Operating System - OpenVMS
cancel
Showing results for 
Search instead for 
Did you mean: 

VMS Alpha V8.2 Watchpoint utility broken

 
David B Sneddon
Honored Contributor

VMS Alpha V8.2 Watchpoint utility broken

Hi Folks,

This question directly relates to the following thread

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=842851

but since no-one seems to want to take that one on...

The (unsupported) Watchpoint utility appears to be broken
on VMS/alpha V8.2.
Any access to the page containing the watchpoint causes a bugcheck.
I don't have the bugcheck code.

So my question, will a working watchpoint utility be
available sometime soon for V8.2?
This would make it easier to resolve my other problem by
identifying what is corrupting memory.

Regards
Dave
13 REPLIES
David B Sneddon
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Correction.

I have found the utility is documented and I would
assume therefore supported.
I had always assumed it to be unsupported (don't
really know why there you go).
So my question still remains. Can we please have a
working copy?

Dave
Volker Halle
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Hi,

I can confirm Dave's observation. WATCHPOINT is documented in the System Analysis Tools manual and as such should be supported.

Example: If you set a watchpoint to a location within a FCB, you'll get an INVEXCEPTN crash, if any memory location inside the page, in which the watchpoint has been set, is touched (even with a READ).

The condition code signalled is 00000414 = %SYSTEM-F-BREAK

Failing Instruction:
SEARCH_FCB_C+00910: LDL R27,#X008C(R12)

The page pointed to by R12 has a protection code of Read/Writ: KE-- NONE in the dump.

Volker.
John Gillings
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Dave,

>Can we please have a working copy?

Please log a case, with a reproducer, so we can elevate it.

Thanks
A crucible of informative mistakes
David B Sneddon
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

John,

This is on my machine at home (hobbyist licenses) as mentioned in
the original thread about the UNXSIGNAL bugcheck.

Dave
Robert Brooks_1
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Can someone with a support contract please log a call against the watchpoint utility? It really makes our lives much easier if these things are initiated by a paying customer.

-- Rob
John Abbott_2
Esteemed Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

We pay & have 8.2 but not currently installed. Big question: Is there enough info. in this thread for me to pass it on without 20 more questions or needing a dump?
What 8.2 patches are installed ? On what hardware ?

PS. Would like these things fixed before we go there!

Kind Regards,
John.
Don't do what Donny Dont does
David B Sneddon
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

John A,

If you have a look through the other thread mentioned above
you will see the origins of this thread.
Since this problem arose whilst trying to determine the
cause of the UNXSIGNAL bugcheck in the other thread, and
it seems to be fairly specific to my hardware configuration
there is a good chance that you will have no problems, unless
of course you try to use the Watchpoint utility.
The issue with the Watchpoint utility seems to relate
to V8.2 and not my hardware (as mentioned by Volker).
I also have 8.2, and support, at work but have not yet
installed it because we use shadowing and I don't want
to potentially screw up any machines at work until I
can resolve the UNXSIGNAL bugcheck issue.
I also don't have a spare machine with which to play at present.
The system in question was upgraded from 7.3-2 to 8.2
and the two current ECOs installed.
It is a Digital Personal Workstation 600au.

Dave
Robert Brooks_1
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

I've asked around within VMS Engineering about the problems with the Watchpoint utility.
This is what I've heard so far . . .

"There's a number of known problems with its current implementation.
In particular, it doesn't work on any SMP system. [name deleted] has a Nemo [V8.3] work item to fix/overhaul it and to port it to I64."

So, there's no need to file an official work request to get the ball rolling. I don't know if the V8.3 work will be backported to V8.2 or not; that decision will be made later.

Has anyone tried the watchpoint utility on a single-CPU system?

As always, thanks for letting us know about this problem!

-- Rob
David B Sneddon
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Rob,

The machine at the heart of this problem is a single-CPU
Digital Personal Workstation 600au...
so in answer to your question -- yes.

(Also, the $WP*DEF macros described in the manual do not
exist in LIB.MLB on V8.2, or as far back as V7.1-2. Is this
an oversight or are they hidden away somewhere else?)

Regards
Dave
Volker Halle
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Here is an easy reproducer for showing, that the watchpoint driver does not work on V8.2 (I'm currently on vacation, so I can't try the same on V7.3-1). This has all been done on a non-SMP machine.

- load WPDRIVER, set MAXBUF=64000

$ANAL/SYS
SDA>CLUE XQP/FCB

Select an address of one of the cached FCBs and set a watchpoint on +FCB$L_EXFCB (I typically used the FCB for [SYSEXE] or [SYSMGR])

$MC WP watch Gxxxxxxx/SILENT/LONG

Then try a DIR command on that directory. I always get an INVEXCEPTN crash (see my previous reply).

Volker.
Volker Halle
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Dave,

I've now tested the same WP setup and commands on V7.3-1 and it works as expected.

I had to set a WATCHPOINT on FCB$L_WCBFL instead of FCB$L_EXFCB, as [SYS0]SYSEXE.DIR (fid=12) used for testing did not have an extension file header.

So it looks like WPDRIVER is just broken in V8.2 - a pity, which prevents us from further analysing your UNXSIGNAL crash.

Volker.
David B Sneddon
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Volker,

Thanks for that -- now we sit back and wait.

Dave
David B Sneddon
Honored Contributor

Re: VMS Alpha V8.2 Watchpoint utility broken

Any developments on this issue will be reported...

Dave