U-Boot UMS on APF & OPOS

This page gather instructions for using U-Boot's USB Mass Storage gadget mode (or UMS) usage on APF6 and OPOS6UL(NANO). This mode allows you to flash rootfs images bigger than the available module RAM, ex: > 200MBytes on the OPOS6UL(NANO). Indeed run update_rootfs script uses RAM to store images while uploading from TFTP, which can be short for big rootfs. UMS also allows you to backup your rootfs on your Host.

• 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 | tail
[...]
[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". On your debian/ubuntu Host it might be auto-mounted under /media/usb1, if no other USB key is present on system and if you activated auto-mounting.

$ 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            (if partition is auto-mounted)
$ sudo mkfs.ext4 -L ROOTFS -O ^64bit /dev/sdc2

Update your rootfs

• Then, you have 2 methods to update your rootfs:

tar method	dd method
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	One alternative way to untaring is to use dd: $ sudo dd if=/tftpboot/xxx-rootfs.ext4 of=/dev/sdc2 (replace xxx with the name of your module)

• Once finished, 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>

Backup your rootfs

$ sudo dd  if=/dev/sdc2 of=/home/xxx/rootfs_xxx.ext4       (takes time ;-) )

• check if it succeed:

$ sudo mount -o loop /home/xxx/rootfs_xxx.ext4 /media/mmc/
$ ls /media/mmc/boot/

Troubleshots

• UMS was reported not working on Windows 7/8 hosts with Virtual Box Ubuntu 15.04 emulated machines...

Links

• OPOS6UL eMMC Data partition