qemu: Use a TAP device instead of slirp for networking

With this patch, a persistent TAP device is set up by poky-qemu-ifup,
which is now run before qemu.  The qemu command line now uses the
device that was constructed (rather than the hard-coded tap0) and it
is told not to run any networking scripts.

When qemu shuts down, poky-qemu-ifdown removes the TAP device.

sudo use - sudo is used to run poky-qemu-ifup.  sudo is no longer used
to run qemu, as qemu no longer needs privileges to set up networking.
poky-qemu-ifdown is run without privileges, as you can remove a TAP
device which you own.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/scripts/poky-qemu-internal b/scripts/poky-qemu-internal
index 62c64727c0..8ff3add511 100755
--- a/scripts/poky-qemu-internal
+++ b/scripts/poky-qemu-internal
@@ -53,8 +53,13 @@ fi
 
 QEMUIFUP=`which poky-qemu-ifup`
 QEMUIFDOWN=`which poky-qemu-ifdown`
+
+USER=`id -u`
+echo 'Setting up tap interface under sudo'
+TAP=`sudo $QEMUIFUP $USER`
+
 KERNEL_NETWORK_CMD="ip=192.168.7.2::192.168.7.1:255.255.255.0"
-QEMU_TAP_CMD="-net tap,vlan=0,ifname=tap0,script=$QEMUIFUP,downscript=$QEMUIFDOWN"
+QEMU_TAP_CMD="-net tap,vlan=0,ifname=$TAP,script=no,downscript=no"
 QEMU_NETWORK_CMD="-net nic,vlan=0 $QEMU_TAP_CMD"
 KERNCMDLINE="mem=$QEMU_MEMORY"
 QEMU_UI_OPTIONS="-show-cursor -usb -usbdevice wacom-tablet"
@@ -298,9 +303,13 @@ else
     echo "Warning: distccd not present, no distcc support loaded."
 fi
 
-echo "Running $QEMU using sudo..."
+
+
+echo "Running $QEMU..."
 echo $QEMUBIN -kernel $ZIMAGE $QEMUOPTIONS $SERIALOPTS $* --append "$KERNCMDLINE"
-sudo $QEMUBIN -kernel $ZIMAGE $QEMUOPTIONS $SERIALOPTS $* --append "$KERNCMDLINE" || /bin/true
+$QEMUBIN -kernel $ZIMAGE $QEMUOPTIONS $SERIALOPTS $* --append "$KERNCMDLINE" || /bin/true
+
+$QEMUIFDOWN $TAP
 
 trap - INT TERM QUIT
 return