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 B40B2C3ABD4 for ; Mon, 12 May 2025 14:24:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:References :In-Reply-To:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=p4jB3wW+qXOV6CUb7Eg9zRzr1KMsYEJogWQ+kb3dg4I=; b=Fjpgso6qFECWvH ZiRWEJG1tx0W0jq2uotdo58ndRda2svIxdWiqjeWOoi8R69a3oPRuD5R6KkDVwbluaSPjQgpfg451 0IA8K6ELFhqwzfpuq0zbXchluu+aaQ1tx0dHOewy1U4JZ7GkpH1zUX0TbZn+8/mc0g3kKK24Wcxcj hBBnY7ah322utLCsG5TjYraubcva8R3sAauQTzmkCS4bqPY2NDstIsfhBHMSQTOfilfbOHajN4J+H 4SG9ZHuA917Vr/nVsW/MecDrPiDs0/hwmD96pFzoP+D8ST6RxAE2QH4Ah4PaQkFLTjR6Pi0UNXrjk ISXDsXXb2GiBucEHSouA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uEU4z-00000009iAq-1Hlh; Mon, 12 May 2025 14:24:29 +0000 Received: from relay1-d.mail.gandi.net ([2001:4b98:dc4:8::221]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uETgl-00000009eKu-0YuK for linux-mtd@lists.infradead.org; Mon, 12 May 2025 13:59:28 +0000 Received: by mail.gandi.net (Postfix) with ESMTPSA id 3EF1E439F3; Mon, 12 May 2025 13:59:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1747058363; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HUmofXhvscOsV22HCTbEBE6mTbH7lup2/FhvFaKJTT0=; b=IGtGo5mrnhcTIR6KHAVd0KcciOdvRmlKgssw6BUtwGWEyYyrGWJijuB7/mfyqfmPhbRjfz kNDgM6HCeU+M1QN0Tt6LK4DICFM9fOAXOTAQL+MPgeQuCANZYN3UP9PJ9ELqZBbdlmay4A 2dic1WtPjBbZNiN625v3i0s9okNaBwkM3BtPIcvc83YuyM3DIkIS6pCnyjGHgqEmhKK36i n7T7zyII7NXZ6iCtre00RJYWswSFVYTyxgctszti/Y6asCVrR0GuqNZRHmExXt8UiCgeI8 2zHoUxmXGgMocFO34860z5VBRddPVLhkO/qW5ldsUrg0BmXicwoKEp9POBc7Ag== From: Miquel Raynal To: =?utf-8?B?Q3PDs2vDoXM=?= Bence Cc: Richard Weinberger , linux-mtd , linux-kernel , Vignesh Raghavendra Subject: Re: [PATCH v3] mtd: Verify written data in paranoid mode In-Reply-To: <4ebe2146-ee1c-4325-8259-be3803475f1f@prolan.hu> (=?utf-8?B?IkNzw7Nrw6Fz?= Bence"'s message of "Mon, 12 May 2025 15:13:20 +0200") References: <20250512084033.69718-1-csokas.bence@prolan.hu> <87frhambri.fsf@bootlin.com> <1200504110.30346467.1747054025727.JavaMail.zimbra@nod.at> <4ebe2146-ee1c-4325-8259-be3803475f1f@prolan.hu> User-Agent: mu4e 1.12.7; emacs 29.4 Date: Mon, 12 May 2025 15:59:22 +0200 Message-ID: <87r00ugcat.fsf@bootlin.com> MIME-Version: 1.0 X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdeftddugeegucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufgjfhgffffkgggtgfesthhqredttderjeenucfhrhhomhepofhiqhhuvghlucftrgihnhgrlhcuoehmihhquhgvlhdrrhgrhihnrghlsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeffgefhjedtfeeigeduudekudejkedtiefhleelueeiueevheekvdeludehiedvfeenucfkphepledtrdekledrudeifedruddvjeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeltddrkeelrdduieefrdduvdejpdhhvghloheplhhotggrlhhhohhsthdpmhgrihhlfhhrohhmpehmihhquhgvlhdrrhgrhihnrghlsegsohhothhlihhnrdgtohhmpdhnsggprhgtphhtthhopeehpdhrtghpthhtoheptghsohhkrghsrdgsvghntggvsehprhholhgrnhdrhhhupdhrtghpthhtoheprhhitghhrghrugesnhhougdrrghtpdhrtghpthhtoheplhhinhhugidqmhhtugeslhhishhtshdrihhnfhhrrgguvggrugdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehvihhgnhgvshhhrhesthhirdgtohhm X-GND-Sasl: miquel.raynal@bootlin.