Re: Build Failure on Cygwin

[Joel Sherrill <joel@rtems.org>]

On Tue, Oct 20, 2020 at 6:39 AM Christian Biesinger <cbiesinger@google.com>
wrote:

> On Mon, Oct 19, 2020 at 9:34 PM Joel Sherrill <joel@rtems.org> wrote:
> > And to this from Christian.
> >
> > > I've seen this error on various toolchains. I believe it to be a gcc
> > > bug; however, since it still seems to be an issue on some platforms,
> > > maybe gdb should avoid using global (nonstatic) threadlocal
> > > variables... (and instead abstract access to this variable through
> > > getters/setters)
> >
> > I emailed Corrina from Cygwin and she thought it was a gdb issue
> > and not a Cygwin issue. I didn't know which project was best to file
> > this on.
>
> Did she have any more thoughts on that? Like, what should gdb do differentl
>

Only this:

"That's GDB only, I think.  thread_local_segv_handler is not defined,
but that's something in GDB which is not created when building on
Cygwin, erroneously."

I've updated my cygwin this week and GCC is 10.2.0 and the
packaged gdb is 8.3.1.

I added V=1 and event-top.o is definitely being linked in. Trying
nm on it, I see this:

$ nm event-top.o  | grep -i segv
0000000000000000 D __emutls_v.thread_local_segv_handler
0000000000000640 t _ZL14handle_sigsegvi

$ nm event-top.o  | c++filt | grep -i segv
0000000000000000 D __emutls_v.thread_local_segv_handler
0000000000000640 t handle_sigsegv(int)

This is the first time I've looked at thread local storage in a symbol
table. We haven't had issues with it like this compiling for RTEMS.

Any ideas for something else to poke at?

--joel


> Christian
>