From: Gerd Hoffmann <kraxel@redhat.com>
Subject: [RHEL-5.1 PATCH 2/10] xen: bimodal drivers, pvfb frontend
Date: Fri, 15 Jun 2007 10:28:36 +0200
Bugzilla: 222128
Message-Id: <46724DB4.40905@redhat.com>
Changelog: [xen] bimodal drivers, pvfb frontend


  Hi,

Starting with Xen 3.1 the 64bit hypervisor can run 32bit-pae paravirtual 
guests.  Some paravirtual drivers have different data structures in 
32bit vs. 64bit mode.  Thus the backend drivers must be bimodal, i.e.

  (a) must be able to deal with multiple protocols.
  (b) need to know which protocol the frontend driver speaks.

This patch makes the paravirt framebuffer frontend driver signal the 
protocol it speaks by adding a node to xenstore.

cheers,
  Gerd

# HG changeset patch
# User kfraser@localhost.localdomain
# Date 1169563646 0
# Node ID b9ffa4b49d9711edba34d490a2263fd909b2acfe
# Parent  ffe52263b430cff6cd31237f5872c71a3622306b
bimodal: pvfb frontend

Create a new node "protocol" in xenstore, add the protocol name it
speaks there.

Signed-off-by: Gerd Hoffmann <kraxel@suse.de>

---
 drivers/xen/fbfront/xenfb.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Index: linux-2.6.18.noarch/drivers/xen/fbfront/xenfb.c
===================================================================
--- linux-2.6.18.noarch.orig/drivers/xen/fbfront/xenfb.c
+++ linux-2.6.18.noarch/drivers/xen/fbfront/xenfb.c
@@ -27,6 +27,7 @@
 #include <asm/hypervisor.h>
 #include <xen/evtchn.h>
 #include <xen/interface/io/fbif.h>
+#include <xen/interface/io/protocols.h>
 #include <xen/xenbus.h>
 #include <linux/kthread.h>
 
@@ -416,7 +417,7 @@ static int __devinit xenfb_probe(struct 
 		goto error_nomem;
 
 	/* set up shared page */
-	info->page = (void *)__get_free_page(GFP_KERNEL);
+	info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 	if (!info->page)
 		goto error_nomem;
 
@@ -580,6 +581,10 @@ static int xenfb_connect_backend(struct 
 			    info->evtchn);
 	if (ret)
 		goto error_xenbus;
+	ret = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
+			    XEN_IO_PROTO_ABI_NATIVE);
+	if (ret)
+		goto error_xenbus;
 	ret = xenbus_printf(xbt, dev->nodename, "feature-update", "1");
 	if (ret)
 		goto error_xenbus;