Major pmap rework to take advantage of the larger address space on amd64

systems.  Of note:
- Implement a direct mapped region using 2MB pages.  This eliminates the
  need for temporary mappings when getting ptes.  This supports up to
  512GB of physical memory for now.  This should be enough for a while.
- Implement a 4-tier page table system.  Most of the infrastructure is
  there for 128TB of userland virtual address space, but only 512GB is
  presently enabled due to a mystery bug somewhere.  The design of this
  was heavily inspired by the alpha pmap.c.
- The kernel is moved into the negative address space(!).
- The kernel has 2GB of KVM available.
- Provide a uma memory allocator to use the direct map region to take
  advantage of the 2MB TLBs.
- Fixed some assumptions in the bus_space macros about the ability
  to fit virtual addresses in an 'int'.

Notable missing things:
- pmap_growkernel() should be able to grow to 512GB of KVM by expanding
  downwards below kernbase.  The kernel must be at the top 2GB of the
  negative address space because of gcc code generation strategies.
- need to fix the >512GB user vm code.

Approved by:	re (blanket)

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/conf/kern.mk b/sys/conf/kern.mk
index ba85101eef9f..253d26765ee0 100644
--- a/sys/conf/kern.mk
+++ b/sys/conf/kern.mk
@@ -57,7 +57,7 @@ CFLAGS+=	-mcmodel=medlow -msoft-float
 # once pmap is ready.  Be excessively careful to not generate FPU code.
 #
 .if ${MACHINE_ARCH} == "amd64"
-CFLAGS+=	-mcmodel=medium -mno-red-zone \
+CFLAGS+=	-mcmodel=kernel -mno-red-zone \
 		-mfpmath=387 -mno-sse -mno-sse2 -mno-mmx -mno-3dnow -msoft-float
 .endif