Re: pmf(9) and Xen domU suspending?

[Iain Hibbert <plunky%rya-online.net@localhost>]

On Sun, 30 Mar 2008, Jared D. McNeill wrote:

> Iain Hibbert wrote:
> > Hi Jared; the manpage is not quite clear on some points, can you clarify?

> > - what is the significance of the bool return value for suspend/resume?
>
> To indicate that the device was successfully suspended or resumed.

and if a function fails (eg during suspend), what happens to the system?

thanks - more questions however :)

in ubt.c, I see usage of "device_pmf_is_registered(self)" to guard against
multiple instances of registering .. apart from I'm not sure this is
possible [via the _attach function], is this recommended?

is it an error to deregister more than once? ie, if a _detach function
fails something, it may be called multiple times..

is it an error to call pmf_deregister() when pmf_register() has not been
called, or possibly failed?

wrt these last two, would it be 'best practice' to pmf_register() at the
start of the _attach function, then pmf_deregister() at the end of the
_detach (and protect that with an _is_registered() check)?

iain