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I am using U-Boot on a Cubieboard 2, sun7i AllWinner A20 board to boot into ArchLinux ARM. The kernel version that I have is the sun7i latest, which is 3.4.103-5-ARCH so, in kernel terms, it's a bit behind the times but it is the most recent from the repos.

I am learning about U-Boot and would like to see if I can boot using a zImage. I already have a uImage that works. This is an exercise to understand its operation.

One reason for doing this is that the boot.txt shipped with ArchLinuxARM contains code to boot with an initramfs-linux.img but only if a zImage is used (the shipped code doesn't cater for an initramfs with a uImage).

I am not asking how to boot an initrams with a uImage - I know how to do that. I am asking how to use a zImage with U-Boot.

My uImage has this header:

# mkimage -l uImage 
Image Name:   Linux-3.4.103-5-ARCH
Created:      Fri Jan 16 13:34:10 2015
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    3327616 Bytes = 3249.62 kB = 3.17 MB
Load Address: 40008000
Entry Point:  40008000

I can boot it manually with the following command sequence:

mmc dev 0
load mmc 0:1 0x48000000 /boot/uImage
load mmc 0:1 0x43000000 /boot/script.bin
setenv bootargs console=${console} root=/dev/sda6 rw rootwait
setenv bootm_boot_mode sec 
bootm 0x48000000

I extract the zImage from the uImage like this:

$ tail -c+65 < uImage > zImage

I check it looks ok

$ file zImage
zImage: Linux kernel ARM boot executable zImage (little-endian)

I then try booting it

mmc dev 0
load mmc 0:1 0x42000000 /boot/zImage
setenv bootargs console=${console} root=/dev/sda6 rw rootwait
bootz 0x42000000

But it doesn't work. All I see is "

Kernel image @ 0x42000000 [ 0x000000 - 0x32c680 ]
Starting kernel ...

I presume it's something to do with the script.bin that I load prior to bootm. If tried loading it prior to bootz but it made no difference. I also read abot a FDT file but I don't think the Arch Linix kernel package provides one. Nonetheless, bootm didn't need one so I would expect that bootz doesn't either (given the kernel image is the same).

To be sure my zimage was ok, I made a new uImage from it and it booted fine.

I derived the above commands and addresses from the boot.txt shipped with ArchLinuxARM.

My U-boot version is:

U-Boot 2015.01-1 (Jan 22 2015 - 16:37:34) Arch Linux ARM
gcc (GCC) 4.9.2 20141224 (prerelease)
GNU ld (GNU Binutils) 2.25

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