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 $
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
54 directory exist on the boot file system, then
56 is prepended to all relative file names used by
58 This makes it possible to locate all files used by
64 directory on the boot file system.
65 If boot and root are the same file systems, then files used by
69 If boot and root are different file systems, then files used by
73 on the boot file system, which is mounted as
75 on the root file system when the kernel is running.
78 provides a scripting language that can be used to
79 automate tasks, do pre-configuration or assist in recovery
81 This scripting language is roughly divided in
83 The smaller one is a set of commands
84 designed for direct use by the casual user, called "builtin
85 commands" for historical reasons.
86 The main drive behind these commands is user-friendliness.
87 The bigger component is an
89 Forth compatible Forth interpreter based on FICL, by
92 During initialization,
94 will probe for a console and set the
96 variable, or set it to serial console
98 if the previous boot stage used that.
99 Then, devices are probed,
108 is initialized, the builtin words are added to its vocabulary, and
110 is processed if it exists.
111 No disk switching is possible while that file is being read.
112 The inner interpreter
123 is processed if available, and, failing that,
125 is read for historical reasons.
126 These files are processed through the
128 command, which reads all of them into memory before processing them,
129 making disk changes possible.
133 has not been tried, and if
137 (not case sensitive), then an
140 If the system gets past this point,
144 will engage interactive mode.
148 builtin commands take parameters from the command line.
150 the only way to call them from a script is by using
153 If an error condition occurs, an exception will be generated,
154 which can be intercepted using
156 Forth exception handling
158 If not intercepted, an error message will be displayed and
159 the interpreter's state will be reset, emptying the stack and restoring
162 The builtin commands available are:
164 .Bl -tag -width Ds -compact
165 .It Ic autoboot Op Ar seconds
166 Proceeds to bootstrap the system after a number of seconds, if not
167 interrupted by the user.
168 Displays a countdown prompt
169 warning the user the system is about to be booted,
170 unless interrupted by a key press.
171 The kernel will be loaded first if necessary.
172 Defaults to 10 seconds.
175 Displays statistics about disk cache usage.
179 .It Ic boot Ar kernelname Op Cm ...
180 .It Ic boot Fl flag Cm ...
181 Immediately proceeds to bootstrap the system, loading the kernel
183 Any flags or arguments are passed to the kernel, but they
184 must precede the kernel name, if a kernel name is provided.
185 Flags are described in
192 Displays text on the screen.
193 A new line will be printed unless
198 Displays memory usage statistics.
199 For debugging purposes only.
201 .It Ic help Op topic Op subtopic
202 Shows help messages read from
206 will list the topics available.
208 .It Ic include Ar file Op Ar
209 Process script files.
210 Each file, in turn, is completely read into memory,
211 and then each of its lines is passed to the command line interpreter.
212 If any error is returned by the interpreter, the include
213 command aborts immediately, without reading any other files, and
214 returns an error itself (see
221 Loads a kernel, kernel loadable module (kld), or file of opaque
222 contents tagged as being of the type
224 Kernel and modules can be either in a.out or ELF format.
225 Any arguments passed after the name of the file to be loaded
226 will be passed as arguments to that file.
227 Currently, argument passing does not work for the kernel.
233 Displays a listing of files in the directory
235 or the root directory if
240 is specified, file sizes will be shown too.
243 Lists all devices with known file systems, where a
245 prefix indicates a device from which it may be
246 possible to load modules.
249 is specified, more details are printed.
252 Displays loaded modules.
255 is specified, more details are shown.
257 .It Ic more Ar file Op Ar
258 Display the files specified, with a pause at each
262 .It Ic pnpscan Op Fl v
263 Scans for Plug-and-Play devices.
264 This is not functional at present.
271 Reads a line of input from the terminal, storing it in
274 A timeout can be specified with
276 though it will be canceled at the first key pressed.
277 A prompt may also be displayed through the
282 Immediately reboots the system.
284 .It Ic set Ar variable
285 .It Ic set Ar variable Ns = Ns Ar value
286 Set loader's environment variables.
288 .It Ic show Op Va variable
289 Displays the specified variable's value, or all variables and their
295 Remove all modules from memory.
297 .It Ic unset Va variable
300 from the environment.
306 .Ss BUILTIN ENVIRONMENT VARIABLES
309 has actually two different kinds of
312 There are ANS Forth's
313 .Em environmental queries ,
314 and a separate space of environment variables used by builtins, which
315 are not directly available to Forth words.
