Date: Sat, 8 May 1999 06:52:01 -0400 (EDT) From: Brian Feldman <green@unixhelp.org> To: Doug Rabson <dfr@nlsystems.com> Cc: eagle <eagle@eagle.phc.igs.net>, John-Mark Gurney <gurney_j@resnet.uoregon.edu>, Lee Cremeans <lcremeans@erols.com>, hackers@FreeBSD.ORG, multimedia@FreeBSD.ORG Subject: Re: G200 GLX and SIGFPU Message-ID: <Pine.BSF.4.10.9905080645480.9882-100000@janus.syracuse.net> In-Reply-To: <Pine.BSF.4.05.9905081136210.18703-100000@herring.nlsystems.com>
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On Sat, 8 May 1999, Doug Rabson wrote:
> On Sat, 8 May 1999, Brian Feldman wrote:
>
> > On Sat, 8 May 1999, eagle wrote:
> >
> > >
> > >
> > > On Sat, 8 May 1999, Doug Rabson wrote:
> > > >
> > > > This should be done by the GL implementation. At Microsoft, we used to
> > > > save/restore the fp flags on entry to Direct3D so that we could force the
> > > > correct mode for our maths to work properly. We had all sorts of trouble
> > > > before doing that (stupid exceptions enabled, people changing fp
> > > > precision etc).
> > > >
> > > > I think in current versions of D3D, there is an api which you can call to
> > > > say 'I agree not to touch the fp flags' which improves performance
> > > > slightly. Mesa should be doing something similar, IMHO.
> > > >
> > > That was my next question shouldn't this be done in the port of MESA since
> > > thats whats throwing the sigfpe, disabling it in flightgear wouldn't help
> > > the problem at all..
> >
> > What about switching to __BETTER_BDE_NPXCW__?
>
> It looks like __BETTER_BDE_NPXCW__ would mask OVF, DIV0 and INV which I
> think is a better default. Is there some reason other than inertia for not
> changing to __BETTER_BDE_NPXCW__?
I've never seen anyone cite one. And think about this: there are ports like
{"/home/green"}$ find /usr/ports -name patch-?? -exec grep fpsetmask {} \;
+ fpsetmask(0);
+ fpsetmask(0);
+ fpsetmask(fpgetmask() & ~FP_X_INV);
+ fpsetmask(0);
>
> I still think Mesa should deal with the flags itself (and save/restore
> them) otherwise it can get hosed by a stupid application changing to 23bit
> precision or something similar.
>
> --
> Doug Rabson Mail: dfr@nlsystems.com
> Nonlinear Systems Ltd. Phone: +44 181 442 9037
>
>
>
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