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From: Pintu Agarwal <pintu.ping@gmail.com>
To: Richard Weinberger <richard@nod.at>
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 13:31:55 +0530	[thread overview]
Message-ID: <CAOuPNLhti3tocN-_D7Q0QaAx5acHpb3AQyWaUKgQPNW3XWu58g@mail.gmail.com> (raw)
In-Reply-To: <1556211076.48404.1626763215205.JavaMail.zimbra@nod.at>

On Tue, 20 Jul 2021 at 12:10, Richard Weinberger <richard@nod.at> wrote:

> > 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?
>
Yes, it is about md5 checksum verification for every partition to
check its integrity before updates.


> But let me advertise ubiblock a second time.
Sorry, I could not understand about the ubiblock request. Is it
possible to elaborate little more ?
We are already using squashfs on top of our UBI volumes (including
rootfs mounting).
This is the kernel command line we pass:
rootfstype=squashfs root=/dev/mtdblock44 ubi.mtd=40,0,30
And CONFIG_MTD_UBI_BLOCK=y is already enabled in our kernel.
Do we need to do something different for ubiblock ?

> If you place your squashfs on a UBI static volume, UBI knows the exact length and you can checksum it
> more easily.
Yes, we use squashfs on UBI volumes, but our volume type is still dynamic.
Also, you said, UBI knows the exact length, you mean the whole image length ?
How can we get this length at runtime ?
Also, how can we get the checksum of the entire UBI volume content
(ignoring the erased/empty/bad block content) ?

Or, you mean to say, the whole checksum logic is in-built inside the
UBI layer and users don't need to worry about the integrity at all ?


Thanks,
Pintu

  reply	other threads:[~2021-07-20  8:02 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
2021-07-20  8:01             ` Pintu Agarwal [this message]
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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