Experimental Physics and
Industrial Control System

Dirk Zimoch <[email protected]> · Tue, 08 Feb 2005 13:50:53 +0100

Hi all,
I have some driver software that contains
double scan_period;
scan_period = 0.05;
The function is executed from startup script, i.e. the executing task is
a floating point task.
However, sometimes when booting R3.13.2, the ioc crashes with "floating
point underflow" while executing
printf ("init_record_generic: scan_period=%f\n", scan_period);
I couldn't even look at the registers, because ti also crashes when it
tries to print the register containing scan_period.
According to the bitpattern, scan_period is not 0.05, but some
denormalized value.
Even more astonishing is that the error only happens sometimes! In rare
cases, everything is OK. When I boot R3.13.5, also everything is OK. I
have compared the driver library compiled for both EPICS versions. It is
exactly the same object code.
We load the driver library in the startup script. Maybe there is
something wrong with the ld command, corrupting constants?
But how can this depend on the EPICS release? Maybe the code is loaded
to another location, but does the location matter?
Why does this only happen with one driver?
Any ideas or solutions?

Dirk
--
Dr. Dirk Zimoch
Swiss Light Source
Paul Scherrer Institut
Computing and Controls
phone +41 56 310 5182
fax   +41 56 310 4413

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System