Re: [Qemu-devel] [PATCH 3/3] s390x: deprecate s390-squash-mcss machine prop

[Cornelia Huck <cohuck@redhat.com>]

On Fri,  1 Dec 2017 15:31:36 +0100
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> With the cssids unrestricted (commit <COMMIT HERE> "s390x/css: unrestrict

I won't add the commit id, as I intend to merge this in one go and I
don't want to edit this every time I rebase prior to pull.

> cssids") the s390-squash-mcss machine property should not be used.
> Actually libvirt never supported this, so the expectation is that
> removing it should be pretty painless.  But let's play nice and deprecate
> it first.
> 
> Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> ---
> 
> I would like to reference a commit for "s390x/css: unrestrict cssids"
> which is currently in RFC status on the list.
> ---
>  hw/s390x/s390-virtio-ccw.c | 6 +++++-
>  qemu-doc.texi              | 8 ++++++++
>  qemu-options.hx            | 8 +++++++-
>  3 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> index 4d65a50334..3796f666e6 100644
> --- a/hw/s390x/s390-virtio-ccw.c
> +++ b/hw/s390x/s390-virtio-ccw.c
> @@ -553,6 +553,10 @@ static inline void machine_set_squash_mcss(Object *obj, bool value,
>      S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>  
>      ms->s390_squash_mcss = value;
> +    if (ms->s390_squash_mcss) {
> +        warn_report("The machine property 's390-squash-mcss' is deprecated"
> +                    " (obsoleted by lifting the cssid restrictions).");

Too bad that we can't warn when this is explicitly set to false - OTOH
I don't really expect anyone doing that.

> +    }
>  }
>  
>  static inline void s390_machine_initfn(Object *obj)
> @@ -582,7 +586,7 @@ static inline void s390_machine_initfn(Object *obj)
>      object_property_add_bool(obj, "s390-squash-mcss",
>                               machine_get_squash_mcss,
>                               machine_set_squash_mcss, NULL);
> -    object_property_set_description(obj, "s390-squash-mcss",
> +    object_property_set_description(obj, "s390-squash-mcss", "(deprecated) "
>              "enable/disable squashing subchannels into the default css",
>              NULL);
>      object_property_set_bool(obj, false, "s390-squash-mcss", NULL);
> diff --git a/qemu-doc.texi b/qemu-doc.texi
> index db2351c746..874432d87c 100644
> --- a/qemu-doc.texi
> +++ b/qemu-doc.texi
> @@ -2501,6 +2501,14 @@ enabled via the ``-machine usb=on'' argument.
>  
>  The ``-nodefconfig`` argument is a synonym for ``-no-user-config``.
>  
> +@subsection -machine virtio-ccw,s390-squash-mcss=on|off (since 2.12.0)
> +
> +The ``s390-squash-mcss=on`` property has been obsoleted by allowing the
> +cssid to be chosen freely. Instead of squashing subchannels into the
> +default channel subsystem image for guests that do not support multiple
> +channel subsystems, all devices can be put into the default channel
> +subsystem image.
> +
>  @section qemu-img command line arguments
>  
>  @subsection convert -s (since 2.0.0)
> diff --git a/qemu-options.hx b/qemu-options.hx
> index f11c4ac960..fe0c29271f 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -43,7 +43,7 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
>      "                suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
>      "                nvdimm=on|off controls NVDIMM support (default=off)\n"
>      "                enforce-config-section=on|off enforce configuration section migration (default=off)\n"
> -    "                s390-squash-mcss=on|off controls support for squashing into default css (default=off)\n",
> +    "                s390-squash-mcss=on|off (deprecated) controls support for squashing into default css (default=off)\n",
>      QEMU_ARCH_ALL)
>  STEXI
>  @item -machine [type=]@var{name}[,prop=@var{value}[,...]]
> @@ -98,6 +98,12 @@ Enables or disables NVDIMM support. The default is off.
>  @item s390-squash-mcss=on|off
>  Enables or disables squashing subchannels into the default css.
>  The default is off.
> +NOTE: This property is deprecated and will be removed in future releases.
> +The ``s390-squash-mcss=on`` property has been obsoleted by allowing the
> +cssid to be chosen freely. Instead of squashing subchannels into the
> +default channel subsystem image for guests that do not support multiple
> +channel subsystems, all devices can be put into the default channel
> +subsystem image.
>  @item enforce-config-section=on|off
>  If @option{enforce-config-section} is set to @var{on}, force migration
>  code to send configuration section even if the machine-type sets the

Looks sane. We should put a note into the 2.12 changelog as well.