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
189 The behavior of this builtin is changed if
197 Displays text on the screen.
198 A new line will be printed unless
203 Displays memory usage statistics.
204 For debugging purposes only.
206 .It Ic help Op topic Op subtopic
207 Shows help messages read from
211 will list the topics available.
213 .It Ic include Ar file Op Ar
214 Process script files.
215 Each file, in turn, is completely read into memory,
216 and then each of its lines is passed to the command line interpreter.
217 If any error is returned by the interpreter, the include
218 command aborts immediately, without reading any other files, and
219 returns an error itself (see
226 Loads a kernel, kernel loadable module (kld), or file of opaque
227 contents tagged as being of the type
229 Kernel and modules can be either in a.out or ELF format.
230 Any arguments passed after the name of the file to be loaded
231 will be passed as arguments to that file.
232 Currently, argument passing does not work for the kernel.
238 Displays a listing of files in the directory
240 or the root directory if
245 is specified, file sizes will be shown too.
248 Lists all devices with known file systems, where a
250 prefix indicates a device from which it may be
251 possible to load modules.
254 is specified, more details are printed.
257 Displays loaded modules.
260 is specified, more details are shown.
262 .It Ic more Ar file Op Ar
263 Display the files specified, with a pause at each
267 .It Ic pnpscan Op Fl v
268 Scans for Plug-and-Play devices.
269 This is not functional at present.
276 Reads a line of input from the terminal, storing it in
279 A timeout can be specified with
281 though it will be canceled at the first key pressed.
282 A prompt may also be displayed through the
287 Immediately reboots the system.
289 .It Ic set Ar variable
290 .It Ic set Ar variable Ns = Ns Ar value
291 Set loader's environment variables.
293 .It Ic show Op Va variable
294 Displays the specified variable's value, or all variables and their
300 Remove all modules from memory.
302 .It Ic unset Va variable
305 from the environment.
311 .Ss BUILTIN ENVIRONMENT VARIABLES
314 has actually two different kinds of
317 There are ANS Forth's
318 .Em environmental queries ,
319 and a separate space of environment variables used by builtins, which
320 are not directly available to Forth words.
321 It is the latter type that this section covers.
323 Environment variables can be set and unset through the
327 builtins, and can have their values interactively examined through the
331 Their values can also be accessed as described in
334 Notice that these environment variables are not inherited by any shell
335 after the system has been booted.
337 A few variables are set automatically by
339 Others can affect the behavior of either
341 or the kernel at boot.
342 Some options may require a value,
343 while others define behavior just by being set.
344 Both types of builtin variables are described below.
345 .Bl -tag -width bootfile
347 Unset this to disable automatic loading of the ACPI module.
348 .It Va autoboot_delay
351 will wait before booting.
352 If this variable is not defined,
354 will default to 10 seconds.
360 will be automatically attempted after processing
364 will be processed normally, defaulting to 10 seconds delay.
366 Instructs the kernel to prompt the user for the name of the root device
367 when the kernel is booted.
369 Instructs the kernel to start in the DDB debugger, rather than
370 proceeding to initialize when booted.
372 Selects gdb-remote mode for the kernel debugger by default.
374 Prevents the kernel from initiating a multi-user startup; instead single-user
375 mode will be entered when the kernel has finished device probing.
376 .It Va boot_userconfig
377 Requests that the kernel's interactive device configuration program
378 be run when the kernel is booted.
380 Setting this variable causes extra debugging information to be printed
381 by the kernel during the boot phase.
383 List of semicolon-separated search path for bootable kernels.
385 .Dq Li kernel;kernel.old .
387 Defines the current console.
389 Selects the default device.
390 Syntax for devices is odd.
392 Sets the list of binaries which the kernel will try to run as the initial
394 The first matching binary is used.
396 .Dq Li /sbin/init:/sbin/oinit:/sbin/init.bak .
400 if the Forth's current state is interpreting.
402 Define the number of lines on the screen, to be used by the pager.
404 Sets the list of directories which will be searched for modules
405 named in a load command or implicitly required by a dependency.
406 The default value for this variable is
407 .Dq Li /boot;/boot/modules;/;/modules .
409 Sets the number of IDE disks as a workaround for some problems in
410 finding the root disk at boot.
411 This has been deprecated in favor of
418 .Dq Li "\e${interpret}" .
419 .It Va root_disk_unit
420 If the code which detects the disk unit number for the root disk is
421 confused, e.g. by a mix of SCSI and IDE disks, or IDE disks with
422 gaps in the sequence (e.g. no primary slave), the unit number can
423 be forced by setting this variable.
425 By default the value of
427 is used to set the root file system
428 when the kernel is booted.
429 This can be overridden by setting
433 The name of a device where the kernel can save a crash dump in case
435 This automatically sets the
441 Other variables are used to override kernel tunable parameters.
444 tunables are available:
447 Set irqX's destination to the given CPUID,
449 If the specified value is larger than the last CPUID,
450 then the first CPUID will be used.