316 It is the latter type that this section covers.
318 Environment variables can be set and unset through the
322 builtins, and can have their values interactively examined through the
326 Their values can also be accessed as described in
329 Notice that these environment variables are not inherited by any shell
330 after the system has been booted.
332 A few variables are set automatically by
334 Others can affect the behavior of either
336 or the kernel at boot.
337 Some options may require a value,
338 while others define behavior just by being set.
339 Both types of builtin variables are described below.
340 .Bl -tag -width bootfile
342 Unset this to disable automatic loading of the ACPI module.
343 .It Va autoboot_delay
346 will wait before booting.
347 If this variable is not defined,
349 will default to 10 seconds.
355 will be automatically attempted after processing
359 will be processed normally, defaulting to 10 seconds delay.
361 Instructs the kernel to prompt the user for the name of the root device
362 when the kernel is booted.
364 Instructs the kernel to start in the DDB debugger, rather than
365 proceeding to initialize when booted.
367 Selects gdb-remote mode for the kernel debugger by default.
369 Prevents the kernel from initiating a multi-user startup; instead single-user
370 mode will be entered when the kernel has finished device probing.
371 .It Va boot_userconfig
372 Requests that the kernel's interactive device configuration program
373 be run when the kernel is booted.
375 Setting this variable causes extra debugging information to be printed
376 by the kernel during the boot phase.
378 List of semicolon-separated search path for bootable kernels.
380 .Dq Li kernel;kernel.old .
382 Defines the current console.
384 Selects the default device.
385 Syntax for devices is odd.
387 Unset this to disable automatic loading of the EHCI module.
389 Sets the list of binaries which the kernel will try to run as the initial
391 The first matching binary is used.
393 .Dq Li /sbin/init:/sbin/oinit:/sbin/init.bak .
397 if the Forth's current state is interpreting.
399 Define the number of lines on the screen, to be used by the pager.
401 Sets the list of directories which will be searched for modules
402 named in a load command or implicitly required by a dependency.
403 The default value for this variable is
404 .Dq Li /boot;/boot/modules;/;/modules .
406 Sets the number of IDE disks as a workaround for some problems in
407 finding the root disk at boot.
408 This has been deprecated in favor of
415 .Dq Li "\e${interpret}" .
416 .It Va root_disk_unit
417 If the code which detects the disk unit number for the root disk is
418 confused, e.g. by a mix of SCSI and IDE disks, or IDE disks with
419 gaps in the sequence (e.g. no primary slave), the unit number can
420 be forced by setting this variable.
422 By default the value of
424 is used to set the root file system
425 when the kernel is booted.
426 This can be overridden by setting
430 The name of a device where the kernel can save a crash dump in case
432 This automatically sets the
438 Other variables are used to override kernel tunable parameters.
441 tunables are available:
444 Set irqX's destination to the given CPUID,
446 If the specified value is larger than the last CPUID,
447 then the first CPUID will be used.
448 This variable should not be used if IO/APIC support is not compiled
451 Limit the amount of physical memory the system will use.
452 By default the size is in bytes, but the
453 .Cm k , K , m , M , g
457 are also accepted and indicate kilobytes, megabytes and gigabytes
459 An invalid suffix will result in the variable being ignored by the
461 .It Va hw.usb.hack_defer_exploration
462 The USB keyboard will sometimes not attach properly unless you set this
464 .It Va kern.emergency_intr_enable
465 Setting this to 1 enables emergency interrupt polling. All interrupt
466 handlers are executed periodically. This mode is very expensive and should
467 only be used to get a system accessible when interrupt routing is
468 otherwise broken. It is primarily used by kernel developers to debug new
470 .It Va kern.emergency_intr_freq
471 Set the polling rate for the emergency interrupt polling code. The
472 default is 10 (hz) to dissuade casual use. If you are doing real work
473 with emergency interrupt polling mode enabled, it is recommended
474 that you use a frequency between 100hz and 300hz.
476 Set the size of a number of statically allocated system tables; see
478 for a description of how to select an appropriate value for this
480 When set, this tunable replaces the value declared in the kernel
481 compile-time configuration file.
482 .It Va kern.ipc.nmbclusters
483 Set the number of mbuf clusters to be allocated.
484 The value cannot be set below the default
485 determined when the kernel was compiled.