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250512_065927_639960_31637042 X-CRM114-Status: GOOD ( 18.86 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org SGVsbG8sCgpPbiAxMi8wNS8yMDI1IGF0IDE1OjEzOjIwICswMiwgQ3PDs2vDoXMgQmVuY2UgPGNz b2thcy5iZW5jZUBwcm9sYW4uaHU+IHdyb3RlOgoKPiBIaSwKPgo+IE9uIDIwMjUuIDA1LiAxMi4g MTQ6NDcsIFJpY2hhcmQgV2VpbmJlcmdlciB3cm90ZToKPj4gLS0tLS0gVXJzcHLDvG5nbGljaGUg TWFpbCAtLS0tLQo+Pj4gVm9uOiAiQ3PDs2vDoXMgQmVuY2UiIDxjc29rYXMuYmVuY2VAcHJvbGFu Lmh1Pgo+Pj4gV2VsbCwgeWVzLCBpbiBvdXIgY2FzZS4gQnV0IHRoZSBwb2ludCBpcywgd2UgaGF2 ZSBhIHN0cmljdCByZXF1aXJlbWVudAo+Pj4gZm9yIGRhdGEgaW50ZWdyaXR5LCB3aGljaCBpcyBu b3QgdW5pcXVlIHRvIHVzIEkgYmVsaWV2ZS4gSSB3b3VsZCB0aGluawo+Pj4gdGhlcmUgYXJlIG90 aGVyIGluZHVzdHJpYWwgY29udHJvbCBhcHBsaWNhdGlvbnMgbGlrZSBvdXJzLCB3aGljaCBkaWN0 YXRlCj4+PiBhIGhpZ2ggZGF0YSBpbnRlZ3JpdHkuCj4+IEluIHlvdXIgbGFzdCBwYXRjaCBzZXQg eW91IHNhaWQgeW91ciBoYXJkd2FyZSBoYXMgYW4gaXNzdWUgdGhhdCBldmVyeQo+PiBub3cgYW5k IHRoYXQgZGF0YSBpcyBub3QgcHJvcGVybHkgd3JpdHRlbi4KPj4gTm93IHlvdSB0YWxrIGFib3V0 IGRhdGEgaW50ZWdyaXR5IHJlcXVpcmVtZW50cy4gSSdtIGNvbmZ1c2VkLgo+Cj4gVGhlIHR3byBw cm9ibGVtcyBhcmUgbm90IHRvbyBkaXNzaW1pbGFyOiBpbiBvbmUgY2FzZSB5b3UgaGF2ZSBhIHJh bmRvbSwKPiBhbmQgX3ZlcnlfIGxvdyBjaGFuY2Ugb2YgZGF0YSBjb3JydXB0aW9uLCBlLmcuIGJl Y2F1c2Ugb2Ygbm9pc2UsIGFnaW5nCj4gaGFyZHdhcmUsIHBvd2VyIHN1cHBseSByaXBwbGUgZXRj LiBCdXQgeW91IHN0aWxsIG5lZWQgdG8gbWFrZSBzdXJlIHRoYXQKPiB0aGUgd3JpdHRlbiBkYXRh IGlzIGFic29sdXRlbHkgY29ycmVjdDsgb3IgaWYgaXQgaXMgbm90LCB0aGUgc3lzdGVtIHdpbGwK PiBpbW1lZGlhdGVseSBlbnRlciBzb21lIGZhaWwtc2FmZSBtb2RlLiBUaGlzIGlzIHRoZSBwcm9i bGVtIHdlIHdhbnQgdG8KPiBzb2x2ZSwgZm9yIGV2ZXJ5Ym9keSB1c2luZyBMaW51eCBpbiBoaWdo IHJlbGlhYmlsaXR5IGVudmlyb25tZW50cy4KPgo+IFRoZSBwcm9ibGVtIHdlIF9oYXZlXyB0aG91 Z2ggaGFwcGVucyB0byBiZSBhIGJpdCBkaWZmZXJlbnQ6IGhlcmUgd2UgYXJlCj4gYmx1cnNlZCB3 aXRoIGEgc3lzdGVtIHRoYXQgY29ycnVwdHMgZGF0YSBhdCBhIG5vdGljZWFibGUKPiBwcm9iYWJp bGl0eS4gQnV0IHRoZSBtb2RlbCBpcyB0aGUgc2FtZTogYSBzdG9jaGFzdGljIHByb2Nlc3MgaW50 cm9kdWNpbmcKPiBiaXQgZXJyb3JzIG9uIHdyaXRlLiBCdXQgSSBzaW5jZXJlbHkgaG9wZSBubyBv bmUgZWxzZSBoYXMgdGhpcyBwcm9ibGVtLAo+IGFuZCB0aGlzIGlzICpub3QqIHRoZSBwcmltYXJ5 IGFpbSBvZiB0aGlzIHBhdGNoOyBpdCBqdXN0IGhhcHBlbnMgdG8KPiBzb2x2ZSBvdXIgaXNzdWUg YXMgd2VsbC4gQnV0IEkgaW50ZW5kIGl0IHRvIGJlIHVzZWZ1bCBmb3IgdGhlIGxhcmdlcgo+IExp bnV4IGNvbW11bml0eSwgdGh1cyB0aGUgcHJpbWFyeSBnb2FsIGlzIHRvIHNvbHZlIHRoZSBmaXJz dCBpc3N1ZS4KCkkgZG9uJ3QgaGF2ZSBhIHN0cm9uZyBvcGluaW9uIHRoZXJlIGJ1dCBJIGRvbid0 IGRpc2xpa2UgdGhpcyBpZGVhCmJlY2F1c2UgaXQgbWlnaHQgYWxzbyBoZWxwIHRyb3VibGVzaG9v dGluZyBlcnJvcnMgc29tZXRpbWVzLiBJdCBpcyB2ZXJ5CmhhcmQgdG8gdW5kZXJzdGFuZCBpc3N1 