1.\" 2.\" Copyright (c) 1999 Daniel C. Sobral 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD: src/sys/boot/common/loader.8,v 1.57 2003/06/29 20:57:55 brueffer Exp $ 27.\" 28.Dd May 20, 2019 29.Dt LOADER 8 30.Os 31.Sh NAME 32.Nm loader 33.Nd kernel bootstrapping final stage 34.Sh DESCRIPTION 35The program called 36.Nm 37is the final stage of 38.Dx Ns 's 39kernel bootstrapping process. 40It is implemented as a 41.Tn BTX 42client and is linked statically to 43.Xr libstand 3 44and located in the 45.Pa /boot 46or 47.Pa / 48directory. 49.Pp 50If a 51.Pa /boot 52directory exist on the boot file system, then 53.Dq /boot/ 54is prepended to all relative file names used by 55.Nm . 56This makes it possible to locate all files used by 57.Nm 58in either 59.Pa / 60or 61.Pa /boot 62directory on the boot file system. 63If boot and root are the same file system, then files used by 64.Nm 65are located in 66.Pa /boot . 67If boot and root are different file systems, then files used by 68.Nm 69are located in 70.Pa / 71on the boot file system, which is mounted as 72.Pa /boot 73on the root file system when the kernel is running. 74.Pp 75During initialization, 76.Nm 77will probe for a console and set the 78.Va console 79variable, or set it to serial console 80.Pq Dq comconsole 81if the previous boot stage used that. 82Then, devices are probed, 83.Va currdev 84and 85.Va loaddev 86are set, and 87.Va LINES 88is set to 24. 89After that, 90.Pa dloader.rc 91is processed if available, and, failing that, 92.Pa boot.conf 93is read for historical reasons. 94These files are processed through the 95.Ic include 96command, which reads all of them into memory before processing them, 97making disk changes possible. 98.Pp 99At this point, if an 100.Ic autoboot 101has not been tried, and if 102.Va autoboot_delay 103is not set to 104.Dq NO 105(not case sensitive), then an 106.Ic autoboot 107will be tried. 108If the system gets past this point, 109.Va prompt 110will be set and 111.Nm 112will engage interactive mode. 113.Sh BUILTIN COMMANDS 114In 115.Nm , 116builtin commands take parameters from the command line. 117.Pp 118The builtin commands available are: 119.Pp 120.Bl -tag -width indent -compact 121.It Ar variable Ns = Ns Ar value 122Assign 123.Ar value 124to 125.Ar variable . 126The value is always assigned to a local variable 127.Ar variable . 128If 129.Ar variable 130is in the list of known kernel environment variables or is a kernel tunable, 131the value is also assigned to the kernel environment variable of the 132given name. 133If the variable name contains a 134.Ql .\& 135it is considered a kernel tunable. 136Local variables are unset if 137.Ar value 138is empty. 139Kernel environment variable will have empty value. 140.Pp 141In other words, the assignment above will set a local variable and 142if applicable, also assign 143.Ar value 144to the kernel environment variable, even if 145.Ar value 146is empty. 147See also 148.Sx KERNEL ENVIRONMENT VARIABLES AND LOCAL VARIABLES . 149.Pp 150.Ar Value 151can be a string or a string expression containing literal text and 152kernel environment variables, like 153.Dq $VAR 154or 155.Dq ${VAR} . 156Escape sequences like 157.Ql \en 158(newline), 159.Ql \et 160(TAB) and 161.Ql \eOOO 162(character with number given in octal) 163can also be used. 164This is actually a general facility of 165.Nm 166which can be used for arguments of all commands. 167.Pp 168.It Ic autoboot Op Ar delay Op Ar prompt 169Proceeds to bootstrap the system after a number of seconds, if not 170interrupted by the user. 171Displays a countdown prompt 172warning the user the system is about to be booted, 173unless interrupted by a key press. 174The kernel will be loaded first if necessary. 175Defaults to 10 seconds. 176.Pp 177.It Ic bcachestat 178Displays statistics about disk cache usage. 