实验3环境初始化

Makefile里的gdb和之前不一样了！要添加$(QEMUOPTS)，不然会导致没有挂载交换分区。

labcodes_answer/lab3_result/Makefile

@@ -210,7 +210,8 @@ endif
 # files for grade script
 
 TARGETS: $(TARGETS)
-
+targets: $(TARGETS)
+all: $(TARGETS)
 .DEFAULT_GOAL := TARGETS
 
 QEMUOPTS = -hda $(UCOREIMG) -drive file=$(SWAPIMG),media=disk,cache=writeback
@@ -225,7 +226,8 @@ qemu-nox: $(UCOREIMG) $(SWAPIMG)
 	$(V)$(QEMU) -serial mon:stdio $(QEMUOPTS) -nographic
 
 TERMINAL := gnome-terminal
-
+gdb: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -S -s -parallel stdio $(QEMUOPTS) -serial null
 debug: $(UCOREIMG) $(SWAPIMG)
 	$(V)$(QEMU) -S -s -parallel stdio $(QEMUOPTS) -serial null &
 	$(V)sleep 2

labcodes_answer/lab3_result/kern/mm/vmm.c

@@ -260,13 +260,32 @@ check_pgfault(void) {
         *(char *)(addr + i) = i;
         sum += i;
     }
+
+    for (i = 0; i < 100; i ++) {
+        	// 获取页目录项和页表项
+        	    pte_t *pte = get_pte(pgdir, addr + i, 0);
+        	    if (pte != NULL && (*pte & PTE_P)) {
+        	        // 检查访问位
+        	        if (*pte & PTE_A) {
+        	            // A 位已置位
+        	            cprintf("Access bit is set.\n");
+        	        } else {
+        	            // A 位未置位
+        	            cprintf("Access bit is not set.\n");
+        	        }
+        	    } else {
+        	        // 页表项不存在或未呈现
+        	        cprintf("PTE not present.\n");
+        	    }
+            }
+
     for (i = 0; i < 100; i ++) {
         sum -= *(char *)(addr + i);
     }
     assert(sum == 0);
 
     page_remove(pgdir, ROUNDDOWN(addr, PGSIZE));
-    free_page(pde2page(pgdir[0]));
+    free_page(pa2page(pgdir[0]));
     pgdir[0] = 0;
 
     mm->pgdir = NULL;