ZXMgd2hpY2ggaGFwcGVuIHRvIGJlIGRpc2NvdmVyZWQgd2F5IGFmdGVyIHRoZXkKaGF2ZSBiZWVu IGdlbmVyYXRlZCAodHlwaWNhbGx5IGR1cmluZyBhIHJlYWQsIHdheSBsYXRlciB0aGFuIGEgImZh dWx0eSIKd3JpdGUpLiBIYXZpbmcgdGhpcyBwYXJhbm9pZCBvcHRpb24gd291bGQgZ2l2ZSBhIG1v cmUgc3luY2hyb25vdXMKYXBwcm9hY2ggd2hpY2ggaXMgZWFzaWVyIHRvIHdvcmsgd2l0aCBzb21l dGltZXMuCgpDaGVlcnMsCk1pcXXDqGwKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fXwpMaW51eCBNVEQgZGlzY3Vzc2lvbiBtYWlsaW5nIGxpc3QK aHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9saW51eC1tdGQvCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay1-d.mail.gandi.net (relay1-d.mail.gandi.net [217.70.183.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 773771DC9BB for ; Mon, 12 May 2025 13:59:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.193 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747058367; cv=none; b=e54iicXukYLxsgFZ0uyEuytPOYk8C6RlF5zFvggwI6yqDLaJBAunTB0RBgcthT6BxA00zcbkuo3ydzdagJLlI+Q5+sUJo7Dpnx8lJavXMco++jKVMv1b25HdlEVxXItMwh+cdTT03ZuCo99i2LuSUT7V1vHdL36crm/qKybfJds= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747058367; c=relaxed/simple; bh=HUmofXhvscOsV22HCTbEBE6mTbH7lup2/FhvFaKJTT0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=YvFeUaNb/4XdEVnUsyxOSaWxpCD80ddUXXXygf0Nfds34ooM8IjaGj7YU8X0HsqTL2JPnXnZXKxBzYk4dzUVB1ILYVeqQKx4WQOwoxNE1AWqRKSjKGvAwd6CMQlgsck5wJDJjqUHKhifmO+MuneCParmgcSVXezucSGq5G0K3DQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=IGtGo5mr; arc=none smtp.client-ip=217.70.183.193 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="IGtGo5mr" Received: by mail.gandi.net (Postfix) with ESMTPSA id 3EF1E439F3; Mon, 12 May 2025 13:59:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1747058363; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HUmofXhvscOsV22HCTbEBE6mTbH7lup2/FhvFaKJTT0=; b=IGtGo5mrnhcTIR6KHAVd0KcciOdvRmlKgssw6BUtwGWEyYyrGWJijuB7/mfyqfmPhbRjfz kNDgM6HCeU+M1QN0Tt6LK4DICFM9fOAXOTAQL+MPgeQuCANZYN3UP9PJ9ELqZBbdlmay4A 2dic1WtPjBbZNiN625v3i0s9okNaBwkM3BtPIcvc83YuyM3DIkIS6pCnyjGHgqEmhKK36i n7T7zyII7NXZ6iCtre00RJYWswSFVYTyxgctszti/Y6asCVrR0GuqNZRHmExXt8UiCgeI8 2zHoUxmXGgMocFO34860z5VBRddPVLhkO/qW5ldsUrg0BmXicwoKEp9POBc7Ag== From: Miquel Raynal To: =?utf-8?B?Q3PDs2vDoXM=?= Bence Cc: Richard Weinberger , linux-mtd , linux-kernel , Vignesh Raghavendra Subject: Re: [PATCH v3] mtd: Verify written data in paranoid mode In-Reply-To: <4ebe2146-ee1c-4325-8259-be3803475f1f@prolan.hu> (=?utf-8?B?IkNzw7Nrw6Fz?