View source for 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:
<pre class="apf">
BIOS> ums 0 mmc 0
UMS: disk start sector: 0x0, count: 0x760000
|
</pre>
* On your Host computer you should see the [[eMMC]] partition like a standard USB key.
<pre class="host">
$ 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
</pre>

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

<pre class="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)
</pre>
{{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.
<pre class="host">
$ 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
</pre>

* To flash entire rootfs, first erase all files on this partition:
<pre class="host">
$ sudo umount /media/usb1            (if partition is auto-mounted)
$ sudo mkfs.ext4 -L ROOTFS -O ^64bit,^metadata_csum,uninit_bg /dev/sdc2
</pre>

==Update your rootfs==
* Then, you have 2 methods to update your rootfs:
{| class="wikitable"
|-
! tar method !! dd method
|-
|
* Then mount it under an arbitrary directory:
<pre class="host">
$ sudo mkdir /tmp/rootfs
$ sudo mount /dev/sdc2 /tmp/rootfs
</pre>

* Untar the archive generated by your bsp (in ''buildroot/output/images/'')
<pre class="host">
$ make shell_env
$ . armadeus_env.sh
$ sudo tar -xvf $ARMADEUS_ROOTFS_TAR -C /tmp/rootfs
</pre>
* then umount the filesystem:
<pre class="host">
$ sudo umount /tmp/rootfs/
$ sync
</pre>
||
* One alternative way to untaring is to use ''dd'':
<pre class="host">
$ sudo dd if=/tftpboot/xxx-rootfs.ext4 of=/dev/sdc2
</pre>
(replace xxx with the name of your module)
|}

* Once finished, you can kill the U-Boot's USB gadget process with a Ctrl-C:
<pre class="apf">
BIOS> ums 0 mmc 0
UMS: disk start sector: 0x0, count: 0x760000
CTRL+C - Operation aborted
BIOS>
</pre>

==Backup your rootfs==
<pre class="host">
$ sudo dd  if=/dev/sdc2 of=/home/xxx/rootfs_xxx.ext4       (takes time ;-) )
</pre>

* check if it succeed:
<pre class="host">
$ sudo mount -o loop /home/xxx/rootfs_xxx.ext4 /media/mmc/
$ ls /media/mmc/boot/
</pre>

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

==Links==
* [[EMMC_OPOS6UL#User_Data_partition_layout|OPOS6UL eMMC Data partition]]
* [[EMMC_OPOS8MM#User_Data_partition_layout|OPOS8MM eMMC Data partition]]

[[Category:U-Boot]]