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From: "Pavel Dovgalyuk" <dovgaluk@ispras.ru>
To: "'Kevin Wolf'" <kwolf@redhat.com>
Cc: peter.maydell@linaro.org, pavel.dovgaluk@ispras.ru,
	quintela@redhat.com, ciro.santilli@gmail.com,
	jasowang@redhat.com, crosthwaite.peter@gmail.com,
	qemu-devel@nongnu.org, armbru@redhat.com, alex.bennee@linaro.org,
	maria.klimushenkova@ispras.ru, mst@redhat.com, kraxel@redhat.com,
	boost.lists@gmail.com, thomas.dullien@googlemail.com,
	pbonzini@redhat.com, mreitz@redhat.com,
	artem.k.pisarenko@gmail.com, dgilbert@redhat.com,
	rth@twiddle.net
Subject: Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices
Date: Thu, 19 Sep 2019 12:05:28 +0300	[thread overview]
Message-ID: <001901d56ec9$620ae260$2620a720$@ru> (raw)
In-Reply-To: <20190919085302.GA10163@localhost.localdomain>

> From: Kevin Wolf [mailto:kwolf@redhat.com]
> > >
> > > However, global -snapshot is just a convenient shortcut for specifying
> > > snapshot=on for all -drive arguments. So if -snapshot is incompatible
> > > with replay, shouldn't manually marking all drives as snapshot=on be
> > > incompatible as well?
> > >
> > > Maybe you're really interested in some specific drive not having
> > > snapshot=on? But then it might be better to check that specific drive
> > > instad of forbidding just the shortcut for setting it.
> >
> > -snapshot adds the flag for top-level drive, making driver operations
> > dependent on temporary file structure.
> >
> > Moving this overlay beneath blkreplay driver makes drive operations
> > deterministic for the top-level device.
> 
> So the real requirement is that blkreplay is the top-level node of any
> guest device, right? And only because of this, you can't use -snapshot
> (or snapshot=on on the blkreplay driver).
> 
> If we instead check e.g. in blk_insert_bs() or blk_attach_dev() that in
> record/replay mode, the root node of the BlockBackend is blkreplay,
> wouldn't we catch many more incorrect setups?

That sounds interesting.
Will it help to check that every backend is connected to blkreplay?
How then this check has to be done?

Pavel Dovgalyuk



  reply	other threads:[~2019-09-19  9:17 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-17 11:57 [Qemu-devel] [for-4.2 PATCH 0/6] Block-related record/replay fixes Pavel Dovgalyuk
2019-09-17 11:57 ` [Qemu-devel] [for-4.2 PATCH 1/6] block: implement bdrv_snapshot_goto for blkreplay Pavel Dovgalyuk
2019-09-17 11:57 ` [Qemu-devel] [for-4.2 PATCH 2/6] replay: disable default snapshot for record/replay Pavel Dovgalyuk
2019-09-17 11:58 ` [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices Pavel Dovgalyuk
2019-09-18  9:18   ` Kevin Wolf
2019-09-18  9:22     ` Pavel Dovgalyuk
2019-09-18  9:33       ` Kevin Wolf
2019-09-18  9:37         ` Pavel Dovgalyuk
2019-09-18  9:44           ` Kevin Wolf
2019-09-18  9:52             ` Pavel Dovgalyuk
2019-09-19  8:53               ` Kevin Wolf
2019-09-19  9:05                 ` Pavel Dovgalyuk [this message]
2019-09-19 11:27                   ` Kevin Wolf
2019-09-19 12:10                     ` Pavel Dovgalyuk
2019-09-19 13:00                       ` Kevin Wolf
2019-09-20  7:25                         ` Pavel Dovgalyuk
2019-09-20 10:01                           ` Kevin Wolf
2019-09-23  6:15                             ` Pavel Dovgalyuk
2019-09-25  9:02                             ` Pavel Dovgalyuk
2019-10-01  8:22                               ` Pavel Dovgalyuk
2019-10-10 15:28                               ` Kevin Wolf
2019-10-11  6:10                                 ` Pavel Dovgalyuk
2019-10-11  9:12                                   ` Kevin Wolf
2019-10-18 12:06                                     ` Pavel Dovgalyuk
2019-10-18 14:16                                       ` Kevin Wolf
2019-09-17 11:58 ` [Qemu-devel] [for-4.2 PATCH 4/6] replay: don't drain/flush bdrv queue while RR is working Pavel Dovgalyuk
2019-09-17 11:58 ` [Qemu-devel] [for-4.2 PATCH 5/6] replay: finish record/replay before closing the disks Pavel Dovgalyuk
2019-09-17 11:58 ` [Qemu-devel] [for-4.2 PATCH 6/6] replay: add BH oneshot event for block layer Pavel Dovgalyuk
2019-09-17 18:09 ` [Qemu-devel] [for-4.2 PATCH 0/6] Block-related record/replay fixes no-reply
2019-09-17 18:10 ` no-reply
2019-09-17 19:01 ` Alex Bennée
2019-09-18  8:26   ` Pavel Dovgalyuk
2019-09-18 10:42     ` Alex Bennée
2019-09-18 11:32       ` Pavel Dovgalyuk
2019-10-11  9:17 ` Kevin Wolf
  -- strict thread matches above, loose matches on Subject: below --
2019-07-29  6:29 [Qemu-devel] " Pavel Dovgalyuk
2019-07-29  6:29 ` [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices Pavel Dovgalyuk

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