xref: /netbsd-src/usr.sbin/installboot/installboot.8 (revision da9817918ec7e88db2912a2882967c7570a83f47)
1.\"	$NetBSD: installboot.8,v 1.73 2009/05/07 07:09:49 lukem Exp $
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3.\" Copyright (c) 2002-2009 The NetBSD Foundation, Inc.
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6.\" This code is derived from software contributed to The NetBSD Foundation
7.\" by Luke Mewburn of Wasabi Systems.
8.\"
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30.Dd October 12, 2008
31.Dt INSTALLBOOT 8
32.Os
33.Sh NAME
34.Nm installboot
35.Nd install disk bootstrap software
36.
37.Sh SYNOPSIS
38.Nm
39.Op Fl fnv
40.Op Fl B Ar s2bno
41.Op Fl b Ar s1bno
42.Op Fl m Ar machine
43.Op Fl o Ar options
44.Op Fl t Ar fstype
45.Ar filesystem
46.Ar primary
47.Op Ar secondary
48.Nm
49.Fl c
50.Op Fl fnv
51.Op Fl m Ar machine
52.Op Fl o Ar options
53.Op Fl t Ar fstype
54.Ar filesystem
55.Nm
56.Fl e
57.Op Fl fnv
58.Op Fl m Ar machine
59.Op Fl o Ar options
60.Ar bootstrap
61.
62.Sh DESCRIPTION
63The
64.Nm
65utility installs and removes
66.Nx
67disk bootstrap software into a file system.
68.Nm
69can install
70.Ar primary
71into
72.Ar filesystem ,
73or disable an existing bootstrap in
74.Ar filesystem .
75.Pp
76One some architectures the options of an existing installed bootstrap,
77or those of a bootstrap file can be changed.
78.Pp
79Generally,
80.Nx
81disk bootstrap software consists of two parts: a
82.Dq primary
83bootstrap program usually written into the disklabel area of the
84file system by
85.Nm ,
86and a
87.Dq secondary
88bootstrap program that usually resides as an ordinary file in the file system.
89.Pp
90When booting, the primary bootstrap program is loaded and invoked by
91the machine's PROM or BIOS.
92After receiving control of the system it loads and runs the secondary
93bootstrap program, which in turn loads and runs the kernel.
94The secondary bootstrap may allow control over various boot parameters
95passed to the kernel.
96.Pp
97Perform the following steps to make a file system bootable:
98.Bl -enum
99.It
100Copy the secondary bootstrap (usually
101.Pa /usr/mdec/boot. Ns Sy MACHINE
102or
103.Pa /usr/mdec/boot )
104to the root directory of the target file system.
105.Pp
106.
107.It
108Use
109.Nm
110to install the primary bootstrap program
111(usually
112.Pa /usr/mdec/bootxx_ Ns Sy FSTYPE )
113into
114.Ar filesystem .
115.Pp
116The following platforms do not require this step if the primary bootstrap
117already exists and the secondary bootstrap file is just being updated:
118.Sy alpha ,
119.Sy amd64 ,
120.Sy amiga ,
121.Sy i386 ,
122.Sy pmax ,
123.Sy sparc64 ,
124and
125.Sy vax .
126.Pp
127The following platform does not require the first step since a
128single bootstrap file is used.
129The single bootstrap is installed like the primary bootstrap on
130other platforms:
131.Sy next68k .
132.Pp
133.El
134.Pp
135The options and arguments recognized by
136.Nm
137are as follows:
138.
139.Bl -tag -width "optionsxxx"
140.
141.It Fl B Ar s2bno
142When hard-coding the blocks of
143.Ar secondary
144into
145.Ar primary ,
146start from block
147.Ar s2bno
148instead of trying to determine the block numbers occupied by
149.Ar secondary
150by examining
151.Ar filesystem .
152If this option is supplied,
153.Ar secondary
154should refer to an actual secondary bootstrap (rather than the
155file name of the one present in
156.Ar filesystem )
157so that its size can be determined.
