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| <== Date ==> | <== Thread ==> |
|---|
| Subject: | Re: [APS Beamline_controls] Access to IO registers from user-spacein recent Linux versions |
| From: | Eric Norum <[email protected]> |
| To: | Mark Rivers <[email protected]> |
| Cc: | Tech-talk Techtalk <[email protected]> |
| Date: | Fri, 10 Jul 2009 11:54:05 -0500 |
On Jul 10, 2009, at 11:08 AM, Mark Rivers wrote:
So it fails. The seg fault happens because the I/O is being done without first calling iopl(3). If I modify the test_io.c program to implement the call to iopl(3) then it works if I run it as root.So on some systems executing iopl(3) and then calling execv() allows I/O port access in the exec'd task, but on some systems it does not.Any ideas why?
That's very strange.
The man page that I have for iopl explicitly states:
Permissions are inherited by fork() and exec().
--
Eric Norum <[email protected]>
Advanced Photon Source
Argonne National Laboratory
(630) 252-4793