1 .\" Copyright (c) 1999 Daniel C. Sobral
2 .\" All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
13 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 .\" $FreeBSD: src/sys/boot/common/loader.8,v 1.57 2003/06/29 20:57:55 brueffer Exp $
26 .\" $DragonFly: src/sys/boot/common/loader.8,v 1.14 2006/10/14 23:06:42 swildner Exp $
28 .\" Note: The date here should be updated whenever a non-trivial
29 .\" change is made to the manual page.
35 .Nd kernel bootstrapping final stage
41 kernel bootstrapping process.
42 On IA32 (i386) architectures, it is a
45 It is linked statically to
47 and usually located in the directory
50 It provides a scripting language that can be used to
51 automate tasks, do pre-configuration or assist in recovery
53 This scripting language is roughly divided in
55 The smaller one is a set of commands
56 designed for direct use by the casual user, called "builtin
57 commands" for historical reasons.
58 The main drive behind these commands is user-friendliness.
59 The bigger component is an
61 Forth compatible Forth interpreter based on FICL, by
64 During initialization,
66 will probe for a console and set the
68 variable, or set it to serial console
70 if the previous boot stage used that.
71 Then, devices are probed,
80 is initialized, the builtin words are added to its vocabulary, and
82 is processed if it exists.
83 No disk switching is possible while that file is being read.
95 is processed if available, and, failing that,
97 is read for historical reasons.
98 These files are processed through the
100 command, which reads all of them into memory before processing them,
101 making disk changes possible.
105 has not been tried, and if
109 (not case sensitive), then an
112 If the system gets past this point,
116 will engage interactive mode.
120 builtin commands take parameters from the command line.
122 the only way to call them from a script is by using
125 If an error condition occurs, an exception will be generated,
126 which can be intercepted using
128 Forth exception handling
130 If not intercepted, an error message will be displayed and
131 the interpreter's state will be reset, emptying the stack and restoring
134 The builtin commands available are:
136 .Bl -tag -width Ds -compact
137 .It Ic autoboot Op Ar seconds
138 Proceeds to bootstrap the system after a number of seconds, if not
139 interrupted by the user.
140 Displays a countdown prompt
141 warning the user the system is about to be booted,
142 unless interrupted by a key press.
143 The kernel will be loaded first if necessary.
144 Defaults to 10 seconds.
147 Displays statistics about disk cache usage.
151 .It Ic boot Ar kernelname Op Cm ...
152 .It Ic boot Fl flag Cm ...
153 Immediately proceeds to bootstrap the system, loading the kernel
155 Any flags or arguments are passed to the kernel, but they
156 must precede the kernel name, if a kernel name is provided.
159 The behavior of this builtin is changed if
167 Displays text on the screen.
168 A new line will be printed unless
173 Displays memory usage statistics.
174 For debugging purposes only.
176 .It Ic help Op topic Op subtopic
177 Shows help messages read from
178 .Pa /boot/loader.help .
181 will list the topics available.
183 .It Ic include Ar file Op Ar
184 Process script files.
185 Each file, in turn, is completely read into memory,
186 and then each of its lines is passed to the command line interpreter.
187 If any error is returned by the interpreter, the include
188 command aborts immediately, without reading any other files, and
189 returns an error itself (see
196 Loads a kernel, kernel loadable module (kld), or file of opaque
197 contents tagged as being of the type
199 Kernel and modules can be either in a.out or ELF format.
200 Any arguments passed after the name of the file to be loaded
201 will be passed as arguments to that file.
202 Currently, argument passing does not work for the kernel.
208 Displays a listing of files in the directory
210 or the root directory if
215 is specified, file sizes will be shown too.
218 Lists all of the devices from which it may be possible to load modules.
221 is specified, more details are printed.
224 Displays loaded modules.
227 is specified, more details are shown.
229 .It Ic more Ar file Op Ar
230 Display the files specified, with a pause at each
234 .It Ic pnpscan Op Fl v
235 Scans for Plug-and-Play devices.
236 This is not functional at present.
243 Reads a line of input from the terminal, storing it in
246 A timeout can be specified with
248 though it will be canceled at the first key pressed.
