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
27 .\" Note: The date here should be updated whenever a non-trivial
28 .\" change is made to the manual page.
34 .Nd kernel bootstrapping final stage
40 kernel bootstrapping process.
41 On IA32 (i386) architectures, it is a
44 It is linked statically to
46 and usually located in the directory
49 It provides a scripting language that can be used to
50 automate tasks, do pre-configuration or assist in recovery
52 This scripting language is roughly divided in
54 The smaller one is a set of commands
55 designed for direct use by the casual user, called "builtin
56 commands" for historical reasons.
57 The main drive behind these commands is user-friendliness.
58 The bigger component is an
60 Forth compatible Forth interpreter based on ficl, by
63 During initialization,
65 will probe for a console and set the
67 variable, or set it to serial console
69 if the previous boot stage used that.
70 Then, devices are probed,
79 is initialized, the builtin words are added to its vocabulary, and
81 is processed if it exists.
82 No disk switching is possible while that file is being read.
94 is processed if available, and, failing that,
96 is read for historical reasons.
97 These files are processed through the
99 command, which reads all of them into memory before processing them,
100 making disk changes possible.
104 has not been tried, and if
108 (not case sensitive), then an
111 If the system gets past this point,
115 will engage interactive mode.
119 builtin commands take parameters from the command line.
121 the only way to call them from a script is by using
124 If an error condition occurs, an exception will be generated,
125 which can be intercepted using
127 Forth exception handling
129 If not intercepted, an error message will be displayed and
130 the interpreter's state will be reset, emptying the stack and restoring
133 The builtin commands available are:
135 .Bl -tag -width Ds -compact
136 .It Ic autoboot Op Ar seconds
137 Proceeds to bootstrap the system after a number of seconds, if not
138 interrupted by the user.
139 Displays a countdown prompt
140 warning the user the system is about to be booted,
141 unless interrupted by a key press.
142 The kernel will be loaded first if necessary.
143 Defaults to 10 seconds.
146 Displays statistics about disk cache usage.
150 .It Ic boot Ar kernelname Op Cm ...
151 .It Ic boot Fl flag Cm ...
152 Immediately proceeds to bootstrap the system, loading the kernel
154 Any flags or arguments are passed to the kernel, but they
155 must precede the kernel name, if a kernel name is provided.
158 The behavior of this builtin is changed if
166 Displays a text on the screen.
167 A new line will be printed unless
172 Displays memory usage statistics.
173 For debugging purposes only.
175 .It Ic help Op topic Op subtopic
176 Shows help messages read from
177 .Pa /boot/loader.help .
180 will list the topics available.
182 .It Ic include Ar file Op Ar
183 Process script files.
184 Each file is, at a turn, completely read into memory,
185 and then have each of its lines passed to the command line interpreter.
186 If any error is returned by the interpreter, the include
187 commands aborts immediately, without reading any other files, and
188 returns an error itself (see
195 Loads a kernel, kernel loadable module (kld), or a file of opaque
196 contents tagged as being of the type
198 Kernel and modules can be either in a.out or elf format.
199 Any arguments passed after the name of the file to be loaded
200 will be passed as arguments to that file.
201 Notice, though, that, at the present, this does not work for the kernel.
207 Displays a listing of files in the directory
209 or the root directory if
214 is specified, file sizes will be shown too.
217 Lists all of the devices from which it may be possible to load modules.
220 is specified, more details are printed.
223 Displays loaded modules.
226 is specified, more details are shown.
228 .It Ic more Ar file Op Ar
229 Display the files specified, with a pause at each
233 .It Ic pnpscan Op Fl v
234 Scans for Plug-and-Play devices.
235 This is not functional at the present.
242 Reads a line of input from the terminal, storing it in
245 A timeout can be specified with
247 though it will be canceled at the first key pressed.