179For depuration only. 180.Pp 181.It Ic boot Oo Fl Ns Ar flag ... Oc Op Ar kernelname 182Immediately proceeds to bootstrap the system, loading the kernel 183if necessary. 184Any flags or arguments are passed to the kernel, but they 185must precede the kernel name, if a kernel name is provided. 186Flags are described in 187.Xr boot 8 . 188See also 189.Va boot_* 190and 191.Va kernel_options 192variables. 193.Pp 194.It Ic cd Op Ar directory 195Change working directory to 196.Ar directory . 197Default is $base. 198.Pp 199.It Ic echo Oo Fl n Oc Op Ar message 200Displays text on the screen. 201A new line will be printed unless 202.Fl n 203is specified. 204See description of assignment 205.Pq Ar variable Ns = Ns Ar value 206.Ar value 207for use of kernel environment variables and escape sequences in 208.Ar message . 209.Pp 210.It Ic else 211Conditional if/else/endif. 212.Pp 213.It Ic elseifexists Ar path 214Conditional 215.Ar path 216exists, i.e.\& file/dir present. 217.Pp 218.It Ic endif 219Conditional if/else/endif. 220.Pp 221.It Ic heap 222Displays memory usage statistics. 223For debugging purposes only. 224.Pp 225.It Ic help Op Ar topic Op Ar subtopic 226Shows help messages read from 227.Pa loader.help . 228The special 229.Ar topic 230.Cm index 231will list all topics available. 232.Pp 233.It Ic ifexists Ar path 234Conditional 235.Ar path 236exists, i.e.\& file/dir present. 237.Pp 238.It Ic ifset Ar kenv_variable 239Conditional kernel environment variable 240.Ar kenv_variable 241exists. 242.Pp 243.It Ic include Ar 244Process script files. 245Each file, in turn, is completely read into memory, 246and then each of its lines is passed to the command line interpreter. 247If any error is returned by the interpreter, the include 248command aborts immediately, without reading any other files, and 249returns an error itself. 250.Pp 251.It Ic load Oo Fl t Ar type Oc Ar file Op Ar argument ... 252Loads a kernel, kernel loadable module (kld), or file of opaque 253contents tagged as being of the type 254.Ar type . 255Kernel and modules can be either in a.out or 256.Tn ELF 257format. 258Any arguments passed after the name of the file to be loaded 259will be passed as arguments to that file. 260.Pp 261.It Ic loadall 262Load the kernel and all modules specified by MODULE_load variables. 263.Pp 264.It Ic local Op Ar local_variable ... 265Displays the specified variable's value, or all local variables and their 266values if 267.Ar local_variable 268is not specified. 269.Pp 270.It Ic ls Oo Fl l Oc Op Ar path 271Displays a listing of files in the directory 272.Ar path , 273or the current directory if 274.Ar path 275is not specified. 276If 277.Fl l 278is specified, file sizes will be shown too. 279.Pp 280.It Ic lsdev Op Fl v 281Lists all devices. 282A 283.Sq * 284prefix indicates a disk slice or partition from which it may be 285possible to load modules. 286If 287.Fl v 288is specified, more details, 289like disk slice or partition size and position, are printed. 290.Pp 291.It Ic lsmod Op Fl v 292Displays loaded modules. 293If 294.Fl v 295is specified, more details are shown. 296.Pp 297.It Ic lunset Ar local_variable 298Unset a local variable. 299Discards the value and removes the variable. 300.Pp 301.It Ic lunsetif Ar local_variable kenv_variable 302Unset local variable 303.Ar local_variable 304if kernel environment variable 305.Ar kenv_variable 306is true, i.e.\& set to 1 or 307.Ql YES . 308.Pp 309.It Ic menu 310Run menu system. 311.Pp 312.It Ic menuadd Ar command_line 313Add script line for the current menu item. 314.Pp 315.It Ic menuclear 316Clear all menu items. 317.Pp 318.It Ic menuitem Ar key description 319Start a new menu item. 320When running the menu system, a line with 321.Ar key 322and 323.Ar description 324is displayed, and an item is chosen by pressing 325.Ar key . 326.Pp 327.It Ic more Ar 328Display the files specified, with a pause at each 329.Va LINES 330displayed. 