[PATCH] x86: fix to parse multiboot command line passed by latest grub

[Wei Yongjun <yjwei@cn.fujitsu.com>]

latest grub had changed to "don't pass filename in multiboot
command line".

The old cmdline format is: "module-name options..."
The new cmdline format is: "options..."

So xen + grub2 always loss the first option, because xen will
skip the first option.

Usually, the module-name is not start with char [a-zA-Z], such
as /boot/vmlinuz, (hd0,1)/boot/vmlinuz, so this patch added
isalpha() test of the first char of modulename/option to
function cmdline_cook(), try to handle both the old and new
cmdline format.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -423,6 +423,8 @@
     p = p ? : "";
     while ( *p == ' ' )
         p++;
+    if (isalpha(*p))
+        return p;
     while ( (*p != ' ') && (*p != '\0') )
         p++;
     while ( *p == ' ' )