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Comment by yakubin | Hacker News Reader

It's weird to me that text encoding is put in the domain of the kernel. But I guess it's the way it needs to be until the world moves to microkernels.

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Yeah, what's even weirder is when it's so integral to the kernel that it can lead to crashes. I've seen more than one case now where someone just fuzzing around on text engines ends up taking down an entire system, at least a couple on mac osx and ios alone. Dangerous stuff. [1] [2]

Linux might not be the most performant in the text engine game but at least it runs in userland.

[1] https://arstechnica.com/gadgets/2013/08/rendering-bug-crashe...

[2] https://www.engadget.com/unusual-buggy-character-string-appl...

I've been waiting for a "true" microkernel OS since 1980s.

QNX and Minix 3 don't count?

This seems to be about the system console built into the kernel.

Yeah, I got that part. I've just assumed that would be handled by a server process in a microkernel architecture. But I've just checked seL4 and it has in-kernel support for the console as well. That's not what I expected.

The system terminal has to be in-kernel otherwise you would not see kernel prints during boot, before any fs (and servers launched from it) is mounted.

Even with a microkernel, there's a lot of power in having a text console even when half the system is not functioning. If this code exists in a separate process, a lot of the handling bugs still need to be fixed to make the OS usable.

Serial port is trivial.

okay... and something needs to be able to decode the text sent to it over the serial port. All the bugs pointed out in the article also happen if you use the serial port console

Yes, and that “something” can be an app like gnome-terminal running on a full-fat text rendering library and GUI framework… on a completely different computer. That software could hypothetically have the same bug, but probably not, and at any rate it‘s not taking up space in the core of a microkernel.

The 120k+ lines of code in drivers/tty/serial in Linux suggests that maybe it's not _that_ trivial.

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