331.Pp 332.It Ic optcd Op Ar directory 333Change the working directory to 334.Ar directory . 335Default is $base. 336Ignore errors. 337This command is like 338.Ic cd , 339but ignores errors when changing the directory. 340.Pp 341.It Ic optinclude Ar 342Process script files. 343Ignore errors. 344This command is like 345.Ic include , 346but ignores errors while executing commands in included files. 347.Pp 348.It Ic pnpscan Op Fl v 349Scans for Plug-and-Play devices. 350This is not functional at present. 351.Pp 352.It Ic pwd 353Prints the working directory. 354.Pp 355.It Ic read Oo Fl p Ar prompt Oc Oo Fl t Ar seconds Oc Op Ar kenv_variable 356Reads a line of input from the terminal, 357storing it in kernel environment variable 358.Ar kenv_variable 359if specified. 360A prompt may be displayed through the 361.Fl p 362flag. 363A timeout can be specified with 364.Fl t , 365though it will be canceled at the first key pressed. 366.Pp 367.It Ic reboot 368Immediately reboots the system. 369.Pp 370.It Ic set Ar kenv_variable 371.It Ic set Ar kenv_variable Ns = Ns Ar value 372Set kernel environment variable 373.Ar kenv_variable 374to the given value, 375if no 376.Ar value 377is given, the empty string is the value. 378.Pp 379.It Ic show Op Ar kenv_variable 380Displays the specified kernel environment variable's value, 381or all variables and their values if 382.Ar kenv_variable 383is not specified. 384.Pp 385.It Ic unload 386Removes all modules from memory. 387.Pp 388.It Ic unset Ar kenv_variable 389Removes 390.Ar kenv_variable 391from the kernel environment. 392.Pp 393.It Ic \&? 394Lists most available commands with a short help text for each. 395.El 396.Ss KERNEL ENVIRONMENT VARIABLES AND LOCAL VARIABLES 397The 398.Nm 399actually has two different kinds of variables. 400These are 401kernel environment variables, 402which are visible to the kernel when it is started, 403and a separate space of local variables used by 404.Nm , 405which are not available to the kernel. 406.Pp 407Both local variable and kernel environment variable 408of the same name are changed by assignment 409.Pq Ar variable Ns = Ns Ar value . 410.Pp 411Kernel environment variables can be set and unset through the 412.Ic set 413and 414.Ic unset 415builtins, and can have their values examined through the 416.Ic show 417and 418.Ic ifset 419builtins. 420Variables in command arguments or 421.Ar value 422in assignments 423.Dq ( $VAR 424and 425.Dq ${VAR} ) 426refers to kernel environment variables. 427.Pp 428Local variables can be unset with 429.Ic lunset 430and 431.Ic lunsetif 432builtin, and can have their values examined through the 433.Ic local 434builtin. 435.Pp 436Notice that these environment variables are not inherited by any shell 437after the system has been booted, but can be examined by 438.Xr kenv 1 . 439.Pp 440Note that a variable can have two instances with differnet values: 441both a local variable instance and a kernel environment variable instance 442can exist for the same name and with different values. 443This can cause confusion and is seldom done on purpose. 444.Pp 445A few variables are set automatically by 446.Nm . 447Others can affect the behavior of either 448.Nm 449or the kernel at boot. 450Some options may require a value, 451while others define behavior just by being set. 452Both types of variables are described below. 453.Bl -tag -width indent 454.It Va acpi_load 455Used for handling automatic loading of the 456.Xr acpi 4 457module. 458To disable automatic loading of the ACPI module use: 459.Pp 460.Dl lunset acpi_load 461.Dl set hint.acpi.0.disabled=1 462.It Va autoboot_delay 463Number of seconds 464.Ic autoboot 465and 466.Ic menu 467will wait before booting. 468Default value is 10 seconds. 469.Pp 470If set to 471.Dq NO , 472no 473.Ic autoboot 474will be automatically attempted after processing 475.Pa dloader.rc , 476though explicit 477.Ic autoboot Ns 's 478will be processed normally, defaulting to 10 seconds delay. 