X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fthreads%2Floader.S;h=535c442c4f1f39a0d59cf43aa51c0e3cc8beee33;hb=c9c283cb3e26a5b6d918ee47dcf8efe28522b18d;hp=5a0262b58733315296f85ae9ff429711c8d81854;hpb=8e05e0a5473ccd3988c98f95e5ec3afad225685b;p=pintos-anon

diff --git a/src/threads/loader.S b/src/threads/loader.S
index 5a0262b..535c442 100644
--- a/src/threads/loader.S
+++ b/src/threads/loader.S
@@ -1,5 +1,6 @@
-#include "mmu.h"
 #include "loader.h"
+#include "mmu.h"
+#include "gdt.h"
 	
 ##############################################################################
 # Kernel loader.
@@ -12,6 +13,11 @@
 # first byte of the kernel, where start.S is linked.
 ##############################################################################
 	
+/* Flags in control register 0 */
+#define CR0_PE 0x00000001      /* Protection Enable. */
+#define CR0_EM 0x00000004      /* (Floating-point) Emulation. */
+#define CR0_PG 0x80000000      /* Paging. */
+
 .globl start				# Entry point	
 start:	.code16				# This runs in real mode
 	cli				# Disable interrupts
@@ -133,33 +139,33 @@ read_sector:
 	cmpl $KERNEL_LOAD_PAGES*8 + 1, %ebx
 	jnz read_sector
 
-##### Create temporary PDE and PTE, set page directory pointer, and turn
-##### on paging.
+##### Create temporary page directory and page table, set page
+##### directory pointer, and turn on paging.
 ##### FIXME? We could use a single 4 MB page instead of 1024 4 kB pages.
 
-	# Create PDE at 64 kB.
+	# Create page directory at 64 kB.
 	movl $0x10000, %edi		
 	movl %edi, %cr3
 
-	# Fill PDE with zeroes.
+	# Fill page directory with zeroes.
 	subl %eax, %eax
 	movl $0x400, %ecx
 	rep stosl
 
-	# Set PDE entries for 0 and LOADER_PHYS_BASE to point to the
-	# PTE.
+	# Set PDEs for 0 and LOADER_PHYS_BASE to point to the
+	# page table.
 	movl $0x11000 | PG_U | PG_W | PG_P, %eax
 	movl %eax, 0x10000
 	movl %eax, 0x10000 | (LOADER_PHYS_BASE >> 20)
 
-	# Initialize PTE.
+	# Initialize page table.
 	movl $PG_U | PG_W | PG_P, %eax
 	movl $0x400, %ecx
 1:	stosl
 	addl $0x1000, %eax
 	loop 1b
 
-	# Enable paging.
+	# Turn on paging.
 	movl %cr0, %eax
 	orl $CR0_PG, %eax
 	movl %eax, %cr0
@@ -206,17 +212,17 @@ panicmsg:
 	.byte 0
 
 ##### Memory size in 4 kB pages.
-	.org LOADER_RAM_PAGES
+	.org LOADER_RAM_PAGES - LOADER_BASE
 ram_pages:
 	.long 0
 
 ##### Command-line arguments inserted by another utility.
 ##### The loader doesn't use these, but we note their
 ##### location here for easy reference.
-	.org LOADER_CMD_LINE
+	.org LOADER_CMD_LINE - LOADER_BASE
 cmd_line:
 	.fill 0x80, 1, 0
 
 ##### Boot-sector signature for BIOS inspection.
-	.org LOADER_BIOS_SIG
+	.org LOADER_BIOS_SIG - LOADER_BASE
 	.word 0xaa55