1.\" $NetBSD: installboot.8,v 1.58 2006/09/24 13:39:36 wiz Exp $ 2.\" 3.\" Copyright (c) 2002-2003 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Luke Mewburn of Wasabi Systems. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd September 24, 2006 38.Dt INSTALLBOOT 8 39.Os 40.Sh NAME 41.Nm installboot 42.Nd install disk bootstrap software 43. 44.Sh SYNOPSIS 45.Nm 46.Op Fl nv 47.Op Fl B Ar s2bno 48.Op Fl b Ar s1bno 49.Op Fl m Ar machine 50.Op Fl o Ar options 51.Op Fl t Ar fstype 52.Ar filesystem 53.Ar primary 54.Op Ar secondary 55.Nm 56.Fl c 57.Op Fl nv 58.Op Fl m Ar machine 59.Op Fl o Ar options 60.Op Fl t Ar fstype 61.Ar filesystem 62.Nm 63.Fl e 64.Op Fl nv 65.Op Fl m Ar machine 66.Op Fl o Ar options 67.Ar bootstrap 68. 69.Sh DESCRIPTION 70The 71.Nm 72utility installs and removes 73.Nx 74disk bootstrap software into a file system. 75.Nm 76can install 77.Ar primary 78into 79.Ar filesystem , 80or disable an existing bootstrap in 81.Ar filesystem . 82.Pp 83Generally, 84.Nx 85disk bootstrap software consists of two parts: a 86.Dq primary 87bootstrap program usually written into the disklabel area of the 88file system by 89.Nm , 90and a 91.Dq secondary 92bootstrap program that usually resides as an ordinary file in the file system. 93.Pp 94When booting, the primary bootstrap program is loaded and invoked by 95the machine's PROM or BIOS. 96After receiving control of the system it loads and runs the secondary 97bootstrap program, which in turn loads and runs the kernel. 98The secondary bootstrap may allow control over various boot parameters 99passed to the kernel. 100.Pp 101Perform the following steps to make a file system bootable: 102.Bl -enum 103.It 104Copy the secondary bootstrap (usually 105.Pa /usr/mdec/boot. Ns Sy MACHINE 106or 107.Pa /usr/mdec/boot ) 108to the root directory of the target file system. 109.Pp 110. 111.It 112Use 113.Nm 114to install the primary bootstrap program 115(usually 116.Pa /usr/mdec/bootxx_ Ns Sy FSTYPE ) 117into 118.Ar filesystem . 119.Pp 120The following platforms do not require this step if the primary bootstrap 121already exists and the secondary bootstrap file is just being updated: 122.Sy alpha , 123.Sy amd64 , 124.Sy amiga , 125.Sy i386 , 126.Sy pmax , 127.Sy sparc64 , 128and 129.Sy vax . 130.Pp 131The following platform does not require the first step since a 132single bootstrap file is used. 133The single bootstrap is installed like the primary bootstrap on 134other platforms: 135.Sy next68k . 136.Pp 137.El 138.Pp 139The options and arguments recognized by 140.Nm 141are as follows: 142. 143.Bl -tag -width "optionsxxx" 144. 145.It Fl B Ar s2bno 146When hard-coding the blocks of 147.Ar secondary 148into 149.Ar primary , 150start from block 151.Ar s2bno 152instead of trying to determine the block numbers occupied by 153.Ar secondary 154by examining 155.Ar filesystem . 156If this option is supplied, 157.Ar secondary 158should refer to an actual secondary bootstrap (rather than the 159file name of the one present in 160.Ar filesystem ) 161so that its size can be determined. 162. 