Re: [PATCH 1/2] ui: Allow injection of vnc display name

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Oct 22, 2024 at 12:04:29PM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Tue, Oct 22, 2024 at 11:54 AM Daniel P. Berrangé <berrange@redhat.com>
> wrote:
> 
> > On Mon, Oct 21, 2024 at 03:14:39PM +0400, Marc-André Lureau wrote:
> > > Hi Roque
> > >
> > > On Fri, Oct 18, 2024 at 1:53 AM Roque Arcudia Hernandez
> > > <roqueh@google.com> wrote:
> > > >
> > > > From: Andrew Keesler <ankeesler@google.com>
> > > >
> > > > Thanks to 72d277a7, 1ed2cb32, and others, EDID (Extended Display
> > Identification
> > > > Data) is propagated by QEMU such that a virtual display presents
> > legitimate
> > > > metadata (e.g., name, serial number, preferred resolutions, etc.) to
> > its
> > > > connected guest.
> > > >
> > > > This change propagates an optional user-provided display name to
> > > > QemuConsole. Future changes will update downstream devices to leverage
> > this
> > > > display name for various uses, the primary one being providing a
> > custom EDID
> > > > name to guests. Future changes will also update other displays (e.g.,
> > spice)
> > > > with a similar option to propagate a display name to downstream
> > devices.
> > > >
> > > > Currently, every virtio-gpu virtual display has the same name: "QEMU
> > > > Monitor". We hope to be able to inject the EDID name of virtual
> > displays in
> > > > order to test guest behavior that is specific to display names. We
> > provide the
> > > > ability to inject the display name from the display configuration as
> > that most
> > > > closely resembles how real displays work (hardware displays contain
> > static EDID
> > > > information that is provided to every connected host).
> > > >
> > > > It should also be noted that EDID names longer than 12 bytes will be
> > truncated
> > > > per spec (I think?).
> > > >
> > > > Signed-off-by: Andrew Keesler <ankeesler@google.com>
> > > > Signed-off-by: Roque Arcudia Hernandez <roqueh@google.com>
> > > > ---
> > > >  include/ui/console.h | 1 +
> > > >  ui/console-priv.h    | 1 +
> > > >  ui/console.c         | 8 ++++++++
> > > >  ui/vnc.c             | 8 +++++++-
> > > >  4 files changed, 17 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/include/ui/console.h b/include/ui/console.h
> > > > index 5832d52a8a..74ab03ed72 100644
> > > > --- a/include/ui/console.h
> > > > +++ b/include/ui/console.h
> > > > @@ -408,6 +408,7 @@ int qemu_console_get_index(QemuConsole *con);
> > > >  uint32_t qemu_console_get_head(QemuConsole *con);
> > > >  int qemu_console_get_width(QemuConsole *con, int fallback);
> > > >  int qemu_console_get_height(QemuConsole *con, int fallback);
> > > > +void qemu_console_set_name(QemuConsole *con, const char *name);
> > > >  /* Return the low-level window id for the console */
> > > >  int qemu_console_get_window_id(QemuConsole *con);
> > > >  /* Set the low-level window id for the console */
> > > > diff --git a/ui/console-priv.h b/ui/console-priv.h
> > > > index 43ceb8122f..9f2769843f 100644
> > > > --- a/ui/console-priv.h
> > > > +++ b/ui/console-priv.h
> > > > @@ -18,6 +18,7 @@ struct QemuConsole {
> > > >      Object parent;
> > > >
> > > >      int index;
> > > > +    const char *name;
> > > >      DisplayState *ds;
> > > >      DisplaySurface *surface;
> > > >      DisplayScanout scanout;
> > > > diff --git a/ui/console.c b/ui/console.c
> > > > index 5165f17125..f377fd8417 100644
> > > > --- a/ui/console.c
> > > > +++ b/ui/console.c
> > > > @@ -1452,6 +1452,14 @@ int qemu_console_get_height(QemuConsole *con,
> > int fallback)
> > > >      }
> > > >  }
> > > >
> > > > +void qemu_console_set_name(QemuConsole *con, const char *name)
> > > > +{
> > > > +    if (con == NULL) {
> > > > +        return;
> > > > +    }
> > > > +    con->name = name;
> > > > +}
> > > > +
> > > >  int qemu_invalidate_text_consoles(void)
> > > >  {
> > > >      QemuConsole *s;
> > > > diff --git a/ui/vnc.c b/ui/vnc.c
> > > > index 93a8dbd253..7d6acc5c2e 100644
> > > > --- a/ui/vnc.c
> > > > +++ b/ui/vnc.c
> > > > @@ -3595,6 +3595,9 @@ static QemuOptsList qemu_vnc_opts = {
> > > >          },{
> > > >              .name = "power-control",
> > > >              .type = QEMU_OPT_BOOL,
> > > > +        },{
> > > > +            .name = "name",
> > > > +            .type = QEMU_OPT_STRING,
> > > >          },
> > > >          { /* end of list */ }
> > > >      },
> > > > @@ -4016,7 +4019,7 @@ void vnc_display_open(const char *id, Error
> > **errp)
> > > >      QemuOpts *opts = qemu_opts_find(&qemu_vnc_opts, id);
> > > >      g_autoptr(SocketAddressList) saddr_list = NULL;
> > > >      g_autoptr(SocketAddressList) wsaddr_list = NULL;
> > > > -    const char *share, *device_id;
> > > > +    const char *share, *device_id, *name;
> > > >      QemuConsole *con;
> > > >      bool password = false;
> > > >      bool reverse = false;
> > > > @@ -4217,6 +4220,9 @@ void vnc_display_open(const char *id, Error
> > **errp)
> > > >      }
> > > >      qkbd_state_set_delay(vd->kbd, key_delay_ms);
> > > >
> > > > +    name = qemu_opt_get(opts, "name");
> > > > +    qemu_console_set_name(vd->dcl.con, name);
> > >
> > > Why not expose a "head_name" property in QemuGraphicConsole?
> >
> > QemuGraphicConsole isn't mapped to any CLI though, is it ?
> >
> >
> No, it would be a bit tedious to do so with multi-head -devices.
> 
> 
> > In QAPI we have DisplayOptions union  for all the local displays,
> > and as a user I think I'd expect 'name' to be settable from
> > those.
> >
> >
> DisplayOptions is meant for the UI display.. Here, the intent is really to
> set the HW EDID name field.

But it is also applicable to the backend, all of which have a
name for the display set in the window titlebar. We should
be looking at both sides IMHO.

> Also DisplayOptions doesn't map to a specific console.

It could be made to contain per-head information if we desired
though, and would be more useful than just the name. There were
some patches a while ago trying to express per-console placement
of windows onto host monitor outputs, for example.

> > own CLI options we can expose.
> >
> > For runtime setting, we have a QMP  "display-update" command, that
> > currently just lets you change VNC listening address, but was intended
> > to allow for any runtime display changes.
> >
> > > This way it should be possible to set the name with QMP qom-set.
> >
> > qom-set isn't a particularly nice interface, as things you can set
> > from that are not introspectable and have no type information that
> > can be queried.
> >
> 
> fwiw, it could be easily exposed to D-Bus, for ex:
> 
> busctl --user set-property org.qemu /org/qemu/Display1/Console_1
> org.qemu.Display1.Console HeadName s "First Monitor"

That could be mapped to whatever interface we expose on the QEMU side,
it doesn't have to be qom-set.

With regards,
Daniel
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