kernel address space & auto-tuning

[Tim Kientzle]

>> 
>>> ...  It may be that the important
>>> part of the change would come next: pick better arbitrary ending
>>> addresses.
>> 
>> Is the location of the register mapping something that the kernel
>> chooses?  Or is it something that is passed to the kernel at boot-time?
>> 
> 
> As near as I can tell, it's a pretty much arbitrary choice on a per-SoC
> basis, always hard-coded with a named constant of some sort in kernel
> source code.  0xE0000000 seems to be a popular choice, with comments
> about it being the address used to bootstrap the initial devmap.  That
> appears to be true for only one SoC.  I think maybe there's been some
> cut and paste propagation here.

Related to another thread, it would be nice to find
ways to get more of these per-SoC values out
of hardcoded constants.

In this case, the FDT should give the size and physical
address of the register map.  Can we use that to
determine the virtual mapping dynamically at runtime?

Tim