Re: Vertical blanking interrupts

From: Matan Ziv-Av (
Date: Sat Feb 15 2003 - 18:22:31 EST

On Sat, 15 Feb 2003, Jeff Mock wrote:

> In particular, the platform is a VIA mini-ITX motherboard that uses
> a VIA PLE133 combined northbridge and Trident Cyberblade graphics
> controller.
> VGAs have a legacy feature to generate a vertical blanking interrupt.
> I don't think windows or linux use this feature.
> I'm having trouble getting the vertical blanking interrupt to work.I'm
> a bit out of my depth with this thing, so be gentle.

>From my experience, many video chipsets are not VGA compatible in
this regard. If you have documentation for your chipset, maybe using
chipset specific code is preferable.

> Does anyone out there have experience getting VGA vertical blanking
> interrupts to work?Why would the VGA device not show up in the
> IRQ routing table?Is this a BIOS bug or are VGA interrupts just not
> supported by the hardware anymore?Any advice appreciated.

You can see code that implements vertical blanking interrupts in svgalib
( This includes standard VGA, as
well support for a few chipsets. Unfortunately, it does not work on my
trident card.

Matan Ziv-Av.               

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