158.
159.It Fl b Ar s1bno
160Install
161.Ar primary
162at block number
163.Ar s1bno
164instead of the default location for the machine and file system type.
165.Sy [ alpha ,
166.Sy pmax ,
167.Sy vax ]
168.
169.It Fl c
170Clear (remove) any existing bootstrap instead of installing one.
171.
172.It Fl e
173Edit the options of an existing bootstrap.
174This can be use to change the options in bootxx_xxxfs files,
175raw disk partitions, and the
176.Pa pxeboot_ia32.bin
177file.
178.Sy [ amd64 , i386 ]
179.
180.It Fl f
181Forces
182.Nm
183to ignore some errors.
184.
185.It Fl m Ar machine
186Use
187.Ar machine
188as the target machine type.
189The default machine is determined from
190.Xr uname 3
191and then
192.Ev MACHINE .
193The following machines are currently supported by
194.Nm :
195.Bd -ragged -offset indent
196.Sy alpha ,
197.Sy amd64 ,
198.Sy amiga ,
199.Sy ews4800mips ,
200.Sy hp300 ,
201.Sy hp700 ,
202.Sy i386 ,
203.Sy landisk ,
204.Sy macppc ,
205.Sy news68k ,
206.Sy newsmips ,
207.Sy next68k ,
208.Sy pmax ,
209.Sy sparc ,
210.Sy sparc64 ,
211.Sy sun2 ,
212.Sy sun3 ,
213.Sy vax ,
214.Sy x68k
215.Ed
216.
217.
218.It Fl n
219Do not write to
220.Ar filesystem .
221.
222.It Fl o Ar options
223Machine specific
224.Nm
225options, comma separated.
226.Pp
227Supported options are (with the machines for they are valid in brackets):
228.
229.Bl -tag -offset indent -width alphasum
230.
231.It Sy alphasum
232.Sy [ alpha ]
233Recalculate and restore the Alpha checksum.
234This is the default for
235.Nx Ns Tn /alpha .
236.
237.It Sy append
238.Sy [ alpha ,
239.Sy pmax ,
240.Sy vax ]
241Append
242.Ar primary
243to the end of
244.Ar filesystem ,
245which must be a regular file in this case.
246.
247.It Sy command=\*[Lt]boot command\*[Gt]
248.Sy [ amiga ]
249Modify the default boot command line.
250.
251.It Sy console=\*[Lt]console name\*[Gt]
252.Sy [ amd64 ,
253.Sy i386 ]
254Set the console device, \*[Lt]console name\*[Gt] must be one of:
255pc, com0, com1, com2, com3, com0kbd, com1kbd, com2kbd or com3kbd.
256.
257.It Sy ioaddr=\*[Lt]ioaddr\*[Gt]
258.Sy [ amd64 ,
259.Sy i386 ]
260Set the IO address to be used for the console serial port.
261Defaults to the IO address used by the system BIOS for the specified port.
262.
263.It Sy keymap=\*[Lt]keymap\*[Gt]
264.Sy [ amd64 ,
265.Sy i386 ]
266Set a boot time keyboard translation map.
267Each character in \*[Lt]keymap\*[Gt] will be replaced by the one following it.
268For example, an argument of
269.Dq zyz
270would swap the lowercase letters
271.Sq y
272and
273.Sq z .
274.
275.It Sy password=\*[Lt]password\*[Gt]
276.Sy [ amd64 ,
277.Sy i386 ]
278Set the password which must be entered before the boot menu can be accessed.
279.
280.It Sy resetvideo
281.Sy [ amd64 ,
282.Sy i386 ]
283Reset the video before booting.
284.
285.It Sy speed=\*[Lt]baud rate\*[Gt]
286.Sy [ amd64 ,
287.Sy i386 ]
288Set the baud rate for the serial console.
289If a value of zero is specified, then the current baud rate (set by the
290BIOS) will be used.
291.
