From: Dr. Michael Weller (eowmob@exp-math.uni-essen.de)
Date: Tue 04 Aug 1998 - 13:18:50 IDT
On 31 Jul 1998, Lukasz Wiechec wrote: > I'm using svgalib for quite a long time, and I'm very pleased > with it. Normally, it works smoothly; there's hangs etc. > > Lately, I began using Zachary Amsden's multimon kernel patch, > which enables using VGA and HGC adapters at the same time. Then I > observed occsional hangs, basically when one process was writing > something to HGC monitor, and other, by svgalib, writing something > else in graph mode to VGA monitor. > > I know that there are very few configurations like mine, but > do you will to get into this problem in you work with development of > svgalib ? Or maybe give me some hints to work on my own --- maybe I'll > try to find some solution. Well, lacking a similar hardware and not having written the plain VGA parts of svgalib myself, I don't really see what I could do. >From a theoretical point of view, I'm not too surprised. Basically, every VGA is also a HGC. When checking out capabilities of the VGA, svgalib may easily switch it to HGC for a short moment. This might also happen when moving fonts in and out of the card. It is quite obvious that there might be collisions, although I don't have a specific point in mind where I could point you to a sourceline and say: Well, look here, this makes the VGA turn into a HGC too. (Which will then result in unpredictable behaviour) Another point is, the kernel's VC switching is not only a pain, but also very sensitive. I don't know this patch and how it works, but if it even slghtly interfere's with VC switching it may easily cause problems with putting a VC in graphics mode (do you have any experience with X, by chance?) Michael. -- Michael Weller: eowmob@exp-math.uni-essen.de, eowmob@ms.exp-math.uni-essen.de, or even mat42b@spi.power.uni-essen.de. If you encounter an eowmob account on any machine in the net, it's very likely it's me.
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