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From:   Pintu Agarwal <pintu.ping@gmail.com>
Date:   Fri, 29 Oct 2021 21:21:33 +0530
Message-ID: <CAOuPNLhzfGDoQsEZB5eH30WvH2w9hyMEU8Bt81SzK-scaAwgwA@mail.gmail.com>
Subject: Re: Kernel 4.14: Using dm-verity with squashfs rootfs - mounting issue
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Sami Tolvanen <samitolvanen@google.com>, snitzer@redhat.com,
        Kernelnewbies <kernelnewbies@kernelnewbies.org>,
        open list <linux-kernel@vger.kernel.org>, dm-devel@redhat.com,
        Mikulas Patocka <mpatocka@redhat.com>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Phillip Lougher <phillip@squashfs.org.uk>, agk@redhat.com
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Hi All,

On Wed, 8 Sept 2021 at 17:38, Greg KH <gregkh@linuxfoundation.org> wrote:

> > > > > No, but you can backport it easily. Back at
> > > > > http://lists.infradead.org/pipermail/openwrt-devel/2019-November/025967.html
> > > > > I provided backports of this feature to OpenWrt, for the 4.14 and 4.19
> > > > > kernels.
> >
> > Can you please let me know where to get the below patches for
> > backporting to our kernel:
> >  create mode 100644
> > target/linux/generic/backport-4.14/390-dm-add-support-to-directly-boot-to-a-mapped-device.patch
> >  create mode 100644
> > target/linux/generic/backport-4.14/391-dm-init-fix-max-devices-targets-checks.patch
> >  create mode 100644
> > target/linux/generic/backport-4.14/392-dm-ioctl-fix-hang-in-early-create-error-condition.patch
> >  create mode 100644
> > target/linux/generic/backport-4.14/393-Documentation-dm-init-fix-multi-device-example.patch
>
> If you are stuck on an older kernel version, then you need to get
> support from the vendor that is forcing you to be on that kernel
> version, as you are already paying them for support.  Please take
> advantage of that, as no one knows what is really in "your kernel".
>

This is to update this thread that now I am able to successfully
bring-up dm-verity with NAND+ubiblock+squashfs on our 4.14 kernel
itself without backporting the patches.
Now, I am able to boot dm-verity using both initramfs and bootloader approach.
The initramfs booting issue was our internal issue which was related
to Kernel size configuration in UEFI.
The bootloader approach issue was related to system image size issue,
where we need to pass the exact image size to find the verity-metadata
offset at the end of system image.

However, I felt that dm-verity documentation still needs to be
enhanced further with a better example.
With the 5.4 Kernel, I may further explore the option of using
dm-mod.create option, then I might get more clarity on how best to use
it.

Thank you all for your help and support!

Regards,
Pintu