479.It Va boot_askname 480Instructs the kernel to prompt the user for the name of the root device 481when the kernel is booted. 482.It Va boot_ddb 483Instructs the kernel to start in the DDB debugger, rather than 484proceeding to initialize when booted. 485.It Va boot_gdb 486Selects gdb-remote mode for the kernel debugger by default. 487.It Va boot_single 488Prevents the kernel from initiating a multi-user startup; instead single-user 489mode will be entered when the kernel has finished device probing. 490.It Va boot_verbose 491Setting this variable causes extra debugging information to be printed 492by the kernel during and after the boot phase. 493.It Va bootfile 494List of semicolon-separated search path for bootable kernels. 495The default is 496.Dq Li kernel . 497.It Va console 498Defines the current console. 499.It Va currdev 500Selects the default device. 501Syntax for devices is odd. 502.It Va default_kernel 503Selects default kernel loaded by 504.Ic menu 505command. 506Defaults to 507.Pa kernel . 508.It Va dumpdev 509The name of a device where the kernel can save a crash dump in case 510of a panic. 511This automatically sets the 512.Va kern.dumpdev 513.Xr sysctl 3 514.Tn MIB 515variable. 516.It Va ehci_load 517Used for handling automatic loading of the 518.Xr ehci 4 519module. 520To disable automatic loading of the EHCI module use: 521.Pp 522.Dl lunset ehci_load 523.Dl set hint.ehci.0.disabled=1 524.It Va xhci_load 525Used for handling automatic loading of the 526.Xr xhci 4 527module. 528To disable automatic loading of the XHCI module use: 529.Pp 530.Dl lunset xhci_load 531.Dl set hint.xhci.0.disabled=1 532.It Va init_chroot 533Directory 534.Xr init 8 535will 536.Fn chroot 537to on startup. 538By setting this variable 539.Dx 540can be run from a subdirectory of the root file system. 541.It Va init_path 542Sets the list of binaries which the kernel will try to run as the initial 543process. 544The first matching binary is used. 545The default list is 546.Dq Li /sbin/init:/sbin/oinit:/sbin/init.bak . 547.It Va kernel_options 548Set kernel boot flags. 549See also 550.Ic boot 551command. 552.It Va LINES 553Define the number of lines on the screen, to be used by the pager. 554.It Va local_modules 555Setting this variable to 556.Dq Li YES 557causes 558.Pa /boot/modules.local 559to be included after 560.Va modules_path 561directories list and passed to kernel for 562.Xr kldload 8 . 563.It Va module_path 564Sets the list of directories which will be searched for modules named in a 565.Nm load 566command or implicitly required by a dependency. 567The default value for this variable is 568.Dq Li ;modules , 569which first searches the current working directory and then 570.Pa modules . 571.It Va num_ide_disks 572Sets the number of IDE disks as a workaround for some problems in 573finding the root disk at boot. 574This has been deprecated in favor of 575.Va root_disk_unit . 576.It Va prompt 577Value of 578.Nm Ns 's 579prompt. 580Defaults to 581.Dq Li OK . 582Kernel environment variables can be used in 583.Va prompt 584by including 585.Dq Li ${VAR} . 586E.g. (note that 587.Ql $ 588must be escaped with 589.Ql \e 590to be included in 591.Va prompt ) : 592.Pp 593.Dl "set prompt=\*q\e${currdev} OK\*q" 594.It Va root_disk_unit 595If the code which detects the disk unit number for the root disk is 596confused, e.g.\& by a mix of 597.Tn SCSI 598and 599.Tn IDE 600disks, or 601.Tn IDE 602disks with 603gaps in the sequence (e.g.\& no primary slave), the unit number can 604be forced by setting this variable. 605.Pp 606See also 607.Va vfs.root.mountfrom 608variable. 609.It Va rootdev 610By default the value of 611.Va currdev 612is used to set the root file system 613when the kernel is booted. 614This can be overridden by setting 615.Va rootdev 616explicitly. 