Re: sun3 port different then many others
Rick Sustek <[email protected]>
| Newsgroups | gmane.os.netbsd.ports.sun3 |
|---|---|
| Message-ID | <[email protected]> |
Yup the frame buffers are memory mapped, at least on all the Sun2 and Sun3 hardware I used to play with back when those machines were *The Thing*. We used to have lots of fun just filling the memory space with random patterns, either from the monitor ROM command line, or from a booted kernel, using a debugger. But DMA controllers usually have a mode where you can program up memory-to-memory transfers, and this can be used quite effectively to quickly update a screen from a prepared buffer in main RAM. I've done this with custom 68k hardware, but not actually on Sun h/w, so can't give any useful details. Have fun, Rick der Mouse wrote: >[quoting order normalized -dM] > > >>>>the cg8 doesn't use DMA ???? >>>>ummm... what does it use ? >>>> >>>> >>>For what? What does the cg8 do that you'd think it would have any >>>use for DMA for? >>> >>> >>Do any of the framebuffers use DMA ? >> >> > >As far as I know they don't. I have seen things which make me suspect >that among the undocumented bits of some of them lurk a DMA engine or >two, but as far as I know the bits remain undocumented and thus unused. > >Pity, too, because it would make sense to be able to DMA stuff (either >video RAM contents or for the more sophisticated boards higher-level >stuff like drawing operations) from host memory to the framebuffer. > >/~\ The ASCII der Mouse >\ / Ribbon Campaign > X Against HTML [email protected] >/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B > > >