[libvirt] [PATCH] virsh: Document change-media --live --config confusion

If 'virsh change-media --live --config ...' is requested, the inactive XML is used as the template for the media change/eject. If the runtime XML has diverged from the inactive XML, say via other update operations, those changes may be undone since the command will sync all non-path XML with the inactive config. To 'fix' this would involve two passes of XML editing and calls to UpdateDevice, which is kind of a pain for a case that won't affect most users. So let's just document it instead https://bugzilla.redhat.com/show_bug.cgi?id=1243342 --- tools/virsh.pod | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/virsh.pod b/tools/virsh.pod index 90ab47d..4c1b7fc 100644 --- a/tools/virsh.pod +++ b/tools/virsh.pod @@ -2794,6 +2794,9 @@ the hypervisor's implementation. Both I<--live> and I<--config> flags may be given, but I<--current> is exclusive. If no flag is specified, behavior is different depending on hypervisor. +If both I<--live> and I<--config> are specified, the inactive device XML +is used as the template for the media change. If your I<--live> device XML +has received runtime changes, they may be removed. If I<--print-xml> is specified, the XML that would be used to change media is printed instead of changing the media. -- 2.7.4

On 04/26/2016 08:49 AM, Cole Robinson wrote:
If 'virsh change-media --live --config ...' is requested, the inactive XML is used as the template for the media change/eject. If the runtime XML has diverged from the inactive XML, say via other update operations, those changes may be undone since the command will sync all non-path XML with the inactive config.
To 'fix' this would involve two passes of XML editing and calls to UpdateDevice, which is kind of a pain for a case that won't affect most users. So let's just document it instead
https://bugzilla.redhat.com/show_bug.cgi?id=1243342 --- tools/virsh.pod | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/tools/virsh.pod b/tools/virsh.pod index 90ab47d..4c1b7fc 100644 --- a/tools/virsh.pod +++ b/tools/virsh.pod @@ -2794,6 +2794,9 @@ the hypervisor's implementation. Both I<--live> and I<--config> flags may be given, but I<--current> is exclusive. If no flag is specified, behavior is different depending on hypervisor. +If both I<--live> and I<--config> are specified, the inactive device XML +is used as the template for the media change. If your I<--live> device XML +has received runtime changes, they may be removed. If I<--print-xml> is specified, the XML that would be used to change media is printed instead of changing the media.
Actually I'm dropping this. I see that Nitesh has patches to properly fix just this type of issue for detach-interface, so it's better to extend that pattern to change-media and detach-disk too - Cole
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Cole Robinson