Re: [PATCH 0/2] monitor openfd commands

[Eric Blake]

On 6/11/20 6:17 AM, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> The monitors currently have a 'getfd' command that lets you pass an fd
> via the monitor socket.  'openfd' is a new command that opens a file
> and puts the fd in the same fd pool.  The file is opened RW and created
> if it doesn't exist.
> It makes it easy to test migration to and from a file.

We have two fd-passing mechanisms: getfd and add-fd.  add-fd is newer, 
and allows things like /dev/fdset/NNN to work anywhere a filename works. 
 I'm guessing that the issue here is that migration hasn't been tweaked 
to work nicely with the newer add-fd, but instead insists on the older 
getfd interface (where you have to use getfd to associate an fd with a 
name, then tell migration to use that special name, but the special name 
is via a different parameter than the normal filename parameter).  At 
which point openfd looks like it is just sugar to make getfd easier to use.

Would it instead be worth modifying migration to work with add-fd?  Or 
does add-fd need the same sort of sugar?

> Dr. David Alan Gilbert (2):
>    qmp: Add 'openfd' command
>    hmp: Add 'openfd' command
>
>   hmp-commands.hx        | 16 +++++++++++++-
>   include/monitor/hmp.h  |  1 +
>   monitor/hmp-cmds.c     | 10 +++++++++
>   monitor/misc.c         | 48 +++++++++++++++++++++++++++++++++---------
>   qapi/misc.json         | 23 +++++++++++++++++++-
>   tests/qtest/test-hmp.c |  2 ++
>   6 files changed, 88 insertions(+), 12 deletions(-)

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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