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From: Kurt Kanzenbach <kurt@linutronix.de>
To: Florian Weimer <fweimer@redhat.com>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>,
 libc-alpha@sourceware.org, Carlos O'Donell <carlos@redhat.com>, Thomas
 Gleixner <tglx@linutronix.de>, Sebastian Andrzej Siewior
 <bigeasy@linutronix.de>
Subject: Re: [PATCH RFC 0/3] nptl: Introduce and use FUTEX_LOCK_PI2
In-Reply-To: <871r8ugxwu.fsf@oldenburg.str.redhat.com>
References: <20210621111650.1164689-1-kurt@linutronix.de>
 <bf4e7c28-11ce-fa4f-65b4-b00196440792@linaro.org> <87h7hql5qm.fsf@kurt>
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Date: Tue, 22 Jun 2021 10:55:36 +0200
Message-ID: <87eecul1mf.fsf@kurt>
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On Tue Jun 22 2021, Florian Weimer wrote:
> * Kurt Kanzenbach:
>
>> At this point __ASSUME_FUTEX_LOCK_PI2 is false meaning the kernel does
>> not have FUTEX_LOCK_PI2 support. But, it calls FUTEX_LOCK_PI2 for
>> clockid monotonic. This will result in ENOSYS unless it's an old kernel
>> which is patched. Is that intended?
>
> That's not quite how the __ASSUME_* macros work.  If not defined, it
> just means that glibc won't assume that the kernel feature is there.  It
> can still use it (the run-time kernel might have it after all), but
> glibc has to check for the feature and has to compile in some sort of
> fallback code.

OK, makes sense. Thanks for the explanation.

Thanks,
Kurt

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