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Date:      Wed, 6 Feb 2002 20:43:10 +1100 (EST)
From:      Bruce Evans <bde@zeta.org.au>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        <cvs-committers@FreeBSD.org>, <cvs-all@FreeBSD.org>, Bruce Evans <bde@FreeBSD.org>
Subject:   RE: cvs commit: src/sys/i386/i386 db_interface.c
Message-ID:  <20020206201716.B2295-100000@gamplex.bde.org>
In-Reply-To: <XFMail.020205215801.jhb@FreeBSD.org>

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On Tue, 5 Feb 2002, John Baldwin wrote:

> On 05-Feb-02 Bruce Evans wrote:
> > On Tue, 5 Feb 2002, John Baldwin wrote:
> >> Err, have you tested this?  In my tests locally this still doesn't work
> >> properly which is why I haven't committed it. :(
> >
> > PS: perhaps you are thinking of the flag in Debugger().  That is
> > ...
>
> Hmm, the problem I was having is that interrupts were still firing while I was
> in ddb.  I could tell because new KTR entries due to clock interrutps kept
> showing up.

This can't happen :-).  Except for bugs which would affect most forms
of interrupt disablement.  Perhaps there is a path through trap() which
enables interrupts even for debugger traps, but only when they are
enabled when the trap occurs.  Ah, I see a related broken path, not
for debugger traps but for pagefaults.  Interrupts are enabled for
pagefaults almost unconditionally, so a pagefault in ddb would cause
problems.  I think this causes the "Context switches not allowed in the
Debugger" message.  I thought that this was caused by a more fundamental
bug.

BTW, why does the spinlocking in kern_clock.c use MTX_QUIET?  nanotime()
for witness timestamps should work normally there.  I noticed this
when I uninlined mtx_*_spin_*().  The `flags' versions are not used
anywhere else.

Bruce


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