248 A prompt may also be displayed through the
253 Immediately reboots the system.
255 .It Ic set Ar variable
256 .It Ic set Ar variable Ns = Ns Ar value
257 Set loader's environment variables.
259 .It Ic show Op Va variable
260 Displays the specified variable's value, or all variables and their
266 Remove all modules from memory.
268 .It Ic unset Va variable
271 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 later ones that this session covers.
290 Environment variables can be set and unset through the use of the
294 builtins, and have their value 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 either
308 or kernel's behavior at boot.
309 While some of these may require a value,
310 others define behavior just by being set.
311 These are described below.
312 .Bl -tag -width bootfile
314 Unset this to disable automatic loading of the ACPI module.
316 .Va hint.acpi.0.disabled
319 .It Va autoboot_delay
322 will wait before booting.
323 If this variable is not defined,
325 will default to 10 seconds.
331 will be automatically attempted after processing
332 .Pa /boot/loader.rc ,
335 will be processed normally, defaulting to 10 seconds delay.
337 Instructs the kernel to prompt the user for the name of the root device
338 when the kernel is booted.
340 Instructs the kernel to start in the DDB debugger, rather than
341 proceeding to initialise when booted.
343 Selects gdb-remote mode for the kernel debugger by default.
345 Prevents the kernel from initiating a multi-user startup, single-user
346 mode will be entered when the kernel has finished device probes.
347 .It Va boot_userconfig
348 Requests that the kernel's interactive device configuration program
349 be run when the kernel is booted.
351 Setting this variable causes extra debugging information to be printed
352 by the kernel during the boot phase.
354 List of semicolon-separated search path for bootable kernels.
356 .Dq Li kernel;kernel.old .
358 Defines the current console.
360 Selects the default device.
361 Syntax for devices is odd.
363 Sets the list of binaries which the kernel will try to run as initial
366 .Dq Li /sbin/init:/sbin/oinit:/sbin/init.bak:/stand/sysinstall .
370 if the Forth's current state is interpreting.
372 Define the number of lines on the screen, to be used by the pager.
374 Sets the list of directories which will be searched in for modules
375 named in a load command or implicitly required by a dependency.
376 The default value for this variable is
377 .Dq Li /;/boot;/modules .
379 Sets the number of IDE disks as a work around for some problems in
380 finding the root disk at boot.
381 This has been deprecated in favor of
388 .Dq Li "${currdev}>" .
389 .It Va root_disk_unit
390 If the code which detects the disk unit number for the root disk is
391 confused, eg. by a mix of SCSI and IDE disks, or IDE disks with
392 gaps in the sequence (eg. no primary slave), the unit number can
393 be forced by setting this variable.
395 By default the value of
397 is used to set the root filesystem
398 when the kernel is booted.
399 This can be overridden by setting
403 A name of device where the kernel can save a crash dump in the case
405 This automatically sets
411 Other variables are used to override kernel tunable parameters.
412 The following tunables are available:
415 Limit the amount of physical memory the system will use.
416 By default the size is in bytes, but the
417 .Cm k , K , m , M , g
421 are also accepted and indicate kilobytes, megabytes and gigabytes
423 An invalid suffix will result in the variable being ignored by the
426 Set the size of a number of statically allocated system tables; see
428 for a description of how to select an appropriate value for this
430 When set, this tunable replaces the value declared in the kernel
431 compile-time configuration file.
432 .It Va kern.ipc.nmbclusters
433 Set the number of mbuf clusters to be allocated.
434 The value cannot be set below the default
435 determined when the kernel was compiled.
438 .It Va kern.vm.kmem.size
439 Sets the size of kernel memory (bytes).
440 This overrides completely the value
441 determined when the kernel was compiled.
444 .It Va kern.maxswzone
445 Limits the amount of KVM to be used to hold swap
446 meta information, which directly governs the
447 maximum amount of swap the system can support.
448 This value is specified in bytes of KVA space
449 and defaults to around 70MBytes.
451 to not reduce this value such that the actual
452 amount of configured swap exceeds 1/2 the
453 kernel-supported swap.
454 The default 70MB allows
455 the kernel to support a maximum of (approximately)
456 14GB of configured swap.