451 This variable should not be used if IO/APIC support is not compiled
454 Limit the amount of physical memory the system will use.
455 By default the size is in bytes, but the
456 .Cm k , K , m , M , g
460 are also accepted and indicate kilobytes, megabytes and gigabytes
462 An invalid suffix will result in the variable being ignored by the
464 .It Va hw.usb.hack_defer_exploration
465 The USB keyboard will sometimes not attach properly unless you set this
467 .It Va kern.emergency_intr_enable
468 Setting this to 1 enables emergency interrupt polling. All interrupt
469 handlers are executed periodically. This mode is very expensive and should
470 only be used to get a system accessible when interrupt routing is
471 otherwise broken. It is primarily used by kernel developers to debug new
473 .It Va kern.emergency_intr_freq
474 Set the polling rate for the emergency interrupt polling code. The
475 default is 10 (hz) to dissuade casual use. If you are doing real work
476 with emergency interrupt polling mode enabled, it is recommended
477 that you use a frequency between 100hz and 300hz.
479 Set the size of a number of statically allocated system tables; see
481 for a description of how to select an appropriate value for this
483 When set, this tunable replaces the value declared in the kernel
484 compile-time configuration file.
485 .It Va kern.ipc.nmbclusters
486 Set the number of mbuf clusters to be allocated.
487 The value cannot be set below the default
488 determined when the kernel was compiled.
492 Toggles the mmx optimizations for the bcopy/copyin/copyout routines
493 .It Va kern.vm.kmem.size
494 Sets the size of kernel memory (bytes).
495 This overrides the value determined when the kernel was compiled.
496 .It Va kern.maxswzone
497 Limits the amount of KVM to be used to hold swap
498 meta information, which directly governs the
499 maximum amount of swap the system can support.
500 This value is specified in bytes of KVA space
501 and defaults to around 70MBytes.
503 to not reduce this value such that the actual
504 amount of configured swap exceeds \(12 the
505 kernel-supported swap.
506 The default 70MB allows
507 the kernel to support a maximum of (approximately)
508 14GB of configured swap.
509 Only mess around with
510 this parameter if you need to greatly extend the
511 KVM reservation for other resources such as the
515 .Va VM_SWZONE_SIZE_MAX .
516 .It Va kern.maxbcache
517 Limits the amount of KVM reserved for use by the
518 buffer cache, specified in bytes.
519 The default maximum is 200MB.
520 This parameter is used to
521 prevent the buffer cache from eating too much
522 KVM in large-memory machine configurations.
523 Only mess around with this parameter if you need to
524 greatly extend the KVM reservation for other resources
525 such as the swap zone or
528 the NBUF parameter will override this limit.
530 .Va VM_BCACHE_SIZE_MAX .
531 .It Va machdep.disable_mtrrs
532 Disable the use of i686 MTRRs (x86 only).
533 .It Va net.inet.tcp.tcbhashsize
534 Overrides the compile-time set value of
536 or the preset default of 512.
537 Must be a power of 2.
538 .It Va vfs.root.mountfrom
539 A semicolon separated list of partitions to try
540 as the kernel root file system.
541 Device format is file system type and partition,
543 Used with boot-only partition, which is
544 typically mounted on root file system as
548 One device example: "hammer:da8s1a"
550 Several devices example: "ufs:da0s1a;hammer:ad1s1d"
553 Each device in the list will be tried in the order specified
554 until the mount succeeds.
557 prompt is displayed for manual entry.
559 You may not specify devtab labels here but you can specify paths available
560 to devfs such as "hammer:serno/L41JYE0G.s1d".
563 When a builtin command is executed, the rest of the line is taken
564 by it as arguments, and it is processed by a special parser which
565 is not used for regular Forth commands.
567 This special parser applies the following rules to the parsed text:
570 All backslash characters are preprocessed.
573 \eb , \ef , \er , \en and \et are processed as in C.
575 \es is converted to a space.
582 Useful for things like
585 \e0xN and \e0xNN are replaced by the hex N or NN.
587 \eNNN is replaced by the octal NNN
591 \e" , \e' and \e$ will escape these characters, preventing them from
592 receiving special treatment in Step 2, described below.
594 \e\e will be replaced with a single \e .
596 In any other occurrence, backslash will just be removed.
599 Every string between non-escaped quotes or double-quotes will be treated
600 as a single word for the purposes of the remaining steps.
606 with the value of the environment variable
609 Space-delimited arguments are passed to the called builtin command.
610 Spaces can also be escaped through the use of \e\e .
613 An exception to this parsing rule exists, and is described in
614 .Sx BUILTINS AND FORTH .
615 .Ss BUILTINS AND FORTH
616 All builtin words are state-smart, immediate words.
617 If interpreted, they behave exactly as described previously.
618 If they are compiled, though,
619 they extract their arguments from the stack instead of the command line.
621 If compiled, the builtin words expect to find, at execution time, the
622 following parameters on the stack:
623 .D1 Ar addrN lenN ... addr2 len2 addr1 len1 N
626 are strings which will compose the command line that will be parsed
627 into the builtin's arguments.
628 Internally, these strings are concatenated in from 1 to N,
629 with a space put between each one.
