[U-Boot] [PATCH] arm: Tegra2: Add a useful default boot env

[Stephen Warren <swarren@wwwdotorg.org>]

On 04/23/2012 11:14 AM, Tom Rini wrote:
> On Mon, Apr 23, 2012 at 09:22:22AM -0700, Tom Warren wrote:
>> Stephen,
>>
>> On Fri, Apr 20, 2012 at 2:40 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>>> On 04/20/2012 01:50 PM, Tom Warren wrote:
>>>> This set of boot cmds from Stephen Warren provides a simple
>>>> default for booting a linux kernel and DT from mmc (eMMC or
>>>> SD-Card, in that order). Tested on Seaboard w/an SD card.
>>> ...
>>>> diff --git a/include/configs/tegra2-common.h b/include/configs/tegra2-common.h
>>> ...
>>>> ?#define CONFIG_EXTRA_ENV_SETTINGS \
>>> ...
>>>> + ? ? "script=/boot.scr.uimg\0" \
>>>
>>> It might be best to make that just /boot.scr. The reason being that I
>>> looked at the Ubuntu Precise images for OMAP, and they don't have
>>> ".uimg" in the filename, even though they're uImage files. It's probably
>>> best to be consistent with the Ubuntu images given the only other
>>> precedent is what I do locally, which can easily be adjusted.
>>
>> I'll change it to /boot.scr, but do we have any stats on other/more
>> distros and what they use?
> 
> Can I suggest that instead of using boot.scr files we just use a text
> file that can be imported to the environment and a command run?

That sounds like a great idea; it avoids a mkimage call and generally
simplifies things. Looking at the code, it's just a list of name=value,
one per line.

TomW, I'd suggest looking at ./include/configs/omap3_beagle.h. In
particular:

a) The load from MMC is only attempted if "mmc rescan" succeeds, rather
than just blasting through the script with lots of failures. The hush
shell might be needed for this; is it enabled on Tegra?

b) See the macros loadbootenv/importbootenv which are the replacement
for boot.scr.

TomR, is there a reason OMAP3 uses FAT for /boot rather than ext2?
Perhaps it's due to the need to load intermediate boot loaders from the
filesystem, and that code needs FAT? On Tegra, we jump straight to
U-Boot from the boot ROM without the need for intermediate filesystem
access, and could make /boot ext2 - do you see any reason not to do this?