上一次中，我们制作了jffs2文件系统，实现了普通分区jffs2的挂载，这一次，我们同样实现了ubifs文件系统的挂载，可以来尝试一下ubifs下普通分区的挂载。

Nandflash分区情况

MTD设备分区情况

~ >: cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00100000 00020000 "mtdblock0 u-boot 1MB"
mtd1: 00f00000 00020000 "mtdblock1 kernel 15MB"
mtd2: 02800000 00020000 "mtdblock2 rootfs 40MB"
mtd3: 05000000 00020000 "mtdblock3 apps 80MB"
mtd4: 05000000 00020000 "mtdblock4 data 80MB"
mtd5: 02800000 00020000 "mtdblock5 backup 40MB"

linux内核分区

~ >: cat /proc/partitions
major minor  #blocks  name

  31        0       1024 mtdblock0
  31        1      15360 mtdblock1
  31        2      40960 mtdblock2
  31        3      81920 mtdblock3
  31        4      81920 mtdblock4
  31        5      40960 mtdblock5

分区对应的块设备

~ >:  ls -l /dev/mtdblock*
brw-rw----    1 root     root       31,   0 Jan  1 00:00 /dev/mtdblock0
brw-rw----    1 root     root       31,   1 Jan  1 00:00 /dev/mtdblock1
brw-rw----    1 root     root       31,   2 Jan  1 00:00 /dev/mtdblock2
brw-rw----    1 root     root       31,   3 Jan  1 00:00 /dev/mtdblock3
brw-rw----    1 root     root       31,   4 Jan  1 00:00 /dev/mtdblock4
brw-rw----    1 root     root       31,   5 Jan  1 00:00 /dev/mtdblock5

建立UBI卷

以mtdblock3为例，以ubifs文件格式挂载到/apps挂载点上

擦除对应分区

~ >: flash_eraseall /dev/mtd3
Erasing 128 Kibyte @ 5000000 - 100% complete.

当前设备

~ >: ls /dev/ubi*
/dev/ubi0      /dev/ubi0_0    /dev/ubi_ctrl
~ >: ubiattach
BusyBox v1.27.1 (2018-04-03 02:25:34 PDT) multi-call binary.

Usage: ubiattach -m MTD_NUM [-d UBI_NUM] [-O VID_HDR_OFF] UBI_CTRL_DEV

Attach MTD device to UBI

        -m MTD_NUM      MTD device number to attach
        -d UBI_NUM      UBI device number to assign
        -O VID_HDR_OFF  VID header offset
~ >: 

建立关联

~ >: ubiattach -m 3 -d 3 /dev/ubi_ctrl
UBI: attaching mtd3 to ubi3
UBI: physical eraseblock size:   131072 bytes (128 KiB)
UBI: logical eraseblock size:    129024 bytes
UBI: smallest flash I/O unit:    2048
UBI: sub-page size:              512
UBI: VID header offset:          512 (aligned 512)
UBI: data offset:                2048
UBI: empty MTD device detected
UBI: max. sequence number:       0
UBI: create volume table (copy #1)
UBI: create volume table (copy #2)
UBI: attached mtd3 to ubi3
UBI: MTD device name:            "mtdblock3 apps 80MB"
UBI: MTD device size:            80 MiB
UBI: number of good PEBs:        640
UBI: number of bad PEBs:         0
UBI: number of corrupted PEBs:   0
UBI: max. allowed volumes:       128
UBI: wear-leveling threshold:    4096
UBI: number of internal volumes: 1
UBI: number of user volumes:     0
UBI: available PEBs:             630
UBI: total number of reserved PEBs: 10
UBI: number of PEBs reserved for bad PEB handling: 6
UBI: max/mean erase counter: 0/0
UBI: image sequence number:  759054630
UBI: background thread "ubi_bgt3d" started, PID 972
~ >:  ls /dev/ubi*
/dev/ubi0      /dev/ubi0_0    /dev/ubi3      /dev/ubi_ctrl
~ >:

建立UBI卷

~ >: ubimkvol -m -n 0 -N apps /dev/ubi3 
~ >: ls /dev/ubi*
/dev/ubi0      /dev/ubi0_0    /dev/ubi3      /dev/ubi3_0    /dev/ubi_ctrl
~ >: ubimkvol
BusyBox v1.27.1 (2018-04-03 02:25:34 PDT) multi-call binary.

