Re: [Xen-devel] [PATCH v3] x86/NMI: Allow processing unknown NMIs when watchdog is enabled

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

On 08/28/2014 03:07 PM, Andrew Cooper wrote:
> >   Run an NMI watchdog on each processor.  If a processor is stuck for
> > -longer than the **watchdog\_timeout**, a panic occurs.
> > +longer than the **watchdog\_timeout**, a panic occurs.  When `force` is
> > +specified, in addition to running an NMI watchdog on each processor,
> > +unknown NMIs will still be processed.
> >
> >   ### watchdog\_timeout
> >   > `= <integer>`
> > diff --git a/xen/arch/x86/nmi.c b/xen/arch/x86/nmi.c
> > index c4427a6..873427f 100644
> > --- a/xen/arch/x86/nmi.c
> > +++ b/xen/arch/x86/nmi.c
> > @@ -43,7 +43,18 @@ static DEFINE_PER_CPU(unsigned int, nmi_timer_ticks);
> >
> >   /* opt_watchdog: If true, run a watchdog NMI on each processor. */
> >   bool_t __initdata opt_watchdog = 0;
> > -boolean_param("watchdog", opt_watchdog);
> > +
> > +/* watchdog_force: If true, process unknown NMIs when running the watchdog. */
> > +bool_t watchdog_force = 0;
> > +
> > +static void __init parse_watchdog(char * s)
> > +{
> > +    opt_watchdog = !!parse_bool(s);
> A lot of code in Xen gets the use of parse_bool() wrong.  In this case,
> opt_watchdog will be set if garbage is passed in the parameter, which is
> a change in behaviour from before.
This is not a change in behavior from before. A bool param if specified 
on the command-line is set to true unless explicitly set to a false-like 
value (e.g. this is how a bare parameter like "watchdog" enables the 
watchdog).
As it has been committed, the behavior has been changed and means 
setting "watchdog" on the command-line does not result in the watchdog 
being enabled.
--
Ross Lagerwall

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