lkml.org 
[lkml]   [2008]   [Jul]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Fwd: Commit 76a2a6ee8a0660a29127f05989ac59ae1ce865fa breaks PXA270 (at least)?
From
Date
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 printk_clock() is obsolete - it has been replaced with cpu_clock().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.



\
 
 \ /
  Last update: 2008-07-30 09:13    [W:0.099 / U:0.968 seconds]
©2003-2014 Jasper Spaans. Advertise on this site