Max Reitz <mre...@redhat.com> writes: > We have a clear replacement, so let's deprecate it. > > Signed-off-by: Max Reitz <mre...@redhat.com> > --- > qapi/block-core.json | 4 ++-- > block.c | 4 ++++ > qemu-doc.texi | 7 +++++++ > qemu-options.hx | 4 ++-- > 4 files changed, 15 insertions(+), 4 deletions(-) > > diff --git a/qapi/block-core.json b/qapi/block-core.json > index 76bf50f813..dfe4d3650c 100644 > --- a/qapi/block-core.json > +++ b/qapi/block-core.json > @@ -1090,7 +1090,7 @@ > # @overlay: reference to the existing block device that will become > # the overlay of @node, as part of creating the snapshot. > # It must not have a current backing file (this can be > -# achieved by passing "backing": "" to blockdev-add). > +# achieved by passing "backing": null to blockdev-add). > # > # Since: 2.5 > ## > @@ -1238,7 +1238,7 @@ > # "node-name": "node1534", > # "file": { "driver": "file", > # "filename": "hd1.qcow2" }, > -# "backing": "" } } > +# "backing": null } } > # > # <- { "return": {} } > # > diff --git a/block.c b/block.c > index bc92ddd5a0..463c4de25b 100644 > --- a/block.c > +++ b/block.c > @@ -2559,6 +2559,10 @@ static BlockDriverState *bdrv_open_inherit(const char > *filename, > /* See cautionary note on accessing @options above */ > backing = qdict_get_try_str(options, "backing"); > if (qdict_is_qnull(options, "backing") || (backing && *backing == '\0')) > { > + if (backing) { > + warn_report("Use of \"backing\": \"\" is deprecated; " > + "use \"backing\": null instead"); > + } > flags |= BDRV_O_NO_BACKING; > qdict_del(options, "backing"); > } > diff --git a/qemu-doc.texi b/qemu-doc.texi > index 8c10956a66..8f57d9ad21 100644 > --- a/qemu-doc.texi > +++ b/qemu-doc.texi > @@ -2537,6 +2537,13 @@ or ``ivshmem-doorbell`` device types. > The ``spapr-pci-vfio-host-bridge'' device type is replaced by > the ``spapr-pci-host-bridge'' device type. > > +@section Block device options > + > +@subsection "backing": "" (since 2.12.0) > + > +In order to prevent QEMU from automatically opening an image's backing > +chain, use ``"backing": null'' instead. > + > @node License > @appendix License > > diff --git a/qemu-options.hx b/qemu-options.hx > index 3728e9b4dd..0ee1a04d00 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -731,8 +731,8 @@ Reference to or definition of the data source block > driver node > > @item backing > Reference to or definition of the backing file block device (default is taken > -from the image file). It is allowed to pass an empty string here in order to > -disable the default backing file. > +from the image file). It is allowed to pass @code{null} here in order to > disable > +the default backing file. > > @item lazy-refcounts > Whether to enable the lazy refcounts feature (on/off; default is taken from > the
Missed in commit c42e8742f, I guess. Reviewed-by: Markus Armbruster <arm...@redhat.com>