From a0470f561bcaa4de8ca4a85ceb5ebe58495bdeeb Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sat, 11 Sep 2004 23:17:23 +0000
Subject: [PATCH] Turn off interrupts on output to lock out interrupt handlers
that might want to write to the console.
---
src/devices/vga.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/devices/vga.c b/src/devices/vga.c
index bc2d6b7..8ab08f6 100644
--- a/src/devices/vga.c
+++ b/src/devices/vga.c
@@ -5,6 +5,7 @@
#include <string.h>
#include "threads/io.h"
#include "threads/mmu.h"
+#include "threads/interrupt.h"
/* VGA text screen support. See [FREEVGA] for more information. */
@@ -38,10 +39,14 @@ vga_init (void)
}
/* Writes C to the VGA text display, interpreting control
- characters in the conventional ways. */
+ characters in the conventional ways. */
void
vga_putc (int c)
{
+ /* Disable interrupts to lock out interrupt handlers
+ that might write to the console. */
+ enum intr_level old_level = intr_disable ();
+
switch (c)
{
case '\n':
@@ -77,6 +82,8 @@ vga_putc (int c)
/* Update cursor position. */
move_cursor ();
+
+ intr_set_level (old_level);
}
/* Clears the screen and moves the cursor to the upper left. */
--
2.30.2