9e1dc7bec3
Create a man page per loader. Loader(8) will have information common to
all of them, while loader_${INTERP}(8) will have information relevant to
that specific loader. Rewrite loader(8) to give an overview and point to
the appropriate man page. Rewrite each of the loader_${INTER}(8) man
pages to contain only the relevant information to that loader. Put all
the common commands, environment variables, etc in loader_simp(8) and
refernce that from the loader_lua or loader_4th man pages. The
loader_lua(8) could use more details about the Lua
integration. Additional organization may be benefitial.
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D31340
129 lines
4.0 KiB
Groff
129 lines
4.0 KiB
Groff
.\" Copyright (c) 1999 Daniel C. Sobral
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.\" All rights reserved.
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.\" Copyright (c) 2021 Warner Losh <imp@FreeBSD.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd September 29, 2021
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.Dt LOADER 8
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.Os
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.Sh NAME
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.Nm loader
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.Nd kernel bootstrapping final stage
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.Sh DESCRIPTION
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The program called
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.Nm
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is the final stage of
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.Fx Ns 's
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kernel bootstrapping process.
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It is responsible for bringing the kernel, kernel modules and other files into
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memory.
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It creates a set of
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.Xr sh 1
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like environment variables that are passed to the kernel.
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It executes boot scripts written in one of several interpreters.
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Together with the scripts, it controls the booting process and
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interaction with the user.
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.Pp
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It provides a scripting language that can be used to
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automate tasks, do pre-configuration or assist in recovery
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procedures.
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This scripting language is roughly divided in
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two main components.
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The smaller one is a set of commands
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designed for direct use by the casual user, called "builtin
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commands" for historical reasons.
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The main drive behind these commands is user-friendliness.
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The larger component is the scripting language built into
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the boot loader.
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.Fx
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provides three different interpreters: Forth, Lua and Simple.
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The Forth loader is based on an ANS Forth compatible
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Forth interpreter based on FICL, by
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.An John Sadler .
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The Lua loader is includes a full Lua interpreter from
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.Pa https://www.lua.org/ .
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The Simple loader only interprets a list of builtin commands
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without any control structure.
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.Pp
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During initialization,
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.Nm
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will probe for a console and set the
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.Va console
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variable, or set it to serial console
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.Pq Dq Li comconsole
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if the previous boot stage used that.
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If multiple consoles are selected, they will be listed separated by spaces.
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Then, devices are probed,
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.Va currdev
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and
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.Va loaddev
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are set, and
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.Va LINES
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is set to 24.
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Finally, an interpreter specific file will be executed.
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.Sh BUILTIN COMMANDS
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The commands common to all interpreters are described in the
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.Xr loader_simp 8
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.Dq BUILTIN COMMANDS
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section.
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.Ss BUILTIN ENVIRONMENT VARIABLES
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The environment variables common to all interpreters are described in the
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.Xr loader_simp 8
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.Dq BUILTIN ENVIRONMENT VARIABLES
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section.
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.Sh SEE ALSO
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.Xr libstand 3 ,
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.Xr loader.conf 5 ,
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.Xr tuning 7 ,
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.Xr boot 8 ,
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.Xr btxld 8 ,
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.Xr loader.efi 8 ,
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.Xr loader_4th 8 ,
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.Xr loader_lua 8 ,
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.Xr loader_simp 8
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.Sh HISTORY
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The
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.Nm
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first appeared in
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.Fx 3.1 .
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The
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.Nm
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scripting language changed to Lua by default in
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.Fx 12.0 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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was written by
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.An Michael Smith Aq msmith@FreeBSD.org .
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.Pp
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FICL was written by
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.An John Sadler Aq john_sadler@alum.mit.edu .
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.Pp
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.An Warner Losh Aq imp@FreeBSD.org
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integrated Lua into the tree based on initial work done by Pedro Souza
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for the 2014 Google Summer of Code.
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