Hey Mark,
/usr/src/linux/init/Kconfig and kernel/Kconfig.preempt are the droids you
are looking for...
config PREEMPT_RCU
def_bool TREE_PREEMPT_RCU
help
This option enables preemptible-RCU code that is common between
the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
So you would want to /not/ pick one of those - however - looking further
choice
prompt "RCU Implementation"
default TREE_RCU
config TREE_RCU
bool "Tree-based hierarchical RCU"
depends on !PREEMPT && SMP
select IRQ_WORK
help
This option selects the RCU implementation that is
designed for very large SMP system with hundreds or
thousands of CPUs. It also scales down nicely to
smaller systems.
config TREE_PREEMPT_RCU
bool "Preemptible tree-based hierarchical RCU"
depends on PREEMPT
select IRQ_WORK
help
This option selects the RCU implementation that is
designed for very large SMP systems with hundreds or
thousands of CPUs, but for which real-time response
is also required. It also scales down nicely to
smaller systems.
Select this option if you are unsure.
config TINY_RCU
bool "UP-only small-memory-footprint RCU"
depends on !PREEMPT && !SMP
help
This option selects the RCU implementation that is
designed for UP systems from which real-time response
is not required. This option greatly reduces the
memory footprint of RCU.
endchoice
Seems you would want TREE_RCU (or TINY_RCU if you really have a UP system)
- but both of those depend on !PREEMPT... which is counter to what you were
asked.
In short - at least in 3.12.0 - I don't think what you've been asked for is
in fact possible - or I'm reading Kconfig wrongly (it's been a while)
Cheers,
malc.
On Fri, Nov 22, 2013 at 7:40 PM, Mark Knecht <markkne...@gmail.com> wrote:
> On Fri, Nov 22, 2013 at 11:21 AM, Volker Armin Hemmann
> <volkerar...@googlemail.com> wrote:
> <SNIP>
> >> which doesn't give me any option to change it in make menuconfig.
> > no, that means it is turned on by some other option.
> >
> > maybe you should use grep.
>
> Geez...
>
>
