[PATCH v2 3/3] xen/arm: allow console=hvc0 to be omitted for guests

[julien.grall@linaro.org (Julien Grall)]

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

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>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
---
 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 1660432..904bd2d 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>
 
@@ -255,6 +256,9 @@ void __init xen_early_init(void)
 		xen_start_info->flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
 	else
 		xen_start_info->flags &= ~(SIF_INITDOMAIN|SIF_PRIVILEGED);
+
+	if (!console_set_on_cmdline && !xen_initial_domain())
+		add_preferred_console("hvc", 0, NULL);
 }
 
 static int __init xen_guest_init(void)
-- 
2.1.4