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Date:   Tue, 9 Nov 2021 11:55:39 +0100
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Trevor Woerner <twoerner@gmail.com>
Cc:     Richard Weinberger <richard@nod.at>,
        Ezequiel Garcia <ezequiel@collabora.com>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Vignesh Raghavendra <vigneshr@ti.com>
Subject: Re: [PATCH 0/3] mtdblock: Advertise about UBI and UBI block
Message-ID: <20211109115539.14e896b2@xps13>
In-Reply-To: <20211028133119.GA21237@localhost>
References: <20210801234509.18774-1-ezequiel@collabora.com>
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        <876982414.38679.1635274892099.JavaMail.zimbra@nod.at>
        <20211028133119.GA21237@localhost>
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Hi Trevor, Ezequiel,

twoerner@gmail.com wrote on Thu, 28 Oct 2021 09:31:19 -0400:

> On Tue 2021-10-26 @ 09:01:32 PM, Richard Weinberger wrote:
> > Trevor,
> > 
> > ----- Ursprüngliche Mail -----  
> > > Von: "Trevor Woerner" <twoerner@gmail.com>
> > > An: "Ezequiel Garcia" <ezequiel@collabora.com>
> > > CC: "linux-mtd" <linux-mtd@lists.infradead.org>, "linux-kernel" <linux-kernel@vger.kernel.org>, "richard"
> > > <richard@nod.at>, "Miquel Raynal" <miquel.raynal@bootlin.com>, "Vignesh Raghavendra" <vigneshr@ti.com>
> > > Gesendet: Dienstag, 26. Oktober 2021 17:03:50
> > > Betreff: Re: [PATCH 0/3] mtdblock: Advertise about UBI and UBI block  
> >   
> > > On Sun 2021-08-01 @ 08:45:02 PM, Ezequiel Garcia wrote:  
> > >> Hi Richard, and everyone else:
> > >> 
> > >> Browsing the internet for "JFFS2 mtd" results in tutorials, articles
> > >> and github.gists0 that point to mtdblock.
> > >> 
> > >> In fact, even the MTD wiki mentions that JFFS2
> > >> needs mtdblock to mount a rootfs:
> > >> 
> > >>   http://www.linux-mtd.infradead.org/faq/jffs2.html
> > >> 
> > >> Moreover, I suspect there may be lots of users
> > >> that still believe mtdblock is somehow needed to
> > >> mount SquashFS.
> > >> 
> > >> I've taken a verbose route and added a pr_warn
> > >> warning if the devices are NAND. I don't think using
> > >> NAND without UBI is too wise, and given the amount
> > >> of outdated tutorials I believe some advertising
> > >> will help.  
> > > 
> > > Not all NAND partitions on a device will contain linux root filesystems. For a
> > > linux root filesystem perhaps using UBI/UBIFS is preferred, yet these messages
> > > print out for each and every NAND partition:
> > > 
> > >	[    0.900827] Creating 8 MTD partitions on "nxp_lpc3220_slc":
> > >	[    0.906431] 0x000000000000-0x000000020000 : "bootrom"
> > >	[    0.913523] mtdblock: MTD device 'bootrom' is NAND, please consider using UBI
> > >	block devices instead.
> > >	[    0.933334] 0x000000020000-0x000000080000 : "uboot"
> > >	[    0.940439] mtdblock: MTD device 'uboot' is NAND, please consider using UBI
> > >	block devices instead.
> > >	[    0.963322] 0x000000080000-0x000000440000 : "fbkernel"
> > >	[    0.970655] mtdblock: MTD device 'fbkernel' is NAND, please consider using
> > >	UBI block devices instead.
> > >	[    0.993361] 0x000000440000-0x000000920000 : "fbrootfs"
> > >	[    1.000725] mtdblock: MTD device 'fbrootfs' is NAND, please consider using
> > >	UBI block devices instead.
> > >	[    1.023315] 0x000000920000-0x000000ce0000 : "c_kernel"
> > >	[    1.030722] mtdblock: MTD device 'c_kernel' is NAND, please consider using
> > >	UBI block devices instead.
> > >	[    1.053444] 0x000000ce0000-0x000000d00000 : "c__atags"
> > >	[    1.060742] mtdblock: MTD device 'c__atags' is NAND, please consider using
> > >	UBI block devices instead.
> > >	[    1.083349] 0x000000d00000-0x000001000000 : "c_rootfs"
> > >	[    1.090702] mtdblock: MTD device 'c_rootfs' is NAND, please consider using
> > >	UBI block devices instead.
> > >	[    1.113335] 0x000001000000-0x000020000000 : "mender"
> > >	[    1.131627] mtdblock: MTD device 'mender' is NAND, please consider using UBI
> > >	block devices instead.
> > > 
> > > NAND tends to be something found on older devices, the firmware/bootloaders
> > > of older devices couldn't possibly understand UBI/UBIFS so many of these
> > > partitions need be "raw" partitions, or use something that predates UBI.
> > > 
> > > Ironically my "mender" partition contains a UBI (with multiple UBIFSes inside)
> > > yet I got the same "please use UBI" message as all the others (lol)
> > > 
> > > I'm specifying my partitions in DT with:
> > > 
> > > partitions {
> > >        compatible = "fixed-partitions";
> > >        #address-cells = <1>;
> > >        #size-cells = <1>;
> > > 
> > >        mtd0@0       { label = "bootrom";   reg = <0x00000000 0x00020000>; };
> > >        mtd1@20000   { label = "uboot";     reg = <0x00020000 0x00060000>; };
> > >        mtd2@80000   { label = "fbkernel";  reg = <0x00080000 0x003c0000>; };
> > >        mtd3@440000  { label = "fbrootfs";  reg = <0x00440000 0x004e0000>; };
> > >        mtd4@920000  { label = "c_kernel";  reg = <0x00920000 0x003c0000>; };
> > >        mtd5@ce0000  { label = "c__atags";  reg = <0x00ce0000 0x00020000>; };
> > >        mtd6@d00000  { label = "c_rootfs";  reg = <0x00d00000 0x00300000>; };
> > >        mtd7@1000000 { label = "mender";    reg = <0x01000000 0x1f000000>; };
> > > };
> > > 
> > > which is why, I assume, I'm getting these messages. Is there a UBI-friendly
> > > way to define them to avoid these messages?  
> > 
> > Hmm, maybe it makes sense to advertise it only once and not for each mtdblock device.  
> 
> Are there known bugs or issues using ubi/jffs2/squashfs on top of mtdblock? Is
> mtdblock being deprecated? If so I could certainly understand warning users of
> the situation.

This message is not actually directed to people with old setups, but
more to people creating new setups. I don't care if the loglevel is
lowered to info, if you think this is better than a warning.

Can someone please send a fix to display this message once?

Thanks,
Miquèl