[Qemu-devel] migration from qemu2.1.2 to qemu2.0

[Qemu-devel] migration from qemu2.1.2 to qemu2.0

[William Dauchy]

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Hello,

I have been testing live migration from qemu2.1.2 to qemu2.2.0 under
kvm - with same config and same command line.

the process crashes with:

Unknown combination of migration flags: 0
qemu: warning: error while loading state section id 2

Don't know if it's supposed to be supported or not.

Thanks,
-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.0

[William Dauchy]

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(sorry bad subject, I meant qemu2.2)

-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> Hello,
> 
> I have been testing live migration from qemu2.1.2 to qemu2.2.0 under
> kvm - with same config and same command line.
> 
> the process crashes with:
> 
> Unknown combination of migration flags: 0
> qemu: warning: error while loading state section id 2
> 
> Don't know if it's supposed to be supported or not.

You don't tell us what that command line is!
If you're using -M pc or -M q35  that's expected; if you're not
it's probably a bug - please show us the command line.

Dave
> 
> Thanks,
> -- 
> William


--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[William Dauchy]

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Hi David,

Thank you for the quick answer.

On Dec09 18:55, Dr. David Alan Gilbert wrote:
> You don't tell us what that command line is!
> If you're using -M pc or -M q35  that's expected; if you're not
> it's probably a bug - please show us the command line.

sorry it's indeed with `-M pc`. So I misunderstood the usage of
supported machines option since I was looking for a way to upgrade the
version and avoiding being stuck on a specific release.
I now understand I am supposed to keep the same version between live
migration and wait for a complete stop/start to upgrade. Or if there is
a trick, please advice.

Thanks,
-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> Hi David,
> 
> Thank you for the quick answer.
> 
> On Dec09 18:55, Dr. David Alan Gilbert wrote:
> > You don't tell us what that command line is!
> > If you're using -M pc or -M q35  that's expected; if you're not
> > it's probably a bug - please show us the command line.
> 
> sorry it's indeed with `-M pc`. So I misunderstood the usage of
> supported machines option since I was looking for a way to upgrade the
> version and avoiding being stuck on a specific release.
> I now understand I am supposed to keep the same version between live
> migration and wait for a complete stop/start to upgrade. Or if there is
> a trick, please advice.

Yes, you've got to keep the same machine type to do a live migration;
think of it like keeping the same motherboard/cpu combination in a real
machine - we can't squash the state from one shape machine into
a different shape machine without the guest getting very confused.

Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[William Dauchy]

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On Dec10 08:58, Dr. David Alan Gilbert wrote:
> Yes, you've got to keep the same machine type to do a live migration;
> think of it like keeping the same motherboard/cpu combination in a real
> machine - we can't squash the state from one shape machine into
> a different shape machine without the guest getting very confused.

I now have done some other tests:

with source -M pc-i440fx-2.1
and target -M pc-i440fx-2.1

still getting:

Unknown combination of migration flags: 0
warning: error while loading state section id 2

-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> On Dec10 08:58, Dr. David Alan Gilbert wrote:
> > Yes, you've got to keep the same machine type to do a live migration;
> > think of it like keeping the same motherboard/cpu combination in a real
> > machine - we can't squash the state from one shape machine into
> > a different shape machine without the guest getting very confused.
> 
> I now have done some other tests:
> 
> with source -M pc-i440fx-2.1
> and target -M pc-i440fx-2.1
> 
> still getting:
> 
> Unknown combination of migration flags: 0
> warning: error while loading state section id 2

As previously requested, please show your full command line.

Dave

--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[William Dauchy]

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On Dec10 17:10, Dr. David Alan Gilbert wrote:
> As previously requested, please show your full command line.

qemu-system-x86_64 -m 2048 -cpu host -nodefconfig -nodefaults -nographic -readconfig /var/lib/qemu/X/config -pidfile /var/lib/qemu/X/pid -M pc-i440fx-2.1 -serial pty -d unimp,guest_errors -daemonize

config file:

[name]
  guest = "X"
  process = "X"

[chardev "compat_monitor0"]
  backend = "socket"
  path = "/var/lib/qemu/X/sock"
  server = "on"
  wait = "off"

[device]
  driver = "virtio-balloon"

[rtc]
  base = "utc"

[mon "compat_monitor0"]
  mode = "control"
  chardev = "compat_monitor0"
  default = "on"

[device]
  driver = "virtio-rng-pci"

[device "scsi0"]
  driver = "virtio-scsi-pci"
  hotplug = "on"

[machine]
  kernel = "/boot-vm/bzImage-3.12-x86_64"
  append = "root=/dev/sda console=ttyS0 ro"
  accel = "kvm"

[netdev "vif15196.1"]
  type = "tap"
  br = "p43"
  vhost = "on"
  vhostforce = "on"
  ifname = "vif15196.1"
  downscript = "no"
  script = "no"
  queues = "1"

