[v2,4/6] Warn on obsolete and deprecated devices.

Print a warning for deprecated and obsolete devices.
Also add support state to device listing.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/core/qdev.c | 8 +++++++-
 qdev-monitor.c | 9 +++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

On Tue, Nov 06, 2018 at 11:23:33AM +0100, Gerd Hoffmann wrote:
> Print a warning for deprecated and obsolete devices.
> Also add support state to device listing.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Should we also add a runtime flag to block these?
E.g. I can see libvirt doing that and passing
the responsibility for what is reasonably
supported to qemu.

> ---
>  hw/core/qdev.c | 8 +++++++-
>  qdev-monitor.c | 9 +++++++++
>  2 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 6b3cc55b27..6205522c3e 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -133,11 +133,17 @@ DeviceState *qdev_create(BusState *bus, const char *name)
>  
>  DeviceState *qdev_try_create(BusState *bus, const char *type)
>  {
> +    ObjectClass *oc;
>      DeviceState *dev;
>  
> -    if (object_class_by_name(type) == NULL) {
> +    oc = object_class_by_name(type);
> +    if (oc == NULL) {
>          return NULL;
>      }
> +    if (qemu_is_deprecated(oc) ||
> +        qemu_is_obsolete(oc)) {
> +        qemu_warn_support_state("device", type, oc);
> +    }
>      dev = DEVICE(object_new(type));
>      if (!dev) {
>          return NULL;
> diff --git a/qdev-monitor.c b/qdev-monitor.c
> index 802c18a74e..80370372f9 100644
> --- a/qdev-monitor.c
> +++ b/qdev-monitor.c
> @@ -115,6 +115,8 @@ static void out_printf(const char *fmt, ...)
>  
>  static void qdev_print_devinfo(DeviceClass *dc)
>  {
> +    ObjectClass *oc = OBJECT_CLASS(dc);
> +
>      out_printf("name \"%s\"", object_class_get_name(OBJECT_CLASS(dc)));
>      if (dc->bus_type) {
>          out_printf(", bus %s", dc->bus_type);
> @@ -128,6 +130,9 @@ static void qdev_print_devinfo(DeviceClass *dc)
>      if (!dc->user_creatable) {
>          out_printf(", no-user");
>      }
> +    if (oc->supported.state != SUPPORT_STATE_UNSPECIFIED) {
> +        out_printf(", %s", SupportState_str(oc->supported.state));
> +    }
>      out_printf("\n");
>  }
>  
> @@ -579,6 +584,10 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
>      if (!dc) {
>          return NULL;
>      }
> +    if (qemu_is_deprecated(OBJECT_CLASS(dc)) ||
> +        qemu_is_obsolete(OBJECT_CLASS(dc))) {
> +        qemu_warn_support_state("device", driver, OBJECT_CLASS(dc));
> +    }
>  
>      /* find bus */
>      path = qemu_opt_get(opts, "bus");
> -- 
> 2.9.3

On Tue, Nov 06, 2018 at 09:36:44AM -0500, Michael S. Tsirkin wrote:
> On Tue, Nov 06, 2018 at 11:23:33AM +0100, Gerd Hoffmann wrote:
> > Print a warning for deprecated and obsolete devices.
> > Also add support state to device listing.
> > 
> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> 
> Should we also add a runtime flag to block these?

Yes, probably.  My priority is to hash out the classification
first though, so it isn't in this series yet.

On the cmd line switches:  How much flexibility do we want on this?  We
can go for a simple -future switch, as suggested by armbru, disallowing
obsolete and deprecated devices.  We could go for a full-blown ...

  -policy {experimental,unsupported,...}={enable,warn,disable}

... or something inbetween.

Comments?  Other ideas?

cheers,
  Gerd

Gerd Hoffmann <kraxel@redhat.com> writes:

> Print a warning for deprecated and obsolete devices.
> Also add support state to device listing.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/core/qdev.c | 8 +++++++-
>  qdev-monitor.c | 9 +++++++++
>  2 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 6b3cc55b27..6205522c3e 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -133,11 +133,17 @@ DeviceState *qdev_create(BusState *bus, const char *name)
>  
>  DeviceState *qdev_try_create(BusState *bus, const char *type)
>  {
> +    ObjectClass *oc;
>      DeviceState *dev;
>  
> -    if (object_class_by_name(type) == NULL) {
> +    oc = object_class_by_name(type);
> +    if (oc == NULL) {
>          return NULL;
>      }
> +    if (qemu_is_deprecated(oc) ||
> +        qemu_is_obsolete(oc)) {
> +        qemu_warn_support_state("device", type, oc);

Looks like this:

    $ qemu-system-x86_64 -nodefaults -S -display none -device cirrus-vga
    qemu-system-x86_64: -device cirrus-vga: warning: device cirrus-vga is obsolete (use "-vga std" instead, see https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/)

I'd prefer:

    $ qemu-system-x86_64 -nodefaults -S -display none -device cirrus-vga
    qemu-system-x86_64: -device cirrus-vga: warning: device cirrus-vga is obsolete
    Use "-vga std" instead, see
    https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/

The obvious way to get it:

   void warn_support_state(const char *type, const char *name,
                           ObjectClass *oc)
   {
       const char *help = oc->supported.help;

       warn_report("%s %s is %s", type, name,
                   SupportState_str(oc->supported.state));
       if (help) {
           error_printf("%s\n", help);
       }
   }

with the ->help suitably capitalized and formatted.

That should make qemu_warn_support_state() usable for the previous
patch, too.

Note I scratched the qemu_ prefix.  Matter of taste, I guess.


> +    }
>      dev = DEVICE(object_new(type));
>      if (!dev) {
>          return NULL;
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