Do you have an example of a situation where a problem in systemd required you to patch the source and recompile, or are you just making a general statement?
Specifically a problem that couldn't be fixed by changing systemd unit files?
(I don't mean for this to sound in bad faith; I'm genuinely curious as a user of systemd)
> Do you have an example of a situation where a problem in systemd required you to patch the source and recompile, or are you just making a general statement?
You could use that argument and say do you need to look at all the code for the dozen shell programs you're calling in that init file to diagnose problems.
1. It's not relating to the service manager part of systemd. It sounds like a problem with systemd-networkd which is a component that is entirely optional and easily replaced even on a systemd-based system (as you admit yourself).
2. The original question was about bugs in systemd that require inspecting C code where the equivalent bug on a non-systemd system could be diagnosed by inspecting shell scripts. ISC DHCP is not written in shell script.
Specifically a problem that couldn't be fixed by changing systemd unit files?
(I don't mean for this to sound in bad faith; I'm genuinely curious as a user of systemd)