On Thu, 22 Jul 2021 at 02:24, Richard Weinberger <richard@xxxxxx> wrote: > > ----- Ursprüngliche Mail ----- > >> 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 Okay I will discuss this internally and check.. > >> 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 ? > > You need a static volume for that. If you update a static volume the length is > known by UBI. > Thank you so much for your reply! 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 ? > > 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 ? 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 ? You mean to say: /dev/ubiX_Y should contain only data blocks ? > > 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 ? >
