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Date:      Wed, 29 Nov 2000 11:43:57 +1100 (EST)
From:      Bruce Evans <bde@zeta.org.au>
To:        Andrew Gallatin <gallatin@cs.duke.edu>
Cc:        current@FreeBSD.ORG
Subject:   Re: missing interrupts (was Re: CURRENT is freezing again ...)
Message-ID:  <Pine.BSF.4.21.0011291131440.2395-100000@besplex.bde.org>
In-Reply-To: <14882.50276.726465.490454@grasshopper.cs.duke.edu>

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On Mon, 27 Nov 2000, Andrew Gallatin wrote:

> 
> 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
> ....
> 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

Oops, I misread the data sheet.  0x60 is correct, 0x30 is wrong.  The
irq number is in the lowest 3 bits.

> appear to work just fine.   What should the alpha port use?

I think it should use non-specific EOIs and send them early (when
there is no ambiguity about which interrupt is being handled), as in
the i386 port.  Sending them late mainly gives the ICU's braindamaged
interrupt priority scheme for longer than necessary.

Bruce



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