Re: TLS on powerpc(32/64)

Prosun Niyogi
2006-09-22T13:53:21Z

How can I tell whether GDB is loading libthread_db?
"info threads" works... I would think libthread_db
must be loaded for that to work.

Also, in gdb(linux-thread_db.c) -

__/* glibc doesn't provide the needed interface. */
if (!td_thr_tls_get_addr_p)
throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR,
_("No TLS library support"));
__/* Caller should have verified that lm != 0. */
gdb_assert (lm != 0);
__/* Get info about the thread. */
thread_info = find_thread_pid (ptid);
thread_db_map_id2thr (thread_info, 1);
__/* Finally, get the address of the variable. */
err = td_thr_tls_get_addr_p
(&thread_info->private->th, (void *) lm,
offset, &address);
So the glibc interface is found... does that not mean
that libthread_db is loaded and found by GDB?

Apologies for the ignorance, just looking for how I
can check to see why td_thr_tls_get_addr_p() doesnt
return an appropriate value.

So judging from the tone of your comment, I should
expect to be able to print the value of a __thread
variable on ppc64, and there arent any known issues
preventing me from doing so? I have tried on SLES, FC,
and now cvs-head, and all three have failed.

Can you suggest where I should look next? I took a
quick look at libthread_db in glibc, and it looks like
none of the fuctions have changed in libc.

Thanks,

Prosun Niyogi

--- Daniel Jacobowitz <drow@false.org> wrote:

> On Thu, Sep 21, 2006 at 04:20:47PM -0700, Prosun
> Niyogi wrote:
> > Hi,
> > I've been struggling the last few days on getting
> gdb
> > to work correctly on a powerpc64 machine. Built as
> > ppc-64-linux, debugging ppc64 binaries linked
> against
> > libpthread. It seems to me that gdb's TLS access
> does
> > not work correctly on these platforms. Attempting
> to
> > print a variable of type __thread doesnt work.
>
> It looks to me like GDB has failed to load
> libthread_db for some
> reason. I don't know why not; you'll have to look
> into it.
>
> --
> Daniel Jacobowitz
> CodeSourcery