Re: [PATCH 0/6] Support kernel-backed user threads on FreeBSD

Mark Kettenis
2016-01-12T19:06:19Z

> From: John Baldwin <jhb@freebsd.org>
> Date: Tue, 12 Jan 2016 10:55:34 -0800
>
> On Monday, January 11, 2016 10:53:50 AM John Baldwin wrote:
> > This set of patches adds support for examining kernel-backed user threads on
> > FreeBSD. There is more history in a comment in fbsd-nat.c, but this target
> > uses ptrace directly (instead of libthread_db) to support the current
> > threading library (libthr) on FreeBSD which uses a kernel thread for each
> > user thread. Support for thread names in both core dumps (via FreeBSD's
> > OS-specific NT_THRMISC core note) and live is supported as is scheduler
> > locking. gcore generates register notes for each thread as well.
> >
> > The first two patches are to binutils to support FreeBSD-specific core
> > notes. The last four are to GDB.
>
> (Apologies for fubar'ing the threading on the patches in this series.)
>
> One other note I forgot to mention is that currently I leave the ptid for
> single-threaded processes as (pid, 0, 0) (i.e. I only use LWPs in PTIDs
> when there is more than one thread). What is the best practice? Should
> I always use LWPs in ptids instead?

I think that is the best approach.