Usage: ubimkvol -N NAME [-s SIZE | -m] UBI_DEVICE

Create UBI volume

        -a ALIGNMENT    Volume alignment (default 1)
        -m              Set volume size to maximum available
        -n VOLID        Volume ID. If not specified,
                        assigned automatically
        -N NAME         Volume name
        -s SIZE         Size in bytes
        -t TYPE         Volume type (static|dynamic)
~ >: 

文件系统挂载

挂载ubi3(即mtdblock3)到/apps挂载点上

~ >: mount -t ubifs -o sync,noatime,rw ubi3:apps /apps/
UBIFS: default file-system created
UBIFS: mounted UBI device 3, volume 0, name "apps"
UBIFS: file system size:   80123904 bytes (78246 KiB, 76 MiB, 621 LEBs)
UBIFS: journal size:       3999744 bytes (3906 KiB, 3 MiB, 31 LEBs)
UBIFS: media format:       w4/r0 (latest is w4/r0)
UBIFS: default compressor: lzo
UBIFS: reserved for root:  3784449 bytes (3695 KiB)
~ >: mount
rootfs on / type rootfs (rw)
ubi0:rootfs on / type ubifs (rw,relatime)
proc on /proc type proc (rw,relatime)
usbfs on /proc/bus/usb type usbfs (rw,relatime)
tmpfs on /dev type tmpfs (rw,relatime)
ramfs on /tmp type ramfs (rw,relatime)
sysfs on /sys type sysfs (rw,relatime)
devpts on /dev/pts type devpts (rw,relatime,mode=600)
ubi3:apps on /apps type ubifs (rw,sync,noatime)

卸载和重挂载

卸载解除关联

~ >: umount /apps/
UBIFS: un-mount UBI device 3, volume 0
~ >: ubidetach -d 3 /dev/ubi_ctrl
UBI: mtd3 is detached from ubi3
~ >:  ls /dev/ubi*
/dev/ubi0      /dev/ubi0_0    /dev/ubi_ctrl

重新建立关系

~ >: ubiattach -m 3 -d 3 /dev/ubi_ctrl
UBI: attaching mtd3 to ubi3
UBI: physical eraseblock size:   131072 bytes (128 KiB)
UBI: logical eraseblock size:    129024 bytes
UBI: smallest flash I/O unit:    2048
UBI: sub-page size:              512
UBI: VID header offset:          512 (aligned 512)
UBI: data offset:                2048
UBI: max. sequence number:       12
UBI: attached mtd3 to ubi3
UBI: MTD device name:            "mtdblock3 apps 80MB"
UBI: MTD device size:            80 MiB
UBI: number of good PEBs:        640
UBI: number of bad PEBs:         0
UBI: number of corrupted PEBs:   0
UBI: max. allowed volumes:       128
UBI: wear-leveling threshold:    4096
UBI: number of internal volumes: 1
UBI: number of user volumes:     1
UBI: available PEBs:             0
UBI: total number of reserved PEBs: 640
UBI: number of PEBs reserved for bad PEB handling: 6
UBI: max/mean erase counter: 2/1
UBI: image sequence number:  759054630
UBI: background thread "ubi_bgt3d" started, PID 992
~ >: ls /dev/ubi*
/dev/ubi0      /dev/ubi0_0    /dev/ubi3      /dev/ubi3_0    /dev/ubi_ctrl

再次关联问题

~ >: ubimkvol -m -n 0 -N apps /dev/ubi3
ubimkvol: UBI_IOCMKVOL: Invalid argument

当再次关联ubi3到mtd3下的时候，发现再次建立UBI卷出错。这也意味着，如果之前已经用ubimkvol建立UBI卷的分区再次挂载时不需要在执行该命令，也就是ubimkvol针对一个分区只能做一次，除非使用flash_eraseall重新格式化。