.\"	$NetBSD: installboot.8,v 1.25 2021/02/26 10:44:31 wiz Exp $
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.Dd February 25, 2021
.Dt INSTALLBOOT 8 amiga
.Os
.Sh NAME
.Nm installboot
.Nd install a bootstrap on an FFS filesystem partition
.Sh SYNOPSIS
.Nm /usr/mdec/installboot
.Op Fl l Ar newcommandline
.Ar bootblock
.Ar device
.Sh DESCRIPTION
.Nm installboot
copies the bootblock to a bootable partition.
The
bootstrap is written into the bootblock area on the partition, right
in front of the superblock, and hence limited in size to
8192 bytes.
.Pp
The bootstrap resides in the first few blocks on the partition
.Pq as specified by Commodore-Amiga Inc.
The bootstrap is loaded into memory by the ROM from bootable devices:
RDB devices, where the partition is marked as bootable, or (not on the
DraCo) floppy disks in Amiga format (880K/1760k).
.Pp
In the presence of more than one bootable partition/floppy disk, the partition
is chosen by the bootpriority (from the RDB), which can be overridden by
the operator from the boot menu (on Amiga machines, hold down the outer
mouse buttons during boot; on DraCo machines, press the left mouse button
when prompted).
.Pp
On RDB devices, the whole bootblock is loaded by the ROM.
The number of
boot blocks in the RDB partition entry must be correct.
.Pp
On floppy disks, the ROM always loads the first two blocks (1024 bytes),
and the bootblock allocates memory and loads the whole bootblock on startup.
.Pp
After receiving control, the bootblock uses the stand-alone
filesystem code in
.Dq libsa.a
to load the kernel from the filesystem on the partition it was started from.
The code for the boot program can be found in
.Pa /usr/mdec/bootxx_fd
.Pq floppy disk code ,
.Pa /usr/mdec/bootxx_ffsv1
.Pq generic RDB disk code for FFSv1 ,
or
.Pa /usr/mdec/bootxx_ffsv2
.Pq generic RDB disk code for FFSv2 .
.Pp
The arguments are:
.Bl -tag -width bootblock
.It Fl l Ar newcommandline
Specify a different command line to replace the default.
.It Ar bootblock
The file containing the bootblock (normally /usr/mdec/bootxx_ffsv1 or
bootxx_ffsv2 for RDB devices).
.It Ar device
The name of the character special device specifying the partition on which the
bootstrap is to be installed.
.El
.Sh EXAMPLES
The following command will install the
boot program for FFSv1 in the bootblock area on
.Dq sd0a :
.Bd -literal -offset indent
installboot /usr/mdec/bootxx_ffsv1 /dev/rsd0a
.Ed
.Sh SEE ALSO
.Xr dd 1 ,
.Xr amiga/boot 8
.Sh HISTORY
The
.Nm
command first appeared in
.Nx 1.3 .
.Sh BUGS
If
.Nm
is accidentally used on the whole disk partition, the RDB will be overwritten,
making your system unusable after the next reboot.
.Pp
Some third-party accelerator boards are not autoconfiguring.
You won't be able to use their memory when booting from the bootblock
after a cold start.
.Pp
Some third-party disk controllers don't support bootblock booting.
.Pp
DraCo ROMs don't support bootblock booting from floppy disks.
.Pp
Most 68060 boards, unlike the DraCo, don't set the SysBase->AttnFlags
bit for the 68060 CPU (a patch program which is called during
AmigaOS startup does this).
You need to add
.Cd options BB060STUPIDROM
to your kernel to boot on such a machine.
.Pp
There is currently no easy way to edit the RDB from within
.Nx .
Therefore, you have to use HDTOOLBOX or a similar tool to
set the partition to bootable, "use custom bootblocks" and the number
of bootblocks to 16 (for bootxx_ffsv1 or bootxx_ffsv2) or 2 (for bootxx_fd),
at least the first time you install the bootblock.
.Pp
As normal
.Xr dd 1
is used to install the bootblock, you can only install onto
your currently used root (or any other mounted) partition from single-user
mode, or while otherwise running in insecure mode.