163.It Fl b Ar s1bno 164Install 165.Ar primary 166at block number 167.Ar s1bno 168instead of the default location for the machine and file system type. 169.Sy [ alpha , 170.Sy pmax , 171.Sy vax ] 172. 173.It Fl c 174Clear (remove) any existing bootstrap instead of installing one. 175. 176.It Fl e 177Edit the options of an existing bootstrap. 178.Sy [ amd64 , i386 ] 179. 180.It Fl m Ar machine 181Use 182.Ar machine 183as the target machine type. 184The default machine is determined from 185.Xr uname 3 186and then 187.Ev MACHINE . 188The following machines are currently supported by 189.Nm : 190.Bd -ragged -offset indent 191.Sy alpha , 192.Sy amd64 , 193.Sy amiga , 194.Sy ews4800mips , 195.Sy hp300 , 196.Sy hp700 , 197.Sy i386 , 198.Sy landisk , 199.Sy macppc , 200.Sy news68k , 201.Sy newsmips , 202.Sy next68k , 203.Sy pmax , 204.Sy sparc , 205.Sy sparc64 , 206.Sy sun2 , 207.Sy sun3 , 208.Sy vax , 209.Sy x68k 210.Ed 211. 212. 213.It Fl n 214Do not write to 215.Ar filesystem . 216. 217.It Fl o Ar options 218Machine specific 219.Nm 220options, comma separated. 221.Pp 222Supported options are (with the machines for they are valid in brackets): 223. 224.Bl -tag -offset indent -width alphasum 225. 226.It Sy alphasum 227.Sy [ alpha ] 228Recalculate and restore the Alpha checksum. 229This is the default for 230.Nx Ns Tn /alpha . 231. 232.It Sy append 233.Sy [ alpha , 234.Sy pmax , 235.Sy vax ] 236Append 237.Ar primary 238to the end of 239.Ar filesystem , 240which must be a regular file in this case. 241. 242.It Sy command=\*[Lt]boot command\*[Gt] 243.Sy [ amiga ] 244Modify the default boot command line. 245. 246.It Sy console=\*[Lt]console name\*[Gt] 247.Sy [ amd64 , 248.Sy i386 ] 249Set the console device, \*[Lt]console name\*[Gt] must be one of: 250pc, com0, com1, com2, com3, com0kbd, com1kbd, com2kbd or com3kbd. 251. 252.It Sy ioaddr=\*[Lt]ioaddr\*[Gt] 253.Sy [ amd64 , 254.Sy i386 ] 255Set the IO address to be used for the console serial port. 256Defaults to the IO address used by the system BIOS for the specified port. 257. 258.It Sy keymap=\*[Lt]keymap\*[Gt] 259.Sy [ amd64 , 260.Sy i386 ] 261Set a boot time keyboard translation map. 262Each character in \*[Lt]keymap\*[Gt] will be replaced by the one following it. 263For example, an argument of 264.Dq zyz 265would swap the lowercase letters 266.Sq y 267and 268.Sq z . 269. 270.It Sy password=\*[Lt]password\*[Gt] 271.Sy [ amd64 , 272.Sy i386 ] 273Set the password which must be entered before the boot menu can be accessed. 274. 275.It Sy resetvideo 276.Sy [ amd64 , 277.Sy i386 ] 278Reset the video before booting. 279. 280.It Sy speed=\*[Lt]baud rate\*[Gt] 281.Sy [ amd64 , 282.Sy i386 ] 283Set the baud rate for the serial console. 284If a value of zero is specified, then the current baud rate (set by the 285BIOS) will be used. 286. 287.It Sy sunsum 288.Sy [ alpha , 289.Sy pmax , 290.Sy vax ] 291Recalculate and restore the Sun and 292.Nx Ns Tn /sparc 293compatible checksum. 294.Em Note : 295The existing 296.Nx Ns Tn /sparc 297disklabel should use no more than 4 partitions. 298. 299.It Sy timeout=\*[Lt]seconds\*[Gt] 300.Sy [ amd64 , 301.Sy i386 ] 302Set the timeout before the automatic boot begins to the given number of seconds. 303.El 304. 