[systemd-devel] systemd hangs after Welcome message when LogLevel=debug

[Holger Schurig]

Educated guess (!)

With LogLevel=debug, you generate huge amounts of output.

With DefaultStandardOutput=syslog, you're asking systemd to send it's
output to syslog.

But while systemd is starting your system the syslog might not be
ready. Probably systemd has some buffer, where it buffers the output.
Once syslog becomes available, it will be fed with the buffer's
contents first. If the output is small enought, as with LogLevel=info,
this actually works. But when you generate gobs of output, the buffer
will overflow and the output routine will wait until the buffer get's
emptied, which it never will ...

So, you might try to use DefaultStandardOutput=syslog-or-kmsg or
DefaultStandardOutput=journal instead. The latter will eventually also
send the output to syslog, which is why it's a default.