Matt,
then what is the use of /dev/port driver file ? When i do "cat /dev/port"
on the standard console, i have also a segmentation fault.
Another question, if i use mmap to map physical addresses of I/O registers,
could i dereference the pointer on virtual adresse to access data or should
i use read/write on the file descriptor ?
Best regards.
Sophie CARAYOL
Matt Porter
<mporter at kernel.cra Pour : scarayol at
assystembrime.com
shing.org> cc : linuxppc-embedded at
ozlabs.org
Objet : Re: Read in
/dev/port with Segmentation Fault
09/06/05 11:12
On Thu, Jun 09, 2005 at 09:30:43AM +0200, scarayol at assystembrime.com wrote:
> Hi all,
>
> I want to access to IO ports on a MPC885. The iopl() is not implemented,
in
> my distribution, to use inw() outw().
> So I use /dev/port. It works for open("/dev/port",..) and lseek() but
when
> i do a read() i have a segmentation fault. I gave all the right to
> /dev/port
> Does anybody have an idea ?
You are trying to use x86-specific interfaces to x86-specific IO space.
By "IO ports" you must mean memory mapped I/O registers since you are
on PPC. From userspace, use mmap() to map physical address space to a
user virtual address range.
-Matt