292.It Sy sunsum
293.Sy [ alpha ,
294.Sy pmax ,
295.Sy vax ]
296Recalculate and restore the Sun and
297.Nx Ns Tn /sparc
298compatible checksum.
299.Em Note :
300The existing
301.Nx Ns Tn /sparc
302disklabel should use no more than 4 partitions.
303.
304.It Sy timeout=\*[Lt]seconds\*[Gt]
305.Sy [ amd64 ,
306.Sy i386 ]
307Set the timeout before the automatic boot begins to the given number of seconds.
308.El
309.
310.It Fl t Ar fstype
311Use
312.Ar fstype
313as the type of
314.Ar filesystem .
315The default operation is to attempt to auto-detect this setting.
316The following file system types are currently supported by
317.Nm :
318.
319.Bl -tag -offset indent -width raid
320.
321.It Sy ffs
322.Bx
323Fast File System.
324.
325.It Sy raid
326Mirrored RAIDframe File System.
327.
328.It Sy raw
329.Sq Raw
330image.
331Note: if a platform needs to hard-code the block offset of the secondary
332bootstrap, it cannot be searched for on this file system type, and must
333be provided with
334.Fl B Ar s2bno .
335.El
336.
337.It Fl v
338Verbose operation.
339.
340.It Ar filesystem
341The path name of the device or file system image that
342.Nm
343is to operate on.
344It is not necessary for
345.Ar filesystem
346to be a currently mounted file system.
347.
348.It Ar primary
349The path name of the
350.Dq primary
351boot block to install.
352The path name must refer to a file in a file system that is currently
353mounted.
354.
355.It Ar secondary
356The path name of the
357.Dq secondary
358boot block, relative to the root of
359the file system in the device or image specified by the
360.Ar filesystem
361argument.
362Note that this may refer to a file in a file system that is not mounted.
363Most systems require
364.Ar secondary
365to be in the
366.Dq root
367directory of the file system, so the leading
368.Dq Pa /
369is not necessary on
370.Ar secondary .
371.Pp
372Only certain combinations of
373platform
374.Pq Fl m Ar machine
375and file system type
376.Pq Fl t Ar fstype
377require that the name of the secondary bootstrap is
378supplied as
379.Ar secondary ,
380so that information such as the disk block numbers occupied
381by the secondary bootstrap can be stored in the primary bootstrap.
382These are:
383.Bl -column "Platform" "File systems" -offset indent
384.It Sy "Platform" Ta Sy "File systems"
385.It macppc Ta ffs, raw
386.It news68k Ta ffs, raw
387.It newsmips Ta ffs, raw
388.It sparc Ta ffs, raid, raw
389.It sun2 Ta ffs, raw
390.It sun3 Ta ffs, raw
391.El
392.El
393.Pp
394.Nm
395exits 0 on success, and \*[Gt]0 if an error occurs.
396.
397.Sh ENVIRONMENT
398.Nm
399uses the following environment variables:
400.
401.Bl -tag -width "MACHINE"
402.
403.It Ev MACHINE
404Default value for
405.Ar machine ,
406overriding the result from
407.Xr uname 3 .
408.
409.El
410.
411.Sh FILES
412Most
413.Nx
414ports will contain variations of the following files:
415.Pp
416.Bl -tag -width /usr/mdec/bootxx_ustarfs
417.
418.It Pa /usr/mdec/bootxx_ Ns Sy FSTYPE
419Primary bootstrap for file system type
420.Sy FSTYPE .
421Installed into the bootstrap area of the file system by
422.Nm .
423.
424.It Pa /usr/mdec/bootxx_fat16
425Primary bootstrap for
426.Tn MS-DOS
427.Sy FAT16
428file systems.
429This differs from
430.Nm bootxx_msdos
431in that it doesn't require the filesystem to have been initialised with
432any
433.Ql reserved sectors .
434It also uses the information in the
435.Ql Boot Parameter Block
436to get the media and filesytem properties.
437.
