Messages in this thread | | | Date | Tue, 15 May 2001 20:18:21 +0200 | From | Ingo Oeser <> | Subject | Re: LANANA: To Pending Device Number Registrants |
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On Tue, May 15, 2001 at 10:44:23AM -0700, James Simmons wrote: > different. I do plan on some day merging drm and fbdev into one interface. So > I plan to change this behavior. I like to see this interface ioctl-less > (is their such a word ???). You mmap to alter buffers. Mmap is much more > flexiable than write for graphics buffers anyways. You use write to pass > "data" to the driver.
The only problem with mmap(): You cannot know, if the page changed under you a**.
What would first mmap()ed page of the screen look like, if some accelerator wrote a line there? Invalidating all mmap()ed pages for each and every accelerator command would be evil. Forbidding reads of that page is evil, too.
I have the same problem with DSPs, which like to mmap() some of their memory into the application, but can alter this memory every instruction the execute.
mmap() has it's beauties, but ...
Regards
Ingo Oeser -- 10.+11.03.2001 - 3. Chemnitzer LinuxTag <http://www.tu-chemnitz.de/linux/tag> <<<<<<<<<<<< been there and had much fun >>>>>>>>>>>> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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