[PATCH 4/6] ARM: mxc: don't allow to compile together i.MX51 and i.MX53

[Nicolas Pitre]

On Mon, 11 Apr 2011, Uwe Kleine-König wrote:

> On Sun, Apr 10, 2011 at 10:02:03PM -0400, Nicolas Pitre wrote:
> > On Sun, 10 Apr 2011, Uwe Kleine-König wrote:
> > 
> > > The two SoCs have different PHYS_OFFSETs so it's not (yet) possible to
> > > compile a single (working) kernel for these.
> > 
> > Really?
> > 
> > Have a look at CONFIG_ARM_PATCH_PHYS_VIRT.  It's in mainline and fully 
> > functional.
> I'm aware of this config item. But still if it's off there must be a
> distinction that's provided by this patch.

Sure.  Instead of a compile time expansion of virt_to_phys() and 
phys_to_virt(), you get a run time patching of the kernel binary 
according to the runtime deduced PHYS_OFFSET.  See commit logs for "git 
log 6fc31d54..b511d75" for the details.

> Currently you can build a
> kernel for i.MX51 + i.MX53 but IIRC it works on no machine.

Maybe it should be fixed?

> When considering ARM_PATCH_PHYS_VIRT there are more SoCs that could be
> built into a single image and so needs a more complicated logic.

The ultimate goal is to structure the code so we can build as many SOCs 
together as possible.

> And I don't want to depend on ARM_PATCH_PHYS_VIRT (yet), e.g. because
> it's new and still depends on EXPERIMENTAL.

When will it be no experimental anymore if no one starts using it?  RMK 
talked about making it enabled by default, and that could allow for the 
removal of a bunch of arch/arm/*/include/mach/memory.h files.


Nicolas