From: Ben Pfaff <blp@cs.stanford.edu>
Date: Wed, 1 Sep 2004 06:14:50 +0000 (+0000)
Subject: Add comments.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ef354f070fc0389e697be0d2d2553f5a87934ae;p=pintos-anon

Add comments.
---

diff --git a/src/threads/interrupt.h b/src/threads/interrupt.h
index e7cd635..7084bf1 100644
--- a/src/threads/interrupt.h
+++ b/src/threads/interrupt.h
@@ -4,6 +4,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+/* Interrupts on or off? */
 enum intr_level 
   {
     INTR_OFF,             /* Interrupts disabled. */
@@ -15,30 +16,36 @@ enum intr_level intr_set_level (enum intr_level);
 enum intr_level intr_enable (void);
 enum intr_level intr_disable (void);
 
+/* Interrupt stack frame. */
 struct intr_frame
   {
-    /* Pushed by the stubs. */
-    uint32_t edi;
-    uint32_t esi;
-    uint32_t ebp;
-    uint32_t esp_dummy;
-    uint32_t ebx;
-    uint32_t edx;
-    uint32_t ecx;
-    uint32_t eax;
-    uint16_t es, :16;
-    uint16_t ds, :16;
-    uint32_t vec_no;
-
-    /* Sometimes pushed by the CPU, otherwise by the stubs. */
-    uint32_t error_code;
-
-    /* Pushed by the CPU. */
-    void (*eip) (void);
-    uint16_t cs, :16;
-    uint32_t eflags;
-    void *esp;
-    uint16_t ss, :16;
+    /* Pushed by intr_entry in intr-stubs.S (see intr-stubs.pl).
+       These are the interrupted task's saved registers. */
+    uint32_t edi;               /* Saved EDI. */
+    uint32_t esi;               /* Saved ESI. */
+    uint32_t ebp;               /* Saved EBP. */
+    uint32_t esp_dummy;         /* Not used. */
+    uint32_t ebx;               /* Saved EBX. */
+    uint32_t edx;               /* Saved EDX. */
+    uint32_t ecx;               /* Saved ECX. */
+    uint32_t eax;               /* Saved EAX. */
+    uint16_t es, :16;           /* Saved ES segment register. */
+    uint16_t ds, :16;           /* Saved DS segment register. */
+
+    /* Pushed by intrXX_stub in intr-stubs.S (see intr-stubs.pl). */
+    uint32_t vec_no;            /* Interrupt vector number. */
+
+    /* Sometimes pushed by the CPU,
+       otherwise by intrXX_stub for consistency. */
+    uint32_t error_code;        /* Error code. */
+
+    /* Pushed by the CPU.
+       These are the interrupted task's saved registers. */
+    void (*eip) (void);         /* Current or next instruction. */
+    uint16_t cs, :16;           /* Code segment for eip. */
+    uint32_t eflags;            /* Saved CPU flags. */
+    void *esp;                  /* Saved stack pointer. */
+    uint16_t ss, :16;           /* Data segment for esp. */
   };
 
 typedef void intr_handler_func (struct intr_frame *);
diff --git a/src/threads/intr-stubs.pl b/src/threads/intr-stubs.pl
index 6ac5a8d..472b125 100755
--- a/src/threads/intr-stubs.pl
+++ b/src/threads/intr-stubs.pl
@@ -31,7 +31,6 @@ for $i (0...255) {
 
 print <<'EOF';
 intr_entry:
-	# FIXME: build a fake stack frame to improve backtraces.
 	# Save caller's registers.
 	pushl %ds
 	pushl %es