[PATCH] xen/arm: allow console=hvc0 to be omitted for guests

[ard.biesheuvel@linaro.org (Ard Biesheuvel)]

This patch registers hvc0 as the preferred console if no console
has been specified explicitly on the kernel command line.

The purpose is to allow platform agnostic kernels and boot images
(such as distro installers) to boot in a Xen/ARM domU without the
need to modify the command line by hand.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---

This applies on top of the patch Julien is cooking up to move the
call to xen_guest_init() to an earlier boot stage. This needs to
be at least before the call to console_init() in start_kernel()
for this patch to do anything meaningful.

 arch/arm/xen/enlighten.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index c7ca936ebd99..61382cafa877 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -24,6 +24,7 @@
 #include <linux/cpuidle.h>
 #include <linux/cpufreq.h>
 #include <linux/cpu.h>
+#include <linux/console.h>
 
 #include <linux/mm.h>
 
@@ -322,6 +323,9 @@ static int __init xen_guest_init(void)
 
 	register_cpu_notifier(&xen_cpu_notifier);
 
+	if (!console_set_on_cmdline)
+		add_preferred_console("hvc", 0, NULL);
+
 	return 0;
 }
 early_initcall(xen_guest_init);
-- 
1.8.3.2