From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) (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 4FF1035E930 for ; Fri, 3 Jul 2026 10:16:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.84.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783073764; cv=none; b=NTbjSggP+rSnA4YJ8lsMvGSFUzQUQeOZ+I16fkZb5PmOVd2eJp8BS59uBc+3/bi+vbYbLjpxh9Bw8oTmZhIrOIAw0cL3T9yO+g8lXPc/hWon2RbltAZnZTBXbo/U0HikD9q6HsYB5JWZSCK6HA9pW08dumWQi9vIIT4B3T3oFec= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783073764; c=relaxed/simple; bh=LqH3H+C4q9HYnTsw0EDWHMQnX/Mq8IYtzP3WOkNlfG0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=ht/Ejhjql9YsZnu/uKw8S3K+9i08RYvbIJKuQ5cxmTma/9soviGjkf0vRWAFFuH4Qssidw5AN9Lftv5wAIJpNi6/nOObMBIH5SHvCEy0fBMvSfCadyAQYpKm+JEdFVVj5qbbYPjZqZepDAB68vkB9yRQnEd8sZdJ734nn1VQFXc= 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=obzf9WEj; arc=none smtp.client-ip=185.246.84.56 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="obzf9WEj" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 7ACA81A0DF7; Fri, 3 Jul 2026 10:16:00 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 440AB60300; Fri, 3 Jul 2026 10:16:00 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 65DC2104C8399; Fri, 3 Jul 2026 12:15:55 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1783073759; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=LqH3H+C4q9HYnTsw0EDWHMQnX/Mq8IYtzP3WOkNlfG0=; b=obzf9WEjWxoGnLgP5gdDIFUep9YV0q6uKwxCVrDG2ikDRkIS039UTqqCKf19nZv+S+SR6a r6cHB5EKUp4xt+aZQQllqq0ZbUH9HBM9jHqrCnmWkwQjVzPqB3sDN9yg2U9uu9nPdPkqZi ChGsp9VsoxZirGpaeSnsU6/Gkt/+r5Yf/sM/HhIB5Iu5E1k4VZ3eNhFaMjxiTTMkBuzQc1 MFvD6AvXkQ8oK6XXF+m2BCCIb1cnbeT/wLw/f9QO+le8oiU5DPmYZTOQcUh4eBey0s8YbD /G5LfqrSZ8Gg//RdcAQbspc+KOA+41OUE05B5mI2kdXNFOrId0m1VLeC/00+pA== From: Miquel Raynal To: Richard Weinberger Cc: Ronan Dalton , Chris Packham , Takahiro Kuwano , pratyush , linux-kernel , Vignesh Raghavendra , linux-mtd , Aryan Srivastava , Michael Walle Subject: Re: [PATCH v2 1/3] Revert "mtd: spi-nor: remove Fujitsu MB85RS1MT support" In-Reply-To: <183302295.10735.1783057556804.JavaMail.zimbra@nod.at> (Richard Weinberger's message of "Fri, 3 Jul 2026 07:45:56 +0200 (CEST)") References: <2b8390c0aaae4203af318f9a5edbb0eb@infineon.com> <20260701020856.217664-1-ronan.dalton@alliedtelesis.co.nz> <490fc98b2996487fba3abd62176bb1dd@infineon.com> <8baaf8a603f7f351b4f7acb7a2df4cb60be9f083.camel@alliedtelesis.co.nz> <99731a393e5649e692afe57f59d5926b@infineon.com> <490633873.5619.1782970758317.JavaMail.zimbra@nod.at> <183302295.10735.1783057556804.JavaMail.zimbra@nod.at> User-Agent: mu4e 1.12.7; emacs 30.2 Date: Fri, 03 Jul 2026 12:15:54 +0200 Message-ID: <87wlvcnztx.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-Last-TLS-Session-Version: TLSv1.3 On 03/07/2026 at 07:45:56 +02, Richard Weinberger wrote: > ----- Urspr=C3=BCngliche Mail ----- >> Von: "Ronan Dalton" >> On Thu, 2026-07-02 at 07:39 +0200, Richard Weinberger wrote: >>> Do you really need (POSIX) file system semantics? >>> You could partition the FRAM into cells and then work with them. >>> e.g. Just dd into it and erase it when needed... >>> Maybe the NVMEM cells mechanism needs some polishing but this sounds >>> reasonable to me. >>=20 >> Yes, that could work for secrets storage. However we also store >> persistent logs and DHCP leases on this flash to minimize read/writes >> on the main flash, and this data is stored as files of varying lengths. >> A filesystem provides the most straightforward way of storing this data >> for us. > > But the storage (FRAM) you chose is not suitable for any real filesystem. > In a previous mail you said you use ext2 on it. > I have a hard time to see how using ext2 on top of mtdblock on an FRAM > does not end in a disaster. > >> That's not to say we couldn't develop some system of using the nvmem >> device as a backend for this data. This may be something we look at in >> the future. > > Maybe FUSE can help with building a super simple filesystem which provides > just enough to fulfill your use case. The NVMEM cells mechanism is very flexible now with layouts. We do have support for ONIE Type-Length-Variable tables as well as an example of support for the environment variables in U-Boot. If you format very slightly your data you can very easily expose automatically one cell per information with a rather simple NVMEM layout driver and consume it this way. Thanks, Miqu=C3=A8l