Use 4Mbyte pages during boot

entry.S

@@ -39,6 +39,11 @@ multiboot_header:
 # Multiboot entry point.  Machine is mostly set up.
 .globl multiboot_entry
 multiboot_entry:
+  # Turn on page size extension for 4Mbyte pages
+  movl    %cr4, %eax
+  orl     $(CR4_PSE), %eax
+  movl    %eax, %cr4
+  # Set page directory
   movl    $(V2P_WO(bootpgdir)), %eax
   movl    %eax, %cr3
   # Turn on paging.

entryother.S

@@ -50,6 +50,10 @@ start32:
   movw    %ax, %fs
   movw    %ax, %gs
 
+  # Turn on page size extension for 4Mbyte pages
+  movl    %cr4, %eax
+  orl     $(CR4_PSE), %eax
+  movl    %eax, %cr4
   # Use bootpgdir as our initial page table
   movl    (start-12), %eax
   movl    %eax, %cr3
@@ -58,7 +62,7 @@ start32:
   orl     $(CR0_PE|CR0_PG|CR0_WP), %eax
   movl    %eax, %cr0
 
-  # Switch to the stack allocated by entryothers()
+  # Switch to the stack allocated by enterothers()
   movl    (start-4), %esp
   # Call mpboot()
   call	 *(start-8)

mmu.h

@@ -37,6 +37,8 @@
 #define CR0_CD		0x40000000	// Cache Disable
 #define CR0_PG		0x80000000	// Paging
 
+#define CR4_PSE         0x00000010	// Page size extension
+
 #define SEG_KCODE 1  // kernel code
 #define SEG_KDATA 2  // kernel data+stack
 #define SEG_KCPU  3  // kernel per-cpu data