Hi Everyone,

The attached patch is an update of my earlier patch
to fix smp problems in kdb.  I started with Ethan
Solomita's patch but I have change a lot of code
since then. I have been exchanging private email with
Ethan over the last week and he has helped find some
of my bugs.  Thanks again.  There are always more bugs
but I think this patch has reached the useful stage.

The changes are:

     -  Splitting up the kdb_state variable to 
        decouple data used for inter-processor
        synchronization from local flags.

     -  Avoid having an extra layer of nesting
        if a processor is already in kdb when the
        kdb inter-processor interrupt is delivered.

     -  When several processors enter kdb at the
        same time treat them more as equals.
        My test is to be able to switch to another
        cpu and see useful state and be able to
        single step.  With the released code or
        Ethans patch the inter-processor NMI 
        interrupt may interrupt the kdb entry code.
        This shows up as a confusing backtrace when
        you switch to another processor.


Jim Houston - Concurrent COmputer Corp.

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