[U-Boot-Users] OneNAND alternative to X-Load

[Stefan Roese]

Hi Pete,

On Wednesday 23 May 2007, Pete MacKay wrote:
> We're developing a PXA-270-based machine that will boot from OneNAND.  I
> wanted to share my ideas (and code) with anyone faced with this challenge,
> since this forum (esp. Kyungmin Park - thank you!!) was quite helpful.
>  I'll start off explaining my u-boot code, then when I get some time I'll
> submit my PXA-270 platform driver as a patch (currently works on 2.6.18).
>
> We use a common approach: in lacking JTAG we have chip select jumpers that
> swap CS0/CS1 between NOR and OneNAND.  The OneNAND has a bottom-mapped 2K
> boot buffer of which 1K is valid, which is where the level 1 boot loader
> fits.  It uses two memory-mapped 'bufferrams' to ping-pong data out of the
> NAND pages, but you want to use BUFFERRAM1 only as writing BUFFERRAM0 can
> corrupt BOOTRAM0 on some revs of the chip.  (We're executing out of
> BOOTRAM0 so that's bad :).
>
> There is open-source code called "x-loader" that is a stripped-down u-boot
> for the level 1 boot loader.  What I did was integrate the level 1
> function into u-boot itself with a custom configuration and linker script.
> In the top u-boot Makefile I added this:
>
> myboard_config	:	unconfig
> 	@./mkconfig $(@:_config=) arm pxa myboard
>
> myboard_onenand_config	:	unconfig
> 	@./mkconfig $(@:_config=) arm pxa myboard
> 	@echo "LDSCRIPT := $(TOPDIR)/board/myboard/u-boot.onenand.lds" >>
> include/config.mk

Did you take a look at the currently implemented NAND booting support in 
U-Boot? Right now the PPC440EPx Sequoia board is the only board in this 
NAND_SPL infrastructure. Please take a look at doc/README.nand-boot-ppc440 
for some more details. And the sequoia board config file too of course.

Your approach is a little different. It would be best, if you could at least 
try to match the infrastructure of nand_spl a little better. For example the 
nand_spl/board/xxx directory with the upon compiletime created links to the 
common files.

Please let me know, if you feel that your OneNAND booting support for your 
board can be implemented in this infrastructure.

Thanks.

Best regards,
Stefan

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