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From: Avi Kivity <avi@redhat.com>
To: Blue Swirl <blauwirbel@gmail.com>
Cc: Lucas Meneghel Rodrigues <lmr@redhat.com>,
	Anthony Liguori <aliguori@us.ibm.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	Jan Kiszka <jan.kiszka@web.de>, Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] pc: Clean up PIC-to-APIC IRQ path
Date: Thu, 01 Sep 2011 08:58:29 +0300	[thread overview]
Message-ID: <4E5F1F05.7050704@redhat.com> (raw)
In-Reply-To: <CAAu8pHucV2HGqt4tnh+GZ=V-wd0+=u=emODB-MZoqrRCtT5LKA@mail.gmail.com>

On 08/31/2011 07:59 PM, Blue Swirl wrote:
> >
> >  That makes it impossible to migrate level-triggered irq lines.  Or at least,
> >  the receiver has to remember the state, instead of (or in addition to) the
> >  sender.
>
> Both ends probably need to remember the state. That should work
> without any multiphase restores and transient suppressors.

State should always correspond to real hardware state - a flip flop or 
capacitor.  Input is not state, it is input.

> It might be also possible to introduce stateful signal lines which
> save and restore their state, then the receiving end could check what
> is the current level. However, if you consider that the devices may be
> restored in random order, if the IRQ line device happens to be
> restored later, the receiver would still get wrong information. Adding
> priorities could solve this, but I think stateless IRQs are the only
> sane way.

I agree that irqs should be stateless, since they don't have any memory 
associated.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

  parent reply	other threads:[~2011-09-01  5:58 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-27 14:16 [Qemu-devel] [PATCH] pc: Clean up PIC-to-APIC IRQ path Jan Kiszka
2011-08-28  7:10 ` Blue Swirl
2011-08-28  9:08   ` Jan Kiszka
2011-08-29 19:25 ` Anthony Liguori
2011-08-29 21:06   ` Jan Kiszka
2011-08-29 21:13     ` Avi Kivity
2011-08-29 21:18       ` Jan Kiszka
2011-08-30 19:19       ` Blue Swirl
2011-08-30 19:28         ` Jan Kiszka
2011-08-30 19:43           ` Blue Swirl
2011-08-31  8:25           ` Peter Maydell
2011-08-31 10:53             ` Jan Kiszka
2011-08-31 17:41               ` Blue Swirl
2011-08-31 18:17                 ` Jan Kiszka
2011-08-31 19:44                   ` Blue Swirl
2011-09-04 10:33                     ` Blue Swirl
2011-09-04 12:25                     ` Gleb Natapov
2011-09-03 19:54               ` Anthony Liguori
2011-09-04 12:13                 ` Jan Kiszka
2011-09-04 13:32                   ` Anthony Liguori
2011-09-04 13:36                     ` Jan Kiszka
2011-09-04 13:41                       ` Anthony Liguori
2011-09-04 13:49                         ` Jan Kiszka
2011-09-04 13:57                           ` Anthony Liguori
2011-09-04 14:37                             ` Anthony Liguori
2011-09-04 15:20                               ` Blue Swirl
2011-09-04 15:31                                 ` Anthony Liguori
2011-09-04 15:44                                   ` Blue Swirl
2011-09-05 10:44                             ` Edgar E. Iglesias
2011-09-04 14:12                         ` Avi Kivity
2011-09-04 14:43                           ` Anthony Liguori
2011-09-04 15:03                             ` Avi Kivity
2011-09-04 15:19                               ` Anthony Liguori
2011-09-04 15:34                                 ` Avi Kivity
2011-09-04 15:27                             ` Blue Swirl
2011-09-04 12:17               ` Avi Kivity
2011-09-04 12:37                 ` Jan Kiszka
2011-09-04 12:43                   ` Avi Kivity
2011-09-04 13:38                   ` Anthony Liguori
2011-09-04 13:42                     ` Jan Kiszka
2011-09-04 13:55                       ` Anthony Liguori
2011-09-04 13:35                 ` Anthony Liguori
2011-08-31  8:28         ` Avi Kivity
2011-08-31 16:59           ` Blue Swirl
2011-08-31 18:04             ` Edgar E. Iglesias
2011-08-31 18:28               ` Jan Kiszka
2011-09-01  5:58             ` Avi Kivity [this message]
2011-09-03 20:07               ` Anthony Liguori
2011-09-03 21:10                 ` Blue Swirl
2011-09-03 21:41                   ` Anthony Liguori
2011-09-04  9:27                     ` Blue Swirl
2011-09-03 19:53             ` Anthony Liguori
2011-09-03 21:01               ` Blue Swirl
2011-09-04 14:49                 ` Anthony Liguori
2011-09-05  8:38               ` Edgar E. Iglesias
2011-09-05  8:51                 ` Avi Kivity
2011-09-05  9:02                   ` Peter Maydell
2011-09-05  9:14                     ` Avi Kivity
2011-09-05  9:22                   ` Edgar E. Iglesias
2011-09-05  9:28                     ` Avi Kivity
2011-09-05 10:47                       ` Edgar E. Iglesias
2011-09-05 19:36                 ` Blue Swirl
2011-09-06  7:46                   ` Avi Kivity
2011-09-01  9:08 ` [Qemu-devel] [PATCH v2] pc: Fix and clean " Jan Kiszka
2011-09-03  8:58   ` Blue Swirl
2011-09-03 11:17     ` Jan Kiszka
2011-09-03 11:37       ` Blue Swirl
2011-09-03 18:14         ` Jan Kiszka

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