From 53618a5036ebbc1324966c4443cd6faa68608906 Mon Sep 17 00:00:00 2001 From: Davin McCall Date: Wed, 22 Jun 2016 09:20:41 +0100 Subject: [PATCH] Update Linux documentation --- doc/linux/DINIT-AS-INIT.md | 68 +++++++++++++++++++++++++++++++--- doc/linux/services/auxfscheck | 2 +- doc/linux/services/boot | 1 + doc/linux/services/hwclock | 13 +++++++ doc/linux/services/loginready | 3 +- doc/linux/services/rcboot.sh | 38 ++++--------------- doc/linux/services/rootfscheck | 2 +- doc/linux/services/rootrw | 1 + doc/linux/services/single | 2 +- doc/linux/services/sshd | 7 ++++ doc/linux/services/syslogd | 7 ++++ 11 files changed, 104 insertions(+), 40 deletions(-) create mode 100644 doc/linux/services/hwclock create mode 100644 doc/linux/services/sshd create mode 100644 doc/linux/services/syslogd diff --git a/doc/linux/DINIT-AS-INIT.md b/doc/linux/DINIT-AS-INIT.md index 2fe3219..5258ae1 100644 --- a/doc/linux/DINIT-AS-INIT.md +++ b/doc/linux/DINIT-AS-INIT.md @@ -5,6 +5,12 @@ in conjunction with other software, to boot your system and replace your current init system (which on most main distributions is now Systemd, Sys V init, or OpenRC). +Be warned that it is not a trivial task to take a system based on a typical +Linux distribution and make it instead boot with Dinit. You need to set up +suitable service description files for your system; at present there are no +automated conversion tools for converting service descriptions or startup +scripts from other systems. + The additional software required can be broken into _essential_ and _optional_ packages, which are detailed in following sections. For example service files, please check the "services" subdirectory. @@ -39,7 +45,8 @@ days. They include: interfaces - /dev/shm - tmpfs - used for shared memory - /dev/pts - devpts - pseudoterminal devices -- /run - tmpfs - storage for program state; used by udev +- /run - tmpfs - storage for program state (replacement for /var/run); used by + udev and some other programs These filesystems (particularly /sys, /proc and /run) need to be mounted quite early as they will be used by early-boot processes. @@ -77,20 +84,66 @@ provide a template for accomplishing the above, but may need some adjustment for your particular configuration. -# Essential packages +# Boot performance compared to Systemd + +Boot performance using Dinit suffers slightly compared to Systemd due to +several factors: + +- Dinit doesn't handle file system mounts/checks and spawns external + processes and/or scripts to manage these +- In the absence of full udev integration, it is more difficult to start + some services as early as possible. For instance, filesystem mounts need + to wait for the appropriate device to be recognized by the kernel and + exported as a device node; similarly network interfaces need to be + recognized before they are configured. With Dinit, the simplest approach + is to wait until udev "settles" (via "udevadm settle") before attempting + mounts and network configuration etc. +- Dinit doesn't do socket activation (yet). What it can do is pre-open a + socket while it launches a daemon, which probably improves boot times a + little but potentially still results in more daemons getting started than + is strictly necessary. + +In the future Dinit might provide functionality to perform basic mounts +without spawning an external process, and will almost certainly support full +socket activation. Some of the more fundamental startup script functionality +might also be offered via some kind of intrinsic service(s). However, where +at all possible, the intention is to keep service functionality separate to +Dinit itself. + + +# Essential packages for building a Dinit-based system + +Other than the obvious system C library and C++ library, you'll need a range +of packages to create a functional Dinit-based system. First, a device node manager. I recommend "Eudev". - Eudev - the Gentoo fork of Udev; https://github.com/gentoo/eudev - Vdev - "a device file manager and filesystem" and a "work in progress"; https://github.com/jcnelson/vdev -- Mdev may also be an option; it is part of the "busybox" utility suite. +- Mdev may also be an option; it is part of the "busybox" utility suite. I + don't personally have any experience with it. Then, a "getty" and "login" program. Both can be found in the util-linux package, at: https://www.kernel.org/pub/linux/utils/util-linux +Also provided in the util-linux package are standard utilities such as fsck +and mount. You'll probably want e2fsprogs (or the equivalent for your chosen +filesystem): http://e2fsprogs.sourceforge.net/ + +The syslog daemon from GNU Inetutils is basic, but functional - which makes +it a good fit for a Dinit-based system. https://www.gnu.org/software/inetutils + +You will need a shell script interpreter / command line, for which you have +a range of options. A common choice is GNU Bash, but many distributions are +using Dash as the /bin/sh shell because it is significantly faster (affecting +boot time). -# Optional packages +- Bash: https://www.gnu.org/software/bash += Dash: http://gondor.apana.org.au/~herbert/dash + + +# Optional packages for building a Dinit-based system ConsoleKit2, to act as seat/sesion manager (functionality otherwise provided by Systemd): @@ -100,6 +153,9 @@ cgmanager, the control group manager; you probably want this if you use ConsoleKit2, and