489 Toggles the mmx optimizations for the bcopy/copyin/copyout routines
490 .It Va kern.vm.kmem.size
491 Sets the size of kernel memory (bytes).
492 This overrides the value determined when the kernel was compiled.
493 .It Va kern.maxswzone
494 Limits the amount of KVM to be used to hold swap
495 meta information, which directly governs the
496 maximum amount of swap the system can support.
497 This value is specified in bytes of KVA space
498 and defaults to around 70MBytes.
500 to not reduce this value such that the actual
501 amount of configured swap exceeds \(12 the
502 kernel-supported swap.
503 The default 70MB allows
504 the kernel to support a maximum of (approximately)
505 14GB of configured swap.
506 Only mess around with
507 this parameter if you need to greatly extend the
508 KVM reservation for other resources such as the
512 .Va VM_SWZONE_SIZE_MAX .
513 .It Va kern.maxbcache
514 Limits the amount of KVM reserved for use by the
515 buffer cache, specified in bytes.
516 The default maximum is 200MB.
517 This parameter is used to
518 prevent the buffer cache from eating too much
519 KVM in large-memory machine configurations.
520 Only mess around with this parameter if you need to
521 greatly extend the KVM reservation for other resources
522 such as the swap zone or
525 the NBUF parameter will override this limit.
527 .Va VM_BCACHE_SIZE_MAX .
528 .It Va machdep.disable_mtrrs
529 Disable the use of i686 MTRRs (x86 only).
530 .It Va net.inet.tcp.tcbhashsize
531 Overrides the compile-time set value of
533 or the preset default of 512.
534 Must be a power of 2.
535 .It Va vfs.root.mountfrom
536 A semicolon separated list of partitions to try
537 as the kernel root file system.
538 Device format is file system type and partition,
540 Used with boot-only partition, which is
541 typically mounted on root file system as
545 One device example: "hammer:da8s1a"
547 Several devices example: "ufs:da0s1a;hammer:ad1s1d"
550 Each device in the list will be tried in the order specified
551 until the mount succeeds.
554 prompt is displayed for manual entry.
556 You may not specify devtab labels here but you can specify paths available
557 to devfs such as "hammer:serno/L41JYE0G.s1d".
560 When a builtin command is executed, the rest of the line is taken
561 by it as arguments, and it is processed by a special parser which
562 is not used for regular Forth commands.
564 This special parser applies the following rules to the parsed text:
567 All backslash characters are preprocessed.
570 \eb , \ef , \er , \en and \et are processed as in C.
572 \es is converted to a space.
579 Useful for things like
582 \e0xN and \e0xNN are replaced by the hex N or NN.
584 \eNNN is replaced by the octal NNN
588 \e" , \e' and \e$ will escape these characters, preventing them from
589 receiving special treatment in Step 2, described below.
591 \e\e will be replaced with a single \e .
593 In any other occurrence, backslash will just be removed.
596 Every string between non-escaped quotes or double-quotes will be treated
597 as a single word for the purposes of the remaining steps.
603 with the value of the environment variable
606 Space-delimited arguments are passed to the called builtin command.
607 Spaces can also be escaped through the use of \e\e .
610 An exception to this parsing rule exists, and is described in
611 .Sx BUILTINS AND FORTH .
612 .Ss BUILTINS AND FORTH
613 All builtin words are state-smart, immediate words.
614 If interpreted, they behave exactly as described previously.
615 If they are compiled, though,
616 they extract their arguments from the stack instead of the command line.
618 If compiled, the builtin words expect to find, at execution time, the
619 following parameters on the stack:
620 .D1 Ar addrN lenN ... addr2 len2 addr1 len1 N
623 are strings which will compose the command line that will be parsed
624 into the builtin's arguments.
625 Internally, these strings are concatenated in from 1 to N,
626 with a space put between each one.
628 If no arguments are passed, a 0
630 be passed, even if the builtin accepts no arguments.
632 While this behavior has benefits, it has its trade-offs.
633 If the execution token of a builtin is acquired (through
641 the builtin behavior will depend on the system state
649 \&! This is particularly annoying for programs that want or need to
651 In this case, the use of a proxy is recommended.
653 .Dl : (boot) boot \&;
656 is a Forth interpreter written in C, in the form of a forth
657 virtual machine library that can be called by C functions and vice
662 each line read interactively is then fed to
666 back to execute the builtin words.
