943,691 Members | Top Members by Rank

Ad:
  • C Discussion Thread
  • Marked Solved
  • Views: 1462
  • C RSS
Mar 23rd, 2008
0

Hardware interactions on Linux

Expand Post »
Does anyone here have any tips on using inb and outb for interacting with hardware on a Linux system? iopl(2) and inb(0x61) don't seem to work very nicely... Infact, inb(0x61) gives me a segfault.



PS: My reliance on this forum is starting to become embarrassing
Reputation Points: 10
Solved Threads: 1
Junior Poster in Training
Crushyerbones is offline Offline
53 posts
since Mar 2008
Mar 23rd, 2008
0

Re: Hardware interactions on Linux

>>Does anyone here have any tips on using inb and outb for interacting with hardware on a Linux system?

Yes -- you can not use them because the os won't let you access the ports directly.

>>Infact, inb(0x61) gives me a segfault.
Yup
Last edited by Ancient Dragon; Mar 23rd, 2008 at 6:22 pm.
Sponsor
Team Colleague
Featured Poster
Reputation Points: 5608
Solved Threads: 2282
Retired and Enjoying Life
Ancient Dragon is online now Online
21,950 posts
since Aug 2005
Mar 24th, 2008
0

Re: Hardware interactions on Linux

>>Does anyone here have any tips on using inb and outb for interacting with hardware on a Linux system?

Yes -- you can not use them because the os won't let you access the ports directly.

>>Infact, inb(0x61) gives me a segfault.
Yup
Damn... My XP machine is also running the same program (modified for windows, obviously) kinda funky... And there's no way I'm getting Vista back on my laptop
Reputation Points: 10
Solved Threads: 1
Junior Poster in Training
Crushyerbones is offline Offline
53 posts
since Mar 2008
Mar 24th, 2008
0

Re: Hardware interactions on Linux

No version of MS-Windows since Win95 nor any version of *nix will allow you to use those inp and outp functions. So putting Vista back won't help you either.
Sponsor
Team Colleague
Featured Poster
Reputation Points: 5608
Solved Threads: 2282
Retired and Enjoying Life
Ancient Dragon is online now Online
21,950 posts
since Aug 2005
Mar 24th, 2008
0

Re: Hardware interactions on Linux

No version of MS-Windows since Win95 nor any version of *nix will allow you to use those inp and outp functions. So putting Vista back won't help you either.
I know, that's why I said modified for windows. As in replacing inb and outb with inportb and outportb.
Reputation Points: 10
Solved Threads: 1
Junior Poster in Training
Crushyerbones is offline Offline
53 posts
since Mar 2008
Aug 11th, 2009
0

Re: Hardware interactions on Linux

I realize that this thread is old, but it is still useful to correct an erroneous assertion about inb(), outb(), etc., especially given that Google drops people in here when looking for an answer to why these functions segfault, even when all the advice featured elsewhere is followed.

The truth is that these functions do in fact work, even under the most recent versions of the kernel (as of 8/11/09). However, they will not work from a user mode program unless the program is run as root (sudo...). It is also true that they will segfault if iopl(3) is not used. iopl(2) is not good enough. It is also true that the method of using ioperm() fails, apparently no matter how it is used. This may have worked in older kernels, but it now always gives a segfault. The only means of using these function seems to be calling iopl(3) first. (Ubuntu Interpid, 2.6.28-15-generic, x86_64 GNU/Linux)
Reputation Points: 10
Solved Threads: 5
Newbie Poster
sbesch is offline Offline
20 posts
since Aug 2009
Aug 17th, 2009
0

Re: Hardware interactions on Linux

Better late than never. Many thanks, this problem cost me a good grade last year
Reputation Points: 10
Solved Threads: 1
Junior Poster in Training
Crushyerbones is offline Offline
53 posts
since Mar 2008

This thread is solved

Either the thread starter or a moderator has marked this thread as solved. You can most likely trust the responses and answers given. There is most likely no reason for any further responses to be posted here. If you have a related question, please start a new thread in this forum instead.

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.
Message:





About Us | Contact Us | Advertise | Acceptable Use Policy
Forum Index | Build Custom RSS Feed


Follow us on Twitter


© 2011 DaniWeb® LLC