249 A prompt may also be displayed through the
254 Immediately reboots the system.
256 .It Ic set Ar variable
257 .It Ic set Ar variable Ns = Ns Ar value
258 Set loader's environment variables.
260 .It Ic show Op Va variable
261 Displays the specified variable's value, or all variables and their
267 Remove all modules from memory.
269 .It Ic unset Va variable
272 from the environment.
278 .Ss BUILTIN ENVIRONMENT VARIABLES
281 has actually two different kinds of
284 There are ANS Forth's
285 .Em environmental queries ,
286 and a separate space of environment variables used by builtins, which
287 are not directly available to Forth words.
288 It is the latter type that this section covers.
290 Environment variables can be set and unset through the
294 builtins, and can have their values interactively examined through the
298 Their values can also be accessed as described in
301 Notice that these environment variables are not inherited by any shell
302 after the system has been booted.
304 A few variables are set automatically by
306 Others can affect the behavior of either
308 or the kernel at boot.
309 Some options may require a value,
310 while others define behavior just by being set.
311 Both types of builtin variables are described below.
312 .Bl -tag -width bootfile
314 Unset this to disable automatic loading of the ACPI module.
315 .It Va autoboot_delay
318 will wait before booting.
319 If this variable is not defined,
321 will default to 10 seconds.
327 will be automatically attempted after processing
328 .Pa /boot/loader.rc ,
331 will be processed normally, defaulting to 10 seconds delay.
333 Instructs the kernel to prompt the user for the name of the root device
334 when the kernel is booted.
336 Instructs the kernel to start in the DDB debugger, rather than
337 proceeding to initialize when booted.
339 Selects gdb-remote mode for the kernel debugger by default.
341 Prevents the kernel from initiating a multi-user startup; instead single-user
342 mode will be entered when the kernel has finished device probing.
343 .It Va boot_userconfig
344 Requests that the kernel's interactive device configuration program
345 be run when the kernel is booted.
347 Setting this variable causes extra debugging information to be printed
348 by the kernel during the boot phase.
350 List of semicolon-separated search path for bootable kernels.
352 .Dq Li kernel;kernel.old .
354 Defines the current console.
356 Selects the default device.
357 Syntax for devices is odd.
359 Sets the list of binaries which the kernel will try to run as the initial
361 The first matching binary is used.
363 .Dq Li /sbin/init:/sbin/oinit:/sbin/init.bak:/stand/sysinstall .
367 if the Forth's current state is interpreting.
369 Define the number of lines on the screen, to be used by the pager.
371 Sets the list of directories which will be searched for modules
372 named in a load command or implicitly required by a dependency.
373 The default value for this variable is
374 .Dq Li /;/boot;/modules .
376 Sets the number of IDE disks as a workaround for some problems in
377 finding the root disk at boot.
378 This has been deprecated in favor of
385 .Dq Li "${currdev}>" .
386 .It Va root_disk_unit
387 If the code which detects the disk unit number for the root disk is
388 confused, e.g. by a mix of SCSI and IDE disks, or IDE disks with
389 gaps in the sequence (e.g. no primary slave), the unit number can
390 be forced by setting this variable.
392 By default the value of
394 is used to set the root file system
395 when the kernel is booted.
396 This can be overridden by setting
400 The name of a device where the kernel can save a crash dump in case
402 This automatically sets the
408 Other variables are used to override kernel tunable parameters.
409 The following tunables are available:
412 Limit the amount of physical memory the system will use.
413 By default the size is in bytes, but the
414 .Cm k , K , m , M , g
418 are also accepted and indicate kilobytes, megabytes and gigabytes
420 An invalid suffix will result in the variable being ignored by the
422 .It Va kern.emergency_intr_enable
423 Setting this to 1 enables emergency interrupt polling. All interrupt
424 handlers are executed periodically. This mode is very expensive and should
425 only be used to get a system accessible when interrupt routing is
426 otherwise broken. It is primarly used by kernel developers to debug new
428 .It Va kern.emergency_intr_freq
429 Set the polling rate for the emergency interrupt polling code. The
430 default is 10 (hz) to dissuade casual use. If you are doing real work
431 with emergency interrupt polling mode enabled, it is recommended
432 that you use a frequency between 100hz and 300hz.
434 Set the size of a number of statically allocated system tables; see
436 for a description of how to select an appropriate value for this
438 When set, this tunable replaces the value declared in the kernel
439 compile-time configuration file.
