Messages in this thread | | | Date | Fri, 26 Apr 2013 16:02:16 +0200 | Subject | Re: Kconfig doesn't support select on choices (was Re: [GIT PULL] nohz: Adaptively stop the tick, finally) | From | Frederic Weisbecker <> |
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2013/4/25 Frederic Weisbecker <fweisbec@gmail.com>: > 2013/4/25 Ingo Molnar <mingo@kernel.org>: >> >> * Frederic Weisbecker <fweisbec@gmail.com> wrote: >> >>> 2013/4/25 Ingo Molnar <mingo@kernel.org>: >>> > >>> > * Frederic Weisbecker <fweisbec@gmail.com> wrote: >>> > >>> >> > depends on VIRT_CPU_ACCOUNTING_GEN >>> >> > >>> >> > It should _really_ select both the RCU and the CPU time accounting model >>> >> > automatically! >>> >> >>> >> Yeah I know. I have yet to fix that in Kconfig (it's a Kconfig limitation). >>> > >>> > Why cannot we simply select it and its dependencies, explicitly, for the >>> > time being? Something like: >>> > >>> > depends on 64BIT >>> > select VIRT_CPU_ACCOUNTING >>> > select VIRT_CPU_ACCOUNTING_GEN >>> > >>> > 90% of the .config's have VIRT_CPU_ACCOUNTING_GEN turned off, because it's >>> > a default-off feature - so dynticks-full is effectively hidden from the >>> > large majority of testers... >>> >>> Whatever we do, it seems that select does not work with choices. >>> >>> Michal, we are running into an issue where a Kconfig option needs to >>> select CONFIG_VIRT_CPU_ACCOUNTING_GEN but this latter option is part of >>> a choice menu so it doesn't work. As a result we are forced to use a >>> "depends on" and this hides the high level option we are interested in >>> (here full dynticks) behind its low level dependency. How hard do you >>> think it would be to fix this? I tried something that worked half-way >>> but I quickly got lost in the Kconfig maze. >> >> While it's not an ideal solution, we could try to create three bools out >> of the choice options, as a workaround? > > I thought about that yeah, at least for a temporary solution. Let's > try it, I'll see what I can get.
Oh wait, looking at how rcu manages its flavour choices against SMP and PREEMPT, I think I can inspire from it. I have the patch ready, just making some tests to be sure.
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