dtrace discuss - Aug 2005 - dtrace with kmdb

I have come up with an issue where the system hangs while executing dtrace and
kmdb. The hang happens while sending a break during boot. {1} ok boot kmdb
Resetting ... Rebooting with command: boot kmdb Boot device: /pci at
1f,4000/scsi at 3/disk at 1,0:a File and args: kmdb Loading kmdb... SunOS
Release 5.10 Version Generic 64-bit Copyright 1983-2005 Sun Microsystems, Inc.
All rights reserved. Use is subject to license terms. NOTICE: enabling probe 0
(fbt:::) NOTICE: enabling probe 1 (dtrace:::ERROR) Hostname: tazmax0 tazmax0
console login: ~ <==== Send Break Here. Then system hung occurs. Can you
please let me know if there are any issues if dtrace is used with kmdb. Also can
you also please let me know that what are the specifications for dtrace probes
in krtld.
This message posted from opensolaris.org

enabling probe 0 (fbt:::)

  Even on a non-kmdb''d box this may _really_ slow down the system,
you''d
  be enabling well over 30,000 probes on the system.

  Look again at what you want to dtrace and narrow down the fbt probes, I
  doubt you really want to enable >30,000 probes :)

Sean.
.
tanu stated:
< I have come up with an issue where the system hangs while executing dtrace
and kmdb. The hang happens while sending a break during boot. {1} ok boot kmdb
Resetting ... Rebooting with command: boot kmdb Boot device: /pci at
1f,4000/scsi at 3/disk at 1,0:a File and args: kmdb Loading kmdb... SunOS
Release 5.10 Version Generic 64-bit Copyright 1983-2005 Sun Microsystems, Inc.
All rights reserved. Use is subject to license terms. NOTICE: enabling probe 0
(fbt:::) NOTICE: enabling probe 1 (dtrace:::ERROR) Hostname: tazmax0 tazmax0
console login: ~ <==== Send Break Here. Then system hung occurs. Can you
please let me know if there are any issues if dtrace is used with kmdb. Also can
you also please let me know that what are the specifications for dtrace probes
in krtld.
< This message posted from opensolaris.org
< _______________________________________________
< dtrace-discuss mailing list
< dtrace-discuss at opensolaris.org

-- 
Sean.
.
sean DoT mcgrath At sun.com http://blogs.sun.com/smg
http://www.sun.com/software/solaris

Hi Tanu,

------------- Begin Included Message -------------

I have come up with an issue where the system hangs while executing dtrace and 
kmdb. The hang happens while sending a break during boot. {1} ok boot kmdb 
Resetting ... Rebooting with command: boot kmdb Boot device: 
/pci at 1f,4000/scsi at 3/disk at 1,0:a File and args: kmdb Loading kmdb...
SunOS Release
5.10 Version Generic 64-bit Copyright 1983-2005 Sun Microsystems, Inc. All 
rights reserved. Use is subject to license terms. NOTICE: enabling probe 0 
(fbt:::) NOTICE: enabling probe 1 (dtrace:::ERROR) Hostname: tazmax0 tazmax0 
console login: ~ <==== Send Break Here. Then system hung occurs. Can you
please
let me know if there are any issues if dtrace is used with kmdb. Also can you 
also please let me know that what are the specifications for dtrace probes in 
krtld.
------------- End Included Message -------------


The bug in which you logged this problem, viz. 6256581, is still being worked. 
As described in the last update, it appears that in Solaris 10 FCS there are a 
number of DTrace probes that seem to be incompatible with kmdb. Augmenting my 
last update with this morning''s work, I can say that the problem probes
are:

1. fbt:krtld:kobj_kdi_get_polled_io:	(These cause the hard hang you report)

2. fbt:krtld:kobj_kdi_mods_changed:	(These cause a fatal debugger error)
   fbt:krtld:kobj_kdi_mod_isloaded:

3. fbt:krtld:kobj_kdi_mod_iter:		(These cause apparently transient
					 problems in kmdb)
					 
4. fbt:unix::				(Enabling all of the probes in this
					 module causes a RED State Exception
					 after ":c" is issued from the
					 kmdb prompt following a break).

I''m just starting to identify the problem probes in the unix module,
and will
update bug 6256581 appropriately once I''ve done so. In the mean time,
if your
customer wishes to boot under kmdb then I recommend that he does not instrument 
any of the probes listed above.

Regards,

Robert