Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change

[Pan Xinhui]

在 2017/2/17 14:05, Michael Ellerman 写道:
> Pan Xinhui <xinhui@xxxxxxxxxxxxxxxxxx> writes:
> > diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> > index 9c0e17c..f6e5c3d 100644
> > --- a/arch/powerpc/xmon/xmon.c
> > +++ b/arch/powerpc/xmon/xmon.c
> > @@ -76,6 +76,7 @@ static int xmon_gate;
> >   #endif /* CONFIG_SMP */
> >
> >   static unsigned long in_xmon __read_mostly = 0;
> > +static int xmon_off = !IS_ENABLED(CONFIG_XMON_DEFAULT);
>
> I think the logic would probably clearer if we invert this to become
> xmon_on.
yep, make sense.

> > @@ -3266,16 +3269,16 @@ static int __init setup_xmon_sysrq(void)
> >   __initcall(setup_xmon_sysrq);
> >   #endif /* CONFIG_MAGIC_SYSRQ */
> >
> > -static int __initdata xmon_early, xmon_off;
> > +static int __initdata xmon_early;
> >
> >   static int __init early_parse_xmon(char *p)
> >   {
> >   	if (!p || strncmp(p, "early", 5) == 0) {
> >   		/* just "xmon" is equivalent to "xmon=early" */
> > -		xmon_init(1);
> >   		xmon_early = 1;
> > +		xmon_off = 0;
> >   	} else if (strncmp(p, "on", 2) == 0)
> > -		xmon_init(1);
> > +		xmon_off = 0;
>
> You've just changed the timing of when xmon gets enabled for the above
> two cases, from here which is called very early, to xmon_setup() which
> is called much later in boot.
>
> That effectively disables xmon for most of the boot, which we do not
> want to do.
Although it is not often that kernel got stucked during boot. Yes, the behavior changed anyway. Will fix that in v3.

> cheers