440 .It Va kern.ipc.nmbclusters
441 Set the number of mbuf clusters to be allocated.
442 The value cannot be set below the default
443 determined when the kernel was compiled.
446 .It Va kern.ipc.nsfbufs
449 buffers to be allocated.
453 Toggles the mmx optimizations for the bcopy/copyin/copyout routines
454 .It Va kern.vm.kmem.size
455 Sets the size of kernel memory (bytes).
456 This overrides the value determined when the kernel was compiled.
457 .It Va kern.maxswzone
458 Limits the amount of KVM to be used to hold swap
459 meta information, which directly governs the
460 maximum amount of swap the system can support.
461 This value is specified in bytes of KVA space
462 and defaults to around 70MBytes.
464 to not reduce this value such that the actual
465 amount of configured swap exceeds \(12 the
466 kernel-supported swap.
467 The default 70MB allows
468 the kernel to support a maximum of (approximately)
469 14GB of configured swap.
470 Only mess around with
471 this parameter if you need to greatly extend the
472 KVM reservation for other resources such as the
476 .Va VM_SWZONE_SIZE_MAX .
477 .It Va kern.maxbcache
478 Limits the amount of KVM reserved for use by the
479 buffer cache, specified in bytes.
480 The default maximum is 200MB.
481 This parameter is used to
482 prevent the buffer cache from eating too much
483 KVM in large-memory machine configurations.
484 Only mess around with this parameter if you need to
485 greatly extend the KVM reservation for other resources
486 such as the swap zone or
489 the NBUF parameter will override this limit.
491 .Va VM_BCACHE_SIZE_MAX .
492 .It Va machdep.disable_mtrrs
493 Disable the use of i686 MTRRs (x86 only).
494 .It Va net.inet.tcp.tcbhashsize
495 Overrides the compile-time set value of
497 or the preset default of 512.
498 Must be a power of 2.
501 When a builtin command is executed, the rest of the line is taken
502 by it as arguments, and it is processed by a special parser which
503 is not used for regular Forth commands.
505 This special parser applies the following rules to the parsed text:
509 All backslash characters are preprocessed.
512 \eb , \ef , \er , \en and \et are processed as in C.
514 \es is converted to a space.
521 Useful for things like
524 \e0xN and \e0xNN are replaced by the hex N or NN.
526 \eNNN is replaced by the octal NNN
530 \e" , \e' and \e$ will escape these characters, preventing them from
531 receiving special treatment in Step 2, described below.
533 \e\e will be replaced with a single \e .
535 In any other occurrence, backslash will just be removed.
538 Every string between non-escaped quotes or double-quotes will be treated
539 as a single word for the purposes of the remaining steps.
545 with the value of the environment variable
548 Space-delimited arguments are passed to the called builtin command.
549 Spaces can also be escaped through the use of \e\e .
552 An exception to this parsing rule exists, and is described in
553 .Sx BUILTINS AND FORTH .
554 .Ss BUILTINS AND FORTH
555 All builtin words are state-smart, immediate words.
556 If interpreted, they behave exactly as described previously.
557 If they are compiled, though,
558 they extract their arguments from the stack instead of the command line.
560 If compiled, the builtin words expect to find, at execution time, the
561 following parameters on the stack:
562 .D1 Ar addrN lenN ... addr2 len2 addr1 len1 N
565 are strings which will compose the command line that will be parsed
566 into the builtin's arguments.
567 Internally, these strings are concatenated in from 1 to N,
568 with a space put between each one.
570 If no arguments are passed, a 0
572 be passed, even if the builtin accepts no arguments.
574 While this behavior has benefits, it has its trade-offs.
575 If the execution token of a builtin is acquired (through
583 the builtin behavior will depend on the system state
591 \&! This is particularly annoying for programs that want or need to
593 In this case, the use of a proxy is recommended.
598 is a Forth interpreter written in C, in the form of a forth
599 virtual machine library that can be called by C functions and vice
604 each line read interactively is then fed to
608 back to execute the builtin words.
615 The words available to
617 can be classified into four groups.
620 Forth standard words, extra
624 words, and the builtin commands;
625 the latter were already described.
628 Forth standard words are listed in the
631 The words falling in the two other groups are described in the
632 following subsections.
