On Thu, 29 Jul 2021 at 22:41, Pintu Agarwal [off-list ref] wrote:

On Thu, 29 Jul 2021 at 17:33, Ezequiel Garcia
[off-list ref] wrote:

quoted

On Thu, 29 Jul 2021 at 08:45, Richard Weinberger [off-list ref] wrote:

quoted

Ezequiel,

----- Ursprüngliche Mail -----

quoted

[snip]

Ouch, so surprised that after all these years someone is doing squashfs/mtdblock
instead of using ubiblock :-)

Can we patch either Kconfig or add some warn_once on mtdblock
usage, suggesting to use ubiblock instead?

a hint in Kconfig makes IMHO sense. Do you want to send a patch?
A warning is too much since on some tiny embedded system with NOR flash mtdblock is still
a good choice.
ubiblock is mostly useful for NAND flash.

quoted

I remember there was still some use case(s) for mtdblock but I can't remember
now what was it, perhaps we should document the expectations?
(Is that for JFFS2 to mount?)

a long time ago mount didn't accept character devices, so you had to pass mtdblockX to mount
JFFS2.
This limitation is gone.

Hi,

Just a further follow-up on this discussion.
Whether to use /dev/mtdblock or /dev/ubiblock for rootfs (squashfs)
mounting during boot.

As suggested here:
Instead of using this in kernel command line:
[    0.000000] Kernel command line: ... rootfstype=squashfs
root=/dev/mtdblock44 ubi.mtd=40,0,30 ...

I used this:
[    0.000000] Kernel command line: ... rootfstype=squashfs
ubi.mtd=40,0,30 ubi.block=0,0 root=/dev/ubiblock0_0 ...

The device is booting fine with ubiblock as well.
But, per say, I could not find any visible difference.
I just observed a slight improvement in boot time, but I need to
double-check on this, with few more reboot cycles.

Apart from this what are the other visible benefits of using ubiblock
which can be explained to be management or internal team ?
I could not find any documentation explaining the difference, except this one:
http://www.linux-mtd.infradead.org/doc/ubi.html#L_ubiblock

Can someone also point me to the respective driver code in case of
using /dev/mtdblock and /dev/ubiblock ?
Apart from theory I also want to check the impact at the code level..

Thanks,
Pintu

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