| blob | 82be9163825498303b6b9fb7e7c6887a54c1c188 |
1 .\" Copyright (c) 1999 Daniel C. Sobral
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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 1.24 2008/09/15 21:23:44 thomas Exp $
27 .\"
28 .\" Note: The date here should be updated whenever a non-trivial
29 .\" change is made to the manual page.
30 .Dd September 6, 2008
31 .Dt LOADER 8
32 .Os
33 .Sh NAME
34 .Nm loader
35 .Nd kernel bootstrapping final stage
36 .Sh DESCRIPTION
37 The program called
38 .Nm
39 is the final stage of
40 .Dx Ns 's
41 kernel bootstrapping process.
42 On IA32 (i386) architectures, it is a
43 .Pa BTX
44 client.
45 It is linked statically to
46 .Xr libstand 3
47 and located in the
48 .Pa /boot
49 or
50 .Pa /
51 directory.
52 .Pp
53 If a
54 .Pa /boot
55 directory exist on the boot file system, then
56 .Dq /boot/
57 is prepended to all relative file names used by
58 .Nm .
59 This makes it possible to locate all files used by
60 .Nm
61 in either
62 .Pa /
63 or
64 .Pa /boot
65 directory on the boot file system.
66 If boot and root are the same file systems, then files used by
67 .Nm
68 are located in
69 .Pa /boot .
70 If boot and root are different file systems, then files used by
71 .Nm
72 are located in
73 .Pa /
74 on the boot file system, which is mounted as
75 .Pa /boot
76 on the root file system when the kernel is running.
77 .Pp
78 .Nm
79 provides a scripting language that can be used to
80 automate tasks, do pre-configuration or assist in recovery
81 procedures.
82 This scripting language is roughly divided in
83 two main components.
84 The smaller one is a set of commands
85 designed for direct use by the casual user, called "builtin
86 commands" for historical reasons.
87 The main drive behind these commands is user-friendliness.
88 The bigger component is an
89 .Tn ANS
90 Forth compatible Forth interpreter based on FICL, by
91 .An John Sadler .
92 .Pp
93 During initialization,
94 .Nm
95 will probe for a console and set the
96 .Va console
97 variable, or set it to serial console
98 .Pq Dq comconsole
99 if the previous boot stage used that.
100 Then, devices are probed,
101 .Va currdev
102 and
103 .Va loaddev
104 are set, and
105 .Va LINES
106 is set to 24.
107 Next,
108 .Tn FICL
109 is initialized, the builtin words are added to its vocabulary, and
110 .Pa boot.4th
111 is processed if it exists.
112 No disk switching is possible while that file is being read.
113 The inner interpreter
114 .Nm
115 will use with
116 .Tn FICL
117 is then set to
118 .Ic interpret ,
119 which is
120 .Tn FICL Ns 's
121 default.
122 After that,
123 .Pa loader.rc
124 is processed if available, and, failing that,
125 .Pa boot.conf
126 is read for historical reasons.
127 These files are processed through the
128 .Ic include
129 command, which reads all of them into memory before processing them,
130 making disk changes possible.
131 .Pp
132 At this point, if an
133 .Ic autoboot
134 has not been tried, and if
135 .Va autoboot_delay
136 is not set to
137 .Dq NO
138 (not case sensitive), then an
139 .Ic autoboot
140 will be tried.
141 If the system gets past this point,
142 .Va prompt
143 will be set and
144 .Nm
145 will engage interactive mode.
146 .Sh BUILTIN COMMANDS
147 In
148 .Nm ,
149 builtin commands take parameters from the command line.
150 Presently,
151 the only way to call them from a script is by using
152 .Pa evaluate
153 on a string.
154 If an error condition occurs, an exception will be generated,
155 which can be intercepted using
156 .Tn ANS
157 Forth exception handling
158 words.
159 If not intercepted, an error message will be displayed and
160 the interpreter's state will be reset, emptying the stack and restoring
161 interpreting mode.
162 .Pp
163 The builtin commands available are:
164 .Pp
165 .Bl -tag -width Ds -compact
166 .It Ic autoboot Op Ar seconds
167 Proceeds to bootstrap the system after a number of seconds, if not
168 interrupted by the user.
