Fixups per Daniel and Eli.   Daniel,
1) Regarding register_raw_read, I just sidestepped the issue
and added a PC field to my saved context.
2) Regarding threads, I could make checkpoint_command refuse
if there are threads -- what's the best way to check that?
I could look at to_shortname, or better, I could add an
access method for the static variable "threaded" in linux-nat.

Mark, I'd still like to have your ok.

2005-12-19  Michael Snyder  <msnyder@redhat.com>

	Checkpoint/Restart for Linux.
	* linux-nat.c: Add support for debugging multiple forks.
	Add #include for linux-fork.h (interface spec).
	(super_mourn_inferior): New function pointer.
	(child_mourn_inferior): New function / target method.
	(linux_target): Claim to_mourn_inferior method pointer.
	(child_follow_fork): Call interface to linux-fork, conditionally
	add new fork processes to list of debugged processes.
	(kill_inferior): Use interface to linux-fork to kill
	multiple processes.

	* linux-fork.h: New file.
	* linux-fork.c: New file.  Support for debugging multiple forks
	of the same program.  Support for checkpoint and restart commands.

	* infrun.c (nullify_last_target_wait_ptid): New function.

	* Makefile.in: Add linux-fork.
	* config/i386/linux.mh: Add linux-fork.
	* doc/gdb.texinfo: Add documentation for linux-fork.
	* doc/gdbint.texinfo: Add internal documentation for checkpoints.
	* NEWS: Mention new functionality.

2005-12-19  Michael Van Meter Snyder  <michsnyd@clwang-lnx.cisco.com>

	Add testing for checkpoint/restart and multiple fork debugging.
	* gdb.base/checkpoint.c: New file.
	* gdb.base/checkpoint.exp: New file.
	* gdb.base/multi-fork.c: New file.
	* gdb.base/multi-fork.exp: New file.
	* gdb.base/pi.txt: New file (data for checkpoint.c test).