Merge pull request #86 from gbowne1/gbowne1-cpuidfix-1

IImplement CPUID support check and CPU info printing

kernel/cpu.c

@@ -2,36 +2,98 @@
 #include "serial.h"
 #include "terminal.h"
 #include "utils.h"
-#include "print.h"
 
-void cpuid(uint32_t function, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx) {
-    __asm__(
-        "cpuid"
-        : "=a"(*eax), "=b"(*ebx), "=c"(*ecx), "=d"(*edx)
-        : "a"(function)
-    );
+// Helper to print a labeled decimal value
+void print_val(const char* label, uint32_t val) {
+    char buf[12];
+    utoa(val, buf, 10);
+    terminal_write(label);
+    terminal_write(buf);
+    terminal_write(" ");
+}
+
+// Safely check if CPUID is supported by attempting to flip bit 21 of EFLAGS
+int check_cpuid_supported() {
+    uint32_t f1, f2;
+    __asm__ volatile (
+        "pushfl\n\t"
+        "pushfl\n\t"
+        "popl %0\n\t"
+        "movl %0, %1\n\t"
+        "xorl $0x200000, %0\n\t"
+        "pushl %0\n\t"
+        "popfl\n\t"
+        "pushfl\n\t"
+        "popl %0\n\t"
+        "popfl\n\t"
+        : "=&r" (f1), "=&r" (f2));
+    return ((f1 ^ f2) & 0x200000) != 0;
 }
 
 void identify_cpu() {
+    if (!check_cpuid_supported()) {
+        terminal_write("CPUID not supported. Likely a 386 or early 486.\n");
+        return;
+    }
+
     uint32_t eax, ebx, ecx, edx;
     char vendor[13];
 
+    // Leaf 0: Vendor String & Max Leaf
     cpuid(0, &eax, &ebx, &ecx, &edx);
-
+    uint32_t max_leaf = eax;
     *(uint32_t *)&vendor[0] = ebx;
     *(uint32_t *)&vendor[4] = edx;
     *(uint32_t *)&vendor[8] = ecx;
     vendor[12] = '\0';
 
-    terminal_write("CPU Vendor: ");
+    terminal_write("Vendor: ");
     terminal_write(vendor);
     terminal_write("\n");
 
-    serial_write("CPU Vendor: ");
-    serial_write(vendor);
-    serial_write("\n");
+    // Leaf 1: Family, Model, Stepping
+    if (max_leaf >= 1) {
+        cpuid(1, &eax, &ebx, &ecx, &edx);
         
-    terminal_write("CPUID max leaf: ");
-    print_hex(eax, false, false);  // You must implement this (see below)
+        uint32_t stepping = eax & 0xF;
+        uint32_t model = (eax >> 4) & 0xF;
+        uint32_t family = (eax >> 8) & 0xF;
+        uint32_t type = (eax >> 12) & 0x3;
+
+        // Handle Extended Family/Model (Required for Pentium 4 and newer)
+        if (family == 0xF) {
+            family += (eax >> 20) & 0xFF;
+            model += ((eax >> 16) & 0xF) << 4;
+        }
+
+        print_val("Family:", family);
+        print_val("Model:", model);
+        print_val("Step:", stepping);
         terminal_write("\n");
+    }
+
+    // Leaf 2: Cache Descriptors
+    if (max_leaf >= 2) {
+        cpuid(2, &eax, &ebx, &ecx, &edx);
+        
+        terminal_write("Cache Descriptors: ");
+        // Note: Leaf 2 returns a list of 1-byte descriptors in the registers.
+        // We look for common Intel ones:
+        uint32_t regs[4] = {eax, ebx, ecx, edx};
+        for (int i = 0; i < 4; i++) {
+            if (regs[i] & 0x80000000) continue; // Reserved bit
+            for (int j = 0; j < 4; j++) {
+                uint8_t desc = (regs[i] >> (j * 8)) & 0xFF;
+                if (desc == 0) continue;
+                
+                // Example decoding for specific chips you mentioned:
+                if (desc == 0x06) terminal_write("8KB L1 I-Cache ");
+                if (desc == 0x0A) terminal_write("8KB L1 D-Cache ");
+                if (desc == 0x41) terminal_write("128KB L2 ");
+                if (desc == 0x43) terminal_write("512KB L2 ");
+                if (desc == 0x2C) terminal_write("32KB L1 D-Cache ");
+            }
+        }
+        terminal_write("\n");
+    }
 }

kernel/cpu.h

@@ -2,8 +2,42 @@
 #define CPU_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
-void cpuid(uint32_t function, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx);
+// Specific Intel Model Definitions for your targets
+#define INTEL_FAM4_486_DX      0x00 // Also 0x01
+#define INTEL_FAM4_486_SX      0x02
+#define INTEL_FAM4_486_DX2     0x03
+#define INTEL_FAM4_486_DX4     0x08
+#define INTEL_FAM5_PENTIUM     0x01 // P5
+#define INTEL_FAM5_PENTIUM_MMX 0x04 // P55C
+#define INTEL_FAM6_PENTIUM_PRO 0x01 // P6
+#define INTEL_FAM6_PENTIUM_II  0x05 // Deschutes
+#define INTEL_FAM6_PENTIUM_III 0x07 // Katmai/Coppermine
+#define INTEL_FAM15_P4_WILLY   0x00 // Willamette
+#define INTEL_FAM15_P4_NORTH   0x02 // Northwood
+#define INTEL_FAM15_P4_PRES    0x03 // Prescott
+
+typedef struct {
+    char vendor[13];
+    uint32_t family;
+    uint32_t model;
+    uint32_t stepping;
+    uint32_t type;
+    uint32_t max_leaf;
+    
+    // Feature flags (optional, but very helpful later)
+    bool has_fpu;
+    bool has_mmx;
+    bool has_sse;
+} cpu_info_t;
+
+// Function Prototypes
+void cpuid(uint32_t leaf, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx);
+bool cpu_check_cpuid_support(void);
 void identify_cpu(void);
 
+// Helper to get the current CPU info after identification
+cpu_info_t* cpu_get_info(void);
+
 #endif // CPU_H