169 Displays a countdown prompt
170 warning the user the system is about to be booted,
171 unless interrupted by a key press.
172 The kernel will be loaded first if necessary.
173 Defaults to 10 seconds.
174 .Pp
175 .It Ic bcachestat
176 Displays statistics about disk cache usage.
177 For depuration only.
178 .Pp
179 .It Ic boot
180 .It Ic boot Ar kernelname Op Cm ...
181 .It Ic boot Fl flag Cm ...
182 Immediately proceeds to bootstrap the system, loading the kernel
183 if necessary.
184 Any flags or arguments are passed to the kernel, but they
185 must precede the kernel name, if a kernel name is provided.
186 Flags are described in
187 .Xr boot 8 .
188 .Pp
189 .Em WARNING :
190 The behavior of this builtin is changed if
191 .Xr loader.4th 8
192 is loaded.
193 .Pp
194 .It Ic echo Xo
195 .Op Fl n
196 .Op Aq message
197 .Xc
198 Displays text on the screen.
199 A new line will be printed unless
200 .Fl n
201 is specified.
202 .Pp
203 .It Ic heap
204 Displays memory usage statistics.
205 For debugging purposes only.
206 .Pp
207 .It Ic help Op topic Op subtopic
208 Shows help messages read from
209 .Pa loader.help .
210 The special topic
211 .Em index
212 will list the topics available.
213 .Pp
214 .It Ic include Ar file Op Ar
215 Process script files.
216 Each file, in turn, is completely read into memory,
217 and then each of its lines is passed to the command line interpreter.
218 If any error is returned by the interpreter, the include
219 command aborts immediately, without reading any other files, and
220 returns an error itself (see
221 .Sx ERRORS ) .
222 .Pp
223 .It Ic load Xo
224 .Op Fl t Ar type
225 .Ar file Cm ...
226 .Xc
227 Loads a kernel, kernel loadable module (kld), or file of opaque
228 contents tagged as being of the type
229 .Ar type .
230 Kernel and modules can be either in a.out or ELF format.
231 Any arguments passed after the name of the file to be loaded
232 will be passed as arguments to that file.
233 Currently, argument passing does not work for the kernel.
234 .Pp
235 .It Ic ls Xo
236 .Op Fl l
237 .Op Ar path
238 .Xc
239 Displays a listing of files in the directory
240 .Ar path ,
241 or the root directory if
242 .Ar path
243 is not specified.
244 If
245 .Fl l
246 is specified, file sizes will be shown too.
247 .Pp
248 .It Ic lsdev Op Fl v
249 Lists all of the devices from which it may be possible to load modules.
250 If
251 .Fl v
252 is specified, more details are printed.
253 .Pp
254 .It Ic lsmod Op Fl v
255 Displays loaded modules.
256 If
257 .Fl v
258 is specified, more details are shown.
259 .Pp
260 .It Ic more Ar file Op Ar
261 Display the files specified, with a pause at each
262 .Va LINES
263 displayed.
264 .Pp
265 .It Ic pnpscan Op Fl v
266 Scans for Plug-and-Play devices.
267 This is not functional at present.
268 .Pp
269 .It Ic read Xo
270 .Op Fl t Ar seconds
271 .Op Fl p Ar prompt
272 .Op Va variable
273 .Xc
274 Reads a line of input from the terminal, storing it in
275 .Va variable
276 if specified.
277 A timeout can be specified with
278 .Fl t ,
279 though it will be canceled at the first key pressed.
280 A prompt may also be displayed through the
281 .Fl p
282 flag.
283 .Pp
284 .It Ic reboot
285 Immediately reboots the system.
286 .Pp
287 .It Ic set Ar variable
288 .It Ic set Ar variable Ns = Ns Ar value
289 Set loader's environment variables.
290 .Pp
291 .It Ic show Op Va variable
292 Displays the specified variable's value, or all variables and their
293 values if
294 .Va variable
295 is not specified.
296 .Pp
297 .It Ic unload
298 Remove all modules from memory.
299 .Pp
300 .It Ic unset Va variable
301 Removes
302 .Va variable
303 from the environment.
304 .Pp
305 .It Ic \&?
306 Same as
307 .Dq help index .
