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Re: Linux/SGI Xsgi server: /dev/opengl ioctl NG1_SETDISPLAYMODE

Subject: Re: Linux/SGI Xsgi server: /dev/opengl ioctl NG1_SETDISPLAYMODE
From: Miguel de Icaza <>
Date: Wed, 17 Sep 1997 22:23:30 -0500
In-reply-to: <> (
Another question regarding the Newport:

>      After waiting for the rex3 FIFO to drain, and the the xmap9 FIFO
> to not be full, it sets the xmap9 mode register for the given "wid":
>         xmap9SetModeReg( rex3, wid, displaymode, 
> ng1_video_timing[bd->boardnum]->cfreq ); 

If the newport registers are available to the userland application,
why the X server does not directly call those routines instead of
relying on the kernel to perform them?  Is it a convention that
applications should only touch the rex3 registers and not attempt to
program any of the other chips on the dcb?

It would make sense since the graphics context switching would not
involve the kernel peeking at the chips on the dcb what their context
is and then the pain of restoring this.  


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