linux-kernel - Re: [PATCH] mtd: parser: cmdline: Support MTD names containing one or more colons

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Date:   Sun, 22 Nov 2020 01:14:14 +0100
From:   Sven Eckelmann <sven@...fation.org>
To:     linux-mtd@...ts.infradead.org, John Audia <graysky@...hlinux.us>,
        Adrian Schmutzler <freifunk@...ianschmutzler.de>,
        jstefek@...to.com
Cc:     Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Richard Weinberger <richard@....at>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        linux-kernel@...r.kernel.org, Marek Vasut <marek.vasut@...il.com>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        linux-mtd@...ts.infradead.org, Ron Minnich <rminnich@...gle.com>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        "Ronald G. Minnich" <rminnich@...il.com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH] mtd: parser: cmdline: Support MTD names containing one or more colons

On Wednesday, 29 April 2020 18:53:47 CET Ronald G. Minnich wrote:
> From: Boris Brezillon <boris.brezillon@...labora.com>
> 
> Looks like some drivers define MTD names with a colon in it, thus
> making mtdpart= parsing impossible. Let's fix the parser to gracefully
> handle that case: the last ':' in a partition definition sequence is
> considered instead of the first one.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@...labora.com>
> Signed-off-by: Ron Minnich <rminnich@...gle.com>
> Tested-by: Ron Minnich <rminnich@...gle.com>
> ---
>  drivers/mtd/parsers/cmdlinepart.c | 23 ++++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)

This change broke OpenWrt booting on some IPQ40xx devices. Here for example 
the parts of the cmdline which the u-boot on an OpenMesh A62 sets 
automatically:

    root=31:11 mtdparts=spi0.0:256k(0:SBL1),128k(0:MIBIB),384k(0:QSEE),64k(0:CDT),64k(0:DDRPARAMS),64k(0:APPSBLENV),512k(0:APPSBL),64k(0:ART),64k(custom),64k(0:KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive) rootfsname=rootfs rootwait

This is then parsed by newpart as: KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive)

And of course, this results in:

    mtd: partition has size 0
    [...]
    /dev/root: Can't open blockdev
    VFS: Cannot open root device "31:11" or unknown-block(31,11): error -6
    Please append a correct "root=" boot option; here are the available partitions:
    1f00           32768 mtdblock0
    (driver?)
    Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(31,11)
    CPU1: stopping
    CPU: 1 PID: 0 Comm: 

This affects OpenWrt since the commit d6a9a92e3217 ("kernel: bump 5.4 to 
5.4.69") because this change was backported to Linux v5.4.69. Reverting 
this change fixes the problem for me.

And if I see it correctly, this is also affecting the kernel (4.14) for
the OpenWrt 18.06.x + 19.07.x branch because it can also be found in
there as part of the v4.14.200 release.

Another workaround is to replace the first "(" with a NULL too. See the
attached patch for the one which I used to fix the OpenWrt bootup.

Kind regards,
	Sven
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