308 .El
309 .Ss BUILTIN ENVIRONMENT VARIABLES
310 The
311 .Nm
312 has actually two different kinds of
313 .Sq environment
314 variables.
315 There are ANS Forth's
316 .Em environmental queries ,
317 and a separate space of environment variables used by builtins, which
318 are not directly available to Forth words.
319 It is the latter type that this section covers.
320 .Pp
321 Environment variables can be set and unset through the
322 .Ic set
323 and
324 .Ic unset
325 builtins, and can have their values interactively examined through the
326 use of the
327 .Ic show
328 builtin.
329 Their values can also be accessed as described in
330 .Sx BUILTIN PARSER .
331 .Pp
332 Notice that these environment variables are not inherited by any shell
333 after the system has been booted.
334 .Pp
335 A few variables are set automatically by
336 .Nm .
337 Others can affect the behavior of either
338 .Nm
339 or the kernel at boot.
340 Some options may require a value,
341 while others define behavior just by being set.
342 Both types of builtin variables are described below.
343 .Bl -tag -width bootfile
344 .It Va acpi_load
345 Unset this to disable automatic loading of the ACPI module.
346 .It Va autoboot_delay
347 Number of seconds
348 .Ic autoboot
349 will wait before booting.
350 If this variable is not defined,
351 .Ic autoboot
352 will default to 10 seconds.
353 .Pp
354 If set to
355 .Dq NO ,
356 no
357 .Ic autoboot
358 will be automatically attempted after processing
359 .Pa loader.rc ,
360 though explicit
361 .Ic autoboot Ns 's
362 will be processed normally, defaulting to 10 seconds delay.
363 .It Va boot_askname
364 Instructs the kernel to prompt the user for the name of the root device
365 when the kernel is booted.
366 .It Va boot_ddb
367 Instructs the kernel to start in the DDB debugger, rather than
368 proceeding to initialize when booted.
369 .It Va boot_gdb
370 Selects gdb-remote mode for the kernel debugger by default.
371 .It Va boot_single
372 Prevents the kernel from initiating a multi-user startup; instead single-user
373 mode will be entered when the kernel has finished device probing.
374 .It Va boot_userconfig
375 Requests that the kernel's interactive device configuration program
376 be run when the kernel is booted.
377 .It Va boot_verbose
378 Setting this variable causes extra debugging information to be printed
379 by the kernel during the boot phase.
380 .It Va bootfile
381 List of semicolon-separated search path for bootable kernels.
382 The default is
383 .Dq Li kernel;kernel.old .
384 .It Va console
385 Defines the current console.
386 .It Va currdev
387 Selects the default device.
388 Syntax for devices is odd.
389 .It Va init_path
390 Sets the list of binaries which the kernel will try to run as the initial
391 process.
392 The first matching binary is used.
393 The default list is
394 .Dq Li /sbin/init:/sbin/oinit:/sbin/init.bak .
395 .It Va interpret
396 Has the value
397 .Dq Li OK
398 if the Forth's current state is interpreting.
399 .It Va LINES
400 Define the number of lines on the screen, to be used by the pager.
401 .It Va module_path
402 Sets the list of directories which will be searched for modules
403 named in a load command or implicitly required by a dependency.
404 The default value for this variable is
405 .Dq Li /boot;/boot/modules;/;/modules .
406 .It Va num_ide_disks
407 Sets the number of IDE disks as a workaround for some problems in
408 finding the root disk at boot.
409 This has been deprecated in favor of
410 .Va root_disk_unit .
411 .It Va prompt
412 Value of
413 .Nm Ns 's
414 prompt.
415 Defaults to
416 .Dq Li "\e${interpret}" .
417 .It Va root_disk_unit
418 If the code which detects the disk unit number for the root disk is
419 confused, e.g. by a mix of SCSI and IDE disks, or IDE disks with
420 gaps in the sequence (e.g. no primary slave), the unit number can
421 be forced by setting this variable.
422 .It Va rootdev
423 By default the value of
424 .Va currdev
425 is used to set the root file system
426 when the kernel is booted.
427 This can be overridden by setting
428 .Va rootdev
429 explicitly.
430 .It Va dumpdev
431 The name of a device where the kernel can save a crash dump in case
432 of a panic.
