On Thu, 05 May 2011 13:36:40 -0700
Jeremy Huddleston <[email protected]> wrote:
> >> Yes, I realize that there are some areas that use 64bit for sbc. Do we
> >> really need 64bits for this? If so, how do we properly to communicate the
> >> 64bit value between server/client? Currently, your changes result in an
> >> implicit cast from 64bit to 32bits in DRI2SwapComplete which will cause
> >> problems if we really do need those extra bits:
> >>
> >> if (swap_complete)
> >> swap_complete(client, swap_data, type, ust, frame,
> >> pPriv->swap_count);
> >>
> >> It looks to me like much more of DRI2 should be rewritten to use 32bit
> >> swap counts, or there should be some other mechanism in place to
> >> communicate the full 64bit value.
> >
> > Yeah there are other mechanisms (the OML sync extension) for
> > communicating the whole 64 bits. Both the swap reply and msc reply
> > deal in the full 64 bits, just the swap event (an unrelated extension)
> > truncates to 32 bits. (Also I think the 64 bit size for swap count in
> > the OML extension is just inertia; getting to a count that high even at
> > 120Hz is going to take awhile.)
>
> Ok, well this all really doesn't sit well with me, but it would put my mind
> slightly at ease if you would do some logging of the problem if we encounter
> it in DRI2SwapComplete. That might give your future self some clue as to
> what is going wrong when you see issues down the road:
>
> if (swap_complete) {
> if (pPriv->swap_count > 0xffffffff)
> ErrorF("something appropriate");
> swap_complete(client, swap_data, type, ust, frame,
> (CARD32)pPriv->swap_count);
> }
Yeah, it's annoying. How about I leave out the error message and handle
wrapping on the client side instead? That way at least the client code
won't notice that the server is only transmitting 32 bits...
--
Jesse Barnes, Intel Open Source Technology Center
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