From mboxrd@z Thu Jan 1 00:00:00 1970 From: sengottuvelan.s@gmail.com (Sengottuvelan S) Date: Sun, 3 Apr 2011 17:19:34 -0700 Subject: i/o opening error for PCI access In-Reply-To: References: Message-ID: To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org 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 wrote: > On Sun, Apr 3, 2011 at 6:11 PM, Sengottuvelan S > 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. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20110403/df3a61b6/attachment-0001.html