[Xen-devel] [PATCH 05/22] char: optionally redirect {, g}printk output to QEMU debug log

[Anthony Liguori <aliguori@xxxxxxxx>]

From: Matt Wilson <msw@xxxxxxxxxx>

When using Vixen, it is helpful to get the Xen messages in a
separate channel than the console output.  Add an option to
output to the QEMU backdoor logging port.

Signed-off-by: Matt Wilson <msw@xxxxxxxxxx>
Signed-off-by: Anthony Liguori <aliguori@xxxxxxxxxx>
---
 xen/drivers/char/console.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 19d0e74..b9412c5 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -85,6 +85,11 @@ static int __read_mostly sercon_handle = -1;
 
 static DEFINE_SPINLOCK(console_lock);
 
+/* send all printk output to QEMU debug log. Input does not change,
+ * nor does dom0 output.
+ */
+static bool_t __read_mostly qemu_debug = false;
+
 /*
  * To control the amount of printing, thresholds are added.
  * These thresholds correspond to the XENLOG logging levels.
@@ -564,10 +569,21 @@ static void __putstr(const char *str)
 {
     ASSERT(spin_is_locked(&console_lock));
 
-    sercon_puts(str);
-    video_puts(str);
+    if ( qemu_debug )
+    {
+        char c;
+        while ( (c = *str++) != '\0' )
+        {
+            outb(c, 0x12);
+        }
+    }
+    else
+    {
+        sercon_puts(str);
+        video_puts(str);
 
-    conring_puts(str);
+        conring_puts(str);
+    }
 
     if ( !console_locks_busted )
         tasklet_schedule(&notify_dom0_con_ring_tasklet);
@@ -762,6 +778,8 @@ void __init console_init_preirq(void)
             p++;
         if ( !strncmp(p, "vga", 3) )
             video_init();
+        else if ( !strncmp(p, "qemu", 4) )
+            qemu_debug = true;
         else if ( !strncmp(p, "none", 4) )
             continue;
         else if ( (sh = serial_parse_handle(p)) >= 0 )
-- 
1.9.1


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel