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From: Richard Weinberger <richard@nod.at>
To: Pintu Agarwal <pintu.ping@gmail.com>
Cc: Greg KH <greg@kroah.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Phillip Lougher <phillip@squashfs.org.uk>,
	Sean Nyekjaer <sean@geanix.com>,
	Kernelnewbies <kernelnewbies@kernelnewbies.org>
Subject: Re: MTD: How to get actual image size from MTD partition
Date: Tue, 20 Jul 2021 08:40:15 +0200 (CEST)	[thread overview]
Message-ID: <1556211076.48404.1626763215205.JavaMail.zimbra@nod.at> (raw)
In-Reply-To: <CAOuPNLh_KY4NaVWSEV2JPp8fx0iy8E1MU8GHT-w7-hMXrvSaeA@mail.gmail.com>

----- Ursprüngliche Mail -----
> Von: "Pintu Agarwal" <pintu.ping@gmail.com>
> Okay thank you.
> We have tried dm-verity with squashfs (for our rootfs) but we are
> facing some mounting issues.
> [...]
> [    4.697757] device-mapper: init: adding target '0 96160 verity 1
> /dev/mtdblock34 /dev/mtdblock39 4096 4096 12020 8 sha256
> d7b8a7d0c01b9aec888930841313a81603a50a2a7be44631c4c813197a50d681
> aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7'
> [    4.704771] device-mapper: verity: sha256 using implementation
> "sha256-generic"
> [...]
> [    4.727366] device-mapper: init: dm-0 is ready
> [    4.912558] VFS: Cannot open root device "dm-0" or
> unknown-block(253,0): error -5
> 
> The same works with ext4 emulation.
> So, not sure if there are any changes missing w.r.t. squashfs on 4.14 kernel ?

I don't know.

> Anyways, I will create a separate thread for dm-verity issue and keep
> this thread still open for UBI image size issue.
> We may use dm-verify for rootfs during booting, but still we need to
> perform integrity check for other nand partitions and UBI volumes.
> 
> So, instead of calculating the checksum for the entire partition, is
> it possible to perform checksum only based on the image size ?
> Right now, we are still exploring what are the best possible
> mechanisms available for this.

I still don't fully understand what you are trying to achieve.
Is it about cryptographic integrity of your storage or detecting
errors after the flashing process?

But let me advertise ubiblock a second time. If you place your squashfs on
a UBI static volume, UBI knows the exact length and you can checksum it
more easily.

Thanks,
//richard

  reply	other threads:[~2021-07-20  6:40 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-16  6:42 Pintu Agarwal
2021-07-16  7:16 ` Richard Weinberger
2021-07-16 15:41 ` Greg KH
2021-07-16 16:26   ` Richard Weinberger
2021-07-19  9:09     ` Pintu Agarwal
2021-07-19  9:28       ` Richard Weinberger
2021-07-20  6:17         ` Pintu Agarwal
2021-07-20  6:40           ` Richard Weinberger [this message]
2021-07-20  8:01             ` Pintu Agarwal
2021-07-21 20:54               ` Richard Weinberger
2021-07-22 11:10                 ` Pintu Agarwal
2021-07-27 21:16                   ` Richard Weinberger
2021-07-29 11:17                     ` Ezequiel Garcia
2021-07-29 11:45                       ` Richard Weinberger
2021-07-29 12:03                         ` Ezequiel Garcia
2021-07-29 17:11                           ` Pintu Agarwal
2021-08-20 18:24                             ` Pintu Agarwal
2021-08-22 14:21                               ` Ezequiel Garcia
2021-08-30 15:58                                 ` Pintu Agarwal
2021-10-29 16:12                                   ` Pintu Agarwal
2021-10-29 16:48                                     ` Ezequiel Garcia
2021-11-08 13:51                                       ` Pintu Agarwal
2021-11-12 13:58                                         ` Ezequiel Garcia

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