Thank you so much Igor! This solved my problems!
Originally I was following the instructions here to get my image using another Linux machine. So I compiled the kernel and uboot image, then followed the instructions at the bottom to flash them into my SD card. However, the instructions seem to work only for uImage, but I got a zImage from compiling the 3.14 kernel, so I changed the first line of uEnv.txt to "bootfile=/boot/zImage", but that gave me a "Wrong Image Format for bootm command" when I tried it on hummingboard. I then did the following in uboot:
setenv bootargs 'console=ttymxc0,115200 video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24,bpp=32'
ext2load mmc 0:1 0x10800000 /boot/zImage
But my screen just went black after the bootz command.
I then tried converting the zImage to uImage by typing the following:
mkimage -A arm -O linux -T kernel -C none -a 0x80008000 -e 0x80008000 -n "Linux kernel" -d arch/arm/boot/zImage uImage
I tried to boot off that uImage and it gave me a black screen again.
What am I doing wrong here?
PS: From the instructions I followed, I did not do anything for following line because I wasn't sure what to do:
<copy the root filesystem and do any other modifications on the mounted partition>
,but I doubt that's the reason?