305.It Fl t Ar fstype 306Use 307.Ar fstype 308as the type of 309.Ar filesystem . 310The default operation is to attempt to auto-detect this setting. 311The following file system types are currently supported by 312.Nm : 313. 314.Bl -tag -offset indent -width raid 315. 316.It Sy ffs 317.Bx 318Fast File System. 319. 320.It Sy raid 321Mirrored RAIDframe File System. 322. 323.It Sy raw 324.Sq Raw 325image. 326Note: if a platform needs to hard-code the block offset of the secondary 327bootstrap, it cannot be searched for on this file system type, and must 328be provided with 329.Fl B Ar s2bno . 330.El 331. 332.It Fl v 333Verbose operation. 334. 335.It Ar filesystem 336The path name of the device or file system image that 337.Nm 338is to operate on. 339It is not necessary for 340.Ar filesystem 341to be a currently mounted file system. 342. 343.It Ar primary 344The path name of the 345.Dq primary 346boot block to install. 347. 348.It Ar secondary 349The path name of the 350.Dq secondary 351boot block, 352relative to the top of 353.Ar filesystem . 354Most systems require 355.Ar secondary 356to be in the 357.Dq root 358directory of the file system, so the leading 359.Dq Pa / 360is not necessary on 361.Ar secondary . 362.Pp 363Only certain combinations of 364platform 365.Pq Fl m Ar machine 366and file system type 367.Pq Fl t Ar fstype 368require that the name of the secondary bootstrap is 369supplied as 370.Ar secondary , 371so that information such as the disk block numbers occupied 372by the secondary bootstrap can be stored in the primary bootstrap. 373These are: 374.Bl -column "Platform" "File systems" -offset indent 375.It Sy "Platform" Ta Sy "File systems" 376.It macppc Ta ffs, raw 377.It news68k Ta ffs, raw 378.It newsmips Ta ffs, raw 379.It sparc Ta ffs, raid, raw 380.It sun2 Ta ffs, raw 381.It sun3 Ta ffs, raw 382.El 383.El 384.Pp 385.Nm 386exits 0 on success, and \*[Gt]0 if an error occurs. 387. 388.Sh ENVIRONMENT 389.Nm 390uses the following environment variables: 391. 392.Bl -tag -width "MACHINE" 393. 394.It Ev MACHINE 395Default value for 396.Ar machine , 397overriding the result from 398.Xr uname 3 . 399. 400.El 401. 402.Sh FILES 403Most 404.Nx 405ports will contain variations of the following files: 406.Pp 407.Bl -tag -width /usr/mdec/bootxx_ustarfs 408. 409.It Pa /usr/mdec/bootxx_ Ns Sy FSTYPE 410Primary bootstrap for file system type 411.Sy FSTYPE . 412Installed into the bootstrap area of the file system by 413.Nm . 414. 415.It Pa /usr/mdec/bootxx_ffsv1 416Primary bootstrap for 417.Sy FFSv1 418file systems 419(the "traditional" 420.Nx 421file system). 422. 423.It Pa /usr/mdec/bootxx_ffsv2 424Primary bootstrap for 425.Sy FFSv2 426file systems. 427. 428.It Pa /usr/mdec/bootxx_lfsv1 429Primary bootstrap for 430.Sy LFSv1 431file systems. 432. 433.It Pa /usr/mdec/bootxx_lfsv2 434Primary bootstrap for 435.Sy LFSv2 436file systems 437(the default LFS version). 438. 439.It Pa /usr/mdec/bootxx_msdos 440Primary bootstrap for 441.Tn MS-DOS 442.Sy FAT 443file systems. 444. 445.It Pa /usr/mdec/bootxx_ustarfs 446Primary bootstrap for 447.Sy TARFS 448boot images. 449This is used by various install media. 450. 