linux-kernel - [PATCH 6/8] earlyprintk,vga,kdb: Fix \b and \r for earlyprintk=vga with kdb

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Message-Id: <1266014369-29547-7-git-send-email-jason.wessel@windriver.com>
Date:	Fri, 12 Feb 2010 16:39:27 -0600
From:	Jason Wessel <jason.wessel@...driver.com>
To:	linux-kernel@...r.kernel.org
Cc:	kgdb-bugreport@...ts.sourceforge.net, mingo@...e.hu,
	Jason Wessel <jason.wessel@...driver.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: [PATCH 6/8] 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@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: H. Peter Anvin <hpa@...or.com>
CC: x86@...nel.org
Signed-off-by: Jason Wessel <jason.wessel@...driver.com>
---
 arch/x86/kernel/early_printk.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index b9c830c..fa99bae 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++;
-- 
1.6.4.rc1

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