From: Paolo Bonzini <pbonzini@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: "quintela@redhat.com" <quintela@redhat.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"Andreas Färber" <afaerber@suse.de>,
"Avi Kivity" <avi@redhat.com>,
"Matthew Ogilvie" <mmogilvi_qemu@miniinfo.net>
Subject: Re: [Qemu-devel] [PATCH v4 5/5] i8259: fix dynamically masking slave IRQs with IMR register
Date: Tue, 04 Sep 2012 12:06:32 +0200 [thread overview]
Message-ID: <5045D2A8.4020208@redhat.com> (raw)
In-Reply-To: <5045CF10.9000603@siemens.com>
Il 04/09/2012 11:51, Jan Kiszka ha scritto:
>> >
>> > I don't mean to say we shouldn't care about them, but there are likely
>> > to be a lot more users doing backwards migration than users running
>> > those guests, let alone migrating them (forwards or backwards). The
>> > pragmatic choice is clear.
> BTW, did anyone actually test backward migration recently? I thought to
> remember I effectively broke it in 1.1 with some changes to the i8259
> (or was it the PIT?) vmstate, and no one really cared about this or my
> first proposals to fix it.
Correct: commit ce967e2 (i8254: Rework & fix interaction with HPET in
legacy mode, 2012-02-01) bumped the PIT version from 2 to 3. RTC
changes will break it more in 1.3.
Honestly, backwards migration only works on "enterprise" qemu-kvm
because it is tested only there. And so far the only sample across
major releases is that RHEL6->RHEL5 migration didn't work.
Here the choice is between changing guest behavior by defaulting to 4/2,
and always transmitting the subsection by defaulting to 0/0. The latter
makes the subsection useless, so at that point we might as well bump the
version number and board said flight to the Pacific.
Paolo
next prev parent reply other threads:[~2012-09-04 10:06 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-03 2:56 [Qemu-devel] [PATCH v4 0/5] Running Microport UNIX (ca 1987) Matthew Ogilvie
2012-09-03 2:56 ` [Qemu-devel] [PATCH v4 1/5] fix some debug printf format strings Matthew Ogilvie
2012-09-03 2:56 ` [Qemu-devel] [PATCH v4 2/5] vl: fix -hdachs/-hda argument order parsing issues Matthew Ogilvie
2012-09-03 2:56 ` [Qemu-devel] [PATCH v4 3/5] qemu-options.hx: mention retrace= VGA option Matthew Ogilvie
2012-09-03 2:56 ` [Qemu-devel] [PATCH v4 4/5] vga: add some optional CGA compatibility hacks Matthew Ogilvie
2012-09-03 2:56 ` [Qemu-devel] [PATCH v4 5/5] i8259: fix dynamically masking slave IRQs with IMR register Matthew Ogilvie
2012-09-03 7:08 ` Paolo Bonzini
2012-09-03 8:40 ` Andreas Färber
2012-09-03 14:39 ` Avi Kivity
2012-09-03 15:42 ` Juan Quintela
2012-09-03 15:45 ` Jan Kiszka
2012-09-03 15:52 ` Avi Kivity
2012-09-03 15:54 ` Jan Kiszka
2012-09-03 15:57 ` Avi Kivity
2012-09-03 16:02 ` Jan Kiszka
2012-09-03 16:15 ` Avi Kivity
2012-09-03 16:23 ` Paolo Bonzini
2012-09-03 16:30 ` Avi Kivity
2012-09-03 16:33 ` Paolo Bonzini
2012-09-03 16:40 ` Jan Kiszka
2012-09-03 16:56 ` Paolo Bonzini
2012-09-04 8:16 ` Avi Kivity
2012-09-04 9:15 ` Paolo Bonzini
2012-09-04 9:20 ` Avi Kivity
2012-09-04 9:29 ` BALATON Zoltan
2012-09-04 9:37 ` Avi Kivity
2012-09-04 9:51 ` Jan Kiszka
2012-09-04 10:06 ` Paolo Bonzini [this message]
2012-09-04 10:44 ` Avi Kivity
2012-09-03 16:30 ` Jan Kiszka
2012-09-03 8:51 ` Jan Kiszka
2012-09-03 8:53 ` Jan Kiszka
2012-09-03 9:34 ` Paolo Bonzini
2012-09-03 10:34 ` Jan Kiszka
2012-09-03 11:11 ` Paolo Bonzini
2012-09-03 11:26 ` Jan Kiszka
2012-09-04 14:29 ` Maciej W. Rozycki
2012-09-04 14:42 ` Paolo Bonzini
2012-09-04 16:01 ` Jan Kiszka
2012-09-04 17:41 ` Maciej W. Rozycki
2012-09-04 17:55 ` Jan Kiszka
2012-09-04 18:27 ` Maciej W. Rozycki
2012-09-04 18:39 ` Jan Kiszka
2012-09-05 4:33 ` Matthew Ogilvie
2012-09-05 15:43 ` Jan Kiszka
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5045D2A8.4020208@redhat.com \
--to=pbonzini@redhat.com \
--cc=afaerber@suse.de \
--cc=avi@redhat.com \
--cc=jan.kiszka@siemens.com \
--cc=mmogilvi_qemu@miniinfo.net \
--cc=qemu-devel@nongnu.org \
--cc=quintela@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).