Require the platform or arch to provide it. The default was pretty
obsolete, assuming a 32bit arch with a split 50/50 mapping. May as well
make it a forced arch thing so that it's known to be correct.
Had to define it for OR1K, it was already defined for all the other
(known) architectures.
This picks up the major work of allowing multiple heap implementations
and enable dlmalloc as an alternate heap to the simple existing one
(now called 'miniheap').
Also added a novm page allocator for memory management on systems too small
or missing an mmu to have a vm. Not much more than a simple bitmap allocator
that the heap pulls from. Allows for other heaps and/or users of physical
memory to coexist and span multiple banks of memory.
This add support for the OpenRISC 1000 architecture, and
as the architecture specification defines an on-chip tick-timer
and interrupt controller, drivers for those are included in
this commit.
Support to utilize the MMU is implemented,
and it can be opted in and out with WITH_KERNEL_VM
