On Fri, 17 Nov 2000 10:30:02 -0800 (PST), John Baldwin <[EMAIL PROTECTED]> said:

    > what the WITNESS code does is perform extra checks on mutex
    > enter's and exit's to ensure that we aren't handling mutexes in
    > such a way that a deadlock is possible. Thus, it verifies that
    > you don't grab mutexes out of order, or that you don't grab
    > sleep mutexes with interrupts disabled, etc.

Is this code meaningful on UP machines? Having been a victim of these
seemingly random freezes since SMPng started, as others have noted, I
decided to compile it in earlier this week. Twice now I've been dumped
into the debugger with this output:

lock order reversal
1st dc0 last acquired @ ../../pci/if_dc.c:2717
2nd 0xc0acdb3c dc1 @ ../../pci/if_dc.c: 2717
3rd 0xc0acab3c dc0 @ ../../pci/if_dc.c: 2929

Debugger ("witness_enter")
Stopped at Debugger+0x39: movb $0, in.Debugger.639

Michael D. Harnois, Redeemer Lutheran Church, Washburn, IA 
[EMAIL PROTECTED]                      [EMAIL PROTECTED] 
 The atheist staring from the attic window is often nearer to God than the
 believer caught up in his own false image of God. -- Martin Buber

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