qemu: Add virtualization support

The virtualized system is configured through kconfig under "External
Options"->"QEMU Virtualization".

To launch the system, simply run "make run". This works both from
output directories, and from the infix root with O= set.

Config.in

@@ -3,3 +3,10 @@ menu "Packages"
 source "$BR2_EXTERNAL_INFIX_PATH/package/Config.in"
 
 endmenu
+
+menu "QEMU Virtualization"
+
+source "$BR2_EXTERNAL_INFIX_PATH/qemu/Config.in"
+
+endmenu
+

Makefile

@@ -18,14 +18,11 @@ $(config):
 	@echo "'make <board>_defconfig' before building an image."
 	@exit 1
 
+
 %: | buildroot/Makefile
 	@+$(call bmake,$@)
 
 buildroot/Makefile:
 	@git submodule update --init
 
-run:
-	@echo "Starting Qemu  ::  Ctrl-a x -- exit | Ctrl-a c -- toggle console/monitor"
-	@(cd $(O)/images && ./qemu.sh)
-
-.PHONY: all run
+.PHONY: all

external.mk

@@ -1 +1,6 @@
 include $(sort $(wildcard $(BR2_EXTERNAL_INFIX_PATH)/package/*/*.mk))
+
+.PHONY: run
+run:
+	@echo "Starting Qemu  ::  Ctrl-a x -- exit | Ctrl-a c -- toggle console/monitor"
+	@$(BR2_EXTERNAL_INFIX_PATH)/qemu/qemu.sh $O

qemu/Config.in

@@ -0,0 +1,68 @@
+config QEMU_MACHINE
+	string
+	default "qemu-system-aarch64 -M virt -cpu cortex-a72" if BR2_aarch64
+
+config QEMU_KERNEL
+	string
+	default "images/Image" if BR2_aarch64
+
+config QEMU_ROOTFS
+	string
+	default "images/rootfs.squashfs"
+
+config QEMU_RW
+	string "Writable layer"
+	default "images/rw.ext4"
+
+config QEMU_CONSOLE
+	string
+	default "ttyAMA0" if BR2_aarch64
+
+choice
+     prompt "Rootfs type"
+     default QEMU_ROOTFS_INITRD
+
+config QEMU_ROOTFS_INITRD
+     bool "Initrd"
+
+config QEMU_ROOTFS_VSCSI
+     bool "Virtio SCSI"
+
+endchoice
+
+choice
+     prompt "Networking"
+     default QEMU_NET_USER
+
+config QEMU_NET_NONE
+     bool "None"
+
+config QEMU_NET_BRIDGE
+     bool "Bridged"
+
+config QEMU_NET_USER
+     bool "User mode"
+
+config QEMU_NET_TAP
+     bool "TAP"
+
+endchoice
+
+config QEMU_NET_MODEL
+	string "Interface model"
+	default "virtio"
+
+config QEMU_NET_BRIDGE_DEV
+	string "Bridge device"
+	depends on QEMU_NET_BRIDGE
+	default "virbr0"
+
+config QEMU_NET_TAP_N
+	int "Number of TAPs"
+	depends on QEMU_NET_TAP
+	default 1
+
+config QEMU_APPEND
+	string "Extra kernel options"
+config QEMU_EXTRA
+	string "Extra QEMU options"

qemu/qemu.sh

@@ -0,0 +1,101 @@
+#!/bin/sh
+
+die()
+{
+    echo "$@" >&2
+    exit 1
+}
+
+load_qemucfg()
+{
+    local tmp=$(mktemp -p /tmp)
+
+    grep ^QEMU_ $1 >$tmp
+    .  $tmp
+    rm $tmp
+
+    [ "$QEMU_MACHINE" ] || die "Missing QEMU_MACHINE"
+    [ "$QEMU_KERNEL"  ] || die "Missing QEMU_KERNEL"
+    [ "$QEMU_ROOTFS"  ] || die "Missing QEMU_ROOTFS"
+    [ "$QEMU_CONSOLE" ] || die "Missing QEMU_CONSOLE"
+}
+
+append_args()
+{
+    echo -n "console=$QEMU_CONSOLE "
+
+    if [ "$QEMU_ROOTFS_INITRD" = "y" ]; then
+	# Size of initrd, rounded up to nearest kb
+	local size=$((($(stat -c %s $QEMU_ROOTFS) + 1023) >> 10))
+	echo -n "root=/dev/ram ramdisk_size=${size} "
+    elif [ "$QEMU_ROOTFS_VSCSI" = "y" ]; then
+	echo -n "root=/dev/vda "
+    fi
+
+    if [ "$V" != "1" ]; then
+	echo -n "quiet "
+    else
+	echo -n "debug "
+    fi
+
+    echo -n "${QEMU_APPEND} "
+}
+
+rootfs_args()
+{
+    if [ "$QEMU_ROOTFS_INITRD" = "y" ]; then
+	echo -n "-initrd $QEMU_ROOTFS "
+    elif [ "$QEMU_ROOTFS_VSCSI" = "y" ]; then
+	echo -n "-drive file=$QEMU_ROOTFS,if=virtio,format=raw,bus=0,unit=0 "
+    fi
+}
+
+rw_args()
+{
+    [ "$QEMU_RW" ] || return
+
+    if ! [ -f $QEMU_RW ]; then
+	echo Creating $QEMU_RW
+	dd if=/dev/zero of=$QEMU_RW bs=16M count=1
+	mkfs.ext4 -L infix-rw $QEMU_RW
+    fi
+
+    echo -n "-drive file=$QEMU_RW,if=virtio,format=raw,bus=0,unit=1 "
+}
+
+net_args()
+{
+    QEMU_NET_MODEL=${QEMU_NET_MODEL:-virtio}
+
+    if [ "$QEMU_NET_BRIDGE" = "y" ]; then
+	QEMU_NET_BRIDGE_DEV=${QEMU_NET_BRIDGE_DEV:-virbr0}
+	echo -n "-nic bridge,br=$QEMU_NET_BRIDGE_DEV,model=$QEMU_NET_MODEL "
+    elif [ "$QEMU_NET_TAP" = "y" ]; then
+	QEMU_NET_TAP_N=${QEMU_NET_TAP_N:-1}
+	for i in $(seq 0 $(($QEMU_NET_TAP_N - 1))); do
+	    echo -n "-nic tap,ifname=qtap$i,script=no,model=$QEMU_NET_MODEL "
+	done
+    elif [ "$QEMU_NET_USER" = "y" ]; then
+	echo -n "-nic user,model=$QEMU_NET_MODEL "
+    else
+	echo -n "-nic none"
+    fi
+}
+
+if [ "$1" ]; then
+    [ -d "$1" ] || die "Usage: qemu.sh <build-dir>"
+    cd $1
+fi
+
+load_qemucfg .config
+
+$QEMU_MACHINE -nographic \
+	      -kernel $QEMU_KERNEL \
+	      $(rootfs_args) \
+	      $(rw_args) \
+	      $(net_args) \
+	      -append "$(append_args)" \
+	      $QEMU_EXTRA
+
+
+