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Date: Mon, 14 Feb 2011 12:40:08 +0100
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: [Qemu-devel] Re: [RFC] prep: enable irq sharing on ide again
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= <andreas.faerber@web.de>, Alexander Graf <agraf@suse.de>, Aurelien Jarno <aurelien@aurel32.net>, QEMU Developers <qemu-devel@nongnu.org>

On 2011-02-14 12:22, Gerd Hoffmann wrote:
> On 02/08/11 00:26, Alexander Graf wrote:
>> The new ISA infrastructure checks for potential irq sharing bugs on
>> interrupt lines, because usually irq lines on isa can't be shared.
>>
>> The PREP spec however mandates that the irq lines for both IDE ports
>> are shared and according to Aurelien this also used to work just fine.
>>
>> So let's add a way to enable this sharing again, so we don't introduce
>> unnecessary regressions over older versions of Qemu.
> 
> Had a patch for that, got shoot down for reasons I don't remember,
> attached for reference.  It basically allows IRQ sharing in case the two
> devices sharing the IRQ are of the same kind.  In that case you usually
> have a single guest driver handling both devices and IRQ sharing works
> most of the time.

Yeah, 3x -serial XXX is also broken for x86 targets as the third device
shares its IRQ with the first - like on real HW...

Jan

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