[v5] virtio-console: notify about the terminal size

[PATCH RFC v5 04/12] char-mux: add support for the terminal size

Filip Hejsek posted 12 patches 1 week ago

Diff against v1 v2 v3 v4
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Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Stefano Garzarella <sgarzare@redhat.com>, "Gonglei (Arei)" <arei.gonglei@huawei.com>, Zhenwei Pi <pizhenwei@bytedance.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Raphael Norwitz <raphael@enfabrica.net>, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, Thomas Huth <thuth@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, "Collin L. Walling" <walling@linux.ibm.com>, Laurent Vivier <lvivier@redhat.com>, Amit Shah <amit@kernel.org>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Yanan Wang <wangyanan55@huawei.com>, Zhao Liu <zhao1.liu@intel.com>, Corey Minyard <minyard@acm.org>, Fam Zheng <fam@euphon.net>, Samuel Thibault <samuel.thibault@ens-lyon.org>, "Alex Bennée" <alex.bennee@linaro.org>, "Dr. David Alan Gilbert" <dave@treblig.org>, Markus Armbruster <armbru@redhat.com>, Jason Wang <jasowang@redhat.com>, Eric Blake <eblake@redhat.com>

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[PATCH RFC v5 04/12] char-mux: add support for the terminal size

Posted by Filip Hejsek 1 week ago

From: Szymon Lukasz <noh4hss@gmail.com>

The terminal size of a mux chardev should be the same as the real
chardev, so listen for CHR_EVENT_RESIZE to be up to date.

We forward CHR_EVENT_RESIZE only to the focused frontend. This means
frontends should update their view of the terminal size on
receiving CHR_EVENT_MUX_IN.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
Signed-off-by: Filip Hejsek <filip.hejsek@gmail.com>
---
 chardev/char-mux.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/chardev/char-mux.c b/chardev/char-mux.c
index 6b36290e2c49f579580d2abb5aa552806f019d4a..4d3d05b82f13e002c766142f9d9c24977b8b9bd2 100644
--- a/chardev/char-mux.c
+++ b/chardev/char-mux.c
@@ -264,9 +264,24 @@ void mux_chr_send_all_event(Chardev *chr, QEMUChrEvent event)
     }
 }
 
+static void mux_update_winsize(Chardev *chr)
+{
+    MuxChardev *d = MUX_CHARDEV(chr);
+    uint16_t cols, rows;
+
+    qemu_chr_fe_get_winsize(&d->chr, &cols, &rows);
+    qemu_chr_resize(chr, cols, rows);
+}
+
 static void mux_chr_event(void *opaque, QEMUChrEvent event)
 {
-    mux_chr_send_all_event(CHARDEV(opaque), event);
+    Chardev *chr = CHARDEV(opaque);
+
+    if (event == CHR_EVENT_RESIZE) {
+        mux_update_winsize(chr);
+    } else {
+        mux_chr_send_all_event(chr, event);
+    }
 }
 
 static GSource *mux_chr_add_watch(Chardev *s, GIOCondition cond)
@@ -382,6 +397,7 @@ static void qemu_chr_open_mux(Chardev *chr,
      */
     *be_opened = muxes_opened;
     qemu_chr_fe_init(&d->chr, drv, errp);
+    mux_update_winsize(chr);
 }
 
 static void qemu_chr_parse_mux(QemuOpts *opts, ChardevBackend *backend,

-- 
2.51.0

Re: [PATCH RFC v5 04/12] char-mux: add support for the terminal size

Posted by Daniel P. Berrangé 6 days, 7 hours ago

On Sun, Sep 21, 2025 at 01:45:34AM +0200, Filip Hejsek wrote:
> From: Szymon Lukasz <noh4hss@gmail.com>
> 
> The terminal size of a mux chardev should be the same as the real
> chardev, so listen for CHR_EVENT_RESIZE to be up to date.
> 
> We forward CHR_EVENT_RESIZE only to the focused frontend. This means
> frontends should update their view of the terminal size on
> receiving CHR_EVENT_MUX_IN.
> 
> Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
> Signed-off-by: Filip Hejsek <filip.hejsek@gmail.com>
> ---
>  chardev/char-mux.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


With regards,
Daniel
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