Re: [PATCH] arm/tegra: select AUTO_ZRELADDR by default

[Nicolas Pitre]

On Fri, 14 Oct 2011, Arnd Bergmann wrote:

> On Friday 14 October 2011, Stephen Warren wrote:
> > Arnd Bergmann wrote at Friday, October 14, 2011 9:30 AM:
> > ...
> > > 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
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