Can't find correct configuration

[Zhihao Cheng]

在 2023/9/5 22:45, Leon Pollak 写道:
Hi
> Hello, all.
> I will be very very thankful for the help to find the correct
> configuration for my NAND.
> I passed through a lot of mails in the lists and google and ChatGPT -
> no success.
> I have 256MB NAND and 248MB partition for UBIFS. I run:
> mkfs.ubifs -v -r rootfs -F -m 2048 -e 126976 -c 1981 -o ./ubifs.img
> ubinize -v -o rootfs.img -m 2048 -p 128KiB -s 512 -O 2048 ubinize.cfg
> -----
> and ubinize.cfg looks like:
> [ubifs]
> mode=ubi
> image=./ubifs.img
> vol_id=0
> vol_size=240MiB
> vol_type=dynamic
> vol_name=ubi_rootfs
> vol_alignment=1
> vol_flags=autoresize
> ------
> Kernel configuration  was with CONFIG_MTD_UBI_BEB_LIMIT=20.
> and here is the kernel log:
> [    2.695659] ubi0: attaching mtd4
> [    3.372343] ubi0: scanning is finished
> [    3.383066] ubi0 warning: ubi_eba_init: cannot reserve enough PEBs
> for bad PEB handling, reserved 4, need 40
> [    3.404320] ubi0: volume 0 ("ubi_rootfs") re-sized from 1982 to 1982 LEBs
> [    3.411667] ubi0: attached mtd4 (name "FS", size 248 MiB)
> [    3.417095] ubi0: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
> [    3.424006] ubi0: min./max. I/O unit sizes: 2048/2048, sub-page size 512
> [    3.430740] ubi0: VID header offset: 2048 (aligned 2048), data offset: 4096
> [    3.437734] ubi0: good PEBs: 1990, bad PEBs: 0, corrupted PEBs: 0
> [    3.443860] ubi0: user volume: 1, internal volumes: 1, max. volumes
> count: 128
> [    3.451117] ubi0: max/mean erase counter: 1/0, WL threshold: 4096,
> image sequence number: 1590570073
> [    3.460295] ubi0: available PEBs: 0, total reserved PEBs: 1990,
> PEBs reserved for bad PEB handling: 4
> [    3.469575] ubi0: background thread "ubi_bgt0d" started, PID 131
> [    4.648718] UBIFS (ubi0:0): background thread "ubifs_bgt0_0" started, PID 136
> [    4.676640] UBIFS (ubi0:0): start fixing up free space
> [   10.250099] UBIFS (ubi0:0): free space fixup complete
> [   10.269046] UBIFS (ubi0:0): UBIFS: mounted UBI device 0, volume 0,
> name "ubi_rootfs"
> [   10.276830] UBIFS (ubi0:0): LEB size: 126976 bytes (124 KiB),
> min./max. I/O unit sizes: 2048 bytes/2048 bytes
> [   10.286794] UBIFS (ubi0:0): FS size: 250142720 bytes (238 MiB, 1970
> LEBs), journal size 9023488 bytes (8 MiB, 72 LEBs)
> [   10.297540] UBIFS (ubi0:0): reserved for root: 0 bytes (0 KiB)
> [   10.303406] UBIFS (ubi0:0): media format: w4/r0 (latest is w5/r0),
> UUID A14D586A-32E2-45D7-A07E-BDC472FDF31D, small LPT model
> 
> My question is: why does this warning about reserved 4, needed 40
> appear? How can I solve this?
> 

Solution: Modify ubinize.cfg,  vol_size=240MiB -> vol_size=235MiB

Why does this warning about reserved 4, needed 40 appear?
The count of bad PEBs reserved by UBI is: total_pebs(nand chip) * 
CONFIG_MTD_UBI_BEB_LIMIT/1024 = 2048 *  20 / 1024 = 40
When fastmap is not enabled, the count of internal PEBs reserved by UBI 
is: UBI_LAYOUT_VOLUME_EBS[2] + WL_RESERVED_PEBS[1] + 
EBA_RESERVED_PEBS[1] = 4

Total PEBs for UBI is 1990(good PEBs: 1990), the max count of user 
volume PEBs is 1990 - 40 - 4 = 1946

In ubinize.cfg, vol_size=240MiB, the count of user volume PEBs is(see 
ubinize.c in mtduitls): vi_size + (leb_size - 1) / leb_size
vi_size = 240M = 240 * 1024 * 1024
leb_size = 128K - 2K(ec) - 2K(vid) = 124 * 1024
result = 1982

So there are 1990 - 1982 - 4 = 4 PEBs reserved for bad PEB handling, 
which is less than 40.

When we set  vol_size=235MiB, the count of user volume PEBs is: (235 * 
1024 * 1024 + 124 * 1024 - 1) / (124 * 1024) = 1941
1990 - 4 - 40 = 1946, finally maybe there is message from kernel like 
"("ubi_rootfs") re-sized from 1941 to 1946 LEBs".