On Fri, Oct 14, 2011 at 9:27 AM, Arnd Bergmann [off-list ref] wrote:

On Friday 14 October 2011, Stephen Warren wrote:

quoted

Arnd Bergmann wrote at Friday, October 14, 2011 9:30 AM:
...

quoted

You mention that tegra30 will require AUTO_ZRELADDR.

Well, just to be clear, here's the situation I think:

Tegra20's SDRAM starts at physical address 0.

Tegra30's SDRAM starts at physical address 2G.

To support that, we could either:

a) Introduce a new Kconfig variable for Tegra30, make T20/T30 mutually
exclusive, and update arch/arm/mach-tegra/Makefile.boot to set zreladdr
etc. based on the new Tegra30 config variable too. Then, there's no need
for AUTO_ZRELADDR anywhere.

b) Have no new config variable, build a unified T20/T30 kernel, leave
Makefile.boot untouched, and rely on using AUTO_ZRELADDR for Tegra30 to
account for the different SDRAM physical addresses.

Ok, thanks for the explanation, that makes it much clearer. For
completeness, you could also do both of the above and make T20/T30 mutually
exclusive unless AUTO_ZRELADDR is set. That might be more complex than
necessary, I don't know.

That is likely to get messy.

Seems like there could be some use for a (silent) option for a
platform to indicate that it can do XIP kernel (or zImage), and thus
not able to use AUTO_ZRELADDR (or other options that require rewriting
text segment of zImage or kernel).

Language gets awkard though, since it'd be a negative option (or all
platforms would need to add it). MACH_XIP_UNSUPPORTED perhaps?


-Olof