Re: Linux and EPICS threads

[Eric Norum <norume@aps.anl.gov>]

Mark Rivers wrote:
> Andrew Johnson wrote:
>
>
> > You will need to worry about more than one thread - each 
> > different scan period has its own thread, so it just takes the user
>
> changing 
>
> > the SCAN field of the record for your code to have to call iopl(3) yet
>
>
> > again, and if it's set to Process Passive then there are several other
>
>
> > tasks that might be used depending on how the processing is initiated.
>
>
> Actually, it's not that bad in my case.  All of the actual I/O is done
> by an MPF server task.  Device support just sends messages to the MPF
> server, so the tasks that process the record do not need iopl()
> privilege.
>
> I've got it working by calling iopl() in the MPF server task
> initialization.  It's not as clean as I'd like, because it requires some
> #ifdef linux code, but it's OK.

I'd recommend calling ioperm() rather than iopl() since ioperm opens 
only a specified window into the inp/outp space so you can't 
accidentally tromp on some other (critical) port.


--
Eric Norum                                 norume@aps.anl.gov
Advanced Photon Source                     Phone: (630) 252-4793
Argonne National Laboratory