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Date: Wed, 13 Jul 2011 16:44:26 -0400 (EDT)
From: Len Brown <lenb@kernel.org>
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To: Ingo Molnar <mingo@elte.hu>
Cc: x86@kernel.org, linux-pm@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Arjan van de Ven <arjan@infradead.org>
Subject: Re: [PATCH] x86 intel power: Initialize MSR_IA32_ENERGY_PERF_BIAS
In-reply-to: <20110415101712.GB28007@elte.hu>
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> So how about informing users, how about making it non-silent? An informative 
> printk that also mentions the power configuration tool, etc. This solves the 
> concerns i mentioned.

Something like this?

                rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);
                if ((epb & 0xF) == 0) {
                        printk_once(KERN_WARN, "x86: updated energy_perf_bias"
                                " to 'normal' from 'performance'\n"
                                "You can view and update epb via utility,"
                                " such as x86_energy_perf_policy(8)\n");
                        epb = (epb & ~0xF) | ENERGY_PERF_BIAS_NORMAL;
                        wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);
                }