Re: bus_dmamem_alloc confusion
On Thu, Oct 21, 2004 at 09:50:52PM -0700, Matthew Dillon wrote:
>
> :Exactly
> :
> : fdM = open("/dev/mem", O_RDWR);
> : ...
> : virt = mmap(0, mem.length,
> : PROT_READ | PROT_WRITE,
> : MAP_PRIVATE | MAP_ANON,
> : fdM,
> : (off_t)mem.baddr);
> :
> :where mem.baddr is the physical address passed back by the kernel.
>
> MAP_PRIVATE? If you intend to write to the memory you definitely
> do not want a private mapping, that will do a copy-on-write for any
> modifications you make via the map and not actually modify the physical
> memory you mapped. Use MAP_SHARED.
>
> MAP_ANON? That's a contradiction in terms. This isn't anonymous
> memory. Don't use MAP_ANON.
You 'da man. That was the problem. I wonder why this worked on
Free/Net? Thanks again!
--
Chuck Tuffli
Agilent Technologies
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