Filesystem from flash script

While there is no issue in executing filesystem_from_usb when booted from SD (provided there are no flash partitions mounted), further preparation is required in order to successfully boot from eMMC/NAND, and use the USB update functionality to update the flash. A USB device is required to have the the Debian distribution on the first partition and a specific set of steps in the "tsinit" script - this ensures that all flash partitions are safely unmounted and the necessary tools are available. See the initramfs USB scripting section for more information on setting up the "tsinit" script.

Using a linux host PC, format a USB drive with the first partition (min. 2GB) formatted ext2/3. Download the distribution tarball and extract it to first partition of the USB drive.

Next, set up the "tsinit" file with the following script outline:

#!/bin/sh

#We only need unmount /mnt/root and use USB if booted from NAND/eMMC
if [ "$bootmode" == "0x1" ]; then
  killall mdnsd >/dev/null #Required to cleanly umount /etc
  sleep 1
  if [ -e /dev/mtd0 ]; then
    umount /mnt/root/ts
  fi
  umount /etc
  umount /mnt/root

  mount -obind /mnt/usbdev /mnt/root
  mount -obind /mnt/root/etc /etc/
fi

echo ""
source /ts.subr
tshwctl --greenledon --redledon
echo "Flashing kernel"
kernel_from_usb >/dev/null 2>&1
if [ "$?" != "0" ]; then
  echo "Failed flashing kernel"
  tshwctl --greenledoff
  while true; do tshwctl --redledon; sleep .5; tshwctl --redledoff; sleep .5 ; done &
  return 1
fi
echo "Flashing filesystem"
eval `filesystem_from_usb`
if [ "$prog_ok" != "1" ] ; then
  echo "Failed flashing filesystem"
  tshwctl --greenledoff
  while true; do tshwctl --redledon; sleep .5; tshwctl --redledoff; sleep .5 ; done &
  return 1
fi

#We only need unmount /mnt/root and use USB if booted from NAND
if [ "$bootmode" == "0x1" ]; then
  umount /etc
  umount /mnt/root
fi

echo "Done"
while true; do tshwctl --greenledon; sleep .5; tshwctl --greenledoff; sleep .5 ; done &