457 Only mess around with
458 this parameter if you need to greatly extend the
459 KVM reservation for other resources such as the
463 .Va VM_SWZONE_SIZE_MAX .
464 .It Va kern.maxbcache
465 Limits the amount of KVM reserved for use by the
466 buffer cache, specified in bytes.
467 The default maximum is 200MB.
468 This parameter is used to
469 prevent the buffer cache from eating too much
470 KVM in large-memory machine configurations.
471 Only mess around with this parameter if you need to
472 greatly extend the KVM reservation for other resources
473 such as the swap zone or
476 the NBUF parameter will override this limit.
478 .Va VM_BCACHE_SIZE_MAX .
479 .It Va machdep.pccard.pcic_irq
480 Overrides the IRQ normally assigned to a PCCARD controller.
481 Typically the first available interrupt will be allocated,
482 which may conflict with other hardware.
483 If this value is set to 0,
484 an interrupt will not be assigned
485 and the controller will operate in polled mode only.
486 .It Va net.inet.tcp.tcbhashsize
487 Overrides the compile-time set value of
489 or the preset default of 512.
490 Must be a power of 2.
493 When a builtin command is executed, the rest of the line is taken
494 by it as arguments, and it is processed by a special parser which
495 is not used for regular Forth commands.
497 This special parser applies the following rules to the parsed text:
501 All backslash characters are preprocessed.
504 \eb , \ef , \er , \en and \et are processed as in C.
506 \es is converted to a space.
513 Useful for things like
516 \e0xN and \e0xNN are replaced by the hex N or NN.
518 \eNNN is replaced by the octal NNN
522 \e" , \e' and \e$ will escape these characters, preventing them from
523 receiving special semantics on the step 2 described below.
525 \e\e will be replaced with a single \e .
527 In any other occurrence, backslash will just be removed.
530 Every string between non-escaped quotes or double-quotes will be treated
531 as a single word for the purposes of the remaining steps.
537 with the value of the environment variable
540 Passes multiple space-delimited arguments to the builtin command called.
541 Spaces can also be escaped through the use of \e\e .
544 An exception to this parsing rule exists, and is described in
545 .Sx BUILTINS AND FORTH .
546 .Ss BUILTINS AND FORTH
547 All builtin words are state-smart, immediate words.
548 If interpreted, they behave exactly as described previously.
549 If they are compiled, though,
550 they extract their arguments from the stack instead of the command line.
552 If compiled, the builtin words expect to find, at execution time, the
553 following parameters on the stack:
554 .D1 Ar addrN lenN ... addr2 len2 addr1 len1 N
557 are strings which will compose the command line that will be parsed
558 into the builtin's arguments.
559 Internally, these strings are concatenated in from 1 to N,
560 with a space put between each one.
562 If no arguments are passed, a 0
564 be passed, even if the builtin accepts no arguments.
566 While this behavior has benefits, it has its trade-offs.
567 If the execution token of a builtin is acquired (through
575 the builtin behavior will depend on the system state
583 \&! This is particular annoying for programs that want or need to
585 In this case, it is recommended to use a proxy.
590 is a Forth interpreter written in C, in the form of a forth
591 virtual machine library that can be called by C functions and vice
596 each line read interactively is then fed to
600 back to execute the builtin words.
607 The words available to
609 can be classified in four groups.
612 Forth standard words, extra
616 words, and the builtin commands.
617 The later were already described.
620 Forth standard words are listed in the
623 The words falling in the two other groups are described in the
624 following subsections.
626 .Bl -tag -width wid-set-super
634 This is the STRING word set's
641 This is the STRING word set's
651 .Ss FREEBSD EXTRA WORDS
652 .Bl -tag -width XXXXXXXX
654 Evaluates the remainder of the input buffer, after having printed it first.
656 Evaluates the remainder of the input buffer under a
662 but without outputting a trailing space.
