From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0BDAF125DE; Sat, 28 Sep 2024 13:45:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727531155; cv=none; b=usgvp8GRR0g4v6TMCa9AOiFI9dFU/qUfCx+enMAHazZUmhijVu4mTpCw6GpZdviaO0sFJV6zc6xrhgLvemO1hJc2esriwygjwOfYpBnZtUPW1FD/ea46R7MhlgkslMLOieQOBfzebJHu2hQ3E+3AYghQnjJLV5V3YPuJRJAhWNw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727531155; c=relaxed/simple; bh=Em0L9ku5aG9RNOTHFg9WI2703n/XMa40ZjERGqjIMys=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=my4qyR9cDMNTypiIK5K63nUjAtvzVJl8/r73R+ElJGXmfbD3nLGbLCjvHJ4L3aEwbb2tzkbQwo8JvG4VVM6Z4+XSBAvhP40vGXPiJ1AQZ5SQVg93E7EotUWtgnoHyTCSQIsvUhBJCH0+NL76jtN7v3xtYmq6HQldR66bpn56szA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jjugqKHr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jjugqKHr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9470FC4CEC3; Sat, 28 Sep 2024 13:45:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727531154; bh=Em0L9ku5aG9RNOTHFg9WI2703n/XMa40ZjERGqjIMys=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=jjugqKHrIv3vNaDuhfHJ1jxkwavZfKlmJCtAseRoK1162VHFQERDhTi0E37QmTb+J gzjDRq6hT4HUMXvV+MUE5JUw+Mi2i+eFGPvl2h822iTkbkRe42cYejCSYvMidto82G OtchMtSO7HMIBa6b+2bMLKo4byvZ5SwsI92V2UvZY2U4jsNU9UfDwfkfHClMPLXzKH QtMd8kf/i+aGbLBXhbo/NkY24Bt/Bn4TfqBD7YDN788jxsNPZKqgsT/WJGzoePAu8g chZgKbr6FwcZ07ExusgJ3+TUPwQ3xg+/fSiW5/Pp4pPPgayJgmoCQlgLyPzOrt1X+Y uyCVg43JL+3Qg== Message-ID: <18e9d774-813b-427e-9938-53853d695e18@kernel.org> Date: Sat, 28 Sep 2024 15:45:49 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 1/2] dt-bindings: mtd: ubi-volume: add 'volume-is-critical' property To: Daniel Golle Cc: Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Zhihao Cheng , John Crispin , linux-mtd@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <7a2e8819-ac70-4070-a731-53994c72cd79@kernel.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 28/09/2024 15:09, Daniel Golle wrote: > On Sat, Sep 28, 2024 at 03:02:47PM +0200, Krzysztof Kozlowski wrote: >> On 28/09/2024 14:47, Daniel Golle wrote: >>> Add the 'volume-is-critical' boolean property which marks a UBI volume >>> as critical for the device to boot. If set it prevents the user from >>> all kinds of write access to the volume as well as from renaming it or >>> detaching the UBI device it is located on. >>> >>> Signed-off-by: Daniel Golle >>> --- >>> .../devicetree/bindings/mtd/partitions/ubi-volume.yaml | 9 +++++++++ >>> 1 file changed, 9 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/mtd/partitions/ubi-volume.yaml b/Documentation/devicetree/bindings/mtd/partitions/ubi-volume.yaml >>> index 19736b26056b..2bd751bb7f9e 100644 >>> --- a/Documentation/devicetree/bindings/mtd/partitions/ubi-volume.yaml >>> +++ b/Documentation/devicetree/bindings/mtd/partitions/ubi-volume.yaml >>> @@ -29,6 +29,15 @@ properties: >>> description: >>> This container may reference an NVMEM layout parser. >>> >>> + volume-is-critical: >>> + description: This parameter, if present, indicates that the UBI volume >>> + contains early-boot firmware images or data which should not be clobbered. >>> + If set, it prevents the user from renaming the volume, writing to it or >>> + making any changes affecting it, as well as detaching the UBI device it is >>> + located on, so direct access to the underlying MTD device is prevented as >>> + well. >>> + type: boolean >> >> UBI volumes are mapping to partitions 1-to-1, right? So rather I would >> propose to use partition.yaml - we already have read-only there with >> very similar description. > > No, that's not the case. > > An MTD partition can be used as UBI device. A UBI device (and hence MTD > partition) can host *several* UBI volumes. > > Marking the MTD partition as 'read-only' won't work, as UBI needs > read-write access to perform bad block relocation, scrubbing, ... OK, so not partition but read-only volume. > > Also, typically not all UBI volumes on a UBI device are > read-only/critical but only a subset of them. > > But you are right that the description is inspired by the description > of the 'read-only' property in partition.yaml ;) > > I initially thought to also name the property 'read-only', just like > for MTD partitions. However, as the desired effect goes beyond > preventing write access to the volume itself, I thought it'd be > better to use a new name. Yeah, maybe... critical indeed covers multiple cases but is also subjective. For some bootloader is critical, for other bootloader still might be fully A/B updateable thus could be modifiable. For others, they want to use fw_setenv from user-space so not critical at all. I am in general not so happy in describing flash layout in DT, because it sounds way too policy or one-use-case specific. UBI volume is purely SW construct. One OS can partition MTD in multiple ways, so maybe I just do not understand why we have in the first place. Best regards, Krzysztof