RE: Bus errors accessing VME with base 7.0.6.1 and latest synApps modules

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Ø  At the top of freeListLib.c add:

Ø  #define EPICS_FREELIST_DEBUG

 

I did that and rebuilt base and synApps.

 

The error is the same:

 

ioc13lab2>

VME Bus Error accessing A16: 0x347e

machine check

Exception next instruction address: 0x0368cf38

Machine Status Register: 0x0008b032

Condition Register: 0x48000884

Task: 0x4441190 "CAS-event"

0x4441190 (CAS-event): task 0x4441190 has had a failure and has been stopped.

0x4441190 (CAS-event): The task has been terminated because it triggered an exception that raised the signal 10.

 

ioc13lab2> tt  0x4441190

0x0012489c vxTaskEntry  +0x48 : epicsThreadEntry ()

0x036a8f18 epicsThreadEntry+0x80 : 0x036073f8 ()

0x036076d0 db_start_events+0x458: db_delete_field_log ()

0x03606be0 db_delete_field_log+0x54 : freeListFree ()

value = 0 = 0x0

 

Other ideas of how to debug it?

 

Thanks,

Mark

 

-----Original Message-----
From: Michael Davidsaver <mdavidsaver at gmail.com>
Sent: Thursday, May 26, 2022 4:26 PM
To: Mark Rivers <rivers at cars.uchicago.edu>
Cc: tech-talk at aps.anl.gov
Subject: Re: Bus errors accessing VME with base 7.0.6.1 and latest synApps modules

 

On 5/26/22 14:00, Mark Rivers wrote:

> It looks like freeListFree() is probably generating an access violation.

 

If so, this would almost certainly be a sign of a bug elsewhere.

(double free, free of stack, ...)

 

Bypassing freeListLib _might_ give some added insight, or perhaps change the fault in some way.

 

At the top of freeListLib.c add:

 

> #define EPICS_FREELIST_DEBUG

 

This will short circuit the free list code, to always call malloc() and free().

 

Or more specifically, callocMustSucceed(), you would find out if any allocation requests are failing.

 

https://github.com/epics-base/epics-base/blob/3fadf4a26cfe33dcb9eb9e4620634e1d3a7b9763/modules/libcom/src/freeList/freeListLib.c#L63-L65