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From: Bernhard Kauer <kauer@os.inf.tu-dresden.de>
To: kvm@vger.kernel.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] i8259 defaults wrong?
Date: Tue, 18 Aug 2009 11:39:54 +0200	[thread overview]
Message-ID: <20090818093932.GA1887@chrom.inf.tu-dresden.de> (raw)
In-Reply-To: <20090817022024.GE1025@MAIL.13thfloor.at>

On Mon, Aug 17, 2009 at 04:20:24AM +0200, Herbert Poetzl wrote:
> looking at the i8259 implementation found in qemu
> as well as in the in-kernel kvm implementation, I
> see that on pic_reset() special_fully_nested_mode
> is set to zero, but the intel(r) 8259A manual says
> on page 15:
> 
>   Fully Nested Mode
>  
>   This mode is entered after initialization unless
>   another mode is programmed.
> 
> any comments are appreciated,

You confuse two modes of the PIC: the FullyNestedMode
and the SpecialFullyNestedMode. See page 18 in the
manual.

The first ist the "default" mode, where an IRQ in
service from a slave masks further interrupts from this
slave.  In SFNM a slave PIC can still issue another
IRQ.


Greetings,

	Bernhard Kauer

      parent reply	other threads:[~2009-08-18 10:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-17  2:20 [Qemu-devel] i8259 defaults wrong? Herbert Poetzl
2009-08-17  9:54 ` [Qemu-devel] " Avi Kivity
2009-08-18  1:02 ` Herbert Poetzl
2009-08-18  7:46   ` Avi Kivity
2009-08-18  9:39 ` Bernhard Kauer [this message]

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