Re: panic: absolutely cannot call smp_ipi_shootdown with interrupts already disabled

On Thu, 18 Sep 2003, Brad Knowles wrote:

> At 4:47 PM -0700 2003/09/17, Doug White wrote:
> 
> >  This came up at the developer summit.  We do need to upgrade/make
> >  significant changes to gdb for it to understand threaded debugging.  The
> >  panics might be interesting as it might be tickling other issues, but
> >  before we can really debug threaded apps we need a new gdb.

The panics had nothing to do with KSE, gdb, or threading
and were recently fixed.

> 	Do we need a rewritten gdb, or can we have both the current gdb 
> and a new tgdb for debugging the threaded stuff?

It is relatively easy to modify the existing threading support
in gdb so that we can at least view the current threads.  Other
kernel support would be needed to attach to threads in other
KSEs and retrieve register sets for threads blocked in the
kernel.  Libthr has similar problems.

> 	The latter approach seems to be something that would be a lot 
> easier to integrate without risk of breaking anything currently 
> existing, and tgdb could even be done as a port until such time as 
> it's fully ready to take over from the built-in gdb in the system.

FreeBSD's threading support is not presently in stock GDB
anyways; it's in gnu/usr.bin/binutils/gdb/freebsd-uthread.c,
not in contrib/gdb/...  I don't see the need for a separate
port.

The two problems are:

  o adding kernel support to attach to threads in different
    KSEs and fetching register sets from threads blocked in
    the kernel

  o making gdb understand not only libc_r, but also libthr
    and libpthread, and how to determine which library it
    is debugging.

-- 
Dan Eischen