Re: [Qemu-devel] [RFC 00/10]: QMP/HMP: Introduce tray handling commands

[Luiz Capitulino <lcapitulino@redhat.com>]

On Mon, 06 Jun 2011 15:31:35 +0200
Markus Armbruster <armbru@redhat.com> wrote:

> Luiz Capitulino <lcapitulino@redhat.com> writes:
> 
> > In a recent discussion on the mailing list regarding the introduction of
> > the BLOCK_TRAY_OPEN and BLOCK_TRAY_CLOSE events[1], it was mentioned that
> > we need to fix the eject command and maybe introduce new commands first.
> >
> > Here's a my proposal.
> >
> > This series introduces three new commands:
> >
> >  o blockdev-tray-open: opens the drive tray. Also Supports removing the inserted
> >    media. The BLOCK_TRAY_OPEN event is emitted if this command succeeds.
> 
> Conflates tray control with media control.  Hmm.
> 
> >  o blockdev-tray-close: closes a drive tray. The BLOCK_TRAY_CLOSE event is
> >    emitted.
> >  o blockdev-media-insert: Inserts a media in the tray. The tray must empty
> >    and already opened. No event is emitted.
> 
> What about separating tray control and media control like this:
> 
> * Tray control: either blockdev-tray-open and blockdev-tray-close, or a
>   single blockdev-tray with a boolean argument.

This might sound like a simple thing, but sometimes I'm really undecided when
something should be a new argument or a new command.

Following Anthony's idea that it can be helpful to think in a C interface,
I slightly prefer this:

 blockdev_tray_open(device);

 ...

 blockdev_tray_close(device);

Than this:

 blockdev_tray(device, TRAY_OPEN);

...

 blockdev_tray(device, TRAY_CLOSE);

> * Media control: blockdev-media to change media.  Tray must be open, may
>   or may not contain media.  Arguments specify new media, or no media.

Yeah, maybe it's better to drop the 'remove' flag from the open command.
But then I think I prefer having blockdev-media-remove and
blockdev-media-insert instead of a single blockdev-media command.