That string turns up in 2 files, I cloned into emc
emc/scr/rtapi/uspace_rtapi_parport.cc - I guess for uspace
implementations (rt_preempt).
emc/src/rtapi/rtapi_parport.h - I guess with a rtapi kernel
On 17/6/21 10:42 am, Jon Elson wrote:
On 6/16/21 6:42 PM, Robert Murphy wrote:
Hi all,
After seeing so many threads of users having issues with PCI & PCIe PP
cards and parallel port not found @xxxxx, is there a way to detect a
physical port, such parport_pc does, I can see there would be an issue
if a system port was given when load hal_parport. I was thinking we
could get rid of the parallel port not found @xxxxx when there is not a
PP card that does match the list of known PP cards of parport_pc.
If a physical port is found Linuxcnc could continue without the info
message, if no physical port is found linuxcnc would stop as it does
when there is a config error.
Well, there may be. I think you can set something up to trap I/O port
timeouts, at least in the normal user environment. I'm not sure such
a service is available through rtapi. What I have seen is that
timeouts when a non-existent port is accessed in an RT function, it is
just ignored, but takes extra time.
So, for instance, you can use hal_parport to talk to any random I/O
port address, and it just carries on normally, whether there is a
device there or not. In fact, it seems like any privileged task can
do that.
So, maybe the PC architecture does not have a system to detect invalid
I/O port addresses that don't respond.
Anyway, for this specific problem, it seems that a test to see if the
port is allocated to parport_lp before making the system call to ask
Linux to relinquish the port would be the way to deal with the error
message. I think this code was developed by Jeff Epler more than 10
years ago, and was mostly tested on the on-mobo 378 port, where it
seemed to have consistent and correct behavior.
The funny thing is that on SOME installs, I never get the message, and
on some other installs, it appears SOME times, but not on all LinuxCNC
startups. That's kind of confusing.
I did look in the source of hal_parport, and while there are some
error messages, the specific one about "parallel port at address xxxx
not found" does not occur. So, I'm guessing that logic is in rtapi,
an area where I have zero experience.
Jon
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