Change to limine bootloader

src/boot.s

@@ -20,8 +20,9 @@ stack_top:
 	.section .text
 	.global _start
 	.type _start, @function
+
 _start:
-	mov $stack_top, %esp
+	mov $stack_top, %rsp
 
 	/* Initialize processor state here */
 

src/kernel.c

@@ -6,10 +6,24 @@
 #if defined(__linux__)
 #error "Not using cross compiler"
 #endif
-#if !defined(__i386__)
-#error "Not using a ix86-elf compiler"
+#if !defined(__x86_64__)
+#error "Not using a x86_64-elf compiler"
 #endif
 
+static inline uint64_t read_msr(uint32_t msr) {
+    uint32_t lo, hi;
+    __asm__ volatile("rdmsr" : "=a"(lo), "=d"(hi) : "c"(msr));
+    return ((uint64_t)hi << 32) | lo;
+}
+
+#define IA32_EFER 0xC0000080
+#define EFER_LMA (1 << 10)
+
+int is_long_mode_active(void) {
+    uint64_t efer = read_msr(IA32_EFER);
+    return (efer & EFER_LMA) != 0;
+}
+
 void kernel_main(void) {
     init_serial();
     if (!test_serial()) {
@@ -17,4 +31,10 @@ void kernel_main(void) {
         return;
     }
     serial_log(S_LOG, "Init serial succesfully.");
+
+    if (!is_long_mode_active()) {
+        serial_log(S_ERR, "Kernel is not in long mode!");
+        return;
+    }
+    serial_log(S_LOG, "Kernel is in long mode.");
 }

src/limine.conf

@@ -0,0 +1,3 @@
+/SimpleKernel
+    protocol: multiboot1
+    kernel_path: boot():/boot/kernel