[libvirt] [PATCH 6/6] util: Don't report CPU frequency for ARM hosts

[Bjoern Walk]

Andrea Bolognani <abologna at redhat.com> [2017-12-11, 05:40PM +0100]:
> Some ARM platforms, such as the original Raspberry Pi, report the
> CPU frequency in the BogoMIPS field of /proc/cpuinfo, so libvirt
> parsed that field and returned it through its API.
> 
> However, not only many more boards don't report any value there,
> but several - including ARMv8-based server hardware, and even the
> more recent Raspberry Pi 3 - use this field as originally intended:
> to report the BogoMIPS value instead of the CPU frequency.
> 
> Since we have no way of detecting how the field is being used,
> it's better to report no information at all rather than something
> ludicrous like "your shiny 96-core aarch64 virtualization host's
> CPUs are running at a whopping 100 MHz".
> 
> Signed-off-by: Andrea Bolognani <abologna at redhat.com>
> ---
>  src/util/virhostcpu.c                                       | 5 +----
>  tests/virhostcpudata/linux-aarch64-rhel74-moonshot.expected | 2 +-
>  tests/virhostcpudata/linux-armv6l-raspberrypi.expected      | 2 +-
>  3 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
> index 3b478fc45..9bc213580 100644
> --- a/src/util/virhostcpu.c
> +++ b/src/util/virhostcpu.c
> @@ -563,10 +563,7 @@ virHostCPUGetInfoParseCPUInfo(FILE *cpuinfo,
>          } else if (ARCH_IS_PPC(arch)) {
>              if (virHostCPUGetInfoParseCPUFrequency(line, "clock", mhz) < 0)
>                  goto cleanup;
> -        } else if (ARCH_IS_ARM(arch)) {
> -            if (virHostCPUGetInfoParseCPUFrequency(line, "BogoMIPS", mhz) < 0)
> -                goto cleanup;
> -        } else if (ARCH_IS_S390(arch)) {
> +        } else if (ARCH_IS_S390(arch) || ARCH_IS_ARM(arch)) {
>              /* No reasonable way to obtain CPU frequency */
>          } else {
>              VIR_WARN("Parser for /proc/cpuinfo needs to be adapted for your architecture");

I'm a bit confused now. If we have a not supported arch, will this
warning not get issued for every line in /proc/cpuinfo? It's the same
for the original code.

> diff --git a/tests/virhostcpudata/linux-aarch64-rhel74-moonshot.expected b/tests/virhostcpudata/linux-aarch64-rhel74-moonshot.expected
> index 24ff0ea0b..6776aa6c2 100644
> --- a/tests/virhostcpudata/linux-aarch64-rhel74-moonshot.expected
> +++ b/tests/virhostcpudata/linux-aarch64-rhel74-moonshot.expected
> @@ -1 +1 @@
> -CPUs: 8/8, MHz: 100, Nodes: 1, Sockets: 1, Cores: 8, Threads: 1
> +CPUs: 8/8, MHz: 0, Nodes: 1, Sockets: 1, Cores: 8, Threads: 1
> diff --git a/tests/virhostcpudata/linux-armv6l-raspberrypi.expected b/tests/virhostcpudata/linux-armv6l-raspberrypi.expected
> index 146bd073e..1c4c713d5 100644
> --- a/tests/virhostcpudata/linux-armv6l-raspberrypi.expected
> +++ b/tests/virhostcpudata/linux-armv6l-raspberrypi.expected
> @@ -1 +1 @@
> -CPUs: 1/1, MHz: 697, Nodes: 1, Sockets: 1, Cores: 1, Threads: 1
> +CPUs: 1/1, MHz: 0, Nodes: 1, Sockets: 1, Cores: 1, Threads: 1
> -- 
> 2.14.3
> 
> --
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> 

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