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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ankur Arora <ankur.a.arora@oracle.com>,
	linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@kernel.org,
	juri.lelli@redhat.com, vincent.guittot@linaro.org,
	dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com,
	mgorman@suse.de, vschneid@redhat.com, frederic@kernel.org,
	efault@gmx.de
Subject: Re: [PATCH 2/7] rcu: limit PREEMPT_RCU configurations
Message-ID: <20241010063207.xIrynIqO@linutronix.de>
References: <20241009165411.3426937-1-ankur.a.arora@oracle.com>
 <20241009165411.3426937-3-ankur.a.arora@oracle.com>
 <20241009180117.GS17263@noisy.programming.kicks-ass.net>
 <37af80bd-a54f-4ee4-9175-6f0f27b685a0@paulmck-laptop>
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In-Reply-To: <37af80bd-a54f-4ee4-9175-6f0f27b685a0@paulmck-laptop>

On 2024-10-09 11:24:09 [-0700], Paul E. McKenney wrote:
> In order to support systems that currently run CONFIG_PREEMPT=3Dn that
=E2=80=A6
> Or am I once again missing your point?

The change is:
| config PREEMPT_RCU
|        bool
|-       default y if PREEMPTION
|+       default y if (PREEMPT || PREEMPT_RT || PREEMPT_DYNAMIC)

Now:
- CONFIG_PREEMPT select PREEMPT_BUILD
- PREEMPT_RT select CONFIG_PREEMPTION
- PREEMPT_DYNAMIC selects PREEMPT_BUILD

and PREEMPT_BUILD select CONFIG_PREEMPTION

so in the end, this change is a nop, right?

> 							Thanx, Paul

Sebastian