[U-Boot] [PATCH 4/4] ARM: tegra: increase CONFIG_SYS_TEXT_BASE

[Stephen Warren <swarren@wwwdotorg.org>]

On 10/18/2012 10:31 AM, Tom Rini wrote:
> On Wed, Oct 17, 2012 at 09:20:31PM -0600, Stephen Warren wrote:
>> On 10/17/2012 06:05 PM, Simon Glass wrote:
>>> On Tue, Oct 16, 2012 at 3:43 PM, Stephen Warren
>>> <swarren@wwwdotorg.org> wrote:
>>>> On 10/16/2012 04:09 PM, Lucas Stach wrote:
...
>>> To ask the opposite question, is it worth increasing by a whole
>>> 16KB so that the base address of U-Boot is a more aligned
>>> number?
>> 
>> That would bloat the binary by about 12KB more than it needs to
>> be. I don't believe there's any particular need for the main
>> U-Boot to be built for any particular address, and we can just
>> continue to bump up this value as/when the SPL grows.
> 
> Well, lets stop and think for a minute more.  Are we likely to add
> new features to SPL on Tegra (direct OS booting, support in one
> binary for both SPL-from-flash and SPL-from-something-else) ?

I don't think so. The only purpose of the SPL on Tegra is to run from
SDRAM on the AVP CPU, set up clocks for the main Cortex-A9 core, and
to cause the A9 to start executing the concatenated main U-Boot image.
The SPL always runs from SDRAM.

(As background, the boot ROM sets up SDRAM on Tegra, and copies the
concatenated SPL+U-Boot binaries into SDRAM from whatever boot device,
so the typical reasons for using SPL don't exist on Tegra).

Allen Martin was thinking about getting the SPL to run from IRAM
rather than SDRAM, and I think only execute on the AVP CPU (e.g. for
use as a slimmed-down flashing tool downloaded via the boot ROM's USB
recovery mechanism). However, I think that would end up being an
entirely separate SPL build (since we'd need both, not cut over), so
the size requirements would not impact in any way the SPL-in-SDRAM
that we have today.