Re: [PATCH V2] migration: file URI

[Steven Sistare <steven.sistare@oracle.com>]

On 6/22/2023 6:12 AM, Daniel P. Berrangé wrote:
> On Wed, Jun 07, 2023 at 11:38:59AM -0700, Steve Sistare wrote:
>> Extend the migration URI to support file:<filename>.  This can be used for
>> any migration scenario that does not require a reverse path.  It can be used
>> as an alternative to 'exec:cat > file' in minimized containers that do not
>> contain /bin/sh, and it is easier to use than the fd:<fdname> URI.  It can
>> be used in HMP commands, and as a qemu command-line parameter.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> 
> In the cases where libvirt wants to save/restore QEMU migration state
> to a file, we also need to have libvirt header and XML document at the
> front of the file.
> 
> IOW, if libvirt is to be able to use this new 'file:' protocol, then
> it neeeds to have the ability to specify an offset too. eg so libvirt
> can tell QEMU to start reading/writing at, for example, 4MB offset
> from the start.
> 
> Should be fairly easy to add on top of this - just requires support
> for a URI parameter, and then a seek once the file is opened.

Will do, probably today - steve