Messages in this thread | | | Subject | Re: Fwd: Commit 76a2a6ee8a0660a29127f05989ac59ae1ce865fa breaks PXA270 (at least)? | From | Peter Zijlstra <> | Date | Wed, 30 Jul 2008 09:55:54 +0200 |
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On Wed, 2008-07-30 at 09:10 +0200, Peter Zijlstra wrote: > On Tue, 2008-07-29 at 23:56 +0100, Russell King - ARM Linux wrote: > > On Tue, Jul 29, 2008 at 03:46:05PM -0700, Andrew Morton wrote: > > > On Tue, 29 Jul 2008 23:31:05 +0100 > > > Russell King - ARM Linux <linux@arm.linux.org.uk> wrote: > > > > > > > But then some bright spark thought it would be a good idea to get > > > > rid of printk_clock(). > > > > > > <does git-log, searches for printk_clock> > > > > > > commit 86faf39d0fc04272b05fab1db6d683f3ac7199d1 > > > Author: Ingo Molnar <mingo@elte.hu> > > > Date: Fri Jan 25 21:07:59 2008 +0100 > > > > > > sched: remove printk_clock references from ia64 > > > > > > remove remaining printk_clock references from ia64. > > > > > > Signed-off-by: Ingo Molnar <mingo@elte.hu> > > > > > > commit b842271fbb9c8b5fd0e1c3e1895a3b67ba5bcc54 > > > Author: Ingo Molnar <mingo@elte.hu> > > > Date: Fri Jan 25 21:07:59 2008 +0100 > > > > > > sched: remove printk_clock() > > > > > > printk_clock() is obsolete - it has been replaced with cpu_clock(). > > > > > > Signed-off-by: Ingo Molnar <mingo@elte.hu> > > > > > > > > > That's it? It rates a 0.5/10 for changelogging :( > > > > > > Looking further on... > > > > > > commit e97126cd9056b3b42cdc862ace2ed66f8026f55b > > > Author: Russell King <rmk@dyn-67.arm.linux.org.uk> > > > Date: Mon Jan 8 19:49:12 2007 +0000 > > > > > > [ARM] Provide basic printk_clock() implementation > > > > > > Current sched_clock() implementations on ARM cause unbootable kernels > > > with PRINTK_TIME support enabled. To avoid this, provide a basic > > > printk_clock() implementation which avoids sched_clock() being called > > > before the page tables have been set up. > > > > > > > > > which I assume is why arm is crashing again? > > > > Precisely - Ingo has effectively progressively backed out my bug fix > > in a round-about manner by making printk require a working sched_clock > > again. > > > > > Really, I think arch-overrideable printk_clock() was a good idea. > > > printk is just _special_. It's called wildly early and it is called in > > > all conceivable contexts and it just must work no matter what. It's > > > totally understandable that an architecture would need to override > > > printk's timestamp generator. > > > > That's one solution, the other is to have that commit reverted. I > > don't really mind which, only that we have a solution ASAP so that > > the current popular ARM SoCs have a bootable kernel again. > > Can't you make sched_clock() return 0 when its called before its up and > running? Otherwise -
> perhaps you can play with the location of > sched_clock_init(). cpu_clock() will return 0 before that.
Sorry - that's only relevant for HAVE_UNSTABLE_SCHED_CLOCK and x86 seems to be the only one using that (which just shows the platforms quality </sarcasm>).
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