438.It Pa /usr/mdec/bootxx_ffsv1
439Primary bootstrap for
440.Sy FFSv1
441file systems
442(the "traditional"
443.Nx
444file system).
445Use
446.Xr dumpfs 8
447to confirm the file system format is
448.Sy FFSv1 .
449.
450.It Pa /usr/mdec/bootxx_ffsv2
451Primary bootstrap for
452.Sy FFSv2
453file systems.
454Use
455.Xr dumpfs 8
456to confirm the file system format is
457.Sy FFSv2 .
458.
459.It Pa /usr/mdec/bootxx_lfsv1
460Primary bootstrap for
461.Sy LFSv1
462file systems.
463.
464.It Pa /usr/mdec/bootxx_lfsv2
465Primary bootstrap for
466.Sy LFSv2
467file systems
468(the default LFS version).
469.
470.It Pa /usr/mdec/bootxx_msdos
471Primary bootstrap for
472.Tn MS-DOS
473.Sy FAT
474file systems.
475.
476.It Pa /usr/mdec/bootxx_ustarfs
477Primary bootstrap for
478.Sy TARFS
479boot images.
480This is used by various install media.
481.
482.It Pa /usr/mdec/boot. Ns Sy MACHINE
483Secondary bootstrap for machine type
484.Sy MACHINE .
485This should be installed into the file system before
486.Nm
487is run.
488.
489.It Pa /usr/mdec/boot
490Synonym for
491.Pa /usr/mdec/boot. Ns Sy MACHINE
492.
493.It Pa /boot. Ns Sy MACHINE
494Installed copy of secondary bootstrap for machine type
495.Sy MACHINE .
496.
497.It Pa /boot
498Installed copy of secondary bootstrap.
499Searched for by the primary bootstrap if
500.Pa /boot. Ns Sy MACHINE
501is not found.
502.
503.El
504.
505.Ss Nx Ns Tn /macppc files
506.
507.Bl -tag -width /usr/mdec/bootxx_ustarfs
508.
509.It Pa /usr/mdec/bootxx
510.Nx Ns Tn /macppc
511primary bootstrap.
512.
513.It Pa /usr/mdec/ofwboot
514.Nx Ns Tn /macppc
515secondary bootstrap.
516.
517.It Pa /ofwboot
518Installed copy of
519.Nx Ns Tn /macppc
520secondary bootstrap.
521.
522.El
523.
524.Ss Nx Ns Tn /next68k files
525.
526.Bl -tag -width /usr/mdec/bootxx_ustarfs
527.
528.It Pa /usr/mdec/boot
529.Nx Ns Tn /next68k
530bootstrap.
531.
532.El
533.
534.Ss Nx Ns Tn /sparc64 files
535.
536.Bl -tag -width /usr/mdec/bootxx_ustarfs
537.
538.It Pa /usr/mdec/bootblk
539.Nx Ns Tn /sparc64
540primary bootstrap.
541.
542.It Pa /usr/mdec/ofwboot
543.Nx Ns Tn /sparc64
544secondary bootstrap.
545.
546.It Pa /ofwboot
547Installed copy of
548.Nx Ns Tn /sparc64
549secondary bootstrap.
550.
551.El
552.
553.Sh EXAMPLES
554.
555.Ss common
556Verbosely install the Berkeley Fast File System primary bootstrap on to disk
557.Sq sd0 :
558.Dl Ic installboot -v /dev/rsd0c /usr/mdec/bootxx_ffs
559Note: the
560.Dq whole disk
561partition (c on some ports, d on others) is used here, since the a partition
562probably is already opened (mounted as
563.Pa / ) ,
564so
565.Nm
566would not be able to access it.
567.Pp
568Remove the primary bootstrap from disk
569.Sq sd1 :
570.Dl Ic installboot -c /dev/rsd1c
571.
572.Ss Nx Ns Tn /amiga
573Modify the command line to change the default from "netbsd -ASn2" to
574"netbsd -S":
575.Dl Ic installboot -m amiga -o command="netbsd -S" /dev/rsd0a /usr/mdec/bootxx_ffs
576.
