block devices on MTD and UBI

[Mike Looijmans <mike.looijmans@topic.nl>]

I think I have everything set up to access MTD (and UBI) devices as 
"block", however, lsblk always ignores them, and refuses to list 
anything but the mmc. I can read ubifs and boot from it though, and 
since UBI runs on top of MTD block devices, MTD block device should be 
working, right?

I also have UBI_BLOCK enabled, so I would expect UBI volumes to appear 
in the "lsblk" as well.

Example U-boot session:

Zynq> mtd list
SF: Detected n25q256ax1 with page size 256 Bytes, erase size 64 KiB, 
total 32 MiB
List of MTD devices:
* nor0
   - device: flash@0
   - parent: spi@e000d000
   - driver: jedec_spi_nor
   - path: /axi/spi@e000d000/flash@0
   - type: NOR flash
   - block size: 0x10000 bytes
   - min I/O: 0x1 bytes
   - 0x000000000000-0x000002000000 : "nor0"
           - 0x000000000000-0x000000100000 : "qspi-boot-bin"
           - 0x000000100000-0x000002000000 : "qspi-rootfs"

Zynq> lsblk
Block Driver          Devices
-----------------------------
efi_blk             : <none>
mmc_blk             : mmc 0
mtd_blk             : <none>
ubi_blk             : <none>
usb_storage_blk     : <none>

Zynq> ubi part qspi-rootfs
Zynq> ubi list
0: qspi-rootfs
Zynq> lsblk
Block Driver          Devices
-----------------------------
efi_blk             : <none>
mmc_blk             : mmc 0
mtd_blk             : <none>
ubi_blk             : <none>
usb_storage_blk     : <none>


I would have expected the SPI NOR flash to appear in the "mtd_blk" 
devices, and would expect the UBI volumes to appear in the "ubi_blk" list.
What am I missing?

What I'm aiming for here is to be able to:
- Read from squashfs in (raw) MTD partition (NOR flash is ideal for that)
- Read kernel/devicetree (fit) from UBI volume
- Read from squashfs inside UBI volume


I can read files from UBIFS (and boot into Linux using bootcmd_ubifs) 
just fine, e.g.:
Zynq> ubifsmount ubi0:qspi-rootfs
Zynq> ls ubi 0
<DIR>        5200  Fri Mar 09 12:34:56 2018  bin
<DIR>         160  Fri Mar 09 12:34:56 2018  dev
<DIR>        4984  Fri Mar 09 12:34:56 2018  etc
...


-- 
Mike Looijmans
System Expert

TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
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