663 .It Ic fclose Pq Ar fd --
665 .It Ic fkey Pq Ar fd -- char
666 Reads a single character from a file.
667 .It Ic fload Pq Ar fd --
670 .It Ic fopen Pq Ar addr len mode Li -- Ar fd
672 Returns a file descriptor, or \-1 in case of failure.
675 parameter selects whether the file is to be opened for read access, write
678 .Dv O_RDONLY , O_WRONLY ,
682 .Pa /boot/support.4th ,
683 indicating read only, write only, and read-write access, respectively.
686 .Pq Ar fd addr len -- len'
694 Returns the actual number of bytes read, or -1 in case of error or end of
696 .It Ic heap? Pq -- Ar cells
697 Return the space remaining in the dictionary heap, in cells.
698 This is not related to the heap used by dynamic memory allocation words.
699 .It Ic inb Pq Ar port -- char
700 Reads a byte from a port.
701 .It Ic key Pq -- Ar char
702 Reads a single character from the console.
703 .It Ic key? Pq -- Ar flag
706 if there is a character available to be read from the console.
711 .It Ic outb Pq Ar port char --
712 Writes a byte to a port.
713 .It Ic seconds Pq -- Ar u
714 Returns the number of seconds since midnight.
715 .It Ic tib> Pq -- Ar addr len
716 Returns the remainder of the input buffer as a string on the stack.
717 .It Ic trace! Pq Ar flag --
718 Activates or deactivates tracing.
722 .Ss FREEBSD DEFINED ENVIRONMENTAL QUERIES
726 if the architecture is IA32.
729 if the architecture is AXP.
732 version at compile time.
737 .Ss SYSTEM DOCUMENTATION
739 .Bl -tag -width /boot/defaults/loader.conf -compact
743 .It Pa /boot/boot.4th
747 .It Pa /boot/boot.conf
749 bootstrapping script.
751 .It Pa /boot/defaults/loader.conf
752 .It Pa /boot/loader.conf
753 .It Pa /boot/loader.conf.local
755 configuration files, as described in
757 .It Pa /boot/loader.rc
759 bootstrapping script.
760 .It Pa /boot/loader.help
763 Contains the help messages.
766 Boot in single user mode:
770 Loads kernel's user configuration file.
771 Notice that a kernel must be loaded before any other
773 command is attempted.
774 .Bd -literal -offset indent
776 load -t userconfig_script /boot/kernel.conf
779 Loads the kernel, a splash screen, and then autoboots in five seconds.
780 .Bd -literal -offset indent
783 load -t splash_image_data /boot/chuckrulez.bmp
787 Sets the disk unit of the root device to 2, and then boots.
788 This would be needed in the case of a two IDE disks system,
789 with the second IDE hardwired to wd2 instead of wd1.
790 .Bd -literal -offset indent
796 .Bl -tag -width /usr/share/examples/bootforth/X
797 .It Pa /boot/loader.4th
798 Extra builtin-like words.
799 .It Pa /boot/support.4th
802 .It Pa /usr/share/examples/bootforth/
806 The following values are thrown by
808 .Bl -tag -width XXXXX -offset indent
810 Any type of error in the processing of a builtin.
821 Out of interpreting text.
823 Need more text to succeed -- will finish on next run.
837 For the purposes of ANS Forth compliance, loader is an
839 ANS Forth System with Environmental Restrictions, Providing
845 parse, pick, roll, refill, to, value, \e, false, true,
848 compile\&, , erase, nip, tuck
853 from the Core Extensions word set, Providing the Exception Extensions
854 word set, Providing the Locals Extensions word set, Providing the
855 Memory-Allocation Extensions word set, Providing
859 bye, forget, see, words,
866 from the Programming-Tools extension word set, Providing the
867 Search-Order extensions word set.
879 .An Michael Smith Aq msmith@FreeBSD.org .
883 .An John Sadler Aq john_sadler@alum.mit.edu .
889 words will read from the input buffer instead of the console.
890 The latter will be fixed, but the former will not.
projects / FreeBSD / FreeBSD.git / blob