Experimental Physics and
Industrial Control System

Korhonen Timo <[email protected]> · Tue, 20 Apr 2010 13:21:31 +0200

Hi Dirk,
Now that Ben pointed this out, it rang a bell.

This probably does not help in any way, but almost exactly ten years

ago there was a discussion thread about aao record in tech-talk,
starting from:
http://www.aps.anl.gov/epics/tech-talk/2000/msg00310.php
I thought however that these issues (memory allocation, etc) would have
been solved already

a long time ago....

If I remember correctly, at that time I assumed Eric (Bjorklund) would
do the changes,

he probably expected that I do and we never cross-checked. :-(
best regards,
Timo

Benjamin Franksen wrote:

On Tuesday 20 April 2010, Dirk Zimoch wrote:

Tim Mooney wrote:

Dirk, I was seeing something similar (though in 3.14.11),

and "dbpr <recordname>,5" showed "DTYP: <nil>",

until I added the line

device(aao,CONSTANT,devAaoSoft,"Soft Channel")

to the .dbd file.

Hi Tim.
That is not the problem:
DTYP: Soft Channel
The ioc also crashes when the aao record is not processed! Thus DTYP

cannot be the problem.

I believe the aao record support is at fault.
The problem is that it does not allocate bptr itself but leaves this to
device support. However, when device support's init_record method is called,
it is too late. Because by then links have already been initialized, thus
cvt_db_addr has been called, which sets the field address to bptr, i.e.
NULL.
This explains why regular puts work but puts via db links lead to a crash.
If you dbpf from the ioc shell or do caput, the cvt_db_addr gets called and
since this is after device support init, bptr will contain a valid pointer
to the array.
You could verify my theory by issuing a 'caput aao1.OUT aao2'. After this,
the IOC should not crash when processing aao1. It shoudl still crash when
processing ao1, until you re-initialize thits OUT link, too.
Solution: Fix aao (and probably aai) record support to either allocate bptr
itself or else call device support's init_record during the first pass of
record support initialization.
Cheers
Ben

--

Timo Korhonen PSI (Paul Scherrer Institut, http://www.psi.ch)
CH-5232 Villigen PSI
tel + 41- 56 3103262 fax + 41 - 56 310 5090
e-mail: [email protected]

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System