Use MSR_IA32_MISC_ENABLE instead

It turned out setting bit 32 of MSR_IA32_PERF_CTL didn't really have any
effect, at least on my system.

My concern about MSR_IA32_MISC_ENABLE disabling speed step was invalid
and so that approach was right after all.

Author: veloek

DisableTurboBoost.xcodeproj/project.pbxproj

@@ -250,7 +250,9 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
+				CURRENT_PROJECT_VERSION = 2;
 				INFOPLIST_FILE = DisableTurboBoost/Info.plist;
+				MARKETING_VERSION = 1.1;
 				MODULE_NAME = no.vtek.DisableTurboBoost;
 				MODULE_START = DisableTurboBoost_start;
 				MODULE_STOP = DisableTurboBoost_stop;
@@ -265,7 +267,9 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
+				CURRENT_PROJECT_VERSION = 2;
 				INFOPLIST_FILE = DisableTurboBoost/Info.plist;
+				MARKETING_VERSION = 1.1;
 				MODULE_NAME = no.vtek.DisableTurboBoost;
 				MODULE_START = DisableTurboBoost_start;
 				MODULE_STOP = DisableTurboBoost_stop;

DisableTurboBoost/DisableTurboBoost.c

@@ -25,31 +25,28 @@ extern void mp_rendezvous_no_intrs(
         void (*action_func)(void *),
         void *arg);
 
-const uint64_t disableTurboBoost = ((uint64_t)1) << 32;
+const uint64_t disableTurboBoost = ((uint64_t)1) << 38;
 
 void disable_tb(__unused void * param_not_used) {
-    wrmsr64(MSR_IA32_PERF_CTL, rdmsr64(MSR_IA32_PERF_CTL) | disableTurboBoost);
+    wrmsr64(MSR_IA32_MISC_ENABLE, rdmsr64(MSR_IA32_MISC_ENABLE) | disableTurboBoost);
 }
 
 void enable_tb(__unused void * param_not_used) {
-    wrmsr64(MSR_IA32_PERF_CTL, rdmsr64(MSR_IA32_PERF_CTL) & ~disableTurboBoost);
+    wrmsr64(MSR_IA32_MISC_ENABLE, rdmsr64(MSR_IA32_MISC_ENABLE) & ~disableTurboBoost);
 }
 
-kern_return_t DisableTurboBoost_start(kmod_info_t * ki, void *d);
-kern_return_t DisableTurboBoost_stop(kmod_info_t *ki, void *d);
-
 kern_return_t DisableTurboBoost_start(kmod_info_t * ki, void *d)
 {
-    uint64_t prev = rdmsr64(MSR_IA32_PERF_CTL);
+    uint64_t prev = rdmsr64(MSR_IA32_MISC_ENABLE);
     mp_rendezvous_no_intrs(disable_tb, NULL);
-    printf("Disabled Turbo Boost: %llx -> %llx\n", prev, rdmsr64(MSR_IA32_PERF_CTL));
+    printf("Disabled Turbo Boost: %llx -> %llx\n", prev, rdmsr64(MSR_IA32_MISC_ENABLE));
     return KERN_SUCCESS;
 }
 
 kern_return_t DisableTurboBoost_stop(kmod_info_t *ki, void *d)
 {
-    uint64_t prev = rdmsr64(MSR_IA32_PERF_CTL);
+    uint64_t prev = rdmsr64(MSR_IA32_MISC_ENABLE);
     mp_rendezvous_no_intrs(enable_tb, NULL);
-    printf("Re-enabled Turbo Boost: %llx -> %llx\n", prev, rdmsr64(MSR_IA32_PERF_CTL));
+    printf("Re-enabled Turbo Boost: %llx -> %llx\n", prev, rdmsr64(MSR_IA32_MISC_ENABLE));
     return KERN_SUCCESS;
 }

DisableTurboBoost/Info.plist

@@ -15,9 +15,9 @@
 	<key>CFBundlePackageType</key>
 	<string>$(PRODUCT_BUNDLE_PACKAGE_TYPE)</string>
 	<key>CFBundleShortVersionString</key>
-	<string>1.0</string>
+	<string>$(MARKETING_VERSION)</string>
 	<key>CFBundleVersion</key>
-	<string>1</string>
+	<string>$(CURRENT_PROJECT_VERSION)</string>
 	<key>NSHumanReadableCopyright</key>
 	<string>Copyright © 2020 Vegard Løkken. All rights reserved.</string>
 	<key>OSBundleLibraries</key>

README.md

@@ -1,6 +1,6 @@
 # DisableTurboBoost
 
-A MacOS kernel extension (kext) for disabling CPU turbo boost to keep temperature (and fan noise) down.
+A macOS kernel extension (kext) for disabling CPU turbo boost to keep temperature (and fan noise) down.
 
 ## Usage
 
@@ -18,11 +18,13 @@ sudo kextload DisableTurboBoost.kext
 
 Run `kextstat |grep DisableTurboBoost` to verify that it's loaded.
 
+Run `sudo kextunload -b no.vtek.DisableTurboBoost` to unload the kext.
+
 ## How it works
 
-This small kernel extension will enable bit 32 of the MSR register `MSR_IA32_PERF_CTL`. This causes the CPU to disable turbo boost, while keeping speed step.
+This small kernel extension will enable bit 38 of the MSR register `MSR_IA32_MISC_ENABLE` which causes the CPU to disable turbo boost.
 
-Other similar extensions choose to enable bit 38 of `MSR_IA32_MISC_ENABLE`, but this also disables speed step causing the CPU to run at a higher frequency (and drain battery faster) than necessary.
+There are some alternatives that enables bit 32 of `MSR_IA32_PERF_CTL`, but that didn't seem to have any impact on my system.
 
 Take a look in the [manual](http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html) for more info.
 
@@ -42,4 +44,4 @@ It will output something about invalid signatures, but the extension might still
 
 ## Credits
 
-The code was written by Vegard Løkken with great inspiration from [nanoant/DisableTurboBoost.kext](https://github.com/nanoant/DisableTurboBoost.kext) and [pyrovski/powertools](https://github.com/pyrovski/powertools).
+The code was based on an outdated repo [nanoant/DisableTurboBoost.kext](https://github.com/nanoant/DisableTurboBoost.kext).