On Tue, 20 Jul 2021 at 12:10, Richard Weinberger [off-list ref] wrote:

quoted

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

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