[PATCH] Fix builtin command line interaction with firmware

It seems that prom_init's early_cmdline_parse is broken on at least
Apple 970 xserves and IBM JS20 blades with SLOF.  The firmware of these
machines returns -1 and 1 respectively when getprop is called for the
bootargs property of /chosen, causing Linux to ignore its builtin
command line in favor of a null string.  This patch makes Linux use its
builtin command line if getprop returns an error or a null string.

Signed-off-by: Amos Waterland <redacted>

---

 arch/powerpc/kernel/prom_init.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

0f0caf0342f39b4437dcb3e9f2f1d62bfb4e3e7d

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index f70bd09..2e63a90 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c

@@ -574,7 +574,7 @@ static void __init early_cmdline_parse(v
 	if ((long)_prom->chosen > 0)
 		l = prom_getprop(_prom->chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
 #ifdef CONFIG_CMDLINE
-	if (l == 0) /* dbl check */
+	if (l <= 0 || p[0] == '\0') /* dbl check */
 		strlcpy(RELOC(prom_cmd_line),
 			RELOC(CONFIG_CMDLINE), sizeof(prom_cmd_line));
 #endif /* CONFIG_CMDLINE */

-- 
1.0.4

It seems that prom_init's early_cmdline_parse is broken on at least
Apple 970 xserves and IBM JS20 blades with SLOF.  The firmware of  
these
machines returns -1 and 1 respectively when getprop is called for the
bootargs property of /chosen, causing Linux to ignore its builtin
command line in favor of a null string.  This patch makes Linux use  
its
builtin command line if getprop returns an error or a null string.

If the user gave no boot arguments on the boot command, -1 and 1
are the only two valid return values even, and -1 is only valid
if no "boot" or "load" command was used to load the kernel.
Makes me wonder what those XServe's do ;-)

(0 isn't valid as the property is encoded with encode-string, which
puts a trailing 0 byte on the empty string.  Doesn't hurt to check
for it anyway of course ;-) ).

Signed-off-by: Amos Waterland <redacted>

Looks good, thanks!

Acked-by: Segher Boessenkool <redacted>