. make vm be able to use malloc() by overriding brk()
and minix_mmap() functions
. phys regions can then be malloc()ed and free()d instead
of being in an avl tree, which is slightly faster
. 'offset' field in phys_region can go too (offset is implied
by position in array) but leads to bigger code changes
Introduce explicit abstractions for different mapping types,
handling the instantiation, forking, pagefaults and freeing of
anonymous memory, direct physical mappings, shared memory and
physically contiguous anonymous memory as separate types, making
region.c more generic.
Also some other genericification like merging the 3 munmap cases
into one.
COW and SMAP safemap code is still implicit in region.c.
complete munmap implementation; single-page references made
a general munmap() implementation possible to write cleanly.
. memory: let the MIOCRAMSIZE ioctl set the imgrd device
size (but only to 0)
. let the ramdisk command set sizes to 0
. use this command to set /dev/imgrd to 0 after mounting /usr
in /etc/rc, so the boot time ramdisk is freed (about 4MB
currently)