617.Pp 618See also 619.Va vfs.root.mountfrom 620variable. 621.El 622.Pp 623Other variables are used to override kernel tunable parameters. 624The following 625.Nm 626tunables are available: 627.Bl -tag -width indent 628.It Va hw.ioapic_enable 629Control use of 630.Tn I/O APIC . 631Set to 1 to enable, 0 to disable. 632Default is 1. 633.It Va hw.irq.X.dest 634Set irqX's destination to the given 635.Tn CPUID , 636which starts from 0. 637If the specified value is larger than the last 638.Tn CPUID , 639then the first 640.Tn CPUID 641will be used. 642This variable should not be used if 643.Tn I/O APIC 644use is disabled. 645.It Va hw.physmem 646Limit the amount of physical memory the system will use. 647By default the size is in bytes, but the 648.Cm k , K , m , M , g 649and 650.Cm G 651suffixes 652are also accepted and indicate kilobytes, megabytes and gigabytes 653respectively. 654An invalid suffix will result in the variable being ignored by the 655kernel. 656.It Va hw.usb.hack_defer_exploration 657The USB keyboard will sometimes not attach properly unless you set this 658variable to 0. 659.It Va kern.emergency_intr_enable 660Setting this to 1 enables emergency interrupt polling. 661All interrupt handlers are executed periodically. 662This mode is very expensive and should 663only be used to get a system accessible when interrupt routing is 664otherwise broken. 665It is primarily used by kernel developers to debug new systems. 666.It Va kern.emergency_intr_freq 667Set the polling rate for the emergency interrupt polling code. 668The default is 10 (hz) to dissuade casual use. 669If you are doing real work 670with emergency interrupt polling mode enabled, it is recommended 671that you use a frequency between 100hz and 300hz. 672.It Va kern.maxusers 673Set the size of a number of statically allocated system tables; see 674.Xr tuning 7 675for a description of how to select an appropriate value for this tunable. 676When set, this tunable replaces the value declared in the kernel 677compile-time configuration file. 678.It Va kern.ipc.nmbclusters 679Set the number of mbuf clusters to be allocated. 680The value cannot be set below the default 681determined when the kernel was compiled. 682Modifies 683.Va NMBCLUSTERS . 684.It Va kern.mmxopt 685Toggles the mmx optimizations for the bcopy/copyin/copyout routines 686.It Va kern.user_scheduler 687Default userland scheduler (usched). 688If set, values can be 689.Dq bsd4 690or 691.Dq dfly . 692Default is 693.Dq dfly . 694.It Va kern.vm.kmem.size 695Sets the size of kernel memory (bytes). 696This overrides the value determined when the kernel was compiled. 697.It Va kern.maxswzone 698Limits the amount of 699.Tn KVM 700to be used to hold swap 701meta information, which directly governs the 702maximum amount of swap the system can support. 703This value is specified in bytes of KVA space 704and defaults to around 70MBytes. 705Care should be taken 706to not reduce this value such that the actual 707amount of configured swap exceeds \(12 the 708kernel-supported swap. 709The default 70MB allows 710the kernel to support a maximum of (approximately) 71114GB of configured swap. 712Only mess around with 713this parameter if you need to greatly extend the 714.Tn KVM 715reservation for other resources such as the 716buffer cache or 717.Va NMBCLUSTERS . 718Modifies 719.Va VM_SWZONE_SIZE_MAX . 720.It Va kern.maxbcache 721Limits the amount of KVM reserved for use by the 722buffer cache, specified in bytes. 723The default maximum is 200MB on 32-bit and 724unspecified on 64-bit. 725This parameter is used to 726prevent the buffer cache from eating too much 727.Tn KVM 728in large-memory machine configurations. 729Only mess around with this parameter if you need to 730greatly extend the 731.Tn KVM 732reservation for other resources 733such as the swap zone or 734.Va NMBCLUSTERS . 