451.It Pa /usr/mdec/boot. Ns Sy MACHINE 452Secondary bootstrap for machine type 453.Sy MACHINE . 454This should be installed into the file system before 455.Nm 456is run. 457. 458.It Pa /usr/mdec/boot 459Synonym for 460.Pa /usr/mdec/boot. Ns Sy MACHINE 461. 462.It Pa /boot. Ns Sy MACHINE 463Installed copy of secondary bootstrap for machine type 464.Sy MACHINE . 465. 466.It Pa /boot 467Installed copy of secondary bootstrap. 468Searched for by the primary bootstrap if 469.Pa /boot. Ns Sy MACHINE 470is not found. 471. 472.El 473. 474.Ss Nx Ns Tn /next68k files 475. 476.Bl -tag -width /usr/mdec/bootxx_ustarfs 477. 478.It Pa /usr/mdec/boot 479.Nx Ns Tn /next68k 480bootstrap. 481. 482.El 483. 484.Ss Nx Ns Tn /sparc64 files 485. 486.Bl -tag -width /usr/mdec/bootxx_ustarfs 487. 488.It Pa /usr/mdec/bootblk 489.Nx Ns Tn /sparc64 490primary bootstrap. 491. 492.It Pa /usr/mdec/ofwboot 493.Nx Ns Tn /sparc64 494secondary bootstrap. 495. 496.It Pa /ofwboot 497Installed copy of 498.Nx Ns Tn /sparc64 499secondary bootstrap. 500. 501.El 502. 503.Sh EXAMPLES 504. 505.Ss common 506Verbosely install the Berkeley Fast File System primary bootstrap on to disk 507.Sq sd0 : 508.Dl Ic installboot -v /dev/rsd0c /usr/mdec/bootxx_ffs 509Note: the 510.Dq whole disk 511partition (c on some ports, d on others) is used here, since the a partition 512probably is already opened (mounted as 513.Pa / ) , 514so 515.Nm 516would not be able to access it. 517.Pp 518Remove the primary bootstrap from disk 519.Sq sd1 : 520.Dl Ic installboot -c /dev/rsd1c 521. 522.Ss Nx Ns Tn /amiga 523Modify the command line to change the default from "netbsd -ASn2" to 524"netbsd -S": 525.Dl Ic installboot -m amiga -o command="netbsd -S" /dev/rsd0a /usr/mdec/bootxx_ffs 526. 527.Ss Nx Ns Tn /ews4800mips 528Install the System V Boot File System primary bootstrap on to disk 529.Sq sd0 , 530with the secondary bootstrap 531.Sq Pa /boot 532already present in the SysVBFS partition on the disk: 533.Dl Ic installboot /dev/rsd0c /usr/mdec/bootxx_bfs 534. 535.Ss Nx Ns Tn /i386 and Nx Ns Tn /amd64 536Install new boot blocks on an existing mounted root file system on 537.Sq wd0 , 538setting the timeout to five seconds, after copying a new secondary 539bootstrap: 540.Dl Ic cp /usr/mdec/boot /boot 541.Dl Ic installboot -v -o timeout=5 /dev/rwd0a /usr/mdec/bootxx_ffsv1 542. 543.Pp 544Create a bootable CD-ROM with an ISO9660 545file system for a system with a serial console: 546.Dl Ic mkdir cdrom 547.Dl Ic cp sys/arch/i386/compile/mykernel/netbsd cdrom/netbsd 548.Dl Ic cp /usr/mdec/boot cdrom/boot 549.Dl Ic cp /usr/mdec/bootxx_cd9660 bootxx 550.Dl Ic installboot -t raw -o console=com0,speed=19200 bootxx \ 551 /usr/mdec/bootxx_cd9660 552.Dl Ic makefs -t cd9660 -o 'bootimage=i386;bootxx,no-emul-boot' boot.iso \ 553 cdrom 554. 555.Pp 556Create a bootable floppy disk with an FFSv1 557file system for a small custom kernel (note: bigger kernels needing 558multiple disks are handled with the ustarfs file system): 559.Dl Ic newfs -s 1440k /dev/rfd0a 560.Bd -ragged -offset indent-two -compact 561.Em Note : 562Ignore the warnings that 563.Xr newfs 8 564displays; it can not write a disklabel, 565which is not a problem for a floppy disk. 566.Ed 567.Dl Ic mount /dev/fd0a /mnt 568.Dl Ic cp /usr/mdec/boot /mnt/boot 569.Dl Ic gzip -9 \*[Lt] sys/arch/i386/compile/mykernel/netbsd \*[Gt] /mnt/netbsd.gz 570.Dl Ic umount /mnt 571.Dl Ic installboot -v /dev/rfd0a /usr/mdec/bootxx_ffsv1 572. 