Bug#960355: Invalid serial console blocks system boot
Package: initramfs-tools-core
Version: 0.137
Putting a serial console on a non-existent/broken serial port
via the last "console=" argument of the kernel command line
causes the initrd to hang without completing the boot process.
If the problematic serial console argument comes first in the kernel
command line, the system boots without issues.
***To reproduce:***
1. Check for a non-connected/disabled serial port.
On the problematic system running
[$] stty -a -F /dev/ttyS1
stty: /dev/ttyS1: Input/output error
The serial ports are registered by the "serial8250" driver but are
probably not wired to anything.
2. Boot with a kernel command line that puts serial console on a
non-existent/broken serial port via last "console=" argument:
console=tty0 console=ttyS1,115200n8
3. Check if system boots successfully
I am using Debian GNU/Linux 11 (bullseye/testing), vanilla kernel
5.7-rc5.
This issue was initially reported multiple times for Debian and Ubuntu
to the systemd maintainers as:
https://github.com/systemd/systemd/issues/15656 (for Ubuntu)
https://github.com/systemd/systemd/issues/15783 (for Debian, duplicate)
I am not sure if the _exact_ cause of both issues is the same,
because I observed the problem on a very minimal system without
console-setup or kbd.
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