Messages in this thread | | | Subject | Re: "double" hpet clocksource && hard freeze [bisected] | From | john stultz <> | Date | Mon, 27 Aug 2007 14:39:55 -0700 |
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On Mon, 2007-08-27 at 17:34 -0300, Luiz Fernando N. Capitulino wrote: > Em Fri, 24 Aug 2007 11:17:34 -0700 > john stultz <johnstul@us.ibm.com> escreveu: > > | On Fri, 2007-08-24 at 08:46 -0400, Bob Picco wrote: > | > john stultz wrote: [Thu Aug 23 2007, 05:41:45PM EDT] > | > > 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. > | > > > | > > Here is a possible quick fix. I'm open to other approaches, but I also > | > > want to avoid too much churn before 2.6.23 goes out. > | > > > | > > Paolo, could you verify this fixes the issue for you? > | > > > | > > thanks > | > > -john > | > > > | > [snip] > | > > | > I saw what was missed by me in my brief examination of this last night. > | > The platform registers the hpet clocksource too. > | > > | > Instead of adding the config flag to hpet driver, how about the patch > | > below? Since you already check for duplication by address then adding > | > a check for by name too seems okay to me. > | > > | > bob > | > > | > > | > Prevent duplicate names being registered with clocksource. This also > | > eliminates the duplication of hpet clock registration when the arch > | > uses the hpet timer and the hpet driver does too. The patch was > | > compile and link tested. > | > | Yea. While I'm still not completely comfortable leaving this up to boot > | order alone (the ia64 hpet clocksource is clearly causing issues on > | x86_64), I think this patch is something we need as well. > > Does -stable need this too?
Looking at the git log, the ia64 clocksource code didn't land until 7/20, so I don't think so.
thanks -john
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