577.Ss Nx Ns Tn /ews4800mips
578Install the System V Boot File System primary bootstrap on to disk
579.Sq sd0 ,
580with the secondary bootstrap
581.Sq Pa /boot
582already present in the SysVBFS partition on the disk:
583.Dl Ic installboot /dev/rsd0c /usr/mdec/bootxx_bfs
584.
585.Ss Nx Ns Tn /i386 and Nx Ns Tn /amd64
586Install new boot blocks on an existing mounted root file system on
587.Sq wd0 ,
588setting the timeout to five seconds, after copying a new secondary
589bootstrap:
590.Dl Ic cp /usr/mdec/boot /boot
591.Dl Ic installboot -v -o timeout=5 /dev/rwd0a /usr/mdec/bootxx_ffsv1
592.
593.Pp
594Create a bootable CD-ROM with an ISO9660
595file system for an i386 system with a serial console:
596.Dl Ic mkdir cdrom
597.Dl Ic cp sys/arch/i386/compile/mykernel/netbsd cdrom/netbsd
598.Dl Ic cp /usr/mdec/boot cdrom/boot
599.Dl Ic cp /usr/mdec/bootxx_cd9660 bootxx
600.Dl Ic installboot -o console=com0,speed=19200 -m i386 -e bootxx
601.Dl Ic makefs -t cd9660 -o 'bootimage=i386;bootxx,no-emul-boot' boot.iso \
602	cdrom
603.
604.Pp
605Create a bootable floppy disk with an FFSv1
606file system for a small custom kernel (note: bigger kernels needing
607multiple disks are handled with the ustarfs file system):
608.Dl Ic newfs -s 1440k /dev/rfd0a
609.Bd -ragged -offset indent-two -compact
610.Em Note :
611Ignore the warnings that
612.Xr newfs 8
613displays; it can not write a disklabel,
614which is not a problem for a floppy disk.
615.Ed
616.Dl Ic mount /dev/fd0a /mnt
617.Dl Ic cp /usr/mdec/boot /mnt/boot
618.Dl Ic gzip -9 \*[Lt] sys/arch/i386/compile/mykernel/netbsd \*[Gt] /mnt/netbsd.gz
619.Dl Ic umount /mnt
620.Dl Ic installboot -v /dev/rfd0a /usr/mdec/bootxx_ffsv1
621.
622.Pp
623Create a bootable FAT file system on
624.Sq wd1a ,
625which should have the same offset and size as a FAT primary partition
626in the Master Boot Record (MBR):
627.Dl Ic newfs_msdos -r 16 /dev/rwd1a
628.Bd -ragged -offset indent-two -compact
629.Em Notes :
630The
631.Fl r Ar 16
632is to reserve space for the primary bootstrap.
633.Xr newfs_msdos 8
634will display an
635.Dq MBR type
636such as
637.Ql 1 ,
638.Ql 4 ,
639or
640.Ql 6 ;
641the MBR partition type of the appropriate primary partition should be
642changed to this value.
643.Ed
644.Dl Ic mount -t msdos /dev/wd1a /mnt
645.Dl Ic cp /usr/mdec/boot /mnt/boot
646.Dl Ic cp path/to/kernel /mnt/netbsd
647.Dl Ic umount /mnt
648.Dl Ic installboot -t raw /dev/rwd1a /usr/mdec/bootxx_msdos
649.Pp
650Make the existing FAT16 filesystem on
651.Sq sd0e
652bootable.
653This can be used to make USB memory bootable provided it has 512 byte
654sectors and that the manufacturer correctly initialised the file system.
655.Dl Ic mount -t msdos /dev/sd0e /mnt
656.Dl Ic cp /usr/mdec/boot /mnt/boot
657.Dl Ic cp path/to/kernel /mnt/netbsd
658.Dl Ic umount /mnt
659.Dl Ic installboot /dev/rsd0e /usr/mdec/bootxx_fat16
660It may also be necessary to use
661.Nm fdisk
662to make the device itself bootable.
