When invoking an LE kernel from a BE boot loader or vice versa
the ATAG_CMDLINE command line will be byte swapped, other ATAGs
are fine because they are 32 bit values.

This patch adds support for a command line option "swx " - which
must be at the start of the command line - and which is used to
detect a need to byte swap the rest of the command line.

Signed-off-by: John Bowler <jbowler@acm.org>

 arch/arm/kernel/setup.c |   29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

--- linux-nslu2.orig/arch/arm/kernel/setup.c	2006-02-06 20:37:00.000000000 +0100
+++ linux-nslu2/arch/arm/kernel/setup.c	2006-02-06 21:49:18.000000000 +0100
@@ -660,7 +660,34 @@ __tagtable(ATAG_REVISION, parse_tag_revi
 
 static int __init parse_tag_cmdline(const struct tag *tag)
 {
-	strlcpy(default_command_line, tag->u.cmdline.cmdline, COMMAND_LINE_SIZE);
+	/* Check the first four bytes for "swx " (swap, but it's
+	 * ok) or " xws" (command line is byte swapped)
+	 */
+	const char *cmdline = tag->u.cmdline.cmdline;
+	u32 size = tag->hdr.size;
+
+	if (size > 0 && !memcmp(cmdline, " xws", 4)) {
+		cmdline += 4;
+
+		if (--size > 0) {
+			const u32 *from = (const u32*)cmdline;
+			u32 *to = (u32*)default_command_line;
+
+			if (size > COMMAND_LINE_SIZE/4)
+				size = COMMAND_LINE_SIZE/4;
+
+			while (size-- > 0)
+				to[size] = swab32(from[size]);
+
+			default_command_line[COMMAND_LINE_SIZE-1] = 0;
+			return 0;
+		}
+	}
+
+	if (size > 0 && !memcmp(cmdline, "swx ", 4))
+		cmdline += 4;
+
+	strlcpy(default_command_line, cmdline, COMMAND_LINE_SIZE);
 	return 0;
 }