Hi all,

The two core goals for this branch are:

- Make VM system / trap handling MP safe.
- Make file system framework MP safe.

What that means is for many I/O operations, page faults and so on, the
global kernel_lock is no longer taken. The code isn't tuned yet although a
quick test I did a while ago on a 4 CPU system showed something like a 40%
reduction in _system_ time while building a kernel.

It's approaching stability and I'd like to invite anyone who is interested
to test. There are known problems, the major ones are:

- Only amd64, i386 and pmax have the necessary code at the moment.
  Other architectures need still need updating.
- ext2fs and lfs are busted. 
- Layered file systems need testing and probably need some work.
- Running nfsd is currently inadvisable due to a locking issue.
  The NFS client should work fine.

If you'd like to test it, the steps are:

- Grab a recent copy of src/common from -current.
- Check out src/sys from anoncvs with the 'vmlocking' tag.
- Build a kernel, install, and with luck it all works OK. :-)

Thanks,
Andrew