Live CD not booting into serial terminal even if kernel command line is given properly

Is this a new report?

Yes

System Info

n/a

Package(s) Affected

n/a

Does a report exist for this bug with the project's home (upstream) and/or another distro?

No

Expected behaviour

After starting Qemu with the Live CD and pressing escape to get to the boot: prompt, the system should provide a console on virtual serial console connected to ttyS0. Expected to work with the following kernel command-line: "linux console=ttyS0,115200n8".

Actual behaviour

After providing kernel command line "linux console=ttyS0,115200n8" and pressing enter Qemu continues to stay in graphical mode, after a while upgrades to the screen resolution from 640x480 graphic mode to something higher, and when switching to the serial console, there is no output at all, even after waiting minutes.

Steps to reproduce

qemu-system-x86_64 -hda disk.qcow2 -cdrom void-musl-base.iso -boot order=d -m 4G -net nic -net user -serial telnet:localhost:1234,server,nowait -display curses
2.
Right after Sea BIOS, Qemu switches into graphical mode, press esc quickly to get to the "boot:" prompt.
3.
Open a telnet connection to localhost 1234
4.
4.1.
Type in the following into the "boot:" prompt:
linux console=ttyS0,115200n8
4.2.
Alternatively, try with these, these also don't work:
linux console=ttyS0,115200n8 debug
linux console=ttyS0,115200n8 single
5.
Observe that even after minutes, serial console stays empty.

Start by reproducing the issue with the provided qemu-system-x86_64 command, then inspect the live image boot configuration and serial-console setup. The fix is complete when booting with console=ttyS0,115200n8 produces output on the connected serial terminal; the issue does not name a source file or test.