The goal of this series is to have a resizable terminal into a guest without having to set up networking and using, e.g. ssh.
The virtio spec allows a virtio-console device to notify the guest about terminal resizes in the host. Linux Kernel implements the driver part of the spec. This series implement the device part in QEMU. This series adds support for a resizable terminal if a virtio console device is connected to the stdio backend. This series also introduces resize messages that can be sent over QMP to notify QEMU about the size of the terminal connented to some chardev. In the libvirt setting, it will allow to implement a resizable terminal for virsh console and other libvirt clients. This patch series was originally authored by Szymon Lukasz and submitted to qemu-devel about 5 years ago. The previous submission can be found at <https://lists.nongnu.org/archive/html/qemu-devel/2020-06/msg09591.html>. I have updated the patches to be compatible with latest master and made a few small changes of my own, including the addition of Windows support. Probably the most important change I made is the swapping of rows and cols fields in resize messages. I would like to hear some feedback on this change from reviewers. The problem is that for a long time, the Linux kernel used a different field order from what was specified in the virtio spec. The kernel implementation was apparently merged around 2010, while the virtio spec came in 2014, so when a previous version of this patch series was being discussed here on this mailing list in 2020, it was decided that QEMU should match the Linux implementation, and ideally, the virtio spec should be changed. However, recently, the Linux kernel implementation was changed to conform to the spec: <https://git.kernel.org/linus/5326ab737a47278dbd16ed3ee7380b26c7056ddd>. As a result, to be compatible with latest kernel releases, QEMU needs to also use the field order matching the specification. I have changed the patch to use the spec-compliant order, so it works correctly with latest kernels now. That leaves the issue of older kernels. There are about 15 years' worth of kernel versions with the swapped field order, including the kernel currently shipped in Debian stable. The effects of the swapped dimensions can sometimes be quite annoying - e.g. if you have a terminal with 24 rows, this will be interpreted as 24 columns, and your shell may limit line editing to this small space, most of which will be taken by your prompt. The patch series in its current form provides no way to disable the console size functionality, so users may end up worse off than if the functionality were not implemented at all. PS: One of the patches adds one additional noop switch case to a bunch of files. I didn't include the maintainers of these files in the Cc list. I hope that's OK. :) v4: changed order of rows and cols fields added support for terminal size on Windows trace event is also emitted for legacy (non-multiport) drivers minor fixes required because of changes in QEMU (DECLARE_INSTANCE_CHECKER, qmp-example) updated version numbers ('Since: 10.2', hw_compat_10_1) v3: add resize messages over QMP, as suggested by Daniel v2: fix adding a new virtio feature bit to the virtio console device --- Filip Hejsek (1): char-win-stdio: add support for terminal size Szymon Lukasz (9): chardev: add cols, rows fields chardev: add CHR_EVENT_RESIZE chardev: add qemu_chr_resize() char-mux: add support for the terminal size main-loop: change the handling of SIGWINCH char-stdio: add support for the terminal size qmp: add chardev-resize command virtio-serial-bus: add terminal resize messages virtio-console: notify the guest about terminal resizes backends/cryptodev-vhost-user.c | 1 + chardev/char-fe.c | 13 ++++++++ chardev/char-mux.c | 18 ++++++++++- chardev/char-stdio.c | 30 +++++++++++++++++++ chardev/char-win-stdio.c | 19 ++++++++++++ chardev/char.c | 26 ++++++++++++++++ hw/block/vhost-user-blk.c | 1 + hw/char/terminal3270.c | 1 + hw/char/trace-events | 1 + hw/char/virtio-console.c | 63 ++++++++++++++++++++++++++++++++++++--- hw/char/virtio-serial-bus.c | 43 ++++++++++++++++++++++++-- hw/core/machine.c | 4 ++- hw/ipmi/ipmi_bmc_extern.c | 1 + hw/scsi/vhost-user-scsi.c | 1 + hw/usb/ccid-card-passthru.c | 1 + hw/usb/dev-serial.c | 1 + hw/usb/redirect.c | 1 + hw/virtio/vhost-user-base.c | 1 + hw/virtio/vhost-user-scmi.c | 1 + include/chardev/char-fe.h | 10 +++++++ include/chardev/char.h | 7 +++++ include/hw/virtio/virtio-serial.h | 5 ++++ include/qemu/main-loop.h | 4 +++ monitor/hmp.c | 1 + monitor/qmp.c | 1 + net/passt.c | 1 + net/vhost-user.c | 1 + qapi/char.json | 22 ++++++++++++++ ui/curses.c | 11 +++---- util/main-loop.c | 21 +++++++++++++ 30 files changed, 298 insertions(+), 13 deletions(-) --- base-commit: 190d5d7fd725ff754f94e8e0cbfb69f279c82b5d change-id: 20250912-console-resize-96c42140ba08 Best regards, -- Filip Hejsek <filip.hej...@gmail.com>
