Quote Originally Posted by peppepz View Post
The problem is that systemd's documentation is scattered all over many places, many of them informal or unofficial. Also, much of it is bitrotten as systemd changes the way it works quite often, pushing the burden of keeping up onto the users. I wouldn't call an init daemon which is documented through an unordered series of 18 blog posts by its author "well documented".
This is extremely unfair, as another responder pointed out. systemd is documented through its man pages, as is conventional. There is also considerable 'bonus' documentation consisting of user-friendly guides to various actions, a FAQ page with background detail, and so on and so on. The manpages alone constitute sufficient conventional documentation. I could just have referred to those, but I wanted to make the point that the systemd developers go above and beyond to provide useful and extensive supplementary documentation and guidance. It seems mean in the extreme to spin this as a bad thing.

Quote Originally Posted by peppepz View Post
I never said that. Upstart, for instance, is much more recent than the 1970s. The value of a system where the boundaries and the functions of each of its components are well defined and well documented, on the other hand, has no age. An administrator can obtain complete knowledge of such a system, reasonably foresee its behaviour, and diagnose faults when things don't work as expected. A kitchen sink that leaves you with a dead console and a wall of text made up of unrelated diagnostic messages because something went wrong is the opposite of that.
The boundaries and functions of systemd, udevd and journald are all perfectly well defined and documented. You can perfectly well obtain complete knowledge of this chain, foresee its behaviour, and debug it. The boundaries and behaviour are different from sysv, but they certainly meet your conditions.

Quote Originally Posted by peppepz View Post
This meant that, for instance, obtaining a working early userspace changed from being fully automatic into something that required dances of pivot_root and file descriptor voodoo.
I have to say I tend to read this line of argument as 'I took the time to learn how the old way worked, and now I don't want to do it again'. Learning new stuff is a pain, yeah, but describing it as 'voodoo' is unwarranted. The 'fully automatic' way that devfs worked was just as much 'voodoo' to someone who was used to the previous method as udev's method is to you. More than anything, your perspective on what is perfectly comprehensible and sensible code and what is 'voodoo' depends on when you came in...

Quote Originally Posted by peppepz View Post
Recently, after going out from the door, devfs has come back through the window in the form of devtmpfs, so in the end the "simple" approach won somehow. And the attitude of systemd developers, and their propension to ignore certain problems of their users, are leading the kernel developers to kill udev altogether and have the kernel load firmware on its own again.
This is a fairly inaccurate description of that whole kerfuffle. There was a bug, developers took potshots at each other as F/OSS developers always do and always have since the beginning of time (proprietary ones too, it just happens in private where you can't see it), Linus blew off steam with a ridiculously over-the-top rant as Linus is prone to do from time to time, then everyone settled down and fixed things. It's fun to read developers yelling at each other, but it doesn't really tell you anything substantive. If we all stopped using every F/OSS project whose developers had been involved in a shouting match with Linus at some point we'd be in some trouble.

Quote Originally Posted by peppepz View Post
That's the funny thing, it should go out without saying, but it doesn't. One of the last systemd releases that I tried just didn't compile on 32 bit architectures because it contained a mismatch in a function signature between a header and the implementation. This means that systemd gets released without even checking if it compiles on x86, which I find quite unsettling when we're talking about one of the critical pieces of a Linux installation.
So you hit a bug. Presumably it got fixed. I can't really discuss it in any more detail since I don't know anything about that specific case. But bugs happen...

Quote Originally Posted by peppepz View Post
Just do a Google search and see for yourself how many third-party packages are being modified to respond to systemd's automatic activation rules.
They're not 'being modified to respond to systemd's automatic activation rules'. They're being modified to *use* systemd's socket activation, because socket activation is an awesome feature and lots of developers want their software to take advantage of it. The whole point of systemd - and upstart - is to provide new capabilities for service initialization and management, capabilities sysv doesn't have. If they didn't do this there'd be no point in their existence. Projects converting to native systemd services in order to take advantage of the features it provides is a *positive* indicator for systemd, not a negative one. They didn't have to do that, after all - they could have just stuck with their sysv scripts.

Quote Originally Posted by peppepz View Post
Do the same search for upstart and see which of the two init systems is more invasive.
See above. The fact that projects are not buying into upstart is not a *good* thing for upstart, it indicates that they don't have confidence enough in that project to take advantage of the capabilities it offers. Why is it a good thing for upstart if upstart offers a native service format that provides extended capabilities, but few projects want to take advantage of that?

Quote Originally Posted by peppepz View Post
The fact that one should modify a server in order to match the behaviour of a superserver, of which the former shouldn't even know the existence, is a violation of the principle of separation of software components.
Again, it is not about 'match[ing] the behaviour' of systemd. It is about taking advantage of useful capabilities that systemd makes available. socket activation is a feature systemd offers for services, not a mandatory requirement. You don't have to make your service socket activated. The fact that developers are doing so is a clear statement that they consider it a beneficial and desirable feature which systemd is providing them.