Re: [Xen-devel] [OSSTEST PATCH 2/2] libvirt: Do not attempt save/restore when migration not advertised

[Jim Fehlig <jfehlig@xxxxxxxx>]

On 10/04/2016 11:02 AM, Ian Jackson wrote:
> Currently, osstest wrongly thinks that ARM can do save/restore,
> because `virsh help' does mention the save command (on all
> architectures).
>
> Additionally, check the virth capabilities xpath
>    /capabilities/host/migration_features
> to try to see whether this host supports migration.
>
> I am not sure if this is the right path to check.  Perhaps
>    /capabilities/host/migration_features/live
> is more correct, but this may be wrong if Xen comes to support save/restore
> on ARM, but not live migration (but perhaps libvirt cannot express this
> distinction in which case perhaps it's right after all).
Looking at the capabilities generation code again, I see that 
virCapabilitiesNew() takes 'offlineMigrate' and 'liveMigrate' parameters. I 
assume offline in this context means save, copy, restore. Martin, is that 
assumption correct?
If so, I think the saverestore_check() below can look for
/capabilities/host/migration_features. The migration check in 1/2 can look for
/capabilities/host/migration_features/live. Is it fair to assume save/restore is 
available when live migration is supported?
Regards,
Jim

> Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> CC: Jim Fehlig <jfehlig@xxxxxxxx>
> ---
>  Osstest/Toolstack/libvirt.pm | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Osstest/Toolstack/libvirt.pm b/Osstest/Toolstack/libvirt.pm
> index b7db7af..250fe47 100644
> --- a/Osstest/Toolstack/libvirt.pm
> +++ b/Osstest/Toolstack/libvirt.pm
> @@ -111,7 +111,9 @@ sub check_for_command($$) {
>
>  sub saverestore_check ($) {
>      my ($self) = @_;
> -    return check_for_command($self, "save");
> +    return
> +       _check_capability($self, '/capabilities/host/migration_features') &&
> +       check_for_command($self, "save");
>  }
>
>  sub migrate ($$$$) {

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