Hi all!
As part of the VAMOS[0] research project at the University of
Erlangen we are looking at multiple integrity errors in linux'
configuration system.
I've been running a check on the mm/ sourcetree for
config Items not defined in Kconfig and found 1 such case. Sourcecode
blocks depending on these Items are not reachable from a vanilla
kernel -- dead code. I've seen such dead blocks made on purpose
e.g. while integrating new features into the kernel but generally
they're just useless.
We found, that CONFIG_NEED_PER_CPU_KM is a dead symbol, so it isn't defined
anywhere. Cause of that the percpu_km.c is never included anywhere. Is
this a intended dead symbol, for use in out of tree development, or is
this just an error?
Regards
Christian Dietrich
--
(λ x . x x) (λ x . x x) -- See how beatiful the lambda is
No documentation is better than bad documentation
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On 07/21/2010 11:22 AM, Christian Dietrich wrote:
> Hi all!
>
> As part of the VAMOS[0] research project at the University of
> Erlangen we are looking at multiple integrity errors in linux'
> configuration system.
>
> I've been running a check on the mm/ sourcetree for
> config Items not defined in Kconfig and found 1 such case. Sourcecode
> blocks depending on these Items are not reachable from a vanilla
> kernel -- dead code. I've seen such dead blocks made on purpose
> e.g. while integrating new features into the kernel but generally
> they're just useless.
>
> We found, that CONFIG_NEED_PER_CPU_KM is a dead symbol, so it isn't defined
> anywhere. Cause of that the percpu_km.c is never included anywhere. Is
> this a intended dead symbol, for use in out of tree development, or is
> this just an error?
Oh, it's new code waiting to be used. It's for cases where SMP is
used w/o MMU. IIRC, it was blackfin.
Thanks.
--
tejun
On Wed, Jul 21, 2010 at 11:12, Tejun Heo wrote:
> On 07/21/2010 11:22 AM, Christian Dietrich wrote:
>> We found, that CONFIG_NEED_PER_CPU_KM is a dead symbol, so it isn't defined
>> anywhere. Cause of that the percpu_km.c is never included anywhere. Is
>> this a intended dead symbol, for use in out of tree development, or is
>> this just an error?
>
> Oh, it's new code waiting to be used. It's for cases where SMP is
> used w/o MMU. IIRC, it was blackfin.
yep. unfortunately, we're in the middle of making a release on top of
2.6.34.x. hopefully we should be able to get a patch out for the
2.6.37 merge window at the latest.
-mike