...

src/arch/x86_64/boot/boot.asm

@@ -39,20 +39,17 @@ section .data
 section .data
     align 8
     multiboot_info:
-        dq 0
+        dd 0
+    multiboot_magic:
+        dd 0
 
 section .text
     bits 32
     _start:
         mov esp, stack_top
 
-        ; Multiboot will place a magic value in eax
-        ; If this magic value is not present, then we might not have multiboot info in ebx,
-        ; therefore we throw an error
-        cmp eax, 0x2BADB002
-        jne error
-
         ; Save multiboot info pointer for later
+        mov [multiboot_magic], eax
         mov [multiboot_info], ebx
 
         ; Check if cpuid is available by flipping bit 21
@@ -150,7 +147,8 @@ section .text
         mov ss, ax
 
         ; Finally, we call in to c
-        mov rdi, [multiboot_info]
+        mov edi, [multiboot_magic]
+        mov esi, [multiboot_info]
         call entry
     .hang:
         hlt

src/arch/x86_64/entry.c

@@ -6,14 +6,27 @@
 #include "multiboot.h"
 #include "util.h"
 #include "vga.h"
+#include <stdint.h>
 #include <stdio.h>
 
-void entry(multiboot_info_t* mbd)
+void entry(uint32_t magic, multiboot_info_t* info)
 {
+    if (magic != 0x2BADB002)
+    {
+        printf("Multiboot magic does not match");
+        panic();
+    }
+
+    if (info == NULL)
+    {
+        printf("Multiboot info is NULL");
+        panic();
+    }
+
     vga_clear();
     idt_init();
     remap_pic();
-    map_memory(mbd);
+    map_memory(info);
     enable_interrupts();
     main();
 }

src/arch/x86_64/mmap.c

@@ -9,9 +9,9 @@ memory_map_t memory_map;
 
 static memory_region_t usable_regions[USABLE_REGION_SIZE];
 
-void map_memory(multiboot_info_t* mbd)
+void map_memory(multiboot_info_t* info)
 {
-    if (!(mbd->flags & (1 << 6)))
+    if (!(info->flags & (1 << 6)))
     {
         printf("Invalid memory map given by bootloader\n");
         panic();
@@ -20,9 +20,9 @@ void map_memory(multiboot_info_t* mbd)
     size_t num_regions = 0;
 
     uint64_t offset = 0;
-    while (offset < mbd->mmap_length)
+    while (offset < info->mmap_length)
     {
-        multiboot_memory_map_t* mmmt = (multiboot_memory_map_t*)(mbd->mmap_addr + offset);
+        multiboot_memory_map_t* mmmt = (multiboot_memory_map_t*)(info->mmap_addr + offset);
 
         if (mmmt->type == MULTIBOOT_MEMORY_AVAILABLE)
         {