boot.txt

#
# SolidRun i.MX6 Debian Boot Script
# 
# Copyright: 2018 Josua Mayer
#
# This is a transitional boot-script to handle updates
# in the boot process with the legacy 2013.10 U-Boot.
#

# parse version variable, if any
# (enabled on builds since March 2018)
if test -n "$ver"; then
	# copy version string to memory
	env export 0x12000000 ver

	# now memory looks like this
	# "ver=U-Boot 2017.11-"...

	# copy major to start of variable
	# 4 bytes from offset 11 to offset 4
	cp.b 0x1200000b 0x12000004 4
	# append minor version
	# 2 bytes from offset 16, to offset 8
	cp.b 0x12000010 0x12000008 2
	# terminate with null byte
	mw.b 0x1200000a 0 1

	# read back variable
	env import 0x12000000
else
	# set fall-back version as 0 (we really don't know)
	setenv ver 0
fi

# apply compatibility hacks for older versions as necessary
if test $ver < 201711; then
	# There are now seperate DTBs for devices without eMMC!
	if test -n "$somrev" && test "$somrev" == "-som-v15"; then
		# Because we can't tell from this U-Boot, assume eMMC is present.
		echo "Assuming eMMC is present,"
		echo "for proper detection, upgrade U-Boot to 2017.11 or later."

		# overriding the somrev variable is enough to fixup the existing autodetectfdt macro
		setenv somrev "-emmc-som-v15"
	fi

	# Letting the original boot logic kick back in, it will now search for a script in /boot/
fi

# unset ver if it didn't exist before
if test $ver == 0; then
	setenv -f ver
fi

echo "Compatibility Boot-script finished, returning to U-Boot."