aarch64, fix gdb with linux-custom

runqemu

@@ -85,6 +85,23 @@ case "$arch" in
       $extra_flags
     "
   ;;
+  'aarch64')
+    if $kgdb; then
+      extra_append="$extra_append kgdboc=ttyAMA0,115200"
+    fi
+    cmd="$qemu_common \
+      -M virt \
+      -append 'root=/dev/sda $extra_append' \
+      -cpu cortex-a57 \
+      -device virtio-net-device,netdev=eth0 \
+      -drive file=${images_dir}/rootfs.cpio,if=scsi,format=raw \
+      -kernel ${images_dir}/Image \
+      -netdev user,id=eth0 \
+      -nographic \
+      -serial stdio \
+      $extra_flags
+    "
+  ;;
   'mips64')
     cmd="$qemu_common \
       -M malta \