On Fri, 18 May 2007, leon zadorin wrote:
I am in a process of investigating some strange app's behaviour, where
having
1) opened display connecton
2) initialised glx
3) attached window to glx and made the glx context current, etc.
4) then de-initialised glx, destroyed window, closed display
connecton, etc. etc.
5) then opened display connection again
6) then trying to initialise glx crashes (at glx creating a context)
on NetBSD-current/macppc port...
I have traced the crash to XSync call in mesa garbage colleciton...
anyway... in a process of my learning (so pardon if my questions ar
rather silly) the whole X thing :-) I have a question about the
following code in:
xc/extras/Mesa/src/mesa/drivers/x11/xm_api.c
or
http://cvsweb.xfree86.org/cvsweb/xc/extras/Mesa/src/mesa/drivers/x11/xm_api.c?rev=HEAD&content-type=text/vnd.viewcvs-markup
void XMesaGarbageCollect( void )
{
XMesaBuffer b, next;
for (b=XMesaBufferList; b; b=next) {
next = b->Next;
if (b->display && b->frontbuffer && b->type == WINDOW) {
#ifdef XFree86Server
/* NOT_NEEDED */
#else
XSync(b->display, False);
if (!window_exists( b->display, b->frontbuffer )) {
/* found a dead window, free the ancillary info */
XMesaDestroyBuffer( b );
}
#endif
}
}
}
The above code checks for vaild (non-null) "display" and "frontbuffer"
before calling Xsync... but how does it know that "b->display" is
still in the open state (i.e. that XCloseDisplay was not called on
"b->display")... or is it guaranteed by some other code that
XMesaBufferList will only have open displays... or is it OK to call
XSync on a closed display?
All my build logs show that xm_api.c is always compiled with
-DXFree86Server, making XMesaGarbageCollect() a no-op. So it would seem
that the way this is built on NetBSD is incorrect.
Marc.
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