Re: [Qemu-devel] [PATCH v2 2/8] configure: add CONFIG_VIRTIO_BLK_DATA_PLANE

[mdroth <mdroth@linux.vnet.ibm.com>]

On Tue, Nov 20, 2012 at 01:31:46PM +0100, Stefan Hajnoczi wrote:
> The virtio-blk-data-plane feature only works with Linux AIO.  Therefore
> add a ./configure option and necessary checks to implement this
> dependency.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  configure | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/configure b/configure
> index 780b19a..633ba6d 100755
> --- a/configure
> +++ b/configure
> @@ -223,6 +223,7 @@ libiscsi=""
>  coroutine=""
>  seccomp=""
>  glusterfs=""
> +virtio_blk_data_plane=""
> 
>  # parse CC options first
>  for opt do
> @@ -871,6 +872,10 @@ for opt do
>    ;;
>    --enable-glusterfs) glusterfs="yes"
>    ;;
> +  --disable-virtio-blk-data-plane) virtio_blk_data_plane="no"
> +  ;;
> +  --enable-virtio-blk-data-plane) virtio_blk_data_plane="yes"
> +  ;;
>    *) echo "ERROR: unknown option $opt"; show_help="yes"
>    ;;
>    esac
> @@ -2233,6 +2238,17 @@ EOF
>  fi
> 
>  ##########################################
> +# adjust virtio-blk-data-plane based on linux-aio
> +
> +if test "$virtio_blk_data_plane" = "yes" -a \
> +	"$linux_aio" != "yes" ; then
> +  echo "Error: virtio-blk-data-plane requires Linux AIO, please try --enable-linux-aio"
> +  exit 1
> +elif test -z "$virtio_blk_data_plane" ; then
> +  virtio_blk_data_plane=$linux_aio
> +fi

$linux_aio gets set automatically if the user has libaio installed and
doesn't specify --disable-linux-aio, so this ends up enabling dataplane by
default in a lot of situations. Since it's experimental I think it should only
be enabled if we pass --enable-virtio-blk-data-plane explicitly.