573.Pp 574Create a bootable FAT file system on 575.Sq wd1a , 576which should have the same offset and size as a FAT primary partition 577in the Master Boot Record (MBR): 578.Dl Ic newfs_msdos -r 16 /dev/rwd1a 579.Bd -ragged -offset indent-two -compact 580.Em Notes : 581The 582.Fl r Ar 16 583is to reserve space for the primary bootstrap. 584.Xr newfs_msdos 8 585will display an 586.Dq MBR type 587such as 588.Ql 1 , 589.Ql 4 , 590or 591.Ql 6 ; 592the MBR partition type of the appropriate primary partition should be 593changed to this value. 594.Ed 595.Dl Ic mount -t msdos /dev/wd1a /mnt 596.Dl Ic cp /usr/mdec/boot /mnt/boot 597.Dl Ic cp path/to/kernel /mnt/netbsd 598.Dl Ic umount /mnt 599.Dl Ic installboot -t raw /dev/rwd1a /usr/mdec/bootxx_msdos 600.Bd -ragged -offset indent-two -compact 601.Em Note : 602It may be necessary to ensure that there is a valid 603.Nx 604disklabel on 605.Sq wd1 606for the primary bootstrap to function correctly. 607.Ed 608. 609.Ss Nx Ns Tn /next68k 610Install the bootstrap on to disk 611.Sq sd0 : 612.Dl Ic installboot /dev/rsd0c /usr/mdec/boot 613.Pp 614. 615.Ss Nx Ns Tn /pmax 616Install the Berkeley Fast File System primary bootstrap on to disk 617.Sq sd0 : 618.Dl Ic installboot /dev/rsd0c /usr/mdec/bootxx_ffs 619.Pp 620.Nx Ns Tn /pmax 621requires that this file system starts at block 0 of the disk. 622.Pp 623Install the ISO 9660 primary bootstrap in the file 624.Pa /tmp/cd-image : 625.Dl Ic installboot -m pmax /tmp/cd-image /usr/mdec/bootxx_cd9660 626.Pp 627Make an ISO 9660 filesystem in the file 628.Pa /tmp/cd-image 629and install the ISO 9660 primary bootstrap in the filesystem, where the 630source directory for the ISO 9660 filesystem contains a kernel, the 631primary bootstrap 632.Pa bootxx_cd9660 633and the secondary bootstrap 634.Pa boot.pmax : 635.Dl Ic mkisofs -o /tmp/cd-image -a -l -v iso-source-dir 636.Dl ... 637.Dl 48 51 iso-source-dir/bootxx_cd9660 638.Dl ... 639.Dl Ic installboot -b `expr 48 \e* 4` /tmp/cd-image /usr/mdec/bootxx_cd9660 640. 641.Ss Nx Ns Tn /sparc 642Install the Berkeley Fast File System primary bootstrap on to disk 643.Sq sd0 , 644with the secondary bootstrap 645.Sq Pa /boot 646already present: 647.Dl Ic installboot /dev/rsd0c /usr/mdec/bootxx /boot 648. 649.Ss Nx Ns Tn /sparc64 650Install the Berkeley Fast File System primary bootstrap on to disk 651.Sq wd0 : 652.Dl Ic installboot /dev/rwd0c /usr/mdec/bootblk 653.Pp 654The secondary 655.Nx Ns Tn /sparc64 656bootstrap is located in 657.Pa /usr/mdec/ofwboot . 658. 659.Ss Nx Ns Tn /sun2 and Nx Ns Tn /sun3 660Install the Berkeley Fast File System primary bootstrap on to disk 661.Sq sd0 , 662with the secondary bootstrap 663.Sq Pa /boot 664already present: 665.Dl Ic installboot /dev/rsd0c /usr/mdec/bootxx /boot 666. 667.Sh SEE ALSO 668.Xr uname 3 , 669.Xr boot 8 , 670.Xr disklabel 8 671. 672.Sh HISTORY 673This implementation of 674.Nm 675appeared in 676.Nx 1.6 . 677. 