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Date: Mon, 16 Nov 2009 22:31:21 +0000
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [Qemu-devel] Re: [PATCH] sparc32 irq clearing (guest Solaris
	performance+NetBSD) fix
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To: Blue Swirl <blauwirbel@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>, Artyom Tarasenko <atar4qemu@googlemail.com>

Blue Swirl wrote:
> This patch makes the interrupts latch: ignore source clearing the
> interrupt. It seems be ~okay for my usual test setup, but does not
> help NetBSD 1.3.3. Some other NetBSD tests are changed, but they
> crashed before.

I'd expect the worst that would happen is "spurious interrupt"
messages under some kernel, according to the earlier description of
how Solaris handles interrupts (which is quite usual).

At least you'd expect the behaviour to be fine because no interrupts
are lost.

Drivers which go wrong because their interrupt handler is called
unnecessarily (or at least the "test device has condition pending"
function) tend to be rather fragile, because it's expected when
interrupt lines are shared between devices.

Then again, some old devices never did shared interrupt lines much.

-- Jamie