From: Kevin Wolf <kwolf@redhat.com>
To: Pavel Dovgalyuk <dovgaluk@ispras.ru>
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: [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices
Date: Fri, 18 Oct 2019 16:16:37 +0200 [thread overview]
Message-ID: <20191018141637.GG6122@localhost.localdomain> (raw)
In-Reply-To: <003901d585ac$6a9b9d30$3fd2d790$@ru>
Am 18.10.2019 um 14:06 hat Pavel Dovgalyuk geschrieben:
> > From: Kevin Wolf [mailto:kwolf@redhat.com]
> > Am 11.10.2019 um 08:10 hat Pavel Dovgalyuk geschrieben:
> > > > From: Kevin Wolf [mailto:kwolf@redhat.com]
> > > > Am 25.09.2019 um 11:02 hat Pavel Dovgalyuk geschrieben:
> > > > > I started playing with -blockdev: added new blockdev for blkreplay and
> > > > > constructed the following command line:
> > > > >
> > > > > -blockdev driver=file,filename=disk.img,node-name=hd0
> > > > > -blockdev driver=blkreplay,file=hd0,node-name=hd0-rr
> > > > > -device virtio-blk-device,drive=hd0-rr
> > > > >
> > > > > However, I get an error: "Could not open 'disk.img': Permission denied"
> > > > > Everything works when I use this file in '-drive' parameter.
> > > > > What am I doing wrong?
> > > >
> > > > The reason why I didn't reply immediately is because I don't see
> > > > anything wrong in the options you used.
> > > >
> > > > Just to confirm, do you still get the same error when you use only the
> > > > first -blockdev option and no other options at all?
> > >
> > > Ok, I tried again and got different error, which was caused by incorrect
> > > QAPI schema for blkreplay.
> > > Now it seems ok, but I still can't boot.
> >
> > Hm... Are you actually using a raw image? If not, you need the format
> > driver, too, and would end up with something like:
> >
> > -blockdev driver=file,filename=disk.qcow2,node-name=hd0
> > -blockdev driver=qcow2,file=hd0,node-name=hd0-qcow2
> > -blockdev driver=blkreplay,file=hd0-qcow2,node-name=hd0-rr
> > -device virtio-blk-device,drive=hd0-rr
> >
> > (The first two can be combined into a single option by using a syntax
> > like file.driver=file,file.filename=disk.qcow2, but defining each node
> > separately is a bit cleaner.)
>
> Ok, this works.
> Now I'm trying to check root of the nodes in blk_insert_bs.
> This command line leads to 2 invocations of this function:
> 1. bs->drv is file
> 2. bs->drv is blkreplay
>
> How then can we check "snapshot" node attachment?
Ah, I see what's going on there... :-/
bdrv_open_inherit() creates an internal temporary BlockBackend for image
format probing. And it creates that BlockBackend even when we don't need
to do image probing because we already explicitly selected a driver. It
would be better if it didn't do that.
Kevin
next prev parent reply other threads:[~2019-10-18 14:18 UTC|newest]
Thread overview: 35+ 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
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 [this message]
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
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=20191018141637.GG6122@localhost.localdomain \
--to=kwolf@redhat.com \
--cc=alex.bennee@linaro.org \
--cc=armbru@redhat.com \
--cc=artem.k.pisarenko@gmail.com \
--cc=boost.lists@gmail.com \
--cc=ciro.santilli@gmail.com \
--cc=crosthwaite.peter@gmail.com \
--cc=dgilbert@redhat.com \
--cc=dovgaluk@ispras.ru \
--cc=jasowang@redhat.com \
--cc=kraxel@redhat.com \
--cc=maria.klimushenkova@ispras.ru \
--cc=mreitz@redhat.com \
--cc=mst@redhat.com \
--cc=pavel.dovgaluk@ispras.ru \
--cc=pbonzini@redhat.com \
--cc=peter.maydell@linaro.org \
--cc=qemu-devel@nongnu.org \
--cc=quintela@redhat.com \
--cc=rth@twiddle.net \
--cc=thomas.dullien@googlemail.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).