xen: add virtual network device driver

The network device frontend driver allows the kernel to access network
devices exported exported by a virtual machine containing a physical
network device driver.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Acked-by: Jeff Garzik <jeff@garzik.org>
Cc: Ian Pratt <ian.pratt@xensource.com>
Cc: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
Cc: netdev@vger.kernel.org

drivers/net/Kconfig

@@ -2486,6 +2486,18 @@ source "drivers/atm/Kconfig"
 
 source "drivers/s390/net/Kconfig"
 
+config XEN_NETDEV_FRONTEND
+	tristate "Xen network device frontend driver"
+	depends on XEN
+	default y
+	help
+	  The network device frontend driver allows the kernel to
+	  access network devices exported exported by a virtual
+	  machine containing a physical network device driver. The
+	  frontend driver is intended for unprivileged guest domains;
+	  if you are compiling a kernel for a Xen guest, you almost
+	  certainly want to enable this.
+
 config ISERIES_VETH
 	tristate "iSeries Virtual Ethernet driver support"
 	depends on PPC_ISERIES

drivers/net/Makefile

@@ -127,6 +127,8 @@ obj-$(CONFIG_PPPOL2TP) += pppox.o pppol2tp.o
 obj-$(CONFIG_SLIP) += slip.o
 obj-$(CONFIG_SLHC) += slhc.o
 
+obj-$(CONFIG_XEN_NETDEV_FRONTEND) += xen-netfront.o
+
 obj-$(CONFIG_DUMMY) += dummy.o
 obj-$(CONFIG_IFB) += ifb.o
 obj-$(CONFIG_MACVLAN) += macvlan.o