added STACK_INITIAL_SIZE to control the number of initial stack pages; added BUILD_BUG_ON() macro to catch compile-time errors

git-svn-id: svn://anubis/hos/trunk@88 5b3e749e-e535-0410-8002-a9bb6afbdfca

kernel/mm/stack.cc

@@ -9,6 +9,11 @@ void stack_bootstrap()
      * running from our temporary stack while segmentation is enabled,
      * set up the "permanent" stack for use while paging
      */
-    u32_t first_stack_page_base = mm_early_page_alloc();
-    mm_early_map(KERNEL_STACK_TOP - PAGE_SIZE, first_stack_page_base, 0, 1);
+    u32_t stack_page_virt = KERNEL_STACK_TOP - PAGE_SIZE;
+    for (int i = 0; i < STACK_INITIAL_SIZE; i++)
+    {
+        u32_t stack_page_phys = mm_early_page_alloc();
+        mm_early_map(stack_page_virt, stack_page_phys, 0, 1);
+        stack_page_virt -= PAGE_SIZE;
+    }
 }

kernel/mm/stack.h

@@ -2,6 +2,8 @@
 #ifndef STACK_H
 #define STACK_H
 
+#define STACK_INITIAL_SIZE 2        /* number of initial stack pages */
+
 void stack_bootstrap();
 
 #endif