[jalgos_eminator]

OpenWRT doesn't use sysv init, it has something called procd (~120KB compressed). Its very reliable, and they have a large install base on mission critical devices.

> And OpenWRT abandoned this goal.

They have not. Individual devices get too old to be supported, but there are plenty of 16 MB devices they still support. Its true that basically every device now has 32MB or more of flash, but there are still plenty out there that don't.

> with a built-in planned obsolescence (what if the new update requires just a bit more space for "calibration data"?). Got it.

The calibration data is from the factory to tune the wifi radios, it doesn't change since its specific to that individual device. I really hate to reply like this on HN, but you don't seem to know what you're talking about. The kinds of constraints you deal with in embedded networking are different than that in general computing. There's a reason systemd wasn't used, and there's a reason OpenWRT devs went through the trouble of developing their own init system. Just because you can't fathom those reasons doesn't mean they don't exist.

[cyberax]

> OpenWRT doesn't use sysv init, it has something called procd (~120KB compressed). Its very reliable, and they have a large install base on mission critical devices.

procd is only slightly better than sysvinit, it has the same ideas, and only adds simple and incorrectly implemented event triggers. And yes, I spent days debugging issues that it caused.

E.g. a USB drive for the logs becomes slow and changes the startup order, so now openvpn starts before the interface acquires the IPv6 address. Boom, broken IPv6 routing.

> They have not. Individual devices get too old to be supported, but there are plenty of 16 MB devices they still support. Its true that basically every device now has 32MB or more of flash, but there are still plenty out there that don't.

And systemd can live just fine at 16MB. I ran it on RouterBoards with 32MB (the smallest ones available) in 2014. It has grown a bit since then, but it can be slimmed down (remove compressors, auditing, SELinux/AppArmor, etc.).

> The calibration data is from the factory to tune the wifi radios, it doesn't change since its specific to that individual device. I really hate to reply like this on HN, but you don't seem to know what you're talking about.

The entire firmware for WiFi chips that were available during 16MB era is around 500KB-1MB. So it must be some other mysterious "calibration" data.

So you're thinking about more and more corner cases, that require the stars to be just right for the size of systemd to matter.

[jalgos_eminator]

> So you're thinking about more and more corner cases, that require the stars to be just right for the size of systemd to matter.

These weren't corner cases, they were everyday reality. We had to intentionally slim down the firmware size to get it to fit comfortably since we added quite a bit of application code. Like I said before, we got a recovery firmware down to ~3MB, and the normal firmware (without our application) was ~8MB. Every megabyte counts at that point, so having a 1MB init system would be a non-starter. We were buying commodity hardware, so we did lots of shopping and there were still plenty of 16MB APs on the market 10 years ago.

You're right its not a problem if you buy new hardware, but OpenWRT is used to support older devices with limited hardware specs. Its one of the reasons people install it, to give new life to old hardware (rather than being forced to buy a new device).

By the way, I use and like systemd on full size computers. I actually know of a product that runs a full rpm based distro (with systemd) on an embedded device and it works great. But systemd isn't one size fits all.