Re: [Xen-devel] [PATCH v2 13/18] libxl: make libxl_cd_insert "eject" + "insert"

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Aug 27, 2014 at 03:04:46AM +0100, Ian Campbell wrote:
> On Wed, 2014-07-30 at 19:23 +0100, Wei Liu wrote:
> > A "cdrom insert" is always processed as "eject" + "insert", with JSON
> > config updated in between. So that we can know the correct state of
> > CDROM later when we try to retrieve domain configuration: if xenstore is
> > "empty", then CDROM is "empty"; otherwise use the information presented
> > in JSON.
> 
> When you say "empty" do you mean literally that the xenstore nodes do
> not exist or that one of them contains the string "empty"? If, as I
> suspect, you mean the former then writing 
>         if xenstore nodes are not present then CDROM is "empty"
> would confuse me less.
> 

The xenstore node still exists, just that "params" doesn't point to
media. I can rephrase this:

  If xenstore entry doesn't point to media file then CDROM is "empty".

> > +    rc = libxl__cdrom_insert(ctx, domid, &empty, NULL);
> > +    if (rc)
> > +        goto out;
> > +
> > +    /* Optimisation: don't insert empty disk twice, and skip
> > +     * manipulating JSON. */
> 
> Do we not need to update the JSON in this case to reflect that it is now
> empty?
> 

We could but we don't have to -- xenstore is primary reference.

Wei.

> Ian/

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