i/o opening error for PCI access

[sengottuvelan.s@gmail.com (Sengottuvelan S)]

Hi Prasad,

question is:  anyother way to access like iopl(3) function?.

FYI, With iopl it is possible. But in my kernel i could not locate iopl
function. Is there any similar function like iopl so that i will set  the
permission as root id.

On Sun, Apr 3, 2011 at 3:47 PM, Prasad Joshi <prasadjoshi124@gmail.com>wrote:

> On Sun, Apr 3, 2011 at 6:11 PM, Sengottuvelan S
> <sengottuvelan.s@gmail.com> wrote:
> > Hi All,
> >
> > I am trying to access /dev/mem in my user process. I could not access
> > because not a privileged access. I tried to use iopl(3) call in linux
> 2.6,
>
> I am not sure, but after reading the manpage, it looks like iopl will
> give access to the IO ports not the files.
>
> > but i am getting unresolved symbol for this.  Is any other way to get
> access
> > in user process. I am not sure how to solve this. Can you someone throw
> some
> > light on this.
> >
> >    if(iopl(3)){
> >         fprintf(stderr, "Cannot get I/O permissions (being root helps)");
> >         return -1;
> >     }
> >   if ((fd = open("/dev/mem", O_RDWR | O_SYNC)) < 0) {
> >         fprintf(stderr, "Failed to open /dev/mem");
> >         return -1;
> >     }
>
> If you look at the file permission, you will notice only root has
> permission to write the /dev/mem
>
> $ ls -l /dev/mem
> crw-r----- 1 root kmem 1, 1 2011-04-03 08:42 /dev/mem
>
> Opening it for read/write will surely fail.
>
> Thanks and Regards,
> Prasad
>
> >
> > --
> > Regards,
> > S. Sengottuvelan.
> >
> > --
> > Regards,
> > S. Sengottuvelan.
> >
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies at kernelnewbies.org
> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >
> >
>



-- 
Regards,
S. Sengottuvelan.
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