673 The words available to
675 can be classified into four groups.
678 Forth standard words, extra
682 words, and the builtin commands;
683 the latter were already described.
686 Forth standard words are listed in the
689 The words falling in the two other groups are described in the
690 following subsections.
692 .Bl -tag -width wid-set-super
700 This is the STRING word set's
707 This is the STRING word set's
717 .Ss DRAGONFLY EXTRA WORDS
718 .Bl -tag -width XXXXXXXX
720 Evaluates the remainder of the input buffer, after having printed it first.
722 Evaluates the remainder of the input buffer under a
728 but without outputting a trailing space.
729 .It Ic fclose Pq Ar fd --
731 .It Ic fkey Pq Ar fd -- char
732 Reads a single character from a file.
733 .It Ic fload Pq Ar fd --
736 .It Ic fopen Pq Ar addr len mode Li -- Ar fd
738 Returns a file descriptor, or \-1 in case of failure.
741 parameter selects whether the file is to be opened for read access, write
744 .Dv O_RDONLY , O_WRONLY ,
749 indicating read only, write only, and read-write access, respectively.
752 .Pq Ar fd addr len -- len'
760 Returns the actual number of bytes read, or -1 in case of error or end of
762 .It Ic heap? Pq -- Ar cells
763 Return the space remaining in the dictionary heap, in cells.
764 This is not related to the heap used by dynamic memory allocation words.
765 .It Ic inb Pq Ar port -- char
766 Reads a byte from a port.
767 .It Ic key Pq -- Ar char
768 Reads a single character from the console.
769 .It Ic key? Pq -- Ar flag
772 if there is a character available to be read from the console.
777 .It Ic outb Pq Ar port char --
778 Writes a byte to a port.
779 .It Ic seconds Pq -- Ar u
780 Returns the number of seconds since midnight.
781 .It Ic tib> Pq -- Ar addr len
782 Returns the remainder of the input buffer as a string on the stack.
783 .It Ic trace! Pq Ar flag --
784 Activates or deactivates tracing.
788 .Ss DRAGONFLY DEFINED ENVIRONMENTAL QUERIES
792 if the architecture is IA32.
793 .It DragonFly_version
795 version at compile time.
800 .Ss SYSTEM DOCUMENTATION
802 .Bl -tag -width /boot/defaults/loader.conf -compact
806 .It Pa /boot/boot.4th
810 .It Pa /boot/boot.conf
812 bootstrapping script.
814 .It Pa /boot/defaults/loader.conf
815 .It Pa /boot/loader.conf
816 .It Pa /boot/loader.conf.local
818 configuration files, as described in
820 .It Pa /boot/loader.rc
822 bootstrapping script.
823 .It Pa /boot/loader.help
826 Contains the help messages.
829 Boot in single user mode:
833 Load kernel's user configuration file.
834 Notice that a kernel must be loaded before any other
836 command is attempted.
837 .Bd -literal -offset indent
839 load -t userconfig_script kernel.conf
842 Load the kernel, a splash screen, and then autoboot in five seconds.
843 .Bd -literal -offset indent
846 load -t splash_image_data chuckrulez.bmp
850 Set the disk unit of the root device to 2, and then boot.
851 This would be needed in a system with two IDE disks,
852 with the second IDE disk hardwired to ad2 instead of ad1.
853 .Bd -literal -offset indent
858 The following values are thrown by
860 .Bl -tag -width XXXXX -offset indent
862 Any type of error in the processing of a builtin.
873 Out of interpreting text.
875 Need more text to succeed -- will finish on next run.
890 For the purposes of ANS Forth compliance, loader is an
892 ANS Forth System with Environmental Restrictions, Providing
898 parse, pick, roll, refill, to, value, \e, false, true,
901 compile\&, , erase, nip, tuck
906 from the Core Extensions word set, Providing the Exception Extensions
907 word set, Providing the Locals Extensions word set, Providing the
908 Memory-Allocation Extensions word set, Providing
912 bye, forget, see, words,
919 from the Programming-Tools extension word set, Providing the
920 Search-Order extensions word set.
932 .An Michael Smith Aq msmith@FreeBSD.org .
936 .An John Sadler Aq john_sadler@alum.mit.edu .
942 words will read from the input buffer instead of the console.
943 The latter will be fixed, but the former will not.
projects / dragonfly.git / blob