433 This automatically sets the
434 .Va kern.dumpdev
435 .Xr sysctl 3
436 MIB variable.
437 .El
438 .Pp
439 Other variables are used to override kernel tunable parameters.
440 The following
441 .Nm
442 tunables are available:
443 .Bl -tag -width Va
444 .It Va hw.irq.X.dest
445 Set irqX's destination to the given CPUID,
446 which starts from 0.
447 If the specified value is larger than the last CPUID,
448 then the first CPUID will be used.
449 This variable should not be used if IO/APIC support is not compiled
450 into kernel.
451 .It Va hw.physmem
452 Limit the amount of physical memory the system will use.
453 By default the size is in bytes, but the
454 .Cm k , K , m , M , g
455 and
456 .Cm G
457 suffixes
458 are also accepted and indicate kilobytes, megabytes and gigabytes
459 respectively.
460 An invalid suffix will result in the variable being ignored by the
461 kernel.
462 .It Va hw.usb.hack_defer_exploration
463 The USB keyboard will sometimes not attach properly unless you set this
464 variable to 0.
465 .It Va kern.emergency_intr_enable
466 Setting this to 1 enables emergency interrupt polling. All interrupt
467 handlers are executed periodically. This mode is very expensive and should
468 only be used to get a system accessible when interrupt routing is
469 otherwise broken. It is primarily used by kernel developers to debug new
470 systems.
471 .It Va kern.emergency_intr_freq
472 Set the polling rate for the emergency interrupt polling code. The
473 default is 10 (hz) to dissuade casual use. If you are doing real work
474 with emergency interrupt polling mode enabled, it is recommended
475 that you use a frequency between 100hz and 300hz.
476 .It Va kern.maxusers
477 Set the size of a number of statically allocated system tables; see
478 .Xr tuning 7
479 for a description of how to select an appropriate value for this
480 tunable.
481 When set, this tunable replaces the value declared in the kernel
482 compile-time configuration file.
483 .It Va kern.ipc.nmbclusters
484 Set the number of mbuf clusters to be allocated.
485 The value cannot be set below the default
486 determined when the kernel was compiled.
487 Modifies
488 .Va NMBCLUSTERS .
489 .It Va kern.ipc.nsfbufs
490 Set the number of
491 .Xr sendfile 2
492 buffers to be allocated.
493 Overrides
494 .Dv NSFBUFS .
495 .It Va kern.mmxopt
496 Toggles the mmx optimizations for the bcopy/copyin/copyout routines
497 .It Va kern.vm.kmem.size
498 Sets the size of kernel memory (bytes).
499 This overrides the value determined when the kernel was compiled.
500 .It Va kern.maxswzone
501 Limits the amount of KVM to be used to hold swap
502 meta information, which directly governs the
503 maximum amount of swap the system can support.
504 This value is specified in bytes of KVA space
505 and defaults to around 70MBytes.
506 Care should be taken
507 to not reduce this value such that the actual
508 amount of configured swap exceeds \(12 the
509 kernel-supported swap.
510 The default 70MB allows
511 the kernel to support a maximum of (approximately)
512 14GB of configured swap.
513 Only mess around with
514 this parameter if you need to greatly extend the
515 KVM reservation for other resources such as the
516 buffer cache or
517 .Va NMBCLUSTERS .
518 Modifies
519 .Va VM_SWZONE_SIZE_MAX .
520 .It Va kern.maxbcache
521 Limits the amount of KVM reserved for use by the
522 buffer cache, specified in bytes.
523 The default maximum is 200MB.
524 This parameter is used to
525 prevent the buffer cache from eating too much
526 KVM in large-memory machine configurations.
527 Only mess around with this parameter if you need to
528 greatly extend the KVM reservation for other resources
529 such as the swap zone or
530 .Va NMBCLUSTERS .
531 Note that
532 the NBUF parameter will override this limit.
533 Modifies
534 .Va VM_BCACHE_SIZE_MAX .
535 .It Va machdep.disable_mtrrs
536 Disable the use of i686 MTRRs (x86 only).
537 .It Va net.inet.tcp.tcbhashsize
538 Overrides the compile-time set value of
539 .Va TCBHASHSIZE
540 or the preset default of 512.
