[build] Drag in Xen and Hyper-V support via network device drivers

Include Xen and Hyper-V support in the all-drivers build by dragging
in the netfront and netvsc drivers, since these are the functional
drivers that provide network interfaces.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/Makefile

@@ -246,13 +246,16 @@ version :
 DRIVERS_ipxe	+= $(DRIVERS_isa_net)
 DRIVERS_ipxe	+= $(DRIVERS_pci_net)
 DRIVERS_ipxe	+= $(DRIVERS_pci_infiniband)
-DRIVERS_ipxe	+= $(DRIVERS_pci_xen)
-DRIVERS_ipxe	+= $(DRIVERS_hyperv)
 
 # Raspberry Pi
 #
 DRIVERS_rpi	+= smsc95xx lan78xx
 
+# Virtualised NIC drivers with hypervisor-specific bus types
+#
+DRIVERS_vmbus_net	+= netvsc
+DRIVERS_xenbus_net	+= netfront
+
 ###############################################################################
 #
 # Drag in the bulk of the build system

src/arch/x86/Makefile

@@ -29,6 +29,10 @@ CFLAGS		+= -DNVALGRIND
 #
 CFLAGS_lkrnprefix	+= -DVERSION="\"$(VERSION)\""
 
+# Include Xen driver in the all-drivers build
+#
+DRIVERS_ipxe		+= $(DRIVERS_xenbus_net)
+
 # Include Hyper-V driver in the all-drivers build
 #
-DRIVERS_hyperv += hyperv
+DRIVERS_ipxe		+= $(DRIVERS_vmbus_net)

src/interface/xen/xenbus.c

@@ -400,3 +400,9 @@ void xenbus_remove ( struct xen_hypervisor *xen __unused,
 		xenbus_remove_device ( xendev );
 	}
 }
+
+/* Drag in objects via xenbus_set_state() */
+REQUIRING_SYMBOL ( xenbus_set_state );
+
+/* Drag in backing hardware device */
+REQUIRE_OBJECT ( hvm );