Use a property to enable the eth0 LAN port on the emulator

Change-Id: I26f4ec7fac9b7a8ad3013914967cf0f8fdec91ff

target/board/generic_x86/buildspec-generic_x86.mk

@@ -1,3 +1,7 @@
 BUILD_ENV_SEQUENCE_NUMBER := 9
 DISABLE_DEXPREOPT := true
 TARGET_ARCH := x86
+
+# The eth0 device should be started with dhcp on boot.
+# Useful for emulators that don't provide a wifi connection.
+NET_ETH0_STARTONBOOT := true

target/board/generic_x86/init.rc

@@ -191,6 +191,7 @@ on boot
 
     class_start default
 
+
 ## Daemon processes to be run by init.
 ##
 service console /system/bin/sh
@@ -241,3 +242,13 @@ service brick /system/bin/wipe nuke
 
 service installd /system/bin/installd
     socket installd stream 600 system system
+
+#
+# Set by PRODUCT_PROPERTY_OVERRIDES in <product>.mk
+on property:net.eth0.startonboot=1
+    setprop ro.com.android.dataroaming true
+    start start_eth0
+
+service start_eth0 /system/bin/netcfg eth0 dhcp
+    oneshot
+    disabled

target/product/generic_x86.mk

@@ -25,3 +25,10 @@ PRODUCT_BRAND := generic_x86
 PRODUCT_DEVICE := generic_x86
 PRODUCT_NAME := generic_x86
 PRODUCT_POLICY := android.policy_phone
+
+# If running on an emulator or some other device that has a LAN connection
+# that isn't a wifi connection. This will instruct init.rc to enable the
+# network connection so that you can use it with ADB
+ifdef NET_ETH0_STARTONBOOT
+  PRODUCT_PROPERTY_OVERRIDES += net.eth0.startonboot=1
+endif