Re: [PATCH v4 2/4] x86/phi: Add enabling of the R3MWAIT during boot

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 2/4] x86/phi: Add enabling of the R3MWAIT during boot
Date	2016-10-20 21:20 +0200
Message-ID	<sur2G-3iX-19@gated-at.bofh.it> (permalink)
References	<stzvj-ck-7@gated-at.bofh.it> <stzvj-ck-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, 18 Oct 2016, Grzegorz Andrejczuk wrote:
> +static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *c)
> +{
> +	if (phi_r3mwait_disabled)
> +		return;

So you return when the command line option to disable the feature was
given. That's not really a good choice if the feature is already enabled
due to BIOS featuritis. This can also happen when you kexec from a enabled
kernel into one which has the command line option set.

You really should make sure that the command line option results in
disabling the feature no matter what.

Thanks,

	tglx

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[PATCH v4 2/4] x86/phi: Add enabling of the R3MWAIT during boot Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com> - 2016-10-18 12:10 +0200
  Re: [PATCH v4 2/4] x86/phi: Add enabling of the R3MWAIT during  boot Thomas Gleixner <tglx@linutronix.de> - 2016-10-20 21:20 +0200

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