The synth fsdriver never got used for anything else but the QTest
testcase for VirtIO 9P. And even there, QTest uses -fsdev synth and
-device virtio-9p-... directly.

Signed-off-by: Greg Kurz <groug@kaod.org>
---
v2: - change "no replacement" to "use '-fsdev synth' instead"
---
 qemu-deprecated.texi |    5 +++++
 qemu-options.hx      |    3 ++-
 vl.c                 |    4 ++++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
index 842e71b11dcc..1a821b68f435 100644
--- a/qemu-deprecated.texi
+++ b/qemu-deprecated.texi
@@ -72,6 +72,11 @@ backend settings instead of environment variables.  To ease migration to
 the new format, the ``-audiodev-help'' option can be used to convert
 the current values of the environment variables to ``-audiodev'' options.
 
+@subsection -virtfs_synth (since 4.1)
+
+The ``-virtfs_synth'' argument is now deprecated. Please use ``-fsdev synth''
+and ``-device virtio-9p-...'' instead.
+
 @section QEMU Machine Protocol (QMP) commands
 
 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
diff --git a/qemu-options.hx b/qemu-options.hx
index 51802cbb266a..03c50ba0f0b2 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1368,7 +1368,8 @@ DEF("virtfs_synth", 0, QEMU_OPTION_virtfs_synth,
 STEXI
 @item -virtfs_synth
 @findex -virtfs_synth
-Create synthetic file system image
+Create synthetic file system image. Note that this option is now deprecated.
+Please use @code{-fsdev synth} and @code{-device virtio-9p-...} instead.
 ETEXI
 
 DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
diff --git a/vl.c b/vl.c
index b6709514c1bb..8456f006edbd 100644
--- a/vl.c
+++ b/vl.c
@@ -3535,6 +3535,10 @@ int main(int argc, char **argv, char **envp)
                 QemuOpts *fsdev;
                 QemuOpts *device;
 
+                warn_report("'-virtfs_synth' is deprecated, please use "
+                             "'-fsdev synth' and '-device virtio-9p-...' "
+                            "instead");
+
                 fsdev = qemu_opts_create(qemu_find_opts("fsdev"), "v_synth",
                                          1, NULL);
                 if (!fsdev) {

On 13/05/2019 12.34, Greg Kurz wrote:
> The synth fsdriver never got used for anything else but the QTest
> testcase for VirtIO 9P. And even there, QTest uses -fsdev synth and
> -device virtio-9p-... directly.
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
> v2: - change "no replacement" to "use '-fsdev synth' instead"
> ---
>  qemu-deprecated.texi |    5 +++++
>  qemu-options.hx      |    3 ++-
>  vl.c                 |    4 ++++
>  3 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
> index 842e71b11dcc..1a821b68f435 100644
> --- a/qemu-deprecated.texi
> +++ b/qemu-deprecated.texi
> @@ -72,6 +72,11 @@ backend settings instead of environment variables.  To ease migration to
>  the new format, the ``-audiodev-help'' option can be used to convert
>  the current values of the environment variables to ``-audiodev'' options.
>  
> +@subsection -virtfs_synth (since 4.1)
> +
> +The ``-virtfs_synth'' argument is now deprecated. Please use ``-fsdev synth''
> +and ``-device virtio-9p-...'' instead.
> +
>  @section QEMU Machine Protocol (QMP) commands
>  
>  @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 51802cbb266a..03c50ba0f0b2 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1368,7 +1368,8 @@ DEF("virtfs_synth", 0, QEMU_OPTION_virtfs_synth,
>  STEXI
>  @item -virtfs_synth
>  @findex -virtfs_synth
> -Create synthetic file system image
> +Create synthetic file system image. Note that this option is now deprecated.
> +Please use @code{-fsdev synth} and @code{-device virtio-9p-...} instead.
>  ETEXI
>  
>  DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
> diff --git a/vl.c b/vl.c
> index b6709514c1bb..8456f006edbd 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -3535,6 +3535,10 @@ int main(int argc, char **argv, char **envp)
>                  QemuOpts *fsdev;
>                  QemuOpts *device;
>  
> +                warn_report("'-virtfs_synth' is deprecated, please use "
> +                             "'-fsdev synth' and '-device virtio-9p-...' "
> +                            "instead");
> +
>                  fsdev = qemu_opts_create(qemu_find_opts("fsdev"), "v_synth",
>                                           1, NULL);
>                  if (!fsdev) {
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>