= Bence"'s message of "Mon, 12 May 2025 15:13:20 +0200") References: <20250512084033.69718-1-csokas.bence@prolan.hu> <87frhambri.fsf@bootlin.com> <1200504110.30346467.1747054025727.JavaMail.zimbra@nod.at> <4ebe2146-ee1c-4325-8259-be3803475f1f@prolan.hu> User-Agent: mu4e 1.12.7; emacs 29.4 Date: Mon, 12 May 2025 15:59:22 +0200 Message-ID: <87r00ugcat.fsf@bootlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdeftddugeegucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufgjfhgffffkgggtgfesthhqredttderjeenucfhrhhomhepofhiqhhuvghlucftrgihnhgrlhcuoehmihhquhgvlhdrrhgrhihnrghlsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeffgefhjedtfeeigeduudekudejkedtiefhleelueeiueevheekvdeludehiedvfeenucfkphepledtrdekledrudeifedruddvjeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeltddrkeelrdduieefrdduvdejpdhhvghloheplhhotggrlhhhohhsthdpmhgrihhlfhhrohhmpehmihhquhgvlhdrrhgrhihnrghlsegsohhothhlihhnrdgtohhmpdhnsggprhgtphhtthhopeehpdhrtghpthhtoheptghsohhkrghsrdgsvghntggvsehprhholhgrnhdrhhhupdhrtghpthhtoheprhhitghhrghrugesnhhougdrrghtpdhrtghpthhtoheplhhinhhugidqmhhtugeslhhishhtshdrihhnfhhrrgguvggrugdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehvihhgnhgvshhhrhesthhirdgtohhm X-GND-Sasl: miquel.raynal@bootlin.com Hello, On 12/05/2025 at 15:13:20 +02, Cs=C3=B3k=C3=A1s Bence wrote: > Hi, > > On 2025. 05. 12. 14:47, Richard Weinberger wrote: >> ----- Urspr=C3=BCngliche Mail ----- >>> Von: "Cs=C3=B3k=C3=A1s Bence" >>> Well, yes, in our case. But the point is, we have a strict requirement >>> for data integrity, which is not unique to us I believe. I would think >>> there are other industrial control applications like ours, which dictate >>> a high data integrity. >> In your last patch set you said your hardware has an issue that every >> now and that data is not properly written. >> Now you talk about data integrity requirements. I'm confused. > > The two problems are not too dissimilar: in one case you have a random, > and _very_ low chance of data corruption, e.g. because of noise, aging > hardware, power supply ripple etc. But you still need to make sure that > the written data is absolutely correct; or if it is not, the system will > immediately enter some fail-safe mode. This is the problem we want to > solve, for everybody using Linux in high reliability environments. > > The problem we _have_ though happens to be a bit different: here we are > blursed with a system that corrupts data at a noticeable > probability. But the model is the same: a stochastic process introducing > bit errors on write. But I sincerely hope no one else has this problem, > and this is *not* the primary aim of this patch; it just happens to > solve our issue as well. But I intend it to be useful for the larger > Linux community, thus the primary goal is to solve the first issue. I don't have a strong opinion there but I don't dislike this idea because it might also help troubleshooting errors sometimes. It is very hard to understand issues which happen to be discovered way after they have been generated (typically during a read, way later than a "faulty" write). Having this paranoid option would give a more synchronous approach which is easier to work with sometimes. Cheers, Miqu=C3=A8l