On Thu, 21 Jun 2001, Jens Owen wrote:
> Vladimir,
>
> Your page looks very helpful. Thanks for putting it together. The only
> comment I have is regarding your first miscellaneous comment:
>
> "While hardware 3d is active nothing except your Xserver should be
> accessing your video card - or your system will lockup hard. In
> particular, frame grabber cards that write directly to video memory
> should be turned off. If you want to use these cards try out v4l module
> in XFree 4.x.x."
>
> I think the intent of this message is good for users--but it's
> misleading to developers trying to understand our architecture. To
> clarify, direct rendering is completely based on the idea of a client
> side driver accessing the hardware directly without using the Xserver to
> exclusively access the device.
>
> However, all access to the video device must be closely coordinated, and
> come from a suite of drivers that know each other well. Using drivers
> that don't cooperate closely, or even mixing older and newer driver
> components can introduce the lockups you describe.
>
> I hope this helps.
Yes this does - thanks ! I'll put in a more general statement.
The reason I wrote it this way is because r128 and radeon use so called
"CCE engine" for 3d. Instead of writing 3d commands into registers they
are written in a memory area and then DMA'ed up to the video card. So, my
impression is that the client does not access the card as DMA setup is
done by the dri driver or drm module. In particular, if one sets up bt848
to dma stuff up to the card simultaneously with hardware GL you will get
at the least engine timeout errors or (often) lockups.
I think what I'll do is leave the statement as it is but create a note
below for developers that explains how it really works. This way users get
properly impressed and developers get the right info too.
Vladimir Dergachev
>
> Regards,
> Jens
>
> Daryll Strauss wrote:
> >
> > This might be useful to some of the folks here, so I thought I would
> > pass it along.
> >
> > - |Daryll
> >
> > ----- Forwarded message from [EMAIL PROTECTED] -----
> >
> > Date: Wed, 20 Jun 2001 14:41:18 -0400 (EDT)
> > From: [EMAIL PROTECTED]
> > To: [EMAIL PROTECTED], [EMAIL PROTECTED]
> > Subject: [Xpert]Guide to debugging DRI installations
> >
> > I've put up a "Guide to debugging DRI installations" at
> >
> > http://www.linuxvideo.org/gatos/dri-debug.html
> >
> > Comments are very welcome. In particular I seem to have lost the e-mail
> > with comparison of FPS numbers from glxgears with software versus hardware
> > 3d. Can whoever wrote it remind me ?
> >
> > Vladimir Dergachev
> >
> > _______________________________________________
> > Xpert mailing list
> > [EMAIL PROTECTED]
> > http://XFree86.Org/mailman/listinfo/xpert
> >
> > ----- End forwarded message -----
> >
> > _______________________________________________
> > Dri-devel mailing list
> > [EMAIL PROTECTED]
> > http://lists.sourceforge.net/lists/listinfo/dri-devel
>
> -- /\
> Jens Owen / \/\ _
> [EMAIL PROTECTED] / \ \ \ Steamboat Springs, Colorado
>
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