634 .Bl -tag -width wid-set-super
642 This is the STRING word set's
649 This is the STRING word set's
659 .Ss FREEBSD EXTRA WORDS
660 .Bl -tag -width XXXXXXXX
662 Evaluates the remainder of the input buffer, after having printed it first.
664 Evaluates the remainder of the input buffer under a
670 but without outputting a trailing space.
671 .It Ic fclose Pq Ar fd --
673 .It Ic fkey Pq Ar fd -- char
674 Reads a single character from a file.
675 .It Ic fload Pq Ar fd --
678 .It Ic fopen Pq Ar addr len mode Li -- Ar fd
680 Returns a file descriptor, or \-1 in case of failure.
683 parameter selects whether the file is to be opened for read access, write
686 .Dv O_RDONLY , O_WRONLY ,
690 .Pa /boot/support.4th ,
691 indicating read only, write only, and read-write access, respectively.
694 .Pq Ar fd addr len -- len'
702 Returns the actual number of bytes read, or -1 in case of error or end of
704 .It Ic heap? Pq -- Ar cells
705 Return the space remaining in the dictionary heap, in cells.
706 This is not related to the heap used by dynamic memory allocation words.
707 .It Ic inb Pq Ar port -- char
708 Reads a byte from a port.
709 .It Ic key Pq -- Ar char
710 Reads a single character from the console.
711 .It Ic key? Pq -- Ar flag
714 if there is a character available to be read from the console.
719 .It Ic outb Pq Ar port char --
720 Writes a byte to a port.
721 .It Ic seconds Pq -- Ar u
722 Returns the number of seconds since midnight.
723 .It Ic tib> Pq -- Ar addr len
724 Returns the remainder of the input buffer as a string on the stack.
725 .It Ic trace! Pq Ar flag --
726 Activates or deactivates tracing.
730 .Ss FREEBSD DEFINED ENVIRONMENTAL QUERIES
734 if the architecture is IA32.
735 .It DragonFly_version
737 version at compile time.
742 .Ss SYSTEM DOCUMENTATION
744 .Bl -tag -width /boot/defaults/loader.conf -compact
748 .It Pa /boot/boot.4th
752 .It Pa /boot/boot.conf
754 bootstrapping script.
756 .It Pa /boot/defaults/loader.conf
757 .It Pa /boot/loader.conf
758 .It Pa /boot/loader.conf.local
760 configuration files, as described in
762 .It Pa /boot/loader.rc
764 bootstrapping script.
765 .It Pa /boot/loader.help
768 Contains the help messages.
771 Boot in single user mode:
775 Load kernel's user configuration file.
776 Notice that a kernel must be loaded before any other
778 command is attempted.
779 .Bd -literal -offset indent
781 load -t userconfig_script /boot/kernel.conf
784 Load the kernel, a splash screen, and then autoboot in five seconds.
785 .Bd -literal -offset indent
788 load -t splash_image_data /boot/chuckrulez.bmp
792 Set the disk unit of the root device to 2, and then boot.
793 This would be needed in a system with two IDE disks,
794 with the second IDE disk hardwired to wd2 instead of wd1.
795 .Bd -literal -offset indent
801 .Bl -tag -width /usr/share/examples/bootforth/X
802 .It Pa /boot/loader.4th
803 Extra builtin-like words.
804 .It Pa /boot/support.4th
807 .It Pa /usr/share/examples/bootforth/
811 The following values are thrown by
813 .Bl -tag -width XXXXX -offset indent
815 Any type of error in the processing of a builtin.
826 Out of interpreting text.
828 Need more text to succeed -- will finish on next run.
842 For the purposes of ANS Forth compliance, loader is an
844 ANS Forth System with Environmental Restrictions, Providing
850 parse, pick, roll, refill, to, value, \e, false, true,
853 compile\&, , erase, nip, tuck
858 from the Core Extensions word set, Providing the Exception Extensions
859 word set, Providing the Locals Extensions word set, Providing the
860 Memory-Allocation Extensions word set, Providing
864 bye, forget, see, words,
871 from the Programming-Tools extension word set, Providing the
872 Search-Order extensions word set.
884 .An Michael Smith Aq msmith@FreeBSD.org .
888 .An John Sadler Aq john_sadler@alum.mit.edu .
894 words will read from the input buffer instead of the console.
895 The latter will be fixed, but the former will not.
projects / dragonfly.git / blob