ubi_eba_init_scan: cannot reserve enough PEBs

[Matthew L. Creech]

Hi,

I have some UBI[FS]-based devices that I keep getting this warning on,
and I'm wondering if someone could help me to understand what it means
(and how to fix it).  Here's an example syslog snippet:

Jan  1 00:00:32 kernel: UBI: attaching mtd1 to ubi0
Jan  1 00:00:32 kernel: UBI: physical eraseblock size:   131072 bytes (128 KiB)
Jan  1 00:00:32 kernel: UBI: logical eraseblock size:    129024 bytes
Jan  1 00:00:32 kernel: UBI: smallest flash I/O unit:    2048
Jan  1 00:00:32 kernel: UBI: sub-page size:              512
Jan  1 00:00:32 kernel: UBI: VID header offset:          512 (aligned 512)
Jan  1 00:00:32 kernel: UBI: data offset:                2048
Jan  1 00:00:32 kernel: UBI warning: ubi_eba_init_scan: cannot reserve
enough PEBs for bad PEB handling, reserved 75, need 81
Jan  1 00:00:32 kernel: UBI: attached mtd1 to ubi0
Jan  1 00:00:32 kernel: UBI: MTD device name:            "ubi"
Jan  1 00:00:32 kernel: UBI: MTD device size:            1019 MiB
Jan  1 00:00:32 kernel: UBI: number of good PEBs:        8117
Jan  1 00:00:32 kernel: UBI: number of bad PEBs:         35
Jan  1 00:00:32 kernel: UBI: max. allowed volumes:       128
Jan  1 00:00:32 kernel: UBI: wear-leveling threshold:    4096
Jan  1 00:00:32 kernel: UBI: number of internal volumes: 1
Jan  1 00:00:32 kernel: UBI: number of user volumes:     1
Jan  1 00:00:32 kernel: UBI: available PEBs:             0
Jan  1 00:00:32 kernel: UBI: total number of reserved PEBs: 8117
Jan  1 00:00:32 kernel: UBI: number of PEBs reserved for bad PEB handling: 75
Jan  1 00:00:32 kernel: UBI: max/mean erase counter: 2/1
Jan  1 00:00:32 kernel: UBI: image sequence number: 0
Jan  1 00:00:32 kernel: UBI: background thread "ubi_bgt0d" started, PID 197

Everything seems okay, except for that complaint about not being able
to reserve enough PEBs.  I'm not sure why I get this, or what I can do
about it.  A search turns up this thread:

http://patchwork.ozlabs.org/patch/42566/

which implies that one of the UBI volumes was too large & didn't leave
enough space for reserved PEBs.  But I don't think that applies to me,
or what I could do about it.  My bring-up process is as follows:

=====
1. My bootloader partition is 5MB out of 1GB, and the rest of NAND is
a UBI partition housing a single UBIFS filesystem.  That's 8152 blocks
@ 128kB each (ignoring OOB).


2. I create my UBIFS image with:

mkfs.ubifs -m 2048 -e 129024 -c 8152 -x lzo -U -v -r ./.tmp/ -o ubifs.img

The only thing I'm unsure about is the "-c 8152", but since that's the
*maximum* LEB count, I'd assumed it was okay to leave it as the full
size of my NAND partition.  (I don't know how many blocks are bad, so
otherwise I'll have to pessimistically limit the size & waste space)


3. I create a UBI image (suitable for flashing) with:

ubinize -o ubi.img -m 2048 -p 128KiB -m 2048 -s 512 ubi.cfg

The file ubi.cfg is as follows:

[ubifs-container]
mode=ubi
image=ubifs.img
vol_id=0
vol_size=100MiB
vol_type=dynamic
vol_name=container
vol_flags=autoresize

Since autoresize is set, presumably vol_size doesn't have much effect,
correct?  My understanding is that when the device boots for the first
time, it'll see the autoresize flag and expand the volume size to fill
whatever space is available after accounting for bad blocks (nearly
1019MB).


4. I add ECC info and use a hardware NAND programmer to flash the device.
=====


Does this all look correct?  Or are my options wrong in one of these steps?

I'm mainly trying to understand what this particular warning means,
and ensure that my procedure is correct.  I'm having other UBI-related
problems on this platform, and want to be sure that this isn't the
cause before I dig further into other possibilities.

Any help is appreciated, thanks!

-- 
Matthew L. Creech