541 Must be a power of 2.
542 .It Va vfs.root.mountfrom
543 File system type and partition, separated by colon,
544 for kernel root file system.
545 Used with boot-only partition, which is typically mounted on root file system as
546 .Pa /boot .
547 Example: "hammer:da8s1a"
548 .El
549 .Ss BUILTIN PARSER
550 When a builtin command is executed, the rest of the line is taken
551 by it as arguments, and it is processed by a special parser which
552 is not used for regular Forth commands.
553 .Pp
554 This special parser applies the following rules to the parsed text:
555 .Bl -enum
556 .It
557 All backslash characters are preprocessed.
558 .Bl -bullet
559 .It
560 \eb , \ef , \er , \en and \et are processed as in C.
561 .It
562 \es is converted to a space.
563 .It
564 \ev is converted to
565 .Tn ASCII
566 11.
567 .It
568 \ez is just skipped.
569 Useful for things like
570 .Dq \e0xf\ez\e0xf .
571 .It
572 \e0xN and \e0xNN are replaced by the hex N or NN.
573 .It
574 \eNNN is replaced by the octal NNN
575 .Tn ASCII
576 character.
577 .It
578 \e" , \e' and \e$ will escape these characters, preventing them from
579 receiving special treatment in Step 2, described below.
580 .It
581 \e\e will be replaced with a single \e .
582 .It
583 In any other occurrence, backslash will just be removed.
584 .El
585 .It
586 Every string between non-escaped quotes or double-quotes will be treated
587 as a single word for the purposes of the remaining steps.
588 .It
589 Replace any
590 .Li $VARIABLE
591 or
592 .Li ${VARIABLE}
593 with the value of the environment variable
594 .Va VARIABLE .
595 .It
596 Space-delimited arguments are passed to the called builtin command.
597 Spaces can also be escaped through the use of \e\e .
598 .El
599 .Pp
600 An exception to this parsing rule exists, and is described in
601 .Sx BUILTINS AND FORTH .
602 .Ss BUILTINS AND FORTH
603 All builtin words are state-smart, immediate words.
604 If interpreted, they behave exactly as described previously.
605 If they are compiled, though,
606 they extract their arguments from the stack instead of the command line.
607 .Pp
608 If compiled, the builtin words expect to find, at execution time, the
609 following parameters on the stack:
610 .D1 Ar addrN lenN ... addr2 len2 addr1 len1 N
611 where
612 .Ar addrX lenX
613 are strings which will compose the command line that will be parsed
614 into the builtin's arguments.
615 Internally, these strings are concatenated in from 1 to N,
616 with a space put between each one.
617 .Pp
618 If no arguments are passed, a 0
619 .Em must
620 be passed, even if the builtin accepts no arguments.
621 .Pp
622 While this behavior has benefits, it has its trade-offs.
623 If the execution token of a builtin is acquired (through
624 .Ic '
625 or
626 .Ic ['] ) ,
627 and then passed to
628 .Ic catch
629 or
630 .Ic execute ,
631 the builtin behavior will depend on the system state
632 .Bf Em
633 at the time
634 .Ic catch
635 or
636 .Ic execute
637 is processed
638 .Ef
639 \&! This is particularly annoying for programs that want or need to
640 handle exceptions.
641 In this case, the use of a proxy is recommended.
642 For example:
643 .Dl : (boot) boot \&;
644 .Sh FICL
645 .Tn FICL
646 is a Forth interpreter written in C, in the form of a forth
647 virtual machine library that can be called by C functions and vice
648 versa.
649 .Pp
650 In
651 .Nm ,
652 each line read interactively is then fed to
653 .Tn FICL ,
654 which may call
655 .Nm
656 back to execute the builtin words.
657 The builtin
658 .Ic include
659 will also feed
660 .Tn FICL ,
661 one line at a time.
662 .Pp
663 The words available to
664 .Tn FICL
665 can be classified into four groups.
666 The
667 .Tn ANS
668 Forth standard words, extra
669 .Tn FICL
670 words, extra
671 .Dx
672 words, and the builtin commands;
673 the latter were already described.
