[Xen-devel] [PATCH 7/9] x86/intel_pstate: add a booting param to select the driver to load

[Wei Wang <wei.w.wang@xxxxxxxxx>]

By default, the intel_pstate driver is loaded.a If
"intel_pstate=disable" is added to the Xen booting param list,
the old pstate driver will be loaded.

Signed-off-by: Wei Wang <wei.w.wang@xxxxxxxxx>
---
 xen/arch/x86/acpi/cpufreq/cpufreq.c       |  9 ++++++---
 xen/arch/x86/acpi/cpufreq/intel_pstate.c  | 16 ++++++++++++++++
 xen/include/acpi/cpufreq/processor_perf.h |  2 ++
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/acpi/cpufreq/cpufreq.c 
b/xen/arch/x86/acpi/cpufreq/cpufreq.c
index fa3678d..c4daf18 100644
--- a/xen/arch/x86/acpi/cpufreq/cpufreq.c
+++ b/xen/arch/x86/acpi/cpufreq/cpufreq.c
@@ -650,9 +650,12 @@ static int __init cpufreq_driver_init(void)
     int ret = 0;
 
     if ((cpufreq_controller == FREQCTL_xen) &&
-        (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL))
-        ret = cpufreq_register_driver(&acpi_cpufreq_driver);
-    else if ((cpufreq_controller == FREQCTL_xen) &&
+        (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)) {
+        if (no_load_intel_pstate)
+            ret = cpufreq_register_driver(&acpi_cpufreq_driver);
+        else
+            ret = intel_pstate_init();
+    } else if ((cpufreq_controller == FREQCTL_xen) &&
         (boot_cpu_data.x86_vendor == X86_VENDOR_AMD))
         ret = powernow_register_driver();
 
diff --git a/xen/arch/x86/acpi/cpufreq/intel_pstate.c 
b/xen/arch/x86/acpi/cpufreq/intel_pstate.c
index f95026f..4c71a23 100644
--- a/xen/arch/x86/acpi/cpufreq/intel_pstate.c
+++ b/xen/arch/x86/acpi/cpufreq/intel_pstate.c
@@ -757,6 +757,8 @@ static struct cpufreq_driver intel_pstate_driver = {
     .name         = "intel_pstate",
 };
 
+int __initdata no_load_intel_pstate = 0;
+
 static int intel_pstate_msrs_not_valid(void)
 {
     /* Check that all the msr's we are using are valid. */
@@ -810,6 +812,9 @@ int __init intel_pstate_init(void)
     if (cpuid_ecx(6) & 0x1)
         set_bit(X86_FEATURE_APERFMPERF, &boot_cpu_data.x86_capability);
 
+    if (no_load_intel_pstate)
+        return -ENODEV;
+
     id = x86_match_cpu(intel_pstate_cpu_ids);
     if (!id)
         return -ENODEV;
@@ -841,3 +846,14 @@ out:
     xfree(all_cpu_data);
     return -ENODEV;
 }
+
+static int __init intel_pstate_setup(char *str)
+{
+    if (!str)
+        return -EINVAL;
+    if (!strcmp(str, "disable"))
+        no_load_intel_pstate = 1;
+
+    return 0;
+}
+custom_param("intel_pstate", intel_pstate_setup);
diff --git a/xen/include/acpi/cpufreq/processor_perf.h 
b/xen/include/acpi/cpufreq/processor_perf.h
index ebff11d..4612289 100644
--- a/xen/include/acpi/cpufreq/processor_perf.h
+++ b/xen/include/acpi/cpufreq/processor_perf.h
@@ -7,6 +7,8 @@
 
 #define XEN_PX_INIT 0x80000000
 
+extern int no_load_intel_pstate;
+
 int intel_pstate_init(void);
 int powernow_cpufreq_init(void);
 unsigned int powernow_register_driver(void);
-- 
1.9.1


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