Re: Global section -- how to track a wild write?

On Tue, 23 Jan 2007 18:26:59 -0800, Arne Vajhøj <arne@xxxxxxxxxx> wrote:

Stanley F. Quayle wrote:
I have a problem. There are several processes that access a global
section.
Infrequently, one of those processes zaps a critical longword in the
section to zero, and the whole system crumbles. The longword should
never change during the running of the system. Which process is
responsible?
Is there a way to make the page with that longword read-only for all
processes, without having to modify the processes themselves? When the
wild write happens, the offending process will ACCVIO. I'm willing to
change the structure of the global section, if necessary, to move that
one item to its own page.
Or is there a different approach that will tag the villian?
This is Alpha. This problem has never been seen on VAX.

The VAX-Alpha fact hints that it could be a 512-8192 problem.

Long time since I have created global sections, but I belive
the RW versis RO are set on a per process basis.

Either track it down analytical or run every process in
debugger with watch on the fields seems as the most
obvious ways to go.

some of the priveleges changed from VAX to Alpha. e.g.
GLOBALDEF(psect-nem) is noshr on Alpha, as we recently discovered.

Arne



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