Running Debian from a USB-drive on a Cubox-i 4

[Pierre <p.metras@videotron.ca>]

Hello,

I've bootstrapped Jessie on my Cubox-i 4 following instructions from
http://techieventures.blogspot.ca/2014/10/install-debian-jessie-with-debian-u.html.
Now, I want to use a USB hard drive for the root filesystem instead of the MMC.
I've changed the /boot/uEnv.txt file to point at /dev/sda1 instead of
/dev/mmcblk0p1 and modified consequently /etc/fstab on the hard drive to mount
/sda1 as root. When I reboot the Cubox-i, the root partition is still on the
MMC card. In the system log, the file system is remounted on the MMC, as if it
does not take into account the kernel parameters passed by the uEnv.txt file.
I've tried multiple variants with always the same result and I need external
eyes and advices about what could be wrong.


Booting the Cubox-i
-------------------------------
U-Boot SPL 2014.10+dfsg1-5 (Apr 07 2015 - 22:16:43)
...
[    2.874180] EXT4-fs (mmcblk0p1): mounted filesystem with ordered data mode. Opts: (null)
...
[    3.928719] systemd[1]: Starting Remount Root and Kernel File Systems...
...
[    4.016591] EXT4-fs (mmcblk0p1): re-mounted. Opts: (null)


root@microbe:/boot# cat uEnv.txt 
mmcargs=setenv bootargs root=/dev/sda1 rootfstype=ext4 rootwait rw console=ttymxc0,115200 console=tty1 consoleblank=0 video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24,bpp=32 rd.dm=0 rd.luks=0 rd.lvm=0 raid=noautodetect pci=nomsi ahci_imx.hotplug=1 quiet vt.global_cursor_default=0


root@microbe:~# df -h
df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/mmcblk0p1  3.6G  564M  2.8G  17% /
udev             10M     0   10M   0% /dev
tmpfs           405M  5.3M  399M   2% /run
tmpfs          1011M     0 1011M   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs          1011M     0 1011M   0% /sys/fs/cgroup


root@microbe:~# cat /proc/partitions 
major minor  #blocks  name

 179        0    3849216 mmcblk0
 179        1    3847536 mmcblk0p1
   8        0  488386584 sda
   8        1  483267298 sda1
   8        2    5116702 sda2


root@microbe:~# mount /dev/sda1 /mnt/
[ 1231.470839] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
root@microbe:~# cat /mnt/etc/fstab 
/dev/sda1         /               ext4     defaults,noatime       0     0
/dev/sda2         none            swap     sw                     0     0
/dev/mmcblk0p1    /media/mmc      ext4     defaults               0     0
/media/mmc/boot   /boot           none     bind                   0     0


u-boot environment variables haven't been touched and seems to be the Cubox-i
defaults.

Thanks
-- 
Pierre