autoresize causes insufficient reservation of PEBs for bad PEB handling

[Richard Weinberger]

Samuel,

On Mon, Jul 6, 2015 at 1:04 PM, Egli, Samuel <samuel.egli at siemens.com> wrote:
> Hi all,
>
> I have difficulties to understand why I get the following warning message
> at linux start up:
>
> ...
> [    4.777488] UBI warning: print_rsvd_warning: cannot reserve enough PEBs \
> for bad PEB handling, reserved 40, need 80
> ...
>
> My assumption is that if I don't specify the size of one volume
> UBI will choose the right size for the volume and reserve the
> right amount of PEBs for bad block handling. With 20/1024 set,vi I
> expect indeed to have 80 blocks reserved. But somehow this
> does not work. I observed that I get this warning when vol_flags
> is set to autoresize. In this case only 40 blocks get reserved.
> Using for all volumes the vol_size parameter and omitting
> autoresize, I can avoid this situation and I get my 80 blocks reserved.
>
> However, I don't understand why and it seems odd to me that
> autoresize would work this way.
>
> Can somebody confirm this observations or explain why this
> works like this. Maybe I'm also doing something wrong.
>
> See below how I generate the ubi image.
>
> General setup
> =============
> flash size: 4096 PEBs
> mtd partition size: 4065 PEBs
> number of volumes: 3
>
> Linux version:
> Linux dxr2 3.14.36-r2 #1 PREEMPT Tue Jun 30 10:26:05 CEST 2015 armv7l GNU/Linux
>
>
> Config 1
> ========
> 2 volumes with fixed size
> 1 volume has vol_flags=autoresize and vol_size not defined
>
> mkfs.ubifs -r ../rootfs/path -o rootfs.ubifs -F -m 2048 -e 126976 -c 4065
> mkfs.ubifs -r ../conf/path -o conf.ubifs -F -m 2048 -e 126976 -c 4065
> ubinize -o rootfs.ubi -m 2048 -p 131072 -O 2048 ubinize.cfg
>
> ubinize.cfg:
>  [rootfs_a]
>  mode=ubi
>  image=rootfs.ubifs
>  vol_id=0
>  vol_type=dynamic
>  vol_name=rootfs_a
>  vol_size=140MiB
>  [rootfs_b]
>  mode=ubi
>  vol_id=1
>  vol_type=dynamic
>  vol_name=rootfs_b
>  vol_size=140MiB
>  [configuration]
>  mode=ubi
>  image=configuration.ubifs
>  vol_id=2
>  vol_type=dynamic
>  vol_name=configuration
>  vol_flags=autoresize
>
> --> only 40 blocks get reserved vor bad PEB handling
>
> Config 2
> ========
> All 3 volumes with fixed size
>
> mkfs.ubifs -r ../rootfs/path -o rootfs.ubifs -F -m 2048 -e 126976 -c 4065
> mkfs.ubifs -r ../conf/path -o conf.ubifs -F -m 2048 -e 126976 -c 4065
>
> ubinize.cfg:
>  [rootfs_a]
>  mode=ubi
>  image=rootfs.ubifs
>  vol_id=0
>  vol_type=dynamic
>  vol_name=rootfs_a
>  vol_size=140MiB
>  [rootfs_b]
>  mode=ubi
>  vol_id=1
>  vol_type=dynamic
>  vol_name=rootfs_b
>  vol_size=140MiB
>  [configuration]
>  mode=ubi
>  image=configuration.ubifs
>  vol_id=2
>  vol_type=dynamic
>  vol_name=configuration
>  vol_size=341MiB

Something I did not notice yesternight, 140+140+341 is 621.
According to your logs the MTD partition is only 508MiB large.

-- 
Thanks,
//richard