Date: Thu, 30 May 2002 13:15:17 -0700 (PDT) From: Tom Tang <tangj@cs.ucdavis.edu> To: Doug White <dwhite@resnet.uoregon.edu> Cc: <freebsd-hackers@FreeBSD.ORG> Subject: Re: KLD mmap question Message-ID: <Pine.LNX.4.33.0205301313230.6952-100000@pc1.cs.ucdavis.edu> In-Reply-To: <20020530121826.D71308-100000@resnet.uoregon.edu>
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Doug,
Thanks for the reply, I'll check it out. However
if you'll notice in my prev mail, I stated that I was
trying to contigmalloc 4K... Hard to believe that
the system doesnt have 4K lying around.
- Tom
On Thu, 30 May 2002, Doug White wrote:
> 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
> dwhite@resnet.uoregon.edu | www.FreeBSD.org
>
>
--
Tom Tang
tangj@cs.ucdavis.edu
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