Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Wed, 30 Jul 2003 00:07:06 -0500

I am writing device support on Linux for a parallel port device.  To talk to the parallel port I use iopl(3) to set the I/O privilege level of the task, and inb() and outb() to write to the I/O ports.  This works fine before iocInit.  After iocInit the code is running in a new epicsThread, and I find that it has "forgotten" the privilege level, and that I need to call iopl(3) again.  This is very inconvenient, because the new thread should not even need to know what kind of device it is talking to.

Is this the correct behavior, and is there a way to change it?  I thought that the the ioc was running as a single task in which all threads should have the same privileges.  Is there a way to make the new threads inherit the privileges from the parent?

Thanks,
Mark Rivers

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System