path: root/dev/todo
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authorP. J. McDermott <pehjota>2012-07-05 00:59:30 (EDT)
committer P. J. McDermott <>2012-07-05 00:59:30 (EDT)
commitdff17acfc750605ad4c96d8abf032ca7717f0fd6 (patch)
tree1f988369acf94cf3c32b97f619bcce42e49b05df /dev/todo
parent9c868983d795c97398acc22c413ac8d7a21bee23 (diff)
Add Boot Sequencing project to wiki.
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+[[!meta field="title" param="Boot Sequencing"]]
+Currently, service init scripts are provided by the monolithic `initscripts`
+binary package. These init scripts are executed in the lexicographic order of
+the symbolic links matching `/etc/rc.d/S*` that target them. The names of these
+symbolic links are currently hardcoded in [the `build` makefile][bf-build] of
+the `basefiles` source package. This monolithic packaging and hardcoding of
+link names is a temporary and poor technical solution that doesn't scale with
+the number and selection of services that can be installed on a system. Init
+scripts should instead be provided by the packages that provide the relevant
+system services. The order in which init scripts are executed should be
+determined by dynamic boot sequencing based on inter-service dependency
+This boot sequencing can be done when the system boots or after a new system
+service is installed. For reference, NetBSD [uses a program called
+"rcorder"][rcorder-doc] to determine a boot sequence at boot time. Many
+GNU/Linux distributions follow (to some degree) the Linux Standard Base (LSB)
+specification, which defines ["Comment Conventions" for dependency
+metadata][lsb-initscrcomconv] and [a method for installing sequentially-named
+symbolic links][lsb-initsrcinstrm]. Conforming implementations perform boot
+sequencing at the time of service installation. Because boot sequencing at boot
+time can slow down system booting, it is better to perform boot sequencing at
+install time.
+Thus, generally speaking, the solution to be adopted in this system is to make
+packages that provide system services also include the necessary init scripts
+(installed in `/etc/init.d`), to include inter-service dependency metadata in
+init scripts, and to use a tool at the time of service package installation to
+generate sequentially-named symoblic links in `/etc/rc.d`.
+An obvious boot sequencing tool is ["insserv"][insserv] maintained by Werner
+Fink and used by Debian and openSUSE. However, this C program (in compliance
+with the LSB) assumes the use of runlevels. This operating system uses the init
+daemon of BusyBox, which [doesn't support runlevels][bb-init.c]. Therefore,
+we'll need to either modify insserv to work without runlevels or write our own
+tool for installing symbolic links to init scripts.
+Additionally, we need to decide how completely we'll conform, if at all, with
+the LSB in this area.
+Hopefully, this can get done by September 2012.