On Thu, 2007-08-23 at 14:05 -0700, john stultz wrote:
> On Thu, 2007-08-23 at 13:41 -0700, Luck, Tony wrote:
> > > I have a double "hpet" entry in "available_clocksource":
> > > $ cat /sys/devices/system/clocksource/clocksource0/available_clocksource
> > > tsc hpet hpet acpi_pm jiffies
> >
> > Oops. If seems that both drivers/char/hpet.c and arch/x86_64/kernel/hpet.c
> > both register a clocksource named "hpet". Probably a result of bringing
> > back to life a long lost patch, and having someone else (John Stultz, according
> > to git blame) make a similar change to a different file in the intervening
> > time.
> >
> > Presumably the thing to do would be merge the x86_64 specific version
> > into the drivers/char/hpet.c version?
>
> Ugh. Yea. i386 has an hpet clocksource as well. We should kill the
> duplication, but at the moment I'm not comfortable that the
> driver/char/hpet.c is ok to be used for i386/x86_64 (Bob: Do you know
> why the shift value is only 10?).
>
>
> I'm a little surprised by this, as the clocksource code use to prevent
> duplicate named clocksources from being registered, so I'm not sure how
> that check got dropped. Also I'm not quite sure I see where the hard
> freeze is coming from.
>
> My initial reaction would be to either ifdef ia64 implementation in
> drivers/char/hpet.c or move the code under the ia64 arch dir until it is
> really usable by all arches.
Ok, since no one screamed too badly about this one, and it does fix this
issue, I'm sending it out for reals.
I think Bob's patch which addresses duplicate clocksources should go in,
but this one is a little more forceful in keeping the wrong hpet
clocksource from possibly being selected.
Andrew, would you mind picking this up?
thanks
-john
The ia64 hpet clocksource was implemented in generic code, and is not
yet ready to replace the i386 and x86_64 implementations. This results
in multiple hpet clocksources being registered, and if the ia64 one is
chosen on x86_64 some users have experienced hangs.
This patch only allows the generic implementation to be used on ia64,
until the duplicate i386 and x86_64 versions can be merged in and
tested.
Signed-off-by: John Stultz <[email protected]>
diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 77bf4aa..c782d8c 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -78,7 +78,17 @@ static struct clocksource clocksource_hpet = {
.shift = 10,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
+
+/* XXX - FIXME: i386, x86_64 and ia64 all have separate
+ * hpet clocksource implementations. They should be merged
+ * and this would be a good place for it.
+ * Right now this is ia64 only.
+ */
+#ifdef CONFIG_IA64
static struct clocksource *hpet_clocksource;
+#else /* this isn't generic enough to use for everyone yet */
+static struct clocksource *hpet_clocksource = (struct clocksource*)0xdead;
+#endif
/* A lock for concurrent access by app and isr hpet activity. */
static DEFINE_SPINLOCK(hpet_lock);
-
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