| Re: [AD] X Multimonitor support |
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On December 14, 2008, Peter Wang wrote:
> On 2008-12-14, Thomas Fjellstrom <tfjellstrom@xxxxxxxxxx> wrote:
> > On December 14, 2008, Thomas Fjellstrom wrote:
> > > On December 14, 2008, Peter Wang wrote:
> > > > On 2008-12-14, Evert Glebbeek <eglebbk@xxxxxxxxxx> wrote:
> > > > > On 14-Dec-08, at 8:13 PM, Peter Wang wrote:
> > > > > > ex_monitorinfo hangs for me. Any ideas?
> > > > >
> > > > > Do you have xinerama enabled in xorg.conf?
> > > > > I had the sane problem (in a VM, admittedly), which was fixed when
> > > > > I enabled xinerama (I didn't realise it was disabled at first).
> > > > > Annoyingly enough though, the program did run properly in gdb...
> > > > > not sure what went on there.
> > > >
> > > > I solved (I think) the problem by adding locks around the Xinerama
> > > > calls, so there was probably some race condition.
> > >
> > > How? Its not like the function that creates the connection and then
> > > queries the extensions is running in multiple threads, it makes no
> > > sense to me. To me, that sounds like broken X. A single thread, making
> > > regular calls into X should not lock up. Its the code that sets up the
> > > X stuff for peats sake, nothing has a pointer to any of it yet.
> >
> > Ok, so its not locking up in the initial setup.. I'm tired.. Anyhow, I
> > still don't see why its locking up when querying xinerama info later on,
> > what could possibly cause it to lock up in that example?
>
> Our X background thread would already be running. Maybe it is calling
> XNextEvent or something concurrently. I don't have time to investigate
> now.
>
> Stop assuming it's a broken installation.
I was thinking more along the lines of broken compatibility from using xcb
since it is quite a bit more strict wrt threading than xlib ever could be.
> I've been running xinerama on
> this system for about a year without trouble. It's not like it's the
> first time we've had problems with threads on X which go away when we
> put in locks (as we should).
>
> Peter
>
>
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--
Thomas Fjellstrom
tfjellstrom@xxxxxxxxxx