This eliminates the reliance on PHYSADDR and KERNPHYSADDR compile-time
symbols (except when the rom-copy code is enabled) by using the current
PC and the assumption that the entry-point routine is in the first 1MB
section of the text segment.
Other cleanups done:
- Reduce the initarm() stack size back to 2K. It got increased to
4 * 2K when this file was supporting multicore armv6, but that
support is now in locore-v6.S.
- When building the temporary startup page tables, map the entire
4GB address space as VA=PA before mapping the kernel at its loaded
location. This allows access to boot parameters stored somewhere
in ram by the bootloader, regardless of where that may be.
- When building the page table entry for supporting EARLY_PRINTF, map
the section as uncached unbuffered, since it is presumably device
registers.
Note that this restores the ability to use loader(8)/ubldr on armv4/5
kernels. That was broken in r283035, the point at which ubldr started
loading an arm kernel at any 2MB boundary.
Also note that after this, there is no reason to set KERNVIRTADDR to
anything other than 0xc0000000, and no need for PHYSADDR or KERNPHYSADDR
symbols at all.