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Diffstat (limited to 'doc/s6-linux-init-maker.html')
| -rw-r--r-- | doc/s6-linux-init-maker.html | 50 |
1 files changed, 29 insertions, 21 deletions
diff --git a/doc/s6-linux-init-maker.html b/doc/s6-linux-init-maker.html index e2e0b2b..e82ce40 100644 --- a/doc/s6-linux-init-maker.html +++ b/doc/s6-linux-init-maker.html @@ -21,7 +21,12 @@ <p> <tt>s6-linux-init-maker</tt> reads configuration options on the command line, and outputs a directory to place in the -root filesystem as well as a script suitable as an init program. +root filesystem. That directory contains a script suitable +as an init program, as well as support file hierarchies to +get a complete +<a href="http://skarnet.org/software/s6/">s6</a> +infrastructure running when the system is booted on that +script. </p> <p> @@ -58,7 +63,7 @@ machine</em> - else the scripts will crash. [ -d <em>dev_style</em> ] \ [ -s <em>env_store</em> ] \ [ -e <em>initial_envvar</em> ] ... \ - <em>dir</em> > <em>stage1</em> + <em>dir</em> </pre> <ul> @@ -66,9 +71,9 @@ machine</em> - else the scripts will crash. <li> s6-linux-init-maker parses options on its command line. </li> <li> It writes data into a directory <em>dir</em>, which must not exist beforehand. </li> - <li> It then prints a script to its standard output. </li> <li> It exits 0 if everything went well, 100 if a user error occurred, -and 111 if a problem occurred during the directory or script creation. </li> +and 111 if a problem occurred during the creation of the directory +or its contents. </li> </ul> <p> @@ -81,35 +86,37 @@ tool can do it, as well as the GNU or busybox <tt>cp -a</tt> or <tt>mv</tt> comm </p> <p> - The <em>stage1</em> script printed by s6-linux-init-maker on its -stdout is then suitable as an init program. The administrator should -copy it to <tt>/sbin/init</tt> and make it executable. + The <tt><em>basedir</em>/init</tt> script +is then suitable as a "stage 1" init program, i.e. the first program +run by the kernel. The administrator should make a symbolic link +from <tt>/sbin/init</tt> to <tt><em>basedir</em>/init</tt>; the +machine will then be ready to boot </p> <h2> Boot sequence </h2> <p> - When the kernel boots, it runs the <em>stage1</em> script, and this is -what happens: + When the kernel boots, it runs the <tt><em>basedir</em>/init</tt> script, +also known as <em>stage 1</em>. and this is what happens: </p> <ul> - <li> <em>stage1</em> is an + <li> <em>stage 1</em> is an <a href="http://skarnet.org/software/execline/">execline</a> script, so the first process run by the kernel is the <a href="http://skarnet.org/software/execline/execlineb.html">execlineb</a> program launcher. </li> - <li> <em>stage1</em> mounts a + <li> <em>stage 1</em> mounts a <a href="https://www.kernel.org/doc/Documentation/filesystems/tmpfs.txt">tmpfs</a> filesystem on <em>tmpfsdir</em>. </li> - <li> <em>stage1</em> copies <tt><em>basedir</em>/run-image</tt> verbatim to + <li> <em>stage 1</em> copies <tt><em>basedir</em>/run-image</tt> verbatim to <em>tmpfsdir</em>. </li> - <li> <em>stage1</em> empties its environment, then reads a global set of environment variables from the + <li> <em>stage 1</em> empties its environment, then reads a global set of environment variables from the <tt><em>basedir</em>/env</tt> <a href="http://skarnet.org/software/s6/s6-envdir.html">environment directory</a>. </li> - <li> <em>stage1</em> forks a child that will block until + <li> <em>stage 1</em> forks a child that will block until <a href="http://skarnet.org/software/s6/s6-svscan.html">s6-svscan</a> is running. </li> - <li> <em>stage1</em> executes, as process 1, into + <li> <em>stage 1</em> executes, as process 1, into <a href="http://skarnet.org/software/s6/s6-svscan.html">s6-svscan</a>, with <tt><em>tmpfsdir</em>/service</tt> as a <a href="http://skarnet.org/software/s6/scandir.html">scan directory</a>. </li> @@ -122,7 +129,7 @@ instead of clogging the system console. </li> <li> If the <tt>-g</tt> option has been given to s6-linux-init-maker, the scan directory will also contain a service for an early getty. </li> <li> s6-svscan starts all the services defined in the scan directory, -and unblocks the child forked by <em>stage1</em>. </li> +and unblocks the child forked by <em>stage 1</em>. </li> <li> This child executes into <em>stage2</em>. </li> </ul> @@ -158,7 +165,7 @@ getty is essentially to make it easier to debug if <em>stage2</em> fails. </li> There is <em>nothing else</em>. In particular, no filesystem has been mounted yet, including <tt>/proc</tt> and <tt>/sys</tt>; and no one-time initialization -has been performed. The point of <em>stage1</em> is only to make it +has been performed. The point of <em>stage 1</em> is only to make it possible to run <em>stage2</em> with a logging infrastructure and a supervision infrastructure already available, and all the real machine and service initialization should happen in <em>stage2</em>. @@ -222,7 +229,8 @@ service manager. <h2> s6-linux-init-maker options </h2> <ul> - <li> <tt>-c</tt> <em>basedir</em> : at boot time, <em>stage1</em> + <li> <tt>-c</tt> <em>basedir</em> : at boot time, <em>stage 1</em>, +which should be accessible as <tt><em>basedir</em>/init</tt>, will read its read-only data from <em>basedir</em>. After running s6-linux-init-maker, the administrator should make sure to copy the created directory <em>dir</em> to <em>basedir</em>. <em>basedir</em> @@ -282,7 +290,7 @@ It must be absolute. Default is <li> <tt>-p</tt> <em>initial_path</em> : the value to set the PATH environment variable to, for all the starting processes. -This will be done as early as possible in <em>stage1</em>. It is +This will be done as early as possible in <em>stage 1</em>. It is absolutely necessary for <a href="http://skarnet.org/software/execline/">execline</a>, <a href="http://skarnet.org/software/s6/">s6</a>, @@ -314,13 +322,13 @@ devtmpfs but not automounted by the kernel at boot time, and 2 means devtmpfs automounted by the kernel at boot time. Default is <strong><tt>2</tt></strong>. </li> <p /> - <li> <tt>-s</tt> <em>env_store</em> : stage1 init sometimes + <li> <tt>-s</tt> <em>env_store</em> : stage 1 init sometimes inherits a few environment variables from the kernel. It empties its environment before spawning stage2 and executing into s6-svscan, in order to prevent those "kernel" environment variables from leaking into the whole process tree. However, sometimes those variables are needed at a later time; in that case, giving the <tt>-s</tt> option -to s6-linux-init-maker makes stage1 init dump the "kernel" environment +to s6-linux-init-maker makes stage 1 init dump the "kernel" environment variables into the <em>env_store</em> directory, via the <a href="http://skarnet.org/software/s6-portable-utils/s6-dumpenv.html">s6-dumpenv</a> program, before erasing them. <em>env_store</em> should obviously be |