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Date:      Mon, 27 Nov 2000 15:42:18 -0500 (EST)
From:      Andrew Gallatin <gallatin@cs.duke.edu>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        current@FreeBSD.ORG
Subject:   Re: missing interrupts (was Re: CURRENT is freezing again ...)
Message-ID:  <14882.50276.726465.490454@grasshopper.cs.duke.edu>
In-Reply-To: <Pine.BSF.4.21.0011190449250.502-100000@besplex.bde.org>
References:  <14869.58648.34403.679348@grasshopper.cs.duke.edu> <Pine.BSF.4.21.0011190449250.502-100000@besplex.bde.org>

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Bruce Evans writes:
 > Possible causes of the problem:
 > 1) isa_handle_intr() claims to send specific EOIs (0x30 | irq) but
 >    actually sends non-specific ones (0x20 | garbage).  Since interrupts
 >    may be handled in non-LIFO order, this results in EOIs being sent
 >    for the wrong interrupts.  I think this just randomizes the
 >    brokenness caused by delaying sending of EOIs.  I can't see how it
 >    would result in an EOI being lost -- the right number of EOIs will
 >    have been sent after all handlers have returned.


I think that sending non-specific EOIs is the problem.  Sending
specific EOIs seem to eliminate my nic timeouts and the need to
manually feed an eoi to recover from a missing interrupt.

My question is: how does one send a specific EOI correctly?  I don't
have decent documentation for this.  Above, you seem to imply that
0x30 is a specific EOI.  That does not seem to work for me (machine
locks at boot).

Linux uses 0xe0.  According to some Tru64 docs I have,
that means "Rotate Priority on specific EOI".  According
to that same documentation, 0x60 is a specific EOI.  Both of these
appear to work just fine.   What should the alpha port use?

Thanks,

Drew





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