[U-Boot] fw_env.conf for gigabyte mp30ar0 or force u-boot console on boot

[Thomas Lamprecht]

Hi,

I'm currently playing with the Gigabyte MP30 AR0 board with an X-Gene 1 CPU
from Applied Micro as we're evaluating ARM.
A first try was to follow 
https://lists.centos.org/pipermail/arm-dev/2016-February/001626.html
and chain loaded TianoCore and then CentOS or Debian (I'm more familiarwith
TianoCore aswe work with OVMF a lot, in retrospect not the best idea as 
I could have worked
with uboot).

Backstory aside, my problem is that after executing:

  > MP30AR0# setenv num_cores 1
  > MP30AR0# setenv DDRBASE2G 1
  > MP30AR0# save; reset

it shows just the first line from u-boot (the version string) and then 
boots directly
into the builtin OpenLinux from Applied Micro, or a Ubuntu configured 
for u-boot if
I insert that as USB device.

I have no access to the u-boot shell anymore and I'm also currently not 
able to read
or change fw environment variable through a linux with u-boot-tools 
(fw_printenv,
fw_savenenv) as I could not find a fw_env.conf file for this board.

cat /proc/mtd outputs:
dev:    size   erasesize  name
mtd0: 000f0000 00010000 "Boot loader"
mtd1: 00010000 00010000 "fdt"
mtd2: 00f00000 00010000 "kern"
mtd3: 01000000 00010000 "ramdisk"

With which I'm not able to write a /etc/fw_env.conf
Reading /dev/mtd0 with `hexdump -C /dev/mtd0` or `strings -tx /dev/mtd0` 
allows me to
guess where the env store starts and ends, I tried to map this guessing 
in a valid
fw_env.conf but had no luck and always got a bad CRC.

Is there a way to really force the u-boot shell at boot so that I can 
reset it there
or has any one experience with the board in question and has a valid 
fw_env.conf so that
I can reset the respective vars through a Linux I'm able to boot?

My goal would be getting the u-boot shell again so that I can try 
booting into a Debian
directly, or chain loading TianoCore if that does not work.

I hope I'm here on the correct list for this, if not I'm sorry and happy 
for all tips and
pointers for a place where I can search/ask for this.

best regards,
Thomas