On Thu, 30 May 2002, Tom Tang wrote:

>   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...

Generally, after the machine is started, memory gets too fragmented to use
contigmalloc.

If you preload the module and do the contigmalloc at attach time it should
succeed.

Doug White                    |  FreeBSD: The Power to Serve
[EMAIL PROTECTED]     |  www.FreeBSD.org


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