Re: [PATCH RFA/RFC] Don't use lwp_from_thread() in thread_db_wait()

[David Taylor <taylor@candd.org>]

> Date: Wed, 13 Mar 2002 12:46:32 -0500
> From: Daniel Jacobowitz <drow@mvista.com>
> 
> On Wed, Mar 13, 2002 at 12:37:08PM -0500, David Taylor wrote:
> > > Date: Tue, 12 Mar 2002 11:23:31 -0500
> > > From: Daniel Jacobowitz <drow@mvista.com>
> > 
> > > Yes, that could probably be arranged.  Someday we should talk to a
> > > vendor of an M:N threads package and see what we have to work with.  I
> > > don't know of any offhand besides NGPT.
> > 
> > If I understand you correctly, then: Solaris.
> 
> Is it really?
> 
> To clarify, LinuxThreads has one thread per process; IBM's NGPT has
> multiple threads per process, but still multiple processes.  I was
> under the impression that Solaris LWPs would have all threads in one
> process.
> 
> (except of course the terminology gets fuzzy here.  One "process" in
> Solaris includes multiple LWPs which can be executing at the same time. 
> If my understanding above is correct it might be more appropriate to
> call Solaris one-thread-per-LWP).

Perhaps I misunderstood.  Or perhaps it's just a terminology issue.

Solaris >= 2.5.1 has a two level threads implementation --

	. threads, sometimes called user threads
	. light weight processes, sometimes called kernel threads

They are all part of one process.  You can have M user threads mapped
onto N LWPs.

There are two sorts of signals in Solaris -- synchronous (some LWP
executing some thread caused the signal -- e.g., SIGILL, SIGSEGV) and
asynchronous (e.g., SIGINT, SIGQUIT, SIGSTOP, SIGKILL).  Synchronous
signals are delivered to the thread/lwp that caused the signal;
asynchronous signals are delivered to the asychronous signal LWP
(ASLWP), arbitrary thread.