa+jDG5J4Tem8CP50bqDhk5/63AJWZvjR5lxYp7szGSOA3RPbofN0ym12T T0YfEUV+3ldYfiCWyUwinvKIcyoAs9srPrl2Xw4lBA1lCk9oc/o+M4gcA8K9NbWupTsM VxF8e3nvA926rfggh5cLSEasyYB8Yo/wQHcL60dA5dJhZKbG0GV6RsPX3dkuteOLY5OX 5cKa78Xtr7feEbrEwvhkgx+Bs5UwTk/CTCGab8zocAZAd4G2A1y4k5xyPgKY7mFCMOuj zkKA== X-Forwarded-Encrypted: i=1; AJvYcCW+2C/ysZ1Cbgdd2t/w0stimUPMSrYPANw/964Wyk2s/xnWZegWB6YQ2oEFhL4G0DtoGFPbS9+E6hUKesfQ6wDCEe9uGcffQ9S9mE/q X-Gm-Message-State: AOJu0YzDqvWeO4GScYbNs4zmO5Er5npUep57xbbT/tXFcOye4iB7TE2B J/c9VTT1d8XasXYKMwgedXo3sC1WHBXwqtx0COPQv89/C1opPPB7TEZsw73D3nw= X-Google-Smtp-Source: AGHT+IGf7AyQcGgtDnxdEc6zeyqopRNu0tZWpw/6iFI0a7xHNGrXDfFFZjth8bXqtf7pRwJfL78atg== X-Received: by 2002:a05:6a21:1a9:b0:1a3:ae75:d6f5 with SMTP id le41-20020a056a2101a900b001a3ae75d6f5mr1505619pzb.20.1712702479019; Tue, 09 Apr 2024 15:41:19 -0700 (PDT) Received: from smtpclient.apple ([103.98.78.154]) by smtp.gmail.com with ESMTPSA id g26-20020aa79f1a000000b006ecee8c8c0fsm7200440pfr.176.2024.04.09.15.41.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Apr 2024 15:41:18 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Joel Fernandes Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (1.0) Subject: Re: [POC][RFC][PATCH 0/2] pstore/mm/x86: Add wildcard memmap to map pstore consistently Date: Wed, 10 Apr 2024 04:11:05 +0530 Message-Id: <9F1B6537-F0BF-46E1-92A2-92C082DDB573@joelfernandes.org> References: Cc: Kees Cook , Steven Rostedt , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , "Guilherme G. Piccoli" , linux-hardening@vger.kernel.org, Guenter Roeck , Ross Zwisler , wklin@google.com, Vineeth Remanan Pillai , Suleiman Souhlal , Linus Torvalds , Catalin Marinas , Will Deacon In-Reply-To: To: "Luck, Tony" X-Mailer: iPhone Mail (21D61) > On Apr 10, 2024, at 3:55=E2=80=AFAM, Luck, Tony wrot= e: >=20 > =EF=BB=BF >>=20 >>> I forgot to mention that this makes it trivial for any machine that does= n't >>> clear memory on soft-reboot, to enable console ramoops (to have access t= o >>> the last boot dmesg without needing serial). >>>=20 >>> I tested this on a couple of my test boxes and on QEMU, and it works rat= her >>> well. >>=20 >> I've long wanted a "stable for this machine and kernel" memory region >> like this for pstore. It would make testing much easier. >=20 > Which systems does this work on? I'd assume that servers (and anything > else with ECC memory) would nuke contents while resetting ECC to clean > state. If that were the case universally, then ramoops pstore backend would not wor= k either? And yet we get the last kernel logs via the pstore for many years now, on em= bedded-ish devices. =46rom my reading, ECC-enabled DRAM is not present on lots of systems and II= RC, pstore ramoops has its own ECC. Or did I miss a recent trend with ECC-enabled DRAM? - Joel >=20 > -Tony