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    SubjectRe: [PATCH] arm64: restore bogomips information in /proc/cpuinfo
    Hello,

    On Wed, Nov 18, 2015 at 10:15:05AM -0800, Yang Shi wrote:
    > 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

    I lost this argument last time around, so I won't re-tread that path this
    time around. I do, however, have some comments on the patch.

    >
    > Signed-off-by: Yang Shi <yang.shi@linaro.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",

    This double newline makes /proc/cpuinfo looks really odd. Can we just
    have one, please?

    > + 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);

    Can we drop this hunk? I don't see a pressing need to print this in
    dmesg.

    With those two changes:

    Acked-by: Will Deacon <will.deacon@arm.com>

    I guess this needs Cc'ing to stable, too.

    Thanks,

    Will


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