gets the memory map from GRUB

kernel/arch/link.ld

@@ -19,6 +19,7 @@ SECTIONS
 	 */
 	.text BLOCK(4K) : ALIGN(4K) /* The first section we want is the text section, this is where most code is */
 	{
+		text_start = .;
 		*(.multiboot) /* Multiboot needs to be early in the file, required by grub */
 		*(.text) /* The text section */
 	}
@@ -33,12 +34,16 @@ SECTIONS
 	.data BLOCK(4K) : ALIGN(4K)
 	{
 		*(.data)
+		end_data = .;
 	}
 
 	/* BSS */
 	.bss BLOCK(4K) : ALIGN(4K)
 	{
+		sbss = .;
 		*(COMMON)
 		*(.bss)
+		ebss = .;
+		endkernel = .;
 	}
 }