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From:   Christian Eggers <ceggers@arri.de>
To:     Peter Zijlstra <peterz@infradead.org>
CC:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        <tglx@linutronix.de>, <linux-rt-users@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: sched: system doesn't boot since  "sched: Add new migrate_disable() implementation"
Date:   Tue, 20 Oct 2020 14:38:06 +0200
Message-ID: <3306981.cWQ2TMxoAe@n95hx1g2>
Organization: Arnold & Richter Cine Technik GmbH & Co. Betriebs KG
In-Reply-To: <20201020113009.GR2628@hirez.programming.kicks-ass.net>
References: <1654655.1jrfHnk7pZ@n95hx1g2> <20201019150935.koqbk57dmahhomdc@linutronix.de> <20201020113009.GR2628@hirez.programming.kicks-ass.net>
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On Tuesday, 20 October 2020, 13:30:09 CEST, Peter Zijlstra wrote:
> On Mon, Oct 19, 2020 at 05:09:35PM +0200, Sebastian Andrzej Siewior wrote:
> > On 2020-10-19 12:21:06 [+0200], Christian Eggers wrote:
> > > I have problems with the latest 5.9-rt releases on i.MX6ULL (!
CONFIG_SMP):
> > …
> > 
> > > Any hints?
> > 
> > Thank you for the report. The reason is the migrate_disable()
> > implementation for !SMP.
> 
> This should fix things I suppose. I'll fold it in.
> 
> ---
> --- a/include/linux/preempt.h
> +++ b/include/linux/preempt.h
> @@ -378,7 +378,12 @@ static inline void preempt_notifier_init
>  extern void migrate_disable(void);
>  extern void migrate_enable(void);
> 
> -#else /* !(CONFIG_SMP && CONFIG_PREEMPT_RT) */
> +#elif defined(CONFIG_PREEMPT_RT)
> +
> +static inline void migrate_disable(void) { }
> +static inline void migrate_enable(void { }
closing bracket missing

> +
> +#else /* !CONFIG_PREEMPT_RT */
> 
>  /**
>   * migrate_disable - Prevent migration of the current task

I didn't understand much of you discussion with Sebastian,
but my system is able to boot now.

# uname -r
5.9.0-rt16+

Best regards
Christian