qemu: add option to enable SLiRP user networking

Reviewed-by: Joakim Bech <joakim.bech@linaro.org>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Igor Opaniuk <igor.opaniuk@linaro.org>
[Rebase on top of master]
Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>

common.mk

@@ -29,6 +29,8 @@ CCACHE ?= $(shell which ccache) # Don't remove this comment (space is needed)
 QEMU_VIRTFS_ENABLE		?= n
 QEMU_VIRTFS_HOST_DIR	?= $(ROOT)
 
+# Enable SLiRP user networking
+QEMU_USERNET_ENABLE		?= n
 ################################################################################
 # Check coherency of compilation mode
 ################################################################################
@@ -196,6 +198,11 @@ QEMU_EXTRA_ARGS +=\
 	-fsdev local,id=fsdev0,path=$(QEMU_VIRTFS_HOST_DIR),security_model=none \
 	-device virtio-9p-device,fsdev=fsdev0,mount_tag=host
 endif
+
+ifeq ($(QEMU_USERNET_ENABLE),y)
+QEMU_EXTRA_ARGS +=\
+	-netdev user,id=vmnic -device virtio-net-device,netdev=vmnic
+endif
 ################################################################################
 # OP-TEE
 ################################################################################
@@ -301,6 +308,10 @@ filelist-tee-common: optee-client xtest helloworld
 			"$(HELLOWORLD_PATH)/ta/8aaaf200-2450-11e4-abe2-0002a5d5c51b.ta" \
 			"444 0 0" 					>> $(fl); \
 	fi
+	@if [ "$(QEMU_USERNET_ENABLE)" = "y" ]; then \
+		echo "slink /etc/rc.d/S02_udhcp_networking /etc/init.d/udhcpc 755 0 0" \
+		>> $(fl); \
+	fi
 	@echo "# Secure storage dir" 					>> $(fl)
 	@echo "dir /data 755 0 0" 					>> $(fl)
 	@echo "dir /data/tee 755 0 0" 					>> $(fl)

docs/qemu.md

@@ -4,7 +4,8 @@
 1. [Introduction](#1-introduction)
 2. [Regular build](#2-regular-build)
 3. [Install files on the device](#3-qemu-console)
-4. [Host-Guest folder sharing in QEMU/QEMUv8 configurations](#4-host-guest-folder-sharing-in-qemuqemuv8-configurations)
+4. [Host-Guest folder sharing](#4-host-guest-folder-sharing)
+5. [SLiRP user networking](#5-slirp-user-networking)
 
 # 1. Introduction
 The instructions here will tell how to run OP-TEE using QEMU. We have two
@@ -31,12 +32,12 @@ It will stop on the QEMU console, to continue, simply
 ## 3.2 ARMv8-A
 It won't stop, it will just boot up QEMU and OP-TEE.
 
-#4. Host-Guest folder sharing in QEMU/QEMUv8 configurations
+# 4. Host-Guest folder sharing
 
 To avoid changing rootfs CPIO archive each time you need to add additional files
 to it, you can also use VirtFS QEMU feature to share a folder between the guest
 and host operating systems. To use this feature enable VirtFS QEMU build in
-build/common.mk (set QEMU_VIRTFS_ENABLE ?= y), adjust QEMU_VIRTFS_HOST_DIR and
+build/common.mk (set `QEMU_VIRTFS_ENABLE ?= y`), adjust `QEMU_VIRTFS_HOST_DIR` and
 rebuild QEMU.
 
 To mount host folder in QEMU, simply run:
@@ -44,6 +45,12 @@ To mount host folder in QEMU, simply run:
 ```bash
 $ mount_shared <mount_point>
 ```
+# 5. SLiRP user networking
+To enable SLiRP user networking just set `QEMU_USERNET_ENABLE ?= y` in `common.mk`.
+After booting QEMU VM, eth0 will automatically receive IP address via DHCP
+
+*Important* Take into account that ICMP doesn't work in SLiRP mode,
+so `ping` utility won't work.
 
 [bios]: https://github.com/linaro-swg/bios_qemu_tz_arm
 [README.md]: ../README.md