On Fri, 14 Oct 2011, Arnd Bergmann 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.

The way I'm restructuring things around this is that AUTO_ZRELADDR will 
always be active by default, just like ARM_PATCH_PHYS_VIRT now.  This 
platform specific exclusion thinking is a step backward so I'd prefer if 
people would refrain from going there for the moment.


Nicolas