663.
664.Pp
665Switch the existing installed bootstrap to use a serial console without
666reinstalling or altering other options such as timeout.
667.Dl Ic installboot -e -o console=com0 /dev/rwd0a
668.Ss Nx Ns Tn /macppc
669Note the
670.Nm
671utility is only required for macppc machines with OpenFirmware version 2
672to boot.
673OpenFirmware 3 cannot load bootblocks specified in the Apple partition
674map.
675.Pp
676Install the Berkeley Fast File System primary bootstrap on to disk
677.Sq wd0 :
678.Dl Ic installboot /dev/rwd0c /usr/mdec/bootxx /ofwboot
679.Pp
680The secondary
681.Nx Ns Tn /macppc
682bootstrap is located in
683.Pa /usr/mdec/ofwboot .
684.Pp
685The primary bootstrap requires the raw
686.Pa ofwboot
687for the secondary bootstrap, not
688.Pa ofwboot.xcf ,
689which is used for the OpenFirmware to load kernels.
690.Ss Nx Ns Tn /next68k
691Install the bootstrap on to disk
692.Sq sd0 :
693.Dl Ic installboot /dev/rsd0c /usr/mdec/boot
694.Pp
695.
696.Ss Nx Ns Tn /pmax
697Install the Berkeley Fast File System primary bootstrap on to disk
698.Sq sd0 :
699.Dl Ic installboot /dev/rsd0c /usr/mdec/bootxx_ffs
700.Pp
701.Nx Ns Tn /pmax
702requires that this file system starts at block 0 of the disk.
703.Pp
704Install the ISO 9660 primary bootstrap in the file
705.Pa /tmp/cd-image :
706.Dl Ic installboot -m pmax /tmp/cd-image /usr/mdec/bootxx_cd9660
707.Pp
708Make an ISO 9660 filesystem in the file
709.Pa /tmp/cd-image
710and install the ISO 9660 primary bootstrap in the filesystem, where the
711source directory for the ISO 9660 filesystem contains a kernel, the
712primary bootstrap
713.Pa bootxx_cd9660
714and the secondary bootstrap
715.Pa boot.pmax :
716.Dl Ic mkisofs -o /tmp/cd-image -a -l -v iso-source-dir
717.Dl ...
718.Dl 48 51 iso-source-dir/bootxx_cd9660
719.Dl ...
720.Dl Ic installboot -b `expr 48 \e* 4` /tmp/cd-image /usr/mdec/bootxx_cd9660
721.
722.Ss Nx Ns Tn /sparc
723Install the Berkeley Fast File System primary bootstrap on to disk
724.Sq sd0 ,
725with the secondary bootstrap
726.Sq Pa /boot
727already present:
728.Dl Ic installboot /dev/rsd0c /usr/mdec/bootxx /boot
729.
730.Ss Nx Ns Tn /sparc64
731Install the Berkeley Fast File System primary bootstrap on to disk
732.Sq wd0 :
733.Dl Ic installboot /dev/rwd0c /usr/mdec/bootblk
734.Pp
735The secondary
736.Nx Ns Tn /sparc64
737bootstrap is located in
738.Pa /usr/mdec/ofwboot .
739.
740.Ss Nx Ns Tn /sun2 and Nx Ns Tn /sun3
741Install the Berkeley Fast File System primary bootstrap on to disk
742.Sq sd0 ,
743with the secondary bootstrap
744.Sq Pa /boot
745already present:
746.Dl Ic installboot /dev/rsd0c /usr/mdec/bootxx /boot
747.
748.Sh SEE ALSO
749.Xr uname 3 ,
750.Xr boot 8 ,
751.Xr disklabel 8 ,
752.Xr dumpfs 8 ,
753.Xr fdisk 8 ,
754.Xr pxeboot 8
755.
756.Sh HISTORY
757This implementation of
758.Nm
759appeared in
760.Nx 1.6 .
