linux-kernel - [PATCH 1/2] x86: intel_epb: Mention firmware in ENERGY_PERF

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Message-Id: <20210817143830.34552-1-pmenzel@molgen.mpg.de>
Date:   Tue, 17 Aug 2021 16:38:29 +0200
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>
Cc:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Paul Menzel <pmenzel@...gen.mpg.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] x86: intel_epb: Mention firmware in ENERGY_PERF_BIAS warning

The warning

    ENERGY_PERF_BIAS: Set to 'normal', was 'performance'

is shown on all my Intel systems, and for a normal user it’s unclear
what to do about it. Change it to

    ENERGY_PERF_BIAS: Set to 'normal', was 'performance' (unchanged by firmware)

so it’s clear, that it might be possible to change the setting in the
system firmware.

Signed-off-by: Paul Menzel <pmenzel@...gen.mpg.de>
---
 arch/x86/kernel/cpu/intel_epb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel_epb.c b/arch/x86/kernel/cpu/intel_epb.c
index f4dd73396f28..3f8c0b59d08a 100644
--- a/arch/x86/kernel/cpu/intel_epb.c
+++ b/arch/x86/kernel/cpu/intel_epb.c
@@ -91,7 +91,7 @@ static void intel_epb_restore(void)
 		val = epb & EPB_MASK;
 		if (val == ENERGY_PERF_BIAS_PERFORMANCE) {
 			val = ENERGY_PERF_BIAS_NORMAL;
-			pr_warn_once("ENERGY_PERF_BIAS: Set to 'normal', was 'performance'\n");
+			pr_warn_once("ENERGY_PERF_BIAS: Set to 'normal', was 'performance' (unchanged by firmware)\n");
 		}
 	}
 	wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, (epb & ~EPB_MASK) | val);
-- 
2.33.0