keymap(5) manpage - update location
VFS: make all IPC asynchronous

By decoupling synchronous drivers from VFS, we are a big step closer to
supporting driver crashes under all circumstances. That is, VFS can't
become stuck on IPC with a synchronous driver (e.g., INET) and can
recover from crashing block drivers during open/close/ioctl or during
communication with an FS.

In order to maintain serialized communication with a synchronous driver,
the communication is wrapped by a mutex on a per driver basis (not major
numbers as there can be multiple majors with identical endpoints). Majors
that share a driver endpoint point to a single mutex object.

In order to support crashes from block drivers, the file reopen tactic
had to be changed; first reopen files associated with the crashed
driver, then send the new driver endpoint to FSes. This solves a
deadlock between the FS and the block driver;
  - VFS would send REQ_NEW_DRIVER to an FS, but he FS only receives it
    after retrying the current request to the newly started driver.
  - The block driver would refuse the retried request until all files
    had been reopened.
  - VFS would reopen files only after getting a reply from the initial
    REQ_NEW_DRIVER.

When a character special driver crashes, all associated files have to
be marked invalid and closed (or reopened if flagged as such). However,
they can only be closed if a thread holds exclusive access to it. To
obtain exclusive access, the worker thread (which handles the new driver
endpoint event from DS) schedules a new job to garbage collect invalid
files. This way, we can signal the worker thread that was talking to the
crashed driver and will release exclusive access to a file associated
with the crashed driver and prevent the garbage collecting worker thread
from dead locking on that file.

Also, when a character special driver crashes, RS will unmap the driver
and remap it upon restart. During unmapping, associated files are marked
invalid instead of waiting for an endpoint up event from DS, as that
event might come later than new read/write/select requests and thus
cause confusion in the freshly started driver.

When locking a filp, the usage counters are no longer checked. The usage
counter can legally go down to zero during filp invalidation while there
are locks pending.

DS events are handled by a separate worker thread instead of the main
thread as reopening files could lead to another crash and a stuck thread.
An additional worker thread is then necessary to unlock it.

Finally, with everything asynchronous a race condition in do_select
surfaced. A select entry was only marked in use after succesfully sending
initial select requests to drivers and having to wait. When multiple
select() calls were handled there was opportunity that these entries
were overwritten. This had as effect that some select results were
ignored (and select() remained blocking instead if returning) or do_select
tried to access filps that were not present (because thrown away by
secondary select()). This bug manifested itself with sendrecs, but was
very hard to reproduce. However, it became awfully easy to trigger with
asynsends only.
VFS: panic when unmount_all fails
PM: don't deliver signals to VM
INET: fix crash recovery script
VFS: fix GCC compilation error
libc/libminc malloc reorganization

  . rename minix malloc sources to minix-* so Makefile
    references aren't ambiguous
  . throw out malloc source file copies in libminc
  . make libminc use phkmalloc instead of minix malloc (slightly faster)
VM: some sanitycheck fixes

minor fixes to restore SANITYCHECKS
VM: forget about 'holes'

  . unused data structures and code
VM: remove unused dma memory support functions from vm

	. unused calls / data structures
VM: static data structure for mem allocation

 . allocate physical memory using a fixed, pre-allocated bitmap so there
   are no call cycles and it's avilable earlier
VM: only single page chunks

 . only reference single pages in process data structures
   to simplify page faults, copy-on-write, etc.
 . this breaks the secondary cache for objects that are
   not one-page-sized; restored in a next commit
VM: simplify slab allocator

	. only keep a list of non-empty, non-full pages with slab objects
	. simplifies alloc/free operations and reduces list management overhead
VM: abstract datastructures a bit

	. a little less duplication in region.c
VM: full munmap

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)
VM: restore >4k secondary cache functionality

	. by storing length in the yielded blocks node again
some coverity fixes.
VM: remove dead code
vm, kernel, top: report memory usage of vm, kernel
coverity appeasement