From feeb7d2d015c03eb95b66d1efafcfe6b908e1e49 Mon Sep 17 00:00:00 2001
From: Sam Demeulemeester <github@x86-secret.com>
Date: Tue, 17 Mar 2026 00:15:46 +0100
Subject: [PATCH] Fix Core Topology Determination on some CPUs (eg: Intel PTL)

---
 app/display.c      |  2 +-
 system/cpuid.h     |  1 +
 system/x86/cpuid.c | 23 +++++++++++------------
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/app/display.c b/app/display.c
index b7739b3..bf6fd8f 100644
--- a/app/display.c
+++ b/app/display.c
@@ -268,7 +268,7 @@ void display_cpu_topology(void)
     if (cpuid_info.topology.is_hybrid) {
         if (cpuid_info.topology.pcore_count > 1) {
 
-            if (cpuid_info.flags.htt &&
+            if (cpuid_info.flags.htt && cpuid_info.topology.thread_per_core > 1 &&
                 (cpuid_info.topology.thread_count - cpuid_info.topology.ecore_count) == cpuid_info.topology.pcore_count) {
                     cpuid_info.topology.pcore_count /= 2;
             }
diff --git a/system/cpuid.h b/system/cpuid.h
index 1e0b2cb..384e757 100644
--- a/system/cpuid.h
+++ b/system/cpuid.h
@@ -146,6 +146,7 @@ typedef union {
 typedef struct {
     int     core_count;
     int     thread_count;
+    int     thread_per_core;
     int     is_hybrid;
     int     ecore_count;
     int     pcore_count;
diff --git a/system/x86/cpuid.c b/system/x86/cpuid.c
index 2200b56..97cbaa3 100644
--- a/system/x86/cpuid.c
+++ b/system/x86/cpuid.c
@@ -126,13 +126,12 @@ void cpuid_init(void)
     }
 
     // Detect CPU Topology (Core/Thread) infos
-    cpuid_info.topology.core_count   = -1;
-    cpuid_info.topology.thread_count = -1;
-    cpuid_info.topology.is_hybrid    =  0;
-    cpuid_info.topology.ecore_count  = -1;
-    cpuid_info.topology.pcore_count  = -1;
-
-    int thread_per_core = 1;
+    cpuid_info.topology.core_count      = -1;
+    cpuid_info.topology.thread_count    = -1;
+    cpuid_info.topology.thread_per_core =  1;
+    cpuid_info.topology.is_hybrid       =  0;
+    cpuid_info.topology.ecore_count     = -1;
+    cpuid_info.topology.pcore_count     = -1;
 
     // Set correct HTT flag according to AP-485
     if (cpuid_info.max_cpuid >= 1 && cpuid_info.flags.htt) {
@@ -154,16 +153,16 @@ void cpuid_init(void)
                 cpuid(0x8000001E, 0, &reg[0], &reg[1], &reg[2], &reg[3]);
 
                 if (((reg[1] >> 8) & 0x3) > 0) {
-                    thread_per_core = 2;
+                    cpuid_info.topology.thread_per_core  = 2;
                 }
             } else if (cpuid_info.flags.htt) {
                 if (cpuid_info.version.extendedFamily >= 8) {
-                    thread_per_core = 2;
+                    cpuid_info.topology.thread_per_core  = 2;
                 } else {
                     cpuid_info.flags.htt = 0; // Pre-ZEN never has SMT
                 }
             }
-            cpuid_info.topology.core_count = cpuid_info.topology.thread_count / thread_per_core;
+            cpuid_info.topology.core_count = cpuid_info.topology.thread_count / cpuid_info.topology.thread_per_core ;
         }
         break;
        case 'C':
@@ -192,7 +191,7 @@ void cpuid_init(void)
 
                 switch((reg[2] >> 8) & 0xFF) {
                     case 1: // SMT
-                        thread_per_core = reg[1] & 0xFF;
+                        cpuid_info.topology.thread_per_core  = reg[1] & 0xFF;
                         break;
                     case 2: // Cores
                         cpuid_info.topology.thread_count = reg[1] & 0xFFFF;
@@ -202,7 +201,7 @@ void cpuid_init(void)
                 }
             }
 
-            cpuid_info.topology.core_count = cpuid_info.topology.thread_count / thread_per_core;
+            cpuid_info.topology.core_count = cpuid_info.topology.thread_count / cpuid_info.topology.thread_per_core ;
 
         } else if (cpuid_info.max_cpuid >= 0x4) {
             cpuid(4, 0, &reg[0], &reg[1], &reg[2], &reg[3]);