Cyclone V SoC Preloader will not run bare metal app

I'm just a beginner myself, so take my advice with a grain of salt, but the options to the mkimage command looks suspect to me:

$(MKIMAGE) -A arm -T standalone -C none -a 0x100040 -e 0 -n "uboot script" -d u-boot.script u-boot.scr

I think what you want is something that looks more like that seen in the following web page (URL split with * instead of / to get past spam filter):

rocketboards . org * foswiki * Documentation * GSRD131ProgrammingFPGA

Here they use:

"$ ~/cv_soc_devkit_ghrd/software/spl_bsp/uboot-socfpga/tools/mkimage -A arm -O linux -T script -C none -a 0 -e 0 -n "My script" -d u-boot.txt u-boot.scr"

There is another way to get the u-boot.scr script file to work, which allows you to bypass using the mkimage command.

When you see this prompt: Hit any key to stop autoboot: 0

Hit a key to stop the boot process. You will be at the bootloader prompt.

Then just type in the commands from the u-boot.txt file, one line at a time. Once that works, then there is a way to

save these commands in the environment so you don't have to re-type them each time the system boots.