Messages in this thread | | | Date | Sun, 19 Dec 1999 22:26:02 -0500 (EST) | From | James Simmons <> | Subject | Re: Thread-private mappings and graphics (was Re: Per-Processor Data |
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On Mon, 20 Dec 1999, Alan Cox wrote:
> > processes memory space. For older ISA cards that use page flipping you > > could use a page fault trick to make it seem that the framebuffer is > > linear when it isn't. Since the framebuffer window is 64K when the page > > This doesnt work. The DMA is direct, PCI DMA doesnt take page faults, > only CPU's do that. For sane cards do overlay mode, for stupid cards you > have to bounce the entire thing, you end up doing a two buffer > > grab1 write2 to fb with CPU > grab2 write1 to fb with CPU > repeat > > loop.
Oops. I should of addressed that in greater detail. I meant that for only for the framebuffer. Since most video cards don't have OpenGL on chip it would maximum performace if we allowed a process like a X client grab a window in the framebuffer to draw directly into. Even if you set the clipping rectangle on low end video cards so accel coomands will be draw only in that rectangle a process can get around this by writing to the framebuffer directly. Braindead yes but it does happen on alot of cards. So set a hardware clipping rectangle. If you need to draw in the framebuffer for software rendering the use this so you don't go off rendering where you shouldn't.
> With ISA cards don't bother. You'll get 5-10fps at best even at low resolution. > You'd be better off reverse engineering an old DOS era cards drivers and > writing a feature connector mode card driver for something like the original > full length hauppauge card
That was aimed at just fbdev. It would be nice if the current X server for fbdev work on old paged isa cards without X code modification. Here we don't care about high end graphics. Their was discussion on the fbdev list also to be able to grab a window for the video4linux guys. Any comments since youa re the one in charge of this. What do you need from the fbdev guys to have video4linux work together?
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