735Note that 736the NBUF parameter will override this limit. 737Modifies 738.Va VM_BCACHE_SIZE_MAX . 739.It Va machdep.disable_mtrrs 740Disable the use of 741.Sy i686 742.Tn MTRRs 743(x86 only). 744.It Va net.inet.tcp.tcbhashsize 745Overrides the compile-time set value of 746.Va TCBHASHSIZE 747or the preset default of 512. 748Must be a power of 2. 749.It Va vfs.root.wakedelay 750Specify an additional delay (default is 2 seconds if unspecified) 751before trying to mount root. 752.It Va vfs.root.mountfrom 753Specify root file system. 754A semicolon separated list of file systems to try 755as the kernel root file system. 756File system format is file system type and disk store, 757separated by colon. 758This variable needs to be set when using a boot-only partition, which is 759typically mounted on root file system as 760.Pa /boot . 761.Pp 762One file system example: 763.Dl hammer:da8s1a 764.Pp 765One file system 766.Nm HAMMER2 767multi volume example: 768.Dl hammer2:da8s1a:da9s1a 769.Pp 770Several file systems, boot list, example: 771.Dl ufs:da0s1a;hammer2:ad1s1d 772.Pp 773Each file system in the list will be tried in the order specified 774until the mount succeeds. 775If all fail, the 776.Ql mountroot> 777prompt is displayed for manual entry. 778.Pp 779You may not specify devtab labels here but you can specify paths available to 780.Xr devfs 5 781such as: 782.Dl hammer:serno/L41JYE0G.s1d 783.It Va vfs.root.realroot 784Root file system and extra options for 785.Nm initrd . 786See 787.Xr initrd 7 . 788.It Va nfsroot.iosize 789Override the default NFS netbooted root mount io block size. 790The default is 8192 which works with most servers. 791suggested values are 8192, 16384, or 32768. 792.It Va nfsroot.rahead 793Override the default read-ahead used by netbooted root mounts. 794The default is 4 which is reasonable. Suggested values are 1 through 8. 795.El 796.Sh FILES 797.Bl -tag -width /boot/defaults/dloader.menu -compact 798.It Pa /boot/boot.conf 799.Nm 800bootstrapping script. 801Deprecated 802.It Pa /boot/defaults/dloader.menu 803.Nm 804menu setup commands -- do not change this file 805.It Pa /boot/defaults/loader.conf 806.Nm 807configuration file, see 808.Xr loader.conf 5 809-- do not change this file 810.It Pa /boot/dloader.menu 811.Nm 812menu setup commands 813.It Pa /boot/dloader.rc 814.Nm 815bootstrapping script 816.It Pa /boot/loader 817.Nm 818itself 819.It Pa /boot/loader.conf 820.It Pa /boot/loader.conf.local 821.Nm 822configuration files, see 823.Xr loader.conf 5 824.It Pa /boot/loader.help 825help messages, used by the 826.Ic help 827command 828.El 829.Sh EXAMPLES 830Boot in single user mode: 831.Pp 832.Dl loadall 833.Dl boot -s 834.Pp 835Load the kernel, a splash screen, and then autoboot in five seconds. 836.Bd -literal -offset indent 837load kernel 838load splash_bmp 839load -t splash_image_data chuckrulez.bmp 840autoboot 5 841.Ed 842.Pp 843Set the disk unit of the root device to 2, and then boot. 844This would be needed in a system with two IDE disks, 845with the second IDE disk hardwired to 846.Pa ad2 847instead of 848.Pa ad1 . 849.Bd -literal -offset indent 850set root_disk_unit=2 851boot kernel 852.Ed 853.Sh SEE ALSO 854.Xr kenv 1 , 855.Xr libstand 3 , 856.Xr acpi 4 , 857.Xr ehci 4 , 858.Xr xhci 4 , 859.Xr loader.conf 5 , 860.Xr tuning 7 , 861.Xr boot 8 , 862.Xr cryptsetup 8 , 863.Xr lvm 8 , 864.Xr pxeboot 8 , 865.Xr pxeboot_tftp 8 , 866.Xr sysctl 8 867.Sh HISTORY 868The 869.Nm 870first appeared in 871.Fx 3.1 . 872.Nm dloader 873was introduced and 874.Tn FORTH 875removed in 876.Dx 2.7 . 877.Sh AUTHORS 878.An -nosplit 879The 880.Nm 881was written by 882.An Michael Smith Aq Mt msmith@FreeBSD.org . 883.Pp 884.Nm dloader 885was written by 886.An Matthew Dillon Aq Mt dillon@backplane.com . 887.Sh BUGS 888A variable can have two instances: local & kernel environment, 889this can cause confusion. 890