OcSmbiosLib: Fixed SMBIOS Type4 External Clock values

Include/Library/OcCpuLib.h

@@ -18,12 +18,6 @@
 #include <IndustryStandard/CpuId.h>
 #include <IndustryStandard/AppleIntelCpuInfo.h>
 
-//
-// External clock value on Sandy Bridge and above (in MHz).
-// Rounded FSB * 4.
-//
-#define OC_CPU_SNB_QPB_CLOCK 0x19U
-
 typedef struct {
   //
   // Note, Vendor and BrandString are reordered for proper alignment.
@@ -69,6 +63,11 @@ typedef struct {
   UINT16                  CoreCount;
   UINT16                  ThreadCount;
 
+  //
+  // External clock for SMBIOS Type4 table.
+  //
+  UINT16                  ExternalClock;
+
   //
   // Platform-dependent frequency for the Always Running Timer (ART), normally
   // 24Mhz. Firmwares may choose to override this. Some CPUs like Xeon Scalable

Library/OcCpuLib/OcCpuLib.c

@@ -1478,6 +1478,26 @@ OcCpuScanProcessor (
     return;
   }
 
+  //
+  // SMBIOS Type4 ExternalClock field is assumed to have X*4 FSB frequency in MT/s.
+  // This value is cosmetics, but we still want to set it properly.
+  // Magic 4 value comes from 4 links in pretty much every modern Intel CPU.
+  // On modern CPUs this is now named Base clock (BCLK).
+  // Note, that this value was incorrect for most Macs since iMac12,x till iMac18,x inclusive.
+  // REF: https://github.com/acidanthera/bugtracker/issues/622#issuecomment-570811185
+  //
+  Cpu->ExternalClock = (UINT16) DivU64x32 (Cpu->FSBFrequency, 1000000);
+  //
+  // This is again cosmetics by errors in FSBFrequency calculation.
+  //
+  if (Cpu->ExternalClock >= 99 && Cpu->ExternalClock <= 101) {
+    Cpu->ExternalClock = 100;
+  } else if (Cpu->ExternalClock >= 132 && Cpu->ExternalClock <= 134) {
+    Cpu->ExternalClock = 133;
+  } else if (Cpu->ExternalClock >= 265 && Cpu->ExternalClock <= 267) {
+    Cpu->ExternalClock = 266;
+  }
+
   DEBUG ((
     DEBUG_INFO,
     "OCCPU: CPUFrequencyFromTSC %11LuHz %5LuMHz\n",

Library/OcSmbiosLib/SmbiosPatch.c

@@ -327,15 +327,7 @@ PatchProcessorInformation (
   SMBIOS_OVERRIDE_V (Table, Standard.Type4->ProcessorId, Original, NULL, NULL);
   SMBIOS_OVERRIDE_S (Table, Standard.Type4->ProcessorVersion, Original, NULL, &StringIndex, NULL);
   SMBIOS_OVERRIDE_V (Table, Standard.Type4->Voltage, Original, NULL, NULL);
-  //
-  // Models newer than Sandybridge require quad pumped bus value instead of a front side bus value.
-  //
-  if (CpuInfo->Model >= CPU_MODEL_SANDYBRIDGE) {
-    Table->CurrentPtr.Standard.Type4->ExternalClock = OC_CPU_SNB_QPB_CLOCK;
-  } else {
-    Table->CurrentPtr.Standard.Type4->ExternalClock = (UINT16) DivU64x32 (CpuInfo->FSBFrequency, 1000000);
-  }
-
+  Table->CurrentPtr.Standard.Type4->ExternalClock = CpuInfo->ExternalClock;
   Table->CurrentPtr.Standard.Type4->MaxSpeed = (UINT16) DivU64x32 (CpuInfo->CPUFrequency, 1000000);
   if (Table->CurrentPtr.Standard.Type4->MaxSpeed % 100 != 0) {
     Table->CurrentPtr.Standard.Type4->MaxSpeed = (UINT16) (((Table->CurrentPtr.Standard.Type4->MaxSpeed + 50) / 100) * 100);
@@ -980,8 +972,7 @@ CreateAppleProcessorSpeed (
 {
 #ifndef OC_PROVIDE_APPLE_PROCESSOR_BUS_SPEED
   //
-  // I believe this table is no longer used.
-  // The code below may be inaccurate as well, since it expects KHz.
+  // This table is not added in all modern Macs.
   //
   (VOID) Table;
   (VOID) Data;
@@ -995,11 +986,7 @@ CreateAppleProcessorSpeed (
     return;
   }
 
-  if (CpuInfo->Model >= CPU_MODEL_SANDYBRIDGE) {
-    Table->CurrentPtr.Type132->ProcessorBusSpeed = OC_CPU_SNB_QPB_CLOCK * 1000;
-  } else {
-    Table->CurrentPtr.Type132->ProcessorBusSpeed = (UINT16) DivU64x32 (CpuInfo->FSBFrequency, 1000);
-  }
+  Table->CurrentPtr.Type132->ProcessorBusSpeed = CpuInfo->ExternalClock * 4;
 
   SmbiosFinaliseStruct (Table);
 #endif