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

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Aug 28, 2014 at 07:14:35PM +0100, Ian Campbell wrote:
> On Thu, 2014-08-28 at 12:25 +0100, Wei Liu wrote:
> > 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.
> 
> "doesn't point to" means doesn't exist or contains the empty string? I
> think it would be good to be explicit there.
> 

Hrm, it's not necessary NIL, it's what the backend thinks there's no
media inside. ISTR seeing "aio:" or just "". They both represent an
empty cdrom. That's why I only use the word "empty" to refer to its
state instead of being explict about the content in "params". This patch
itself won't care about the incarnation of that state anyway.

Wei.

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