[libvirt] [PATCH v2 4/4] util: Don't report CPU frequency for ARM hosts

[Andrea Bolognani]

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                                       | 6 ++++--
 tests/virhostcpudata/linux-aarch64-rhel74-moonshot.expected | 2 +-
 tests/virhostcpudata/linux-armv6l-raspberrypi.expected      | 2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
index 2259c9f2f..24fbe42f6 100644
--- a/src/util/virhostcpu.c
+++ b/src/util/virhostcpu.c
@@ -543,12 +543,14 @@ virHostCPUParseFrequency(FILE *cpuinfo,
     const char *prefix = NULL;
     char line[1024];
 
+    /* No sensible way to retrieve CPU frequency */
+    if (ARCH_IS_ARM(arch))
+        return 0;
+
     if (ARCH_IS_X86(arch))
         prefix = "cpu MHz";
     else if (ARCH_IS_PPC(arch))
         prefix = "clock";
-    else if (ARCH_IS_ARM(arch))
-        prefix = "BogoMIPS";
 
     if (!prefix) {
         VIR_WARN("Parser for /proc/cpuinfo needs to be adapted for your architecture");
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