Reknit

A SysVinit-inspired init system for the Cynosure 2 kernel.

Using Reknit

Simply copy init.lua into anywhere on your filesystem that has Cynosure 2 installed, preferably in /sbin/init.lua, and pass the parameter init=path/to/init.lua to the kernel. In the near future you can install the reknit package through UPT.

Example configuration for CLDR:

flags init=path/to/init.lua

Communication

Reknit expects to be sent messages (internally referred to as telinits) in the form of signals. These should be directly sent through an ioctl on /proc/events. For example, to switch to runlevel 2:

local fd = open("/proc/events", "r")
ioctl(fd, "send", 1, "telinit", getpid(), "runlevel", 2)
close(fd)
-- wait for the "response" signal

A few things of note:

• The sent message must always take the form "telinit", yourpid, "request"[, argument]. The second parameter must be a valid PID or Reknit will not process the request. This is so, when e.g. requesting the runlevel, Reknit knows which process to respond to.
• Reknit will always respond through a signal in the form "response", "request", true|false. It is good practice to wait for this signal before continuing.

Configuration

Reknit's inittab file uses almost the exact same format as SysVinit. Each line is a service, and each service is a list of parameters delimited by the colon (:).

Service syntax:

id:runlevels:action:path

Example:

shell:0:respawn:/bin/sh.lua

• id can be however long you want. At the moment, it is not used.
• runlevels is a number where each digit indicates at what level(s) the action should be executed. It can be 0123456789 or if it is not a number Reknit will only start it when instructed to.
• action defines the behaviour of the service. At the moment, 3 actions are supported:
  • once: the service will be executed only once without Reknit waiting for it to finish.
  • wait: the service will be executed and Reknit will wait for it to finish.
  • respawn: the service will be executed and Reknit will respawn it if it dies.