Subject: Re: question about mmap
To: Jachym Holecek <freza@liberouter.org>
From: Chan-youn Park <phygeeks@gmail.com>
List: tech-kern
Date: 03/10/2005 09:37:12
Oh, and by the way, I'm programming on NetBSD 1.6.2.
On Wed, 9 Mar 2005 10:01:57 +0100, Jachym Holecek <freza@liberouter.org> wrote:
> Hi,
>
> > [... Can't bus_space_mmap(), mmap routine looks correct ...]
> >
> > here, pmemt and pmema is the tag and physical address of the DSP
> > memory space which are get using pci_mapreg_info.
>
> Just to make sure -- do you 1) also call pci_mapreg_map() or 2) call
> bus_space_map() before allowing accessing that space by method?
>
> Btw, memory protection value of "1" you're seeing is relevant and means
> "allow reads" (PROT_READ that is, see /usr/include/sys/mman.h), which is
> correct.
>
> > And below is a part of a test application program to see the DSP memory space.
> > ----
> > tdsph = open("/dev/tdsp", O_RDWR, 0);
> > sram.addr = mmap(0, sram.len, PROT_READ, MAP_SHARED, tdsph,
> > (off_t)sram.offset);
>
> Does mmap() succeed? Is sram.offset really correct (relative to start of
> SRAM window)?
>
> > while(i < sram.len){
> > addr = (u_int8_t*)sram.addr + i;
> > [...]
>
> Does the DSP SRAM (and the bus hierarchy it's connected to) allow you 8bit
> accesses?
>
> > What should I check to see what is wrong? And in addition, is there a
> > good simple code that I can study the usage of device mmap function?
>
> Hmm, I couldn't see anything obviously wrong. After checking the
> questions above, we can look at more code...
>
> Regards,
> -- Jachym Holecek
>