On Thu, Jul 22, 2021 at 1:11 PM Pintu Agarwal <pintu.ping@gmail.com> wrote:
On Thu, 22 Jul 2021 at 02:24, Richard Weinberger <richard@nod.at> wrote:
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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 ?
From that command line I understand that you are *not* using squashfs on top of UBI. You use mtdblock. ubiblock is a mechanism to turn an UBI volume into a read-only block device. See: http://www.linux-mtd.infradead.org/doc/ubi.html#L_ubiblock
Okay, you mean to say, we should use this ? ubi.mtd=5 ubi.block=0,0 root=/dev/ubiblock0_0 Instead of this: root=/dev/mtdblock44 ubi.mtd=40,0,30
Yes. But it is not only about a different command line. It is a different concept. You use a emulated block device on top of UBI, and not directly on top of an MTD part.
Sorry, I could not get this part. How static volume can give image len ? You mean there is some interface available in kernel to get actual image len ?
use the ubinfo tool. Static volumes know exactly how much they are filled.
Also, how can we get the checksum of the entire UBI volume content (ignoring the erased/empty/bad block content) ?
Just read from the volume. /dev/ubiX_Y.
I think this also will give the entire volume size, but we still don't know how many pages have real data ?
"ubiinfo /dev/ubiX_Y" will tell you if the volume is of type static.
For example: Suppose, my raw partition/volume is of size 10MB But my actual data inside it is of size ~3MB (may be split across?) Then, how can we get the actual size of the data content ?
See above.
You mean to say: /dev/ubiX_Y should contain only data blocks ?
Yes. An UBI volume contains only "user data". -- Thanks, //richard