U-Boot UMS on APF & OPOS

Infos for U-Boot's USB Mass Storage gadget mode (or UMS) usage on APF6 and OPOS6UL.

• First, keep your USB debug cable and connect a second USB cable on APF6_Dev or OPOS6ULDev's OTG port.
• Under U-Boot type:

BIOS> ums 0 mmc 0
UMS: disk start sector: 0x0, count: 0x760000
|

• On your host computer you should see the eMMC partition like a standard USB key.

$ dmesg
[...]
[26828.348088] sd 13:0:0:0: [sdc] Mode Sense: 0f 00 00 00
[26828.348395] sd 13:0:0:0: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[26828.354177]  sdc: sdc1 sdc2
[26828.356782] sd 13:0:0:0: [sdc] Attached SCSI disk

Here the device is /dev/sdc and all partitions have been automounted by the host:

[26830.002168] EXT4-fs (sdc1): mounting ext2 file system using the ext4 subsystem
[26830.054358] EXT4-fs (sdc2): mounting ext2 file system using the ext4 subsystem
[26830.078638] EXT4-fs (sdc2): warning: mounting unchecked fs, running e2fsck is recommended
[26830.114382] EXT4-fs (sdc2): mounted filesystem without journal. Opts: (null)
[26830.135564] EXT4-fs (sdc1): warning: mounting unchecked fs, running e2fsck is recommended
[26830.268450] EXT4-fs (sdc1): mounted filesystem without journal. Opts: (null)

Warning: Before doing the following procedure, be sure that your device name is correct. You can erase all your host datas if you do it wrong !!!

• The rootfs is under the sdc2 and is named "rootfs". In debian/ubuntu it's mounted under /media/usb1 if no other USB key is present on system.

$ ls /media/usb1/
bin  boot  dev  etc  home  init  lib  lib32  linuxrc  lost+found  media  mnt  opt  proc  root  run  sbin  sys  tmp  usr  var

• To flash entire rootfs, first erase all files on this partition:

$ sudo umount /media/usb1
$ sudo mkfs.ext4 /dev/sdc2

• Then mount it under an arbitrary directory:

$ sudo mkdir /tmp/rootfs
$ sudo mount /dev/sdc2 /tmp/rootfs

• Untar the archive generated by your bsp (in buildroot/output/images/)

$ make shell_env
$ . armadeus_env.sh
$ sudo tar -xvf $ARMADEUS_ROOTFS_TAR -C /tmp/rootfs

• then umount the filesystem:

$ sudo umount /tmp/rootfs/
$ sync

• Once unmounted, you can kill the U-Boot's USB gadget process with a Ctrl-C:

BIOS> ums 0 mmc 0
UMS: disk start sector: 0x0, count: 0x760000
CTRL+C - Operation aborted
BIOS>