Messages in this thread | | | Date | Wed, 9 Dec 2009 10:11:20 -0800 | Subject | Re: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64 | From | Tony Luck <> |
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On Wed, Dec 9, 2009 at 12:52 AM, Luming Yu <luming.yu@gmail.com> wrote: > Commenting out the change make -32 Lockdep kernel boot. > > Tony, please let me know whether you can reproduce..
Yes. Commenting this out makes the system bootable for me.
> kernel/lockdep.c > static int save_trace(struct stack_trace *trace) > { > trace->nr_entries = 0; > trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; > trace->entries = stack_trace + nr_stack_trace_entries; > > trace->skip = 3; > > save_stack_trace(trace); > #if 0 > > /* > * Some daft arches put -1 at the end to indicate its a full trace. > * > * <rant> this is buggy anyway, since it takes a whole extra entry so a > * complete trace that maxes out the entries provided will be reported > * as incomplete, friggin useless </rant> > */ > if (trace->entries[trace->nr_entries-1] == ULONG_MAX) > trace->nr_entries--; > #endif
This happens because ia64 save_stack_trace() is currently an empty stub, so it doesn't set trace->nr_entries.
Options: 1) Add trace->nr_entries = 1; to ia64 stub. 2) Change the generic code to defend against an unexpected failure in save_stack_trace()
if (trace->nr_entries > 0 && trace->entries[trace->nr_entries-1] == ULONG_MAX) trace->nr_entries--; 3) Delete the code in the "daft"[1] architectures, and drop this hunk from the generic code.
-Tony
[1] arm, parisc, s390, sh, x86 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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