From 61eaf539b9fb4926ed57e38f6545100c3432cf1b Mon Sep 17 00:00:00 2001
From: Jason Wessel <jason.wessel@windriver.com>
Date: Thu, 20 May 2010 21:04:31 -0500
Subject: [PATCH] earlyprintk,vga,kdb: Fix \b and \r for earlyprintk=vga with
 kdb

Allow kdb to work properly with with earlyprintk=vga by interpreting
the backspace and carriage return output characters.  These
interpretation of these characters is used for simple line editing
provided in the kdb shell.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@redhat.com>
CC: H. Peter Anvin <hpa@zytor.com>
CC: x86@kernel.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
 arch/x86/kernel/early_printk.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index b9c830c12b4a..fa99bae75ace 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -41,6 +41,14 @@ static void early_vga_write(struct console *con, const char *str, unsigned n)
 				writew(0x720, VGABASE + 2*(max_xpos*j + i));
 			current_ypos = max_ypos-1;
 		}
+#ifdef CONFIG_KGDB_KDB
+		if (c == '\b') {
+			if (current_xpos > 0)
+				current_xpos--;
+		} else if (c == '\r') {
+			current_xpos = 0;
+		} else
+#endif
 		if (c == '\n') {
 			current_xpos = 0;
 			current_ypos++;