[U-Boot] Kernel XIP

[Camilo Andres Roca Duarte]

Dear U-boot team
I'm currently working on an embedded system that uses U-boot as a second
step bootloader. I'm testing the booting time of the kernel with binary
formats. Before I was able to flash the first level bootloader, the u-boot
and the kernel (uImage) into the nand flash of the embedded system with the
following command on u-boot:
bootcmd=nand read.jffs2 0x22000000 0x200000 0xB00000; bootm 0x22000000

- I would like to know if the bootm command is actually loading the
complete kernel to RAM or if it is loading only the required pages from
flash.

- Also, please correct me if I'm wrong but from the description of the
bootm command, it seemed to me as if the bootm command should be enough to
actually start the kernel, nevertheless I encountered myself with needing
to previously read the kernel from the flash, to later be able to boot it,
why is that so?

- I have also tried an xipImage for the kernel, nevertheless once I use
this binary format, uboot promts an error: can't get kernel image!
I checked the tutorial available at your website
<http://www.denx.de/wiki/bin/view/DULG/ConfigureLinuxForXIP>, and I
confirmed that my linux configuration creates an xipImage (not a uImage as
stated in the tutorial). Does u-boot supports kernel execution in place?
and if so, does it only loads the necesary pages or does it fully loads the
kernel from the nand flash.

Thanks for your attention
Kind regards
_________________________________________
Camilo Andres Roca Duarte
Communication and Media Engineering Student
Hochschule Offenburg