UBI/UBIFS無法使用loop-back方式mount, 不過我們可以使用NAND simulator將UBI燒入到nandsim中.
root@vista:~# mkfs.ubifs -m 2KiB -e 129024 -c 2048 -r ubifs-root -x zlib ubifs.img
root@vista:~# cat ubi.ini
[ubi_rfs]
mode=ubi
image=ubifs.img
vol_id=0
vol_type=dynamic
vol_name=ubi_rfs
vol_alignment=1
vol_flags=autoresize
root@vista:~# ubinize -o my.ubi -p 128KiB -m 2KiB -O 512 ubi.ini
ubinize: volume size was not specified in section "ubi_rfs", assume minimum to fit image "ubifs.img"1806336 bytes (1.7 MiB)
root@vista:~# modprobe nandsim first_id_byte=0x20 second_id_byte=0xaa third_id_byte=0x00 fourth_id_byte=0x15
root@vista:~# ubiformat /dev/mtd0 -f my.ubi
ubiformat: mtd0 (nand), size 268435456 bytes (256.0 MiB), 2048 eraseblocks of 131072 bytes (128.0 KiB), min. I/O size 2048 bytes
libscan: scanning eraseblock 2047 -- 100 % complete
ubiformat: 2048 eraseblocks have valid erase counter, mean value is 3
ubiformat: flashing eraseblock 15 -- 100 % complete
ubiformat: formatting eraseblock 2047 -- 100 % complete
ubiformat: formatting eraseblock 2047 -- 100 % complete
root@vista:~# ubiattach -m 0
UBI device number 0, total 2048 LEBs (264241152 bytes, 252.0 MiB), available 0 LEBs (0 bytes), LEB size 129024 bytes (126.0 KiB)
root@vista:~# ubinfo -a
UBI version: 1
Count of UBI devices: 1
UBI control device major/minor: 10:55
Present UBI devices: ubi0
ubi0
Volumes count: 1
Logical eraseblock size: 129024 bytes, 126.0 KiB
Total amount of logical eraseblocks: 2048 (264241152 bytes, 252.0 MiB)
Amount of available logical eraseblocks: 0 (0 bytes)
Maximum count of volumes 128
Count of bad physical eraseblocks: 0
Count of reserved physical eraseblocks: 40
Current maximum erase counter value: 9
Minimum input/output unit size: 2048 bytes
Character device major/minor: 245:0
Present volumes: 0
Volume ID: 0 (on ubi0)
Type: dynamic
Alignment: 1
Size: 2002 LEBs (258306048 bytes, 246.3 MiB)
State: OK
Name: ubi_rfs
Character device major/minor: 245:1
root@vista:~# mount -t ubifs /dev/ubi0_0 www
Usage: mkfs.ubifs [OPTIONS] target
Make a UBIFS file system image from an existing directory tree
Options:
-r, -d, --root=DIR build file system from directory DIR
-m, --min-io-size=SIZE minimum I/O unit size
-e, --leb-size=SIZE logical erase block size
-c, --max-leb-cnt=COUNT maximum logical erase block count
-x, --compr=TYPE compression type - "lzo", "favor_lzo", "zlib" or
"none" (default: "lzo")
# mkfs.ubifs -F -r </path/to/your/rootfs/tree> -m <min io size> -e <LEB size> -c
<Erase Blocks count> -o </path/to/output/Image.ubifs>
<min io size> Equals the page-size of the used NAND-Flash
<LEB size> Logical Erase Block size
<Erase Blocks count> maximum logical erase block count
mkfs.ubifs -m 2KiB -e 129024 -c 2048 -r ubifs-root -x zlib ubifs.img這些相關參數是先用ubiformat確認的, 不過-e是在mount failed的時候看dmesg的
Usage: ubinize [-o filename] [-p ] [-m ] [-s ] [-O ] [-e ]
[-x ] [-Q ] [-v] [-h] [-V] [--output=] [--peb-size=]
[--min-io-size=] [--sub-page-size=] [--vid-hdr-offset=]
[--erase-counter=] [--ubi-ver=] [--image-seq=] [--verbose] [--help]
[--version] ini-file
-p, --peb-size= size of the physical eraseblock of the flash
this UBI image is created for in bytes,
kilobytes (KiB), or megabytes (MiB)
(mandatory parameter)
-m, --min-io-size= minimum input/output unit size of the flash
in bytes
-O, --vid-hdr-offset= offset if the VID header from start of the
physical eraseblock (default is the next
minimum I/O unit or sub-page after the EC
header)
# ubinize -vv -o <output image> -m <min io size> -p <PEB size>KiB
-s <subpage-size> -O <VID-hdr-offset> <configuration file>
<min io size> Equals the page-size of the used NAND-Flash
<PEB size> Physical Erase Block size (in KiB) - Equals the block size of
the NAND-Flash
<Erase Blocks count> Count of the available Erase Blocks
<subpage-size> Subpage size in bytes. Default value is the minimum
input/output size (page-size)
<VID-hdr-offset> offset if the VID header from start of the PEB
(default is the next min I/O unit or sub-page after the EC header)
<configuration file> Path to a configuration file.
ubinize -o my.ubi -p 128KiB -m 2KiB -O 512 ubi.ini這些參數也是在ubiformat修正的, 如-O 512
參考資料：
- http://www.linux-mtd.infradead.org/faq/ubifs.html#L_loop_mount, Can UBIFS mount loop-back devices?
- https://elinux.org/UBIFS, UBIFS
- http://www.linux-mtd.infradead.org/faq/nand.html#L_nand_nandsim, How do I use NAND simulator?