631 If no arguments are passed, a 0
633 be passed, even if the builtin accepts no arguments.
635 While this behavior has benefits, it has its trade-offs.
636 If the execution token of a builtin is acquired (through
644 the builtin behavior will depend on the system state
652 \&! This is particularly annoying for programs that want or need to
654 In this case, the use of a proxy is recommended.
656 .Dl : (boot) boot \&;
659 is a Forth interpreter written in C, in the form of a forth
660 virtual machine library that can be called by C functions and vice
665 each line read interactively is then fed to
669 back to execute the builtin words.
676 The words available to
678 can be classified into four groups.
681 Forth standard words, extra
685 words, and the builtin commands;
686 the latter were already described.
689 Forth standard words are listed in the
692 The words falling in the two other groups are described in the
693 following subsections.
695 .Bl -tag -width wid-set-super
703 This is the STRING word set's
710 This is the STRING word set's
720 .Ss DRAGONFLY EXTRA WORDS
721 .Bl -tag -width XXXXXXXX
723 Evaluates the remainder of the input buffer, after having printed it first.
725 Evaluates the remainder of the input buffer under a
731 but without outputting a trailing space.
732 .It Ic fclose Pq Ar fd --
734 .It Ic fkey Pq Ar fd -- char
735 Reads a single character from a file.
736 .It Ic fload Pq Ar fd --
739 .It Ic fopen Pq Ar addr len mode Li -- Ar fd
741 Returns a file descriptor, or \-1 in case of failure.
744 parameter selects whether the file is to be opened for read access, write
747 .Dv O_RDONLY , O_WRONLY ,
752 indicating read only, write only, and read-write access, respectively.
755 .Pq Ar fd addr len -- len'
763 Returns the actual number of bytes read, or -1 in case of error or end of
765 .It Ic heap? Pq -- Ar cells
766 Return the space remaining in the dictionary heap, in cells.
767 This is not related to the heap used by dynamic memory allocation words.
768 .It Ic inb Pq Ar port -- char
769 Reads a byte from a port.
770 .It Ic key Pq -- Ar char
771 Reads a single character from the console.
772 .It Ic key? Pq -- Ar flag
775 if there is a character available to be read from the console.
780 .It Ic outb Pq Ar port char --
781 Writes a byte to a port.
782 .It Ic seconds Pq -- Ar u
783 Returns the number of seconds since midnight.
784 .It Ic tib> Pq -- Ar addr len
785 Returns the remainder of the input buffer as a string on the stack.
786 .It Ic trace! Pq Ar flag --
787 Activates or deactivates tracing.
791 .Ss DRAGONFLY DEFINED ENVIRONMENTAL QUERIES
795 if the architecture is IA32.
796 .It DragonFly_version
798 version at compile time.
803 .Ss SYSTEM DOCUMENTATION
805 .Bl -tag -width /boot/defaults/loader.conf -compact
809 .It Pa /boot/boot.4th
813 .It Pa /boot/boot.conf
815 bootstrapping script.
817 .It Pa /boot/defaults/loader.conf
818 .It Pa /boot/loader.conf
819 .It Pa /boot/loader.conf.local
821 configuration files, as described in
823 .It Pa /boot/loader.rc
825 bootstrapping script.
826 .It Pa /boot/loader.help
829 Contains the help messages.
832 Boot in single user mode:
836 Load kernel's user configuration file.
837 Notice that a kernel must be loaded before any other
839 command is attempted.
840 .Bd -literal -offset indent
842 load -t userconfig_script kernel.conf
845 Load the kernel, a splash screen, and then autoboot in five seconds.
846 .Bd -literal -offset indent
849 load -t splash_image_data chuckrulez.bmp
853 Set the disk unit of the root device to 2, and then boot.
854 This would be needed in a system with two IDE disks,
855 with the second IDE disk hardwired to ad2 instead of ad1.
856 .Bd -literal -offset indent
862 .Bl -tag -width /usr/share/examples/bootforth/X
864 Extra builtin-like words.
868 .It Pa /usr/share/examples/bootforth/
872 The following values are thrown by
874 .Bl -tag -width XXXXX -offset indent
876 Any type of error in the processing of a builtin.
887 Out of interpreting text.
889 Need more text to succeed -- will finish on next run.
905 For the purposes of ANS Forth compliance, loader is an
907 ANS Forth System with Environmental Restrictions, Providing
913 parse, pick, roll, refill, to, value, \e, false, true,
916 compile\&, , erase, nip, tuck
921 from the Core Extensions word set, Providing the Exception Extensions
922 word set, Providing the Locals Extensions word set, Providing the
923 Memory-Allocation Extensions word set, Providing
927 bye, forget, see, words,
934 from the Programming-Tools extension word set, Providing the
935 Search-Order extensions word set.
947 .An Michael Smith Aq msmith@FreeBSD.org .
951 .An John Sadler Aq john_sadler@alum.mit.edu .
957 words will read from the input buffer instead of the console.
958 The latter will be fixed, but the former will not.
projects / dragonfly.git / blob