201 lines
5.6 KiB
Markdown
201 lines
5.6 KiB
Markdown
Title: My experiences using runit in Arch Linux
|
|
|
|
In around 2012,
|
|
after using busybox runit instead of sysvinit in my
|
|
[Dirtbags Tiny Linux](https://woozle.org/neale/g.cgi/ctf/dbtl)
|
|
distribution,
|
|
I decided to try it out on my laptop, too.
|
|
Here's how that went.
|
|
|
|
My older paper on specifics of the conversion
|
|
is still online: [Runit on Arch](arch-runit.html)
|
|
|
|
Motivation
|
|
==========
|
|
|
|
I wanted to see if I could get a working system without having systemd
|
|
installed at all.
|
|
Not because I hate systemd,
|
|
but because I love runit.
|
|
I am acutely aware that a lot of people have strong opinions about systemd.
|
|
Please: you don't need to share them with me.
|
|
I don't care.
|
|
|
|
Replacing init
|
|
--------------
|
|
|
|
First and most obvious was to get a getty running with my own
|
|
`/sbin/init`.
|
|
At the time,
|
|
arch had just switched over to systemd,
|
|
and had a recently-maintained systemv-init.
|
|
Copying that,
|
|
I was able to write a new init in Bourne shell.
|
|
The resulting init did the following:
|
|
|
|
* Mount and set up special filesystems (proc, sys, dev)
|
|
* Set the system clock
|
|
* Populate /dev (with `mdev -s`)
|
|
* Load drivers (by reading `modalias` files in /sys)
|
|
* Set the hostname
|
|
* Bring up the loopback network interface
|
|
* Set up cryptographic devices, if there are any
|
|
* `fsck -A`
|
|
* Remount / read-write
|
|
* Mount everything else
|
|
* Hand off to `runsvdir`
|
|
|
|
Not bad, really.
|
|
|
|
|
|
Setting up runit services
|
|
-------------------------
|
|
|
|
I won't go into this too much, it's well-documented elsewhere.
|
|
At this point, I was able to get a getty going,
|
|
but X11 wasn't recognizing the keyboard or mouse.
|
|
|
|
|
|
Making X11 work
|
|
---------------
|
|
|
|
X11 at the time wanted `udev`,
|
|
so I just ran that from init.
|
|
But, a few months later,
|
|
X was able to start with `udev`,
|
|
so I took it out and figured out the keyboard and mouse problem.
|
|
|
|
It had something to do with `evdev`;
|
|
I think `udev` provided some sort of `evdev` help to X11,
|
|
so I had to create some files in `/etc/X11/xorg.conf.d`
|
|
to disable `AutoAddDevices`.
|
|
Then the keyboard and mouse worked.
|
|
|
|
I never looked into how to get evdev working again.
|
|
|
|
|
|
Hot-plugging devices (like udev)
|
|
--------------------------------
|
|
|
|
For a while,
|
|
you could echo something into a file under `/proc`
|
|
and the kernel would run that for every uevent.
|
|
You could set that program to `mdev` from busybox,
|
|
and have a pretty well working system at that point.
|
|
|
|
Newer kernels disabled support for this legacy interface.
|
|
Now, you're supposed to monitor for Netlink events.
|
|
But that's not too tough, it turns out.
|
|
The kernel docs even have an example program to gather uevents.
|
|
|
|
|
|
Wayland
|
|
-------
|
|
|
|
All you had to do was make a group with a certain name and add yourself to it.
|
|
You also had to have write access to `/dev/dri/*` for the X11 stuff.
|
|
Wayland was actually pretty low on crazy requirements.
|
|
No consolekit or policykit or whatnottery needed.
|
|
|
|
|
|
That's all?
|
|
-----------
|
|
|
|
Yup!
|
|
|
|
|
|
Retrospective View
|
|
==================
|
|
|
|
After two years with this setup,
|
|
I'm back to Ubuntu now,
|
|
which means soon I'll have systemd.
|
|
Looking back on it, here's how it went.
|
|
|
|
|
|
It was blazing fast
|
|
-------------------
|
|
|
|
My new Ubuntu install boots a lot slower than my runit thing did.
|
|
Maybe 2-3 times slower.
|
|
Of course, it's doing way more.
|
|
This is the cost of having a general-use distribution:
|
|
you have to account for lots of cases,
|
|
and need lots more support software.
|
|
You can't rely on the machine owner to debug when,
|
|
for instance,
|
|
the console user doesn't have write access to the DRI device.
|
|
|
|
|
|
It was easy (for me)
|
|
--------------------
|
|
|
|
Runit is really nice.
|
|
I like it a lot.
|
|
For old Unix beardos like me,
|
|
having everything in Bourne shell is an attractive proposition.
|
|
|
|
|
|
|
|
It required high wizardry
|
|
-------------------------
|
|
|
|
The head guy from the Archbang distribution tried to duplicate my work once,
|
|
and failed to make everything work.
|
|
We never did sort out what he needed to change.
|
|
This was not something I'd recommend trying if you're not an expert
|
|
and/or unwilling to debug a massively broken system for weeks.
|
|
|
|
|
|
Stuff that never quite worked
|
|
-----------------------------
|
|
|
|
I had to set up a `dmix` device for ALSA,
|
|
which usually worked,
|
|
but sometimes things would get an exclusive lock on the sound hardware,
|
|
which prevented other things from making sound.
|
|
|
|
I could never get Chrome to get sound from the USB webcam I had to use at work.
|
|
It would list it as a microphone source,
|
|
and occasionally if I kept selecting every mic source over and over,
|
|
it would start working.
|
|
But it was never consistent,
|
|
and I was never able to figure out why not.
|
|
|
|
I never figured out how to get X11 to use evdev devices.
|
|
|
|
|
|
Parting thoughts
|
|
----------------
|
|
|
|
Systemd fixes a lot of really ugly hacks.
|
|
Things had become super kludgy,
|
|
and systemd cleans it all up.
|
|
I can't speak to systemd's architecture.
|
|
It was annoying at times when stuff seemed to depend on systemd,
|
|
but after looking into it,
|
|
I was always able to find another way to do it.
|
|
|
|
Bear in mind, I never tried to run Gnome or KDE.
|
|
But I don't think people who want Gnome are going to want to futz around
|
|
with writing run scripts for lid button events.
|
|
|
|
The Linux kernel does not,
|
|
to my mind,
|
|
appear to be making any huge changes for systemd.
|
|
Nothing I ran into here was out of reach for my project.
|
|
|
|
Linux can still be used in a traditionally Unixy way.
|
|
But you have got to bear in mind how un-Unixy things like X11 are.
|
|
Wayland might be better, I don't know enough to say yet.
|
|
|
|
My point is, Unix lost its roots decades ago with X11,
|
|
or maybe even before with the Berkeley socket API,
|
|
which didn't work from a shell script.
|
|
I think it would be cool if somebody tried to make Linux
|
|
look more like Plan9,
|
|
and maybe the current backlash will kick that off.
|
|
Runit is a way could do that.
|
|
Please feel free to contact me :)
|
|
|