Re: Periodic clock synchronization in vmt(4)

[Iain Hibbert <plunky%ogmig.net@localhost>]

On Fri, 15 Mar 2013, Julio Merino wrote:

> On Fri, Mar 15, 2013 at 5:32 AM, Iain Hibbert <plunky%ogmig.net@localhost> 
> wrote:
> > On Thu, 14 Mar 2013, Julio Merino wrote:
> >
> >> Could anyone please review the attached patch?  It appears to work as
> >> intended, but the sysctl API is really confusing and I don't know if
> >> I got all details right.
> >
> > seems ok but as you make the machdep.vmt.clock_sync.period node, what
> > happens if more than one vmt device attaches?  I don't know if that can
> > happen of course..  for ubt(4) I made a node for each instance of the
> > driver, using device_xname()
>
> I don't think more than one vmt can attach.  It wouldn't make sense
> because this driver handles global "resources" like the clock and
> power events.

It is not crystal clear to me what it does, since I am not familiar with
VMWare Tools.. it seems to be a conduit between the host and a guest, but
the manpage refers to "the guest" so is it only possible to run a single
guest? If so, is it unreasonable that this restriction might be removed in
the future?

> But what would be the right to do?  Use device_xname()?  It feels like
> so, but then it doesn't make much sense as mentioned above.

Well, you could ignore errors which might occur if the vmt node already
existed..

I think using the xname is better though, since the sysctl will appear on
the host, where all the console messages will be prefixed with that. And,
this removes all question of what to do if more than one guest can be run

iain