Dtrace status - material for someone's TODO list.

Hello;

Last year I did an attempt to merge some of the changes from illumos'
Dtrace into FreeBSD. I don't use Dtrace a lot, so this was done mainly
for fun.

In general, merging changes from Illumos was pretty straightforward;
just a matter of readapting the paths to match our layout.

I was able to merge some basic stuff (semilog plots) and fixes but we
are at a point now where they are building upon their own developments
and we need to merge their stuff in the same order they did. Some of
their changes (KVM and zones) we can just ignore.

As of lately, I got stuck because our userland support is different
from the Solaris stuff. The conflicts I am seeing now are not easy
for my (non-)level of inner Dtrace-foo and I am not working more
on this so I will post the links to the patches in the hope that someone
will pick up where I left:

- 1368 enablings on defunct providers prevent providers from unregistering

http://people.freebsd.org/~pfg/patches/dtrace/illumos-gate-8e6add739e38.diff

- 1455 DTrace tracemem() should take an optional size argument

http://people.freebsd.org/~pfg/patches/dtrace/illumos-gate-571b0355c2e3.diff

Once done with those we can continue bringing the nicer features:

http://dtrace.org/blogs/eschrock/2011/10/26/your-mdb-fell-into-my-dtrace/

Cheers,

Pedro.