Craig Vespe ([log in to unmask]) wrote:
:    Watch out setting data breakpoints in NM debug if you're in PRIV
:    mode.  It seems if you set a data breakpoint on data that is not
:    on the current page, a page fault occurs and as you're in PRIV mode -
:    crash.  We discovered this "feature" a couple (3?) years ago and
:    basically abandoned data breaks because of it (as we're almost
:    always PM when in debug).
 
That's close, Craig.  The problem is in setting data breakpoints
on a page where the OS later wants to do a STORE (STB, STH, STW)
while interrupts are disabled.
 
I don't know what you mean be "current page" (page with SP? DP?, PC?),
but assuming you mean SP (top-of-stack), that's the first page
I'd *NEVER* put a data breakpoint in ... when you resume from Debug,
there's an excellent chance MPE will shortly want to run on your
stack, and modify bytes in the "current page" (above your SP) while
interrupts are disabled --> system abort.
 
It would be nice to find out if this is a fixable problem, if the
user interest warranted the HP work involved.
 
Stan Sieler
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