Date: 30 May 2002 16:18:54 -0600 From: Eric Anholt <eanholt@gladstone.uoregon.edu> To: freebsd-hackers@FreeBSD.ORG Subject: Re: KLD mmap question Message-ID: <1022797135.1008.3.camel@anholt.dyndns.org> In-Reply-To: <Pine.LNX.4.33.0205301209280.6101-100000@pc1.cs.ucdavis.edu> References: <Pine.LNX.4.33.0205301209280.6101-100000@pc1.cs.ucdavis.edu>
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On Thu, 2002-05-30 at 13:14, Tom Tang wrote: > Hello, > > I have a question about implementing mmap functions in > device drivers. Thinking it would be simple, I contigmalloc'd > a buffer of PAGE_SIZE and returned it using atop like other > mmap device implementations. However when my userland program > mmaps the device with offset 0, when I try accessing the returned > pointer, it returns me invalid memory address. Any help would > be appreciated... An associated question: while I was looking at the DRM's mmap for the shared memory area, I think I figured out that you didn't need memory that was going to be mmapped to be physically contiguous (since the device pager would get each page of it separately). Was I right? -- Eric Anholt <eanholt@gladstone.uoregon.edu> http://gladstone.uoregon.edu/~eanholt/dri/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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