linux-kernel - [PATCH] arm64: restore bogomips information in /proc/cpuinfo

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Date:	Wed, 18 Nov 2015 10:15:05 -0800
From:	Yang Shi <yang.shi@...aro.org>
To:	Will.Deacon@....com, Catalin.Marinas@....com
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linaro-kernel@...ts.linaro.org, yang.shi@...aro.org
Subject: [PATCH] arm64: restore bogomips information in /proc/cpuinfo

As what Pavel Machek reported [1], some userspace applications depend on
bogomips showed by /proc/cpuinfo.

Although there is much less legacy impact on aarch64 than arm, but it does
break libvirt.

Basically, this patch reverts commit 326b16db9f69fd0d279be873c6c00f88c0a4aad5
("arm64: delay: don't bother reporting bogomips in /proc/cpuinfo"), but with
some tweak due to context change.

[1] https://lkml.org/lkml/2015/1/4/132

Signed-off-by: Yang Shi <yang.shi@...aro.org>
---
 arch/arm64/kernel/cpuinfo.c | 5 +++++
 arch/arm64/kernel/smp.c     | 7 ++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 706679d..8d4ba77 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -30,6 +30,7 @@
 #include <linux/seq_file.h>
 #include <linux/sched.h>
 #include <linux/smp.h>
+#include <linux/delay.h>
 
 /*
  * In case the boot CPU is hotpluggable, we record its initial state and
@@ -112,6 +113,10 @@ static int c_show(struct seq_file *m, void *v)
 		 */
 		seq_printf(m, "processor\t: %d\n", i);
 
+		seq_printf(m, "BogoMIPS\t: %lu.%02lu\n\n",
+			   loops_per_jiffy / (500000UL/HZ),
+			   loops_per_jiffy / (5000UL/HZ) % 100);
+
 		/*
 		 * Dump out the common processor features in a single line.
 		 * Userspace should read the hwcaps with getauxval(AT_HWCAP)
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index b1adc51..1bed772 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -326,7 +326,12 @@ static void __init hyp_mode_check(void)
 
 void __init smp_cpus_done(unsigned int max_cpus)
 {
-	pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
+	unsigned long bogosum = loops_per_jiffy * num_online_cpus();
+
+	pr_info("SMP: Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
+		num_online_cpus(), bogosum / (500000/HZ),
+		(bogosum / (5000/HZ)) % 100);
+
 	setup_cpu_features();
 	hyp_mode_check();
 	apply_alternatives_all();
-- 
2.0.2

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