setup stack

boot/main.asm

@@ -21,22 +21,20 @@
     call print_str
     call pm_switch
 
-    jmp $                           ; hang. this shouldn't happen
+    jmp $                           ; hang. this should never happen
 
 load_kernel:
     mov bx, KERNEL_OFFSET
     mov dh, 16
     mov dl, [BOOT_DISK]
     call disk_read
-
     ret
 
 [bits 32]
 
 pm_begin:
    jmp KERNEL_OFFSET
 
-
 BOOT_DISK:
     db 0
 
@@ -57,6 +55,6 @@ PROT_MODE_MSG:
 %include "gdt.asm"
 %include "pm.asm"
  
-times 510-($-$$) db 0
-dw 0xaa55
+times 510-($-$$) db 0               ; empty
+dw 0xaa55                           ; magic number
 

boot/pm.asm

@@ -19,8 +19,5 @@ pm_init:
     mov fs, ax
     mov gs, ax
 
-    mov ebp, 0x9000
-    mov esp, ebp
-
     call pm_begin
 

kernel/entry.asm

@@ -1,10 +1,15 @@
 [bits 32]
+[global start]
 [extern kmain]
-_start:
+start:
+    ; initialise stack
+    mov esp, sys_stack
     call kmain
     jmp $               ; this should happen when returning from kernel main
                         ; shutdown?
 
+; multiboot headers to be put here
+
 ; loads interrupt descriptor table
 [global idt_load]
 [extern idtp]
@@ -429,3 +434,8 @@ irq15:
     push byte 47
     jmp irq_common_stub
 
+; bss definition
+section .bss
+    resb 8192               ; stack grows downwards. so reserve space,
+sys_stack:                  ; and then declare the identifier
+

kernel/link.ld

@@ -1,31 +1,30 @@
-ENTRY(_start)
+ENTRY(start)
+_start_ = 0x1000;
 
 SECTIONS
 {
-	. = 0x1000;
-
-	.text BLOCK(1K) : ALIGN(1K)
+	.text _start_ :
 	{
+        _code_ = .;
 		*(.text)
-	}
-
-	/* Read-only data. */
-	.rodata BLOCK(1K) : ALIGN(1K)
-	{
 		*(.rodata)
+        . = ALIGN(4K);
 	}
 
-	/* Read-write data (initialized) */
-	.data BLOCK(1K) : ALIGN(1K)
+	.data :
 	{
+        _data_ = .;
 		*(.data)
+        . = ALIGN(4K);
 	}
 
-	/* Read-write data (uninitialized) and stack */
-	.bss BLOCK(1K) : ALIGN(1K)
+	.bss :
 	{
-		*(COMMON)
+        _bss_ = .;
 		*(.bss)
+        . = ALIGN(8K);
 	}
+
+    _end_ = .;
 }