[U-Boot] [PATCH v3 09/14] tegra20: add u-boot.t2 target

[Allen Martin]

On Sat, Jun 09, 2012 at 12:12:09PM -0700, Simon Glass wrote:
> Hi Allen,
> 
> On Fri, Jun 8, 2012 at 2:16 PM, Allen Martin <amartin at nvidia.com<mailto:amartin at nvidia.com>> wrote:
> Add target for tegra20 u-boot image.  This is a concatenation of tegra
> spl and normal u-boot binaries.
> 
> Signed-off-by: Allen Martin <amartin at nvidia.com<mailto:amartin at nvidia.com>>
> ---
>  .gitignore                      |    1 +
>  Makefile                        |   11 +++++++++++
>  board/nvidia/seaboard/config.mk<http://config.mk> |    1 +
>  3 files changed, 13 insertions(+)
>  create mode 100644 board/nvidia/seaboard/config.mk<http://config.mk>
> 
> diff --git a/.gitignore b/.gitignore
> index 0f32fd8..b9192bf 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -39,6 +39,7 @@
>  /u-boot.ais
>  /u-boot.dtb
>  /u-boot.sb<http://u-boot.sb>
> +/u-boot.t2
> 
> What does t2 mean? If it is a binary file of some sort  perhaps
u-boot-t2.bin would be better?

It's just means "tegra2".  I was following the convention that other
SPL builds use.  I don't have a strong opinion on the name though.

> +ifeq ($(CONFIG_OF_SEPARATE),y)
> +T2_UBOOT=$(obj)u-boot-dtb.bin
> +else
> +T2_UBOOT=$(obj)u-boot.bin
> +endif
> 
> What is this logic for? The dtb file is separate but that doesn't
> necessarily mean that it must be immediately after the U-Boot
> image. We provide other options for packaging it, like
> getenv(). Maybe if you want to create this composite binary you
> should change its name (u-boot-dtb-t2.bin or u-boot-t2.bin) to
> indicate what it contains?

This just picks up the name of the u-boot binary so it glues the SPL
to the right thing depending if devicetree is in use or not.

> 
> +$(obj)u-boot.t2:       $(obj)spl/u-boot-spl.bin $(T2_UBOOT)
> +               $(OBJCOPY) ${OBJCFLAGS} --pad-to=$(PAD_TO) -O binary $(obj)spl/u-boot-spl $(obj)spl/u-boot-spl-pad.bin
> +               cat $(obj)spl/u-boot-spl-pad.bin $(T2_UBOOT) > $(obj)u-boot.t2
> +               rm $(obj)spl/u-boot-spl-pad.bin
> +
> 
> I echo Stephen's comments. But also SPL is supposed to load U-Boot,
> so shouldn't this t2 binary do that?

The t2 binary is the SPL and u-boot concatenated together into one
binary.  The whole thing will get loaded into memory by the tegra
BootROM.  The SPL knows the address of the real u-boot at compile time
and uses that as the address for the Cortex A9 to jump to when it
comes out of reset. 

-Allen
-- 
nvpublic