Kernel panic - not syncing: broken padding

I'm testing MMU Linux and have a strange phenomena.

I have stored my kernel 'linux.initramfs.gz' in flash using elf2flash and then nios2-flash-programmer (with the option '--mmu').

When I'm turning the board on, the boot fails on a 'Kernel panic - not syncing: broken padding'.

However, when I'm resetting the CPU (using the CPU reset switch), the boot is running fine without error.

I suppose it is a problem of MMU configuration that the bootloader doesn't perform but the kernel do, but I am not sure?

Is there another solution to boot as fast as possible a Linux kernel?

Have I to use 'uboot'? And if so, is it possible to make uboot starting with no delay nor query?

TIA for any idea,

-- Fred