maybe if you want to use containers: https://github.com/lxc/cgmanager -However, I believe that cgmanage works with the old (v1) cgroups interface. +(However, I believe that cgmanage works with the old v1 cgroups interface. I expect that v2 cgroups together with cgroup namespaces as found in newer -kernels will render it obselete. +kernels will render it obselete). + +Both ConsoleKit2 and cgmanager use Dbus: +https://dbus.freedesktop.org/ diff --git a/doc/linux/services/auxfscheck b/doc/linux/services/auxfscheck index 0878b04..5eccc38 100644 --- a/doc/linux/services/auxfscheck +++ b/doc/linux/services/auxfscheck @@ -3,7 +3,7 @@ type = scripted command = /sbin/fsck -A -R -C -a restart = false -runs-on-console = true +options = runs-on-console depends-on = early-filesystems depends-on = udevd diff --git a/doc/linux/services/boot b/doc/linux/services/boot index b0eb681..7269ca4 100644 --- a/doc/linux/services/boot +++ b/doc/linux/services/boot @@ -12,3 +12,4 @@ depends-on = tty6 waits-for = late-filesystems waits-for = dhcpcd +waits-for = sshd diff --git a/doc/linux/services/hwclock b/doc/linux/services/hwclock new file mode 100644 index 0000000..4ce05c7 --- /dev/null +++ b/doc/linux/services/hwclock @@ -0,0 +1,13 @@ +# Set system time from hardware clock + +type = scripted +logfile = /run/hwclock.log +command = /sbin/hwclock --hctosys + +# Optional, not necessary, and not recommended: +#stop-command = /sbin/hwclock --systohc + +restart = false + +depends-on = udevd +depends-on = early-filesystems diff --git a/doc/linux/services/loginready b/doc/linux/services/loginready index de50fdc..4659ed4 100644 --- a/doc/linux/services/loginready +++ b/doc/linux/services/loginready @@ -2,8 +2,9 @@ type = internal restart = false -runs-on-console = yes +options = runs-on-console depends-on = rcboot waits-for = dbusd waits-for = udevd +waits-for = syslogd diff --git a/doc/linux/services/rcboot.sh b/doc/linux/services/rcboot.sh index f752ef1..c59d052 100755 --- a/doc/linux/services/rcboot.sh +++ b/doc/linux/services/rcboot.sh @@ -3,19 +3,15 @@ export PATH=/usr/bin:/usr/sbin:/bin:/sbin umask 0077 if [ "$1" != "stop" ]; then - - # Get system time from hardware clock - /sbin/hwclock --adjust - /sbin/hwclock --hctosys # cleanup # (delete /tmp etc) + rm -rf /tmp/* /tmp/.[^.]* /tmp/..?* + rm -rf /var/lock/* /var/lock/.[^.]* /var/lock/..?* + rm -rf /var/run/* /var/run/.[^.]* /var/run/..?* + # Create (empty) utmp database : > /var/run/utmp - rm -f -r /tmp/* - rm -f -r /tmp/.[^.]* - rm -f -r /tmp/..?* - rm -f /var/locks/* - rm -f -r /var/run/dbus/* + mkdir /var/run/dbus # Configure random number generator cat /var/state/random-seed > /dev/urandom @@ -26,34 +22,16 @@ if [ "$1" != "stop" ]; then # You can put other static configuration here: #/sbin/ifconfig eth0 192.168.1.38 netmask 255.255.255.0 broadcast 192.168.1.255 - /bin/hostname myhost + echo "myhost" > /proc/sys/kernel/hostname - # networking daemons - /usr/libexec/syslogd - /usr/sbin/sshd - /usr/libexec/inetd - # /usr/sbin/alsactl restore - # Prevent spurious messages from kernel to console - # (syslog will still catch them). Default in 2.4.18 is "7 4 1 7". - # in particular this prevents "unknown scancode" messages from unrecognized - # keys on funky keyboards, and module loading messages. - echo "3 4 1 7" > /proc/sys/kernel/printk - - # Printing - #/etc/init.d/hplip start - /etc/init.d/cups start - else # The system is being shut down - # kill some stuff - #if [ -e /var/run/gpm.pid ]; then kill `cat /var/run/gpm.pid`; fi - - /etc/init.d/cups stop # echo "Saving random number seed..." - dd if=/dev/urandom of=/var/state/random-seed bs=512 count=1 2> /dev/null + POOLSIZE=`cat /proc/sys/kernel/random/poolsize` + dd if=/dev/urandom of=/var/state/random-seed bs="$POOLSIZE" count=1 2> /dev/null fi; diff --git a/doc/linux/services/rootfscheck b/doc/linux/services/rootfscheck index 3975d12..83d0bca 100644 --- a/doc/linux/services/rootfscheck +++ b/doc/linux/services/rootfscheck @@ -3,7 +3,7 @@ type = scripted command = /etc/dinit.d/rootfscheck.sh start restart = false -runs-on-console = yes +options = runs-on-console depends-on = early-filesystems depends-on = udevd diff --git a/doc/linux/services/rootrw b/doc/linux/services/rootrw index 2dea27b..1d29cdd 100644 --- a/doc/linux/services/rootrw +++ b/doc/linux/services/rootrw @@ -8,4 +8,5 @@ logfile = /run/rootrw.log depends-on = early-filesystems depends-on = udevd +waits-for = hwclock waits-for = rootfscheck diff --git a/doc/linux/services/single b/doc/linux/services/single index 1046717..1805ffc 100644 --- a/doc/linux/services/single +++ b/doc/linux/services/single @@ -1,4 +1,4 @@ type = process command = /bin/sh restart = false -runs-on-console = true +options = runs-on-console diff --git a/doc/linux/services/sshd b/doc/linux/services/sshd new file mode 100644 index 0000000..39212ce --- /dev/null +++ b/doc/linux/services/sshd @@ -0,0 +1,7 @@ +type = process +smooth-recovery = true +command = /usr/sbin/sshd -D + +depends-on = loginready +depends-on = rcboot +waits-for = syslogd diff --git a/doc/linux/services/syslogd b/doc/linux/services/syslogd new file mode 100644 index 0000000..5d20a5f --- /dev/null +++ b/doc/linux/services/syslogd @@ -0,0 +1,7 @@ +type = bgprocess +smooth-recovery = true +command = /usr/libexec/syslogd +pid-file = /var/run/syslog.pid +options = starts-log + +depends-on = rcboot -- 2.25.1