ubi_update_fastmap: could not find an early PEB

[Nikita V. Youshchenko]

Hello.

I'm trying to make ubi fastmap working on a vendor kernel, based on linux 
3.0.15, on target hardware. For that I've successfully backported the 
patchset and it's dependences from 'fastmap' branch of 
git://git.infradead.org/linux-ubi.git

I'm able to compile and boot resulting kernel.

However, as for now, I can't make it working.

# ubiattach /dev/ubi_ctrl -m 2
UBI: fastmap pool size: 256
UBI: attaching mtd2 to ubi0
UBI: physical eraseblock size:   131072 bytes (128 KiB)
UBI: logical eraseblock size:    126976 bytes
UBI: smallest flash I/O unit:    2048
UBI: VID header offset:          2048 (aligned 2048)
UBI: data offset:                4096
UBI: max. sequence number:       0
UBI: attached mtd2 to ubi0
UBI: MTD device name:            "nand.ubi"
UBI: MTD device size:            992 MiB
UBI: number of good PEBs:        7918
UBI: number of bad PEBs:         18
UBI: number of corrupted PEBs:   0
UBI: max. allowed volumes:       128
UBI: wear-leveling threshold:    4096
UBI: number of internal volumes: 1
UBI: number of user volumes:     1
UBI: available PEBs:             4531
UBI: total number of reserved PEBs: 3387
UBI: number of PEBs reserved for bad PEB handling: 79
UBI: max/mean erase counter: 4/1
UBI: image sequence number:  0
UBI: background thread "ubi_bgt0d" started, PID 2705
UBI device number 0, total 7918 LEBs (1005395968 bytes, 958.8 MiB), 
available 4531 LEBs (575328256 bytes, 548.7 MiB), LEB size 126976 bytes 
(124.0 KiB)

# ubidetach /dev/ubi_ctrl -m 2
UBI error: ubi_update_fastmap: could not find an early PEB
UBI: mtd2 is detached from ubi0


... and fastmap is not created and thus not used.

As far as I understand, this happens because all PEBs at the beginning of 
device are occupied. But this will always be the case after creating image 
with ubinize...

How to overcome this?

Nikita