674 The
675 .Tn ANS
676 Forth standard words are listed in the
677 .Sx STANDARDS
678 section.
679 The words falling in the two other groups are described in the
680 following subsections.
681 .Ss FICL EXTRA WORDS
682 .Bl -tag -width wid-set-super
683 .It Ic .env
684 .It Ic .ver
685 .It Ic -roll
686 .It Ic 2constant
687 .It Ic >name
688 .It Ic body>
689 .It Ic compare
690 This is the STRING word set's
691 .Ic compare .
692 .It Ic compile-only
693 .It Ic endif
694 .It Ic forget-wid
695 .It Ic parse-word
696 .It Ic sliteral
697 This is the STRING word set's
698 .Ic sliteral .
699 .It Ic wid-set-super
700 .It Ic w@
701 .It Ic w!
702 .It Ic x.
703 .It Ic empty
704 .It Ic cell-
705 .It Ic -rot
706 .El
707 .Ss DRAGONFLY EXTRA WORDS
708 .Bl -tag -width XXXXXXXX
709 .It Ic \&$ Pq --
710 Evaluates the remainder of the input buffer, after having printed it first.
711 .It Ic \&% Pq --
712 Evaluates the remainder of the input buffer under a
713 .Ic catch
714 exception guard.
715 .It Ic .#
716 Works like
717 .Ic .
718 but without outputting a trailing space.
719 .It Ic fclose Pq Ar fd --
720 Closes a file.
721 .It Ic fkey Pq Ar fd -- char
722 Reads a single character from a file.
723 .It Ic fload Pq Ar fd --
724 Processes a file
725 .Em fd .
726 .It Ic fopen Pq Ar addr len mode Li -- Ar fd
727 Opens a file.
728 Returns a file descriptor, or \-1 in case of failure.
729 The
730 .Ar mode
731 parameter selects whether the file is to be opened for read access, write
732 access, or both.
733 The constants
734 .Dv O_RDONLY , O_WRONLY ,
735 and
736 .Dv O_RDWR
737 are defined in
738 .Pa support.4th ,
739 indicating read only, write only, and read-write access, respectively.
740 .It Xo
741 .Ic fread
742 .Pq Ar fd addr len -- len'
743 .Xc
744 Tries to read
745 .Em len
746 bytes from file
747 .Em fd
748 into buffer
749 .Em addr .
750 Returns the actual number of bytes read, or -1 in case of error or end of
751 file.
752 .It Ic heap? Pq -- Ar cells
753 Return the space remaining in the dictionary heap, in cells.
754 This is not related to the heap used by dynamic memory allocation words.
755 .It Ic inb Pq Ar port -- char
756 Reads a byte from a port.
757 .It Ic key Pq -- Ar char
758 Reads a single character from the console.
759 .It Ic key? Pq -- Ar flag
760 Returns
761 .Ic true
762 if there is a character available to be read from the console.
763 .It Ic ms Pq Ar u --
764 Waits
765 .Em u
766 microseconds.
767 .It Ic outb Pq Ar port char --
768 Writes a byte to a port.
769 .It Ic seconds Pq -- Ar u
770 Returns the number of seconds since midnight.
771 .It Ic tib> Pq -- Ar addr len
772 Returns the remainder of the input buffer as a string on the stack.
773 .It Ic trace! Pq Ar flag --
774 Activates or deactivates tracing.
775 Does not work with
776 .Ic catch .
777 .El
778 .Ss DRAGONFLY DEFINED ENVIRONMENTAL QUERIES
779 .Bl -tag -width Ds
780 .It arch-i386
781 .Ic TRUE
782 if the architecture is IA32.
783 .It DragonFly_version
784 .Dx
785 version at compile time.
786 .It loader_version
787 .Nm
788 version.
789 .El
790 .Ss SYSTEM DOCUMENTATION
791 .Sh FILES
792 .Bl -tag -width /boot/defaults/loader.conf -compact
793 .It Pa /boot/loader
794 .Nm
795 itself.
796 .It Pa /boot/boot.4th
797 Additional
798 .Tn FICL
799 initialization.
800 .It Pa /boot/boot.conf
801 .Nm
802 bootstrapping script.
