1.\" Copyright (c) 1999 Daniel C. Sobral 2.\" All rights reserved. 3.\" Copyright (c) 2021 Warner Losh <imp@FreeBSD.org> 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.Dd September 29, 2021 27.Dt LOADER 8 28.Os 29.Sh NAME 30.Nm loader 31.Nd kernel bootstrapping final stage 32.Sh DESCRIPTION 33The program called 34.Nm 35is the final stage of 36.Fx Ns 's 37kernel bootstrapping process. 38It is responsible for bringing the kernel, kernel modules and other files into 39memory. 40It creates a set of 41.Xr sh 1 42like environment variables that are passed to the kernel. 43It executes boot scripts written in one of several interpreters. 44Together with the scripts, it controls the booting process and 45interaction with the user. 46.Pp 47It provides a scripting language that can be used to 48automate tasks, do pre-configuration or assist in recovery 49procedures. 50This scripting language is roughly divided in 51two main components. 52The smaller one is a set of commands 53designed for direct use by the casual user, called "builtin 54commands" for historical reasons. 55The main drive behind these commands is user-friendliness. 56The larger component is the scripting language built into 57the boot loader. 58.Fx 59provides three different interpreters: Forth, Lua and Simple. 60The Forth loader is based on an ANS Forth compatible 61Forth interpreter based on FICL, by 62.An John Sadler . 63The Lua loader is a full Lua interpreter from 64.Pa https://www.lua.org/ . 65The Simple loader only interprets a list of builtin commands 66without any control structure. 67.Pp 68During initialization, 69.Nm 70will probe for a console and set the 71.Va console 72variable, or set it to serial console 73.Pq Dq Li comconsole 74if the previous boot stage used that. 75If multiple consoles are selected, they will be listed separated by spaces. 76Then, devices are probed, 77.Va currdev 78and 79.Va loaddev 80are set, and 81.Va LINES 82is set to 24. 83Finally, an interpreter specific file will be executed. 84.Sh BUILTIN COMMANDS 85The commands common to all interpreters are described in the 86.Xr loader_simp 8 87.Dq BUILTIN COMMANDS 88section. 89.Ss BUILTIN ENVIRONMENT VARIABLES 90The environment variables common to all interpreters are described in the 91.Xr loader_simp 8 92.Dq BUILTIN ENVIRONMENT VARIABLES 93section. 94.Sh SEE ALSO 95.Xr libsa 3 , 96.Xr loader.conf 5 , 97.Xr tuning 7 , 98.Xr boot 8 , 99.Xr btxld 8 , 100.Xr loader.efi 8 , 101.Xr loader_4th 8 , 102.Xr loader_lua 8 , 103.Xr loader_simp 8 104.Sh HISTORY 105The 106.Nm 107first appeared in 108.Fx 3.1 . 109The 110.Nm 111scripting language changed to Lua by default in 112.Fx 12.0 . 113.Sh AUTHORS 114.An -nosplit 115The 116.Nm 117was written by 118.An Michael Smith Aq msmith@FreeBSD.org . 119.Pp 120FICL was written by 121.An John Sadler Aq john_sadler@alum.mit.edu . 122.Pp 123.An Warner Losh Aq imp@FreeBSD.org 124integrated Lua into the tree based on initial work done by Pedro Souza 125for the 2014 Google Summer of Code. 126