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From:   Pintu Agarwal <pintu.ping@gmail.com>
Date:   Thu, 10 Jun 2021 18:21:18 +0530
Message-ID: <CAOuPNLhPiVgi5Q343VP-p7vwBtA1-A5jt8Ow4_2eF4ZwsiA+eQ@mail.gmail.com>
Subject: Re: qemu: arm: mounting ubifs using nandsim on busybox
To:     Richard Weinberger <richard@nod.at>
Cc:     linux-kernel <linux-kernel@vger.kernel.org>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>
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On Wed, 9 Jun 2021 at 23:52, Richard Weinberger <richard@nod.at> wrote:
>
> Pintu,
>
> ----- Urspr=C3=BCngliche Mail -----
> > Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-blo=
ck(31,0)
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
> >
> > If any one has used nandsim on qemu before, please let us know the exac=
t steps.
>
> nandsim works as expected. It creates a new and *erased* NAND for you.
> So you have no UBI volumes. Therfore UBIFS cannot be mounted.
> I suggest creating a tiny initramfs that creates UBI volumes before mount=
ing UBIFS on
> one of the freshly created (and empty) volumes.
>
oh sorry I forgot to mention this.
I am able to create and update volumes manually after booting the
system with initramfs.
{{{
Creating rootfs volume:
mknod /dev/ubi0 c 250 0
mknod /dev/ubi0_0 c 250 1
ubiattach /dev/ubi_ctrl -m 2
ubimkvol /dev/ubi0 -N rootfs -m
ubiupdatevol /dev/ubi0_0 ubifs-rootfs.img
mount -t ubifs ubi0:rootfs ubi-root/
}}}

But I wanted to do all these automatically during boot time itself.
Also I wanted to use ubinize.cfg as is from the original system and
simulate everything using qemu and nadsim (if possible)
So I thought it must be possible by setting some parameters in qemu such as=
:
mtdparts=3Dnand:,
-device nand,chip_id=3D0x39,drive=3Dmtd0,
-drive if=3Dmtd,file=3D./ubi-boot.img,id=3Dmtd0,
anything else ?

Or maybe do something at the boot time itself to load the volume image ?
If there are some possibilities please let me know.
With this I can use my original setup as it is and verify everything
with different kernel versions.

Thanks,
Pintu