803 Deprecated.
804 .It Pa /boot/defaults/loader.conf
805 .It Pa /boot/loader.conf
806 .It Pa /boot/loader.conf.local
807 .Nm
808 configuration files, as described in
809 .Xr loader.conf 5 .
810 .It Pa /boot/loader.rc
811 .Nm
812 bootstrapping script.
813 .It Pa /boot/loader.help
814 Loaded by
815 .Ic help .
816 Contains the help messages.
817 .El
818 .Sh EXAMPLES
819 Boot in single user mode:
820 .Pp
821 .Dl boot -s
822 .Pp
823 Load kernel's user configuration file.
824 Notice that a kernel must be loaded before any other
825 .Ic load
826 command is attempted.
827 .Bd -literal -offset indent
828 load kernel
829 load -t userconfig_script kernel.conf
830 .Ed
831 .Pp
832 Load the kernel, a splash screen, and then autoboot in five seconds.
833 .Bd -literal -offset indent
834 load kernel
835 load splash_bmp
836 load -t splash_image_data chuckrulez.bmp
837 autoboot 5
838 .Ed
839 .Pp
840 Set the disk unit of the root device to 2, and then boot.
841 This would be needed in a system with two IDE disks,
842 with the second IDE disk hardwired to ad2 instead of ad1.
843 .Bd -literal -offset indent
844 set root_disk_unit=2
845 boot kernel
846 .Ed
847 .Pp
848 See also:
849 .Bl -tag -width /usr/share/examples/bootforth/X
850 .It Pa loader.4th
851 Extra builtin-like words.
852 .It Pa support.4th
853 .Pa loader.conf
854 processing words.
855 .It Pa /usr/share/examples/bootforth/
856 Assorted examples.
857 .El
858 .Sh ERRORS
859 The following values are thrown by
860 .Nm :
861 .Bl -tag -width XXXXX -offset indent
862 .It 100
863 Any type of error in the processing of a builtin.
864 .It -1
865 .Ic Abort
866 executed.
867 .It -2
868 .Ic Abort"
869 executed.
870 .It -56
871 .Ic Quit
872 executed.
873 .It -256
874 Out of interpreting text.
875 .It -257
876 Need more text to succeed -- will finish on next run.
877 .It -258
878 .Ic Bye
879 executed.
880 .It -259
881 Unspecified error.
882 .El
883 .Sh SEE ALSO
884 .Xr libstand 3 ,
885 .Xr loader.conf 5 ,
886 .Xr tuning 7 ,
887 .Xr boot 8 ,
888 .Xr btxld 8 ,
889 .Xr loader.4th 8 ,
890 .Xr sysctl 8
891 .Sh STANDARDS
892 For the purposes of ANS Forth compliance, loader is an
893 .Bf Em
894 ANS Forth System with Environmental Restrictions, Providing
895 .Ef
896 .Bf Li
897 .No .( ,
898 .No :noname ,
899 .No ?do ,
900 parse, pick, roll, refill, to, value, \e, false, true,
901 .No <> ,
902 .No 0<> ,
903 compile\&, , erase, nip, tuck
904 .Ef
905 .Em and
906 .Li marker
907 .Bf Em
908 from the Core Extensions word set, Providing the Exception Extensions
909 word set, Providing the Locals Extensions word set, Providing the
910 Memory-Allocation Extensions word set, Providing
911 .Ef
912 .Bf Li
913 \&.s,
914 bye, forget, see, words,
915 \&[if],
916 \&[else]
917 .Ef
918 .Em and
919 .Li [then]
920 .Bf Em
921 from the Programming-Tools extension word set, Providing the
922 Search-Order extensions word set.
923 .Ef
924 .Sh HISTORY
925 The
926 .Nm
927 first appeared in
928 .Fx 3.1 .
929 .Sh AUTHORS
930 .An -nosplit
931 The
932 .Nm
933 was written by
934 .An Michael Smith Aq msmith@FreeBSD.org .
935 .Pp
936 .Tn FICL
937 was written by
938 .An John Sadler Aq john_sadler@alum.mit.edu .
939 .Sh BUGS
940 The
941 .Ic expect
942 and
943 .Ic accept
944 words will read from the input buffer instead of the console.
945 The latter will be fixed, but the former will not.