678.Sh AUTHORS 679The machine independent portion of this implementation of 680.Nm 681was written by Luke Mewburn. 682The following people contributed to the various machine dependent 683back-ends: 684Simon Burge (pmax), 685Chris Demetriou (alpha), 686Matthew Fredette (sun2, sun3), 687Matthew Green (sparc64), 688Ross Harvey (alpha), 689Michael Hitch (amiga), 690Paul Kranenburg (sparc), 691David Laight (i386), 692Christian Limpach (next68k), 693Luke Mewburn (macppc), 694Matt Thomas (vax), 695Izumi Tsutsui (news68k, newsmips), 696and 697UCHIYAMA Yasushi (ews4800mips). 698. 699.Sh BUGS 700There are not currently primary bootstraps to support all file systems 701types which are capable of being the root file system. 702.Pp 703If a disk has been converted from 704.Sy FFS 705to 706.Sy RAID 707without the contents of the disk erased, then the original 708.Sy FFS 709installation may be auto-detected instead of the 710.Sy RAID 711installation. In this case, the 712.Fl t Ar raid 713option must be provided. 714. 715.Ss Nx Ns Tn /alpha 716The 717.Nx Ns Tn /alpha 718primary bootstrap program can only load the secondary bootstrap program 719from file systems starting at the beginning (block 0) of disks. 720Similarly, the secondary bootstrap program can only load kernels from 721file systems starting at the beginning of disks. 722.Pp 723The size of primary bootstrap programs is restricted to 7.5KB, even 724though some file systems (e.g., ISO 9660) are able to accommodate larger 725ones. 726. 727.Ss Nx Ns Tn /hp300 728The disk must have a boot partition large enough to hold the bootstrap code. 729Currently the primary bootstrap must be a LIF format file. 730. 731.Ss Nx Ns Tn /i386 and Nx Ns Tn /amd64 732The bootstrap must be installed in the 733.Nx 734partition that starts at the beginning of the mbr partition. 735If that is a valid filesystem and contains the 736.Pa /boot 737program then it will be used as the root filesystem, otherwise the 738.Sq a 739partition will be booted. 740.Pp 741The size of primary bootstrap programs is restricted to 8KB, even 742though some file systems (e.g., ISO 9660) are able to accommodate larger 743ones. 744. 745.Ss Nx Ns Tn /next68k 746The size of bootstrap programs is restricted to the free space before 747the file system at the beginning of the disk minus 8KB. 748. 749.Ss Nx Ns Tn /pmax 750The 751.Nx Ns Tn /pmax 752secondary bootstrap program can only load kernels from file 753systems starting at the beginning of disks. 754.Pp 755The size of primary bootstrap programs is restricted to 7.5KB, even 756though some file systems (e.g., ISO 9660) are able to accommodate larger 757ones. 758. 759.Ss Nx Ns Tn /sun2 and Nx Ns Tn /sun3 760The 761.Nx Ns Tn /sun2 762and 763.Nx Ns Tn /sun3 764secondary bootstrap program can only load kernels from file 765systems starting at the beginning of disks. 766. 767.Ss Nx Ns Tn /vax 768The 769.Nx Ns Tn /vax 770secondary bootstrap program can only load kernels from file systems 771starting at the beginning of disks. 772.Pp 773The size of primary bootstrap programs is restricted to 7.5KB, even 774though some file systems (e.g., ISO 9660) are able to accommodate larger 775ones. 776