On Fri, Jul 21, 2023 at 09:17:53AM +0100, Valentin Schneider wrote: > On 20/07/23 17:30, Valentin Schneider wrote: > > index bdd7eadb33d8f..1ff2aab24e964 100644 > > --- a/kernel/rcu/Kconfig > > +++ b/kernel/rcu/Kconfig > > @@ -332,4 +332,37 @@ config RCU_DOUBLE_CHECK_CB_TIME > > Say Y here if you need tighter callback-limit enforcement. > > Say N here if you are unsure. > > > > +config RCU_DYNTICKS_RANGE_BEGIN > > + int > > + depends on !RCU_EXPERT > > + default 31 if !CONTEXT_TRACKING_WORK > > You'll note that this should be 30 really, because the lower *2* bits are > taken by the context state (CONTEXT_GUEST has a value of 3). > > This highlights the fragile part of this: the Kconfig values are hardcoded, > but they depend on CT_STATE_SIZE, CONTEXT_MASK and CONTEXT_WORK_MAX. The > static_assert() will at least capture any misconfiguration, but having that > enforced by the actual Kconfig ranges would be less awkward. > > Do we currently have a way of e.g. making a Kconfig file depend on and use > values generated by a C header? Why not just have something like a boolean RCU_DYNTICKS_TORTURE Kconfig option and let the C code work out what the number of bits should be? I suppose that there might be a failure whose frequency depended on the number of bits, which might be an argument for keeping something like RCU_DYNTICKS_RANGE_BEGIN for fault isolation. But still using RCU_DYNTICKS_TORTURE for normal testing. Thoughts? Thanx, Paul