761.
762.Sh AUTHORS
763The machine independent portion of this implementation of
764.Nm
765was written by Luke Mewburn.
766The following people contributed to the various machine dependent
767back-ends:
768Simon Burge (pmax),
769Chris Demetriou (alpha),
770Matthew Fredette (sun2, sun3),
771Matthew Green (sparc64),
772Ross Harvey (alpha),
773Michael Hitch (amiga),
774Paul Kranenburg (sparc),
775David Laight (i386),
776Christian Limpach (next68k),
777Luke Mewburn (macppc),
778Matt Thomas (vax),
779Izumi Tsutsui (news68k, newsmips),
780and
781UCHIYAMA Yasushi (ews4800mips).
782.
783.Sh BUGS
784There are not currently primary bootstraps to support all file systems
785types which are capable of being the root file system.
786.Pp
787If a disk has been converted from
788.Sy FFS
789to
790.Sy RAID
791without the contents of the disk erased, then the original
792.Sy FFS
793installation may be auto-detected instead of the
794.Sy RAID
795installation.
796In this case, the
797.Fl t Ar raid
798option must be provided.
799.
800.Ss Nx Ns Tn /alpha
801The
802.Nx Ns Tn /alpha
803primary bootstrap program can only load the secondary bootstrap program
804from file systems starting at the beginning (block 0) of disks.
805Similarly, the secondary bootstrap program can only load kernels from
806file systems starting at the beginning of disks.
807.Pp
808The size of primary bootstrap programs is restricted to 7.5KB, even
809though some file systems (e.g., ISO 9660) are able to accommodate larger
810ones.
811.
812.Ss Nx Ns Tn /hp300
813The disk must have a boot partition large enough to hold the bootstrap code.
814Currently the primary bootstrap must be a LIF format file.
815.
816.Ss Nx Ns Tn /i386 and Nx Ns Tn /amd64
817The bootstrap must be installed in the
818.Nx
819partition that starts at the beginning of the mbr partition.
820If that is a valid filesystem and contains the
821.Pa /boot
822program then it will be used as the root filesystem, otherwise the
823.Sq a
824partition will be booted.
825.Pp
826The size of primary bootstrap programs is restricted to 8KB, even
827though some file systems (e.g., ISO 9660) are able to accommodate larger
828ones.
829.
830.Ss Nx Ns Tn /macppc
831Due to restrictions in
832.Nm
833and the secondary bootstrap implementation, file systems where kernels exist
834must start at the beginning of disks.
835.Pp
836Currently,
837.Nm
838doesn't recognize an existing Apple partition map on the disk
839and always writes a faked map to make disks bootable.
840.Pp
841The
842.Nx Ns Tn /macppc
843bootstrap program can't load kernels from
844.Sy FFSv2
845partitions.
846.Ss Nx Ns Tn /next68k
847The size of bootstrap programs is restricted to the free space before
848the file system at the beginning of the disk minus 8KB.
849.
850.Ss Nx Ns Tn /pmax
851The
852.Nx Ns Tn /pmax
853secondary bootstrap program can only load kernels from file
854systems starting at the beginning of disks.
855.Pp
856The size of primary bootstrap programs is restricted to 7.5KB, even
857though some file systems (e.g., ISO 9660) are able to accommodate larger
858ones.
859.
860.Ss Nx Ns Tn /sun2 and Nx Ns Tn /sun3
861The
862.Nx Ns Tn /sun2
863and
864.Nx Ns Tn /sun3
865secondary bootstrap program can only load kernels from file
866systems starting at the beginning of disks.
867.
868.Ss Nx Ns Tn /vax
869The
870.Nx Ns Tn /vax
871secondary bootstrap program can only load kernels from file systems
872starting at the beginning of disks.
873.Pp
874The size of primary bootstrap programs is restricted to 7.5KB, even
875though some file systems (e.g., ISO 9660) are able to accommodate larger
876ones.
877