[Xen-devel] [PATCH v2 7/9] x86/intel_pstate: add a booting param to select the driver to load

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

By default, the old P-state driver (acpi-freq) is used. Adding
"intel_pstate=enable" to the Xen booting param list to enable the
use of intel_pstate. However, if intel_pstate is enabled on a
machine which does not support the driver (e.g. Nehalem), the
old P-state driver will be loaded due to the failure loading of
intel_pstate.

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 | 21 +++++++++++++++++++--
 xen/include/asm-x86/acpi.h               |  2 ++
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/acpi/cpufreq/cpufreq.c 
b/xen/arch/x86/acpi/cpufreq/cpufreq.c
index fa3678d..f75f356 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 (load_intel_pstate)
+            ret = intel_pstate_init();
+        if (!load_intel_pstate)
+            ret = cpufreq_register_driver(&acpi_cpufreq_driver);
+    } 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 052a0d0..c1a8b11 100644
--- a/xen/arch/x86/acpi/cpufreq/intel_pstate.c
+++ b/xen/arch/x86/acpi/cpufreq/intel_pstate.c
@@ -766,6 +766,8 @@ static struct cpufreq_driver intel_pstate_driver = {
     .name         = "intel_pstate",
 };
 
+int __initdata load_intel_pstate = 0;
+
 static int intel_pstate_msrs_not_valid(void)
 {
     /* Check that all the msr's we are using are valid. */
@@ -819,10 +821,14 @@ int __init intel_pstate_init(void)
     if (cpuid_ecx(6) & 0x1)
         set_bit(X86_FEATURE_APERFMPERF, &boot_cpu_data.x86_capability);
 
-    id = x86_match_cpu(intel_pstate_cpu_ids);
-    if (!id)
+    if (!load_intel_pstate)
         return -ENODEV;
 
+    id = x86_match_cpu(intel_pstate_cpu_ids);
+    if (!id) {
+        load_intel_pstate = 0;
+        return -ENODEV;
+    }
     cpu_info = (struct cpu_defaults *)id->driver_data;
 
     copy_pid_params(&cpu_info->pid_policy);
@@ -850,3 +856,14 @@ out:
     xfree(all_cpu_data);
     return -ENODEV;
 }
+
+static int __init intel_pstate_setup(char *str)
+{
+    if (!str)
+        return -EINVAL;
+    if (!strcmp(str, "enable"))
+        load_intel_pstate = 1;
+
+    return 0;
+}
+custom_param("intel_pstate", intel_pstate_setup);
diff --git a/xen/include/asm-x86/acpi.h b/xen/include/asm-x86/acpi.h
index 505d7e7..1a97545 100644
--- a/xen/include/asm-x86/acpi.h
+++ b/xen/include/asm-x86/acpi.h
@@ -32,6 +32,8 @@
 #define COMPILER_DEPENDENT_INT64   long long
 #define COMPILER_DEPENDENT_UINT64  unsigned long long
 
+extern int load_intel_pstate;
+
 extern int intel_pstate_init(void);
 
 /*
-- 
1.9.1


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel