Mount UBI with nandsim

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?