From: Geert U. <ge...@li...> - 2001-12-04 15:35:24
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On Mon, 3 Dec 2001, Sottek, Matthew J wrote: > >oo, are there cases where extra pitch memory is used for things? the area > is > >so broken up and in small chunks that i didnt think any hardware developer > >would use it. but if intel's do that, i'd imagine there is probably > something > >there. this certainly causes problems i wasn't aware of. > > Well I don't use the extra, but I could :) I was looking for a cheap example > of when you wouldn't want mmap to happen. Some hardware have tiled memory > framebuffers that might not work correctly unless you knew about the > tiling. Intel's tiled memory isn't a problem, but I think some might be. > > The extra pitch-width area isn't useless. You can put other surfaces there. > You think of the area as being broken up, but really it is just a thinner > area with the same pitch as the framebuffer. i.e. if your framebuffer is > 800x600 at 16bit, on Intel hardware you have a fb pitch of 2048. That > is an area of 448x600 with a pitch of 2048 that can be used. There exist PowerMac graphics cards that put the hardware cursor in that area. Gr{oetje,eeting}s, Geert P.S. Matt: I'm still reading your document (I'm halfway). I'll post my list of questions and comments after I've finished reading the whole document. So far it looks nice! -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@li... In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds |