[patch 20/24] Xen-paravirt_ops: Add early printk support via hvc console

[Jeremy Fitzhardinge <jeremy@goop.org>]

[-- Attachment #1: xen-hvc-earlyprintk.patch --]
[-- Type: text/plain, Size: 1910 bytes --]

Add early printk support via hvc console, enable using
"earlyprintk=xen" on the kernel command line.

From: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>

---
 arch/x86_64/kernel/early_printk.c |    8 ++++++++
 drivers/xen/console/hvc_xen.c     |   24 ++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

===================================================================
--- a/arch/x86_64/kernel/early_printk.c
+++ b/arch/x86_64/kernel/early_printk.c
@@ -196,6 +196,10 @@ static struct console simnow_console = {
 	.flags =	CON_PRINTBUFFER,
 	.index =	-1,
 };
+
+#ifdef CONFIG_XEN
+extern struct console xenboot_console;
+#endif
 
 /* Direct interface for emergencies */
 struct console *early_console = &early_vga_console;
@@ -243,6 +247,10 @@ static int __init setup_early_printk(cha
  		simnow_init(buf + 6);
  		early_console = &simnow_console;
  		keep_early = 1;
+#ifdef CONFIG_XEN
+	} else if (!strncmp(buf, "xen", 3)) {
+ 		early_console = &xenboot_console;
+#endif
 	}
 
 	if (keep_early)
===================================================================
--- a/drivers/xen/hvc-console.c
+++ b/drivers/xen/hvc-console.c
@@ -133,3 +133,27 @@ module_init(xen_init);
 module_init(xen_init);
 module_exit(xen_fini);
 console_initcall(xen_cons_init);
+
+static void xenboot_write_console(struct console *console, const char *string,
+				  unsigned len)
+{
+	unsigned int linelen, off = 0;
+	const char *pos;
+
+	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
+		linelen = pos-string+off;
+		if (off + linelen > len)
+			break;
+		write_console(0, string+off, linelen);
+		write_console(0, "\r\n", 2);
+		off += linelen + 1;
+	}
+	if (off < len)
+		write_console(0, string+off, len-off);
+}
+
+struct console xenboot_console = {
+	.name		= "xenboot",
+	.write		= xenboot_write_console,
+	.flags		= CON_PRINTBUFFER | CON_BOOT,
+};

--