[device "vif15196.1"]
  driver = "virtio-net-pci"
  netdev = "vif15196.1"
  mac = "00:16:3e:2e:ea:7c"
  mq = "on"
  vectors = "3"

[drive "disk0"]
  if = "none"
  id = "disk0"
  cache = "none"
  aio = "native"
  format = "raw"
  file = "/dev/sda"

[device "disk0"]
  driver = "scsi-hd"
  drive = "disk0"
  scsi-id = "0"
  removable = "on"
  dpofua = "off"

[drive "swap0"]
  if = "none"
  id = "swap0"
  cache = "none"
  aio = "native"
  format = "raw"
  file = "/dev/sdb"

[device "swap0"]
  driver = "scsi-hd"
  drive = "swap0"
  scsi-id = "1"
  removable = "on"
  dpofua = "off"

[smp-opts]
  cpus = "1"
  sockets = "1"
  cores = "1"
  threads = "1"
  maxcpus = "16"

-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[William Dauchy]

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+ maybe the last patch from Paulo "kvm/apic: fix 2.2->2.1 migration" is
related?
-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> On Dec10 17:10, Dr. David Alan Gilbert wrote:
> > As previously requested, please show your full command line.
> 
> qemu-system-x86_64 -m 2048 -cpu host -nodefconfig -nodefaults -nographic -readconfig /var/lib/qemu/X/config -pidfile /var/lib/qemu/X/pid -M pc-i440fx-2.1 -serial pty -d unimp,guest_errors -daemonize

OK, and just checking, 2.2->2.2 and 2.1->2.1 works for you?
It's just 2.1->2.2 that's breaking?

> config file:
> 
> [name]
>   guest = "X"
>   process = "X"
> 
> [chardev "compat_monitor0"]
>   backend = "socket"
>   path = "/var/lib/qemu/X/sock"
>   server = "on"
>   wait = "off"
> 
> [device]
>   driver = "virtio-balloon"
> 
> [rtc]
>   base = "utc"
> 
> [mon "compat_monitor0"]
>   mode = "control"
>   chardev = "compat_monitor0"
>   default = "on"
> 
> [device]
>   driver = "virtio-rng-pci"
> 
> [device "scsi0"]
>   driver = "virtio-scsi-pci"
>   hotplug = "on"
> 
> [machine]
>   kernel = "/boot-vm/bzImage-3.12-x86_64"
>   append = "root=/dev/sda console=ttyS0 ro"
>   accel = "kvm"

Hmm, I've never tried using the kernel stuff with migration, but I believe it's
supposed to work; I always just pass a normal device.

> [netdev "vif15196.1"]
>   type = "tap"
>   br = "p43"
>   vhost = "on"
>   vhostforce = "on"
>   ifname = "vif15196.1"
>   downscript = "no"
>   script = "no"
>   queues = "1"
> 
> [device "vif15196.1"]
>   driver = "virtio-net-pci"
>   netdev = "vif15196.1"
>   mac = "00:16:3e:2e:ea:7c"
>   mq = "on"
>   vectors = "3"
> 
> [drive "disk0"]
>   if = "none"
>   id = "disk0"
>   cache = "none"
>   aio = "native"
>   format = "raw"
>   file = "/dev/sda"
> 
> [device "disk0"]
>   driver = "scsi-hd"
>   drive = "disk0"
>   scsi-id = "0"
>   removable = "on"
>   dpofua = "off"
> 
> [drive "swap0"]
>   if = "none"
>   id = "swap0"
>   cache = "none"
>   aio = "native"
>   format = "raw"
>   file = "/dev/sdb"
> 
> [device "swap0"]
>   driver = "scsi-hd"
>   drive = "swap0"
>   scsi-id = "1"
>   removable = "on"
>   dpofua = "off"
> 
> [smp-opts]
>   cpus = "1"
>   sockets = "1"
>   cores = "1"
>   threads = "1"
>   maxcpus = "16"
> 
> -- 
> William


--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> + maybe the last patch from Paulo "kvm/apic: fix 2.2->2.1 migration" is
> related?

It's worth a go - but I did want to check which direction you were
having the problem with.

Dave
> -- 
> William


--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Paolo Bonzini]

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On 10/12/2014 18:28, William Dauchy wrote:
> + maybe the last patch from Paulo "kvm/apic: fix 2.2->2.1 migration" is
> related?

No, it's only for 2.2->2.1.

The error it fixes was reported by Igor Mammedov:

source:
 qemu-system-x86_64-2.2 -enable-kvm -smp 2 -m 512  -monitor stdio   -M pc-i440fx-2.1
 (qemu) stop
 (qemu) migrate "exec:gzip -c > STATEFILE.gz"

target:
 qemu-system-x86_64-2.1 -enable-kvm -smp 2 -m 512 -monitor stdio -M pc-i440fx-2.1 -incoming "exec: gzip -c -d STATEFILE.gz"
 qemu: warning: error while loading state for instance 0x1 of device 'apic'
 qemu-system-x86_64-2.1: load of migration failed: No such file or directory

Paolo
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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[William Dauchy]

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On Dec10 17:31, Dr. David Alan Gilbert wrote:
> OK, and just checking, 2.2->2.2 and 2.1->2.1 works for you?
> It's just 2.1->2.2 that's breaking?

yes
-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> On Dec10 17:31, Dr. David Alan Gilbert wrote:
> > OK, and just checking, 2.2->2.2 and 2.1->2.1 works for you?
> > It's just 2.1->2.2 that's breaking?
> 
> yes

OK - that shouldn't happen.

Can you try stripping your config down to the bare minimum and see if
it goes away?   e.g. balloon, rng-pci, network I guess you can probably
test without easily enough.  If you can also try with a normal boot off
disk rather than kernel that would be good.

Hopefully one of those will turn out to be the culprit.

Thanks,

Dave

> -- 
> William


--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[William Dauchy]

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On Dec10 18:21, Dr. David Alan Gilbert wrote:
> Can you try stripping your config down to the bare minimum and see if
> it goes away?   e.g. balloon, rng-pci, network I guess you can probably
> test without easily enough.  If you can also try with a normal boot off
> disk rather than kernel that would be good.

harder to reproduce now (I have less and less VM running on 2.1 and cant
reproduce on my dev platform wiath fresh VM on 2.1->2.2 scenario)
anyway I was wondering if the option `-cpu host` could be the cause of
the issues since the HW is not always the same accross the
infrastructure.

Thanks,
-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> On Dec10 18:21, Dr. David Alan Gilbert wrote:
> > Can you try stripping your config down to the bare minimum and see if
> > it goes away?   e.g. balloon, rng-pci, network I guess you can probably
> > test without easily enough.  If you can also try with a normal boot off
> > disk rather than kernel that would be good.
> 
> harder to reproduce now (I have less and less VM running on 2.1 and cant
> reproduce on my dev platform wiath fresh VM on 2.1->2.2 scenario)
> anyway I was wondering if the option `-cpu host` could be the cause of
> the issues since the HW is not always the same accross the
> infrastructure.

Oh yes, -cpu host on two different hosts would definitely do that.
Hmm, it might even do it on the same hardware between different qemus;
certainly it's a bad idea to use -cpu host  if you want to bounce
around a mixed bag of systems.

Dave

--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Paolo Bonzini]

On 11/12/2014 14:44, William Dauchy wrote:
> harder to reproduce now (I have less and less VM running on 2.1 and
> cant reproduce on my dev platform wiath fresh VM on 2.1->2.2
> scenario) anyway I was wondering if the option `-cpu host` could be
> the cause of the issues since the HW is not always the same accross
> the infrastructure.

Yes, that's possible.

Paolo

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[William Dauchy]

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On Dec11 14:05, Dr. David Alan Gilbert wrote:
> Hmm, it might even do it on the same hardware between different qemus;

I dont get your last statement;
my common use case is to live migrate an old userland to a new one
(so 2.1 to 2.2 here); so if I guarantee same HW, it should work, right?
-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> On Dec11 14:05, Dr. David Alan Gilbert wrote:
> > Hmm, it might even do it on the same hardware between different qemus;
> 
> I dont get your last statement;
> my common use case is to live migrate an old userland to a new one
> (so 2.1 to 2.2 here); so if I guarantee same HW, it should work, right?

I wouldn't trust -host cpu  to be the same on the same HW between
different QEMUs, especially on newer hardware than your older QEMU new
about.

Dave


--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[William Dauchy]

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On Dec11 14:34, Dr. David Alan Gilbert wrote:
> > I dont get your last statement;
> > my common use case is to live migrate an old userland to a new one
> > (so 2.1 to 2.2 here); so if I guarantee same HW, it should work, right?
> 
> I wouldn't trust -host cpu  to be the same on the same HW between
> different QEMUs, especially on newer hardware than your older QEMU new
> about.

understood.
What are your recommendations then? Using kvm64 proc?

Thanks for your feedback,
-- 
William

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Re: [Qemu-devel] migration from qemu2.1.2 to qemu2.2

[Dr. David Alan Gilbert]

* William Dauchy (william@gandi.net) wrote:
> On Dec11 14:34, Dr. David Alan Gilbert wrote:
> > > I dont get your last statement;
> > > my common use case is to live migrate an old userland to a new one
> > > (so 2.1 to 2.2 here); so if I guarantee same HW, it should work, right?
> > 
> > I wouldn't trust -host cpu  to be the same on the same HW between
> > different QEMUs, especially on newer hardware than your older QEMU new
> > about.
> 
> understood.
> What are your recommendations then? Using kvm64 proc?

I'd recommend doing -cpu help on your oldest qemu  and pick the CPU that's
as new as possible but not newer than your oldest hardware.

Dave

> 
> Thanks for your feedback,
> -- 
> William


--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK