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1 .\" $NetBSD: boot26.8,v 1.4 2003/07/26 20:17:38 salo Exp $
2 .\"
3 .\" Copyright (c) 2000, 2001 Ben Harris
4 .\" All rights reserved.
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28 .Dd September 4, 2009
29 .Dt BOOT26 8 acorn26
30 .Os
31 .Sh NAME
32 .Nm boot26
33 .Nd Bootloader for
34 .Nx Ns /acorn26
35 .Sh SYNOPSIS
36 .Nm *boot26
37 .Op Fl acdqsv
38 .Op Ar file
39 .Sh DESCRIPTION
40 .Nm
41 is a program that runs under
42 .Tn RISC OS
43 and launches the
44 .Nx Ns /acorn26
45 kernel. It needs to be installed in a RISC OS
46 filesystem and given file type FFA (Module). The kernel it is to load
47 also needs to be stored in a
48 .Tn RISC OS
49 filesystem.
50 .Pp
51 It takes the following options, which set flags in the
52 .Va boothowto
53 variable in the booted kernel (see
54 .Xr boothowto 9 ) :
55 .Bl -tag -width Fl
56 .It Fl a
57 .Pq Dv RB_ASKNAME
58 Cause the kernel to prompt the user for the name of the device containing the
59 root filesystem. This also causes
60 .Nm
61 to prompt for the name of the kernel to be loaded.
62 .It Fl s
63 .Pq Dv RB_SINGLE
64 Cause the kernel to ask
65 .Nm init
66 to boot into single-user mode.
67 .It Fl d
68 .Pq Dv RB_KDB
69 Cause the kernel to enter the kernel debugger as soon as possible.
70 .It Fl c
71 .Pq Dv RB_USERCONF
72 Enter the in-kernel device configuration manager before attaching any
73 devices.
74 .It Fl q
75 .Pq Dv RB_QUIET
76 Cause the kernel to emit fewer messages than normal while starting up.
77 .It Fl v
78 .Pq Dv RB_VERBOSE
79 Cause the kernel to emit more messages than normal while starting up.
80 .El
81 .Pp
82 .Nm
83 attempts to load the kernel from the RISC OS file specified as
84 .Ar file ,
85 or from
86 .Pa netbsd
87 if
88 .Ar file
89 is not specified. The file must be an ELF image, and may have been compressed
90 using
91 .Xr gzip 1 .
92 .Ss Use as a module
93 .Nm
94 is implemented as a RISC OS relocatable module. It can be loaded into memory
95 by running
96 .Ql *RMLoad boot26 .
97 After this,
98 .Nx
99 can be booted by running
100 .Ql *boot26
101 as usual, but the command will be handled by the module.
102 .Pp
103 It should also be possible to arrange for
104 .Nm
105 to be loaded from ROM (e.g. from the ROM on an expansion card), in which case
106 .Nx
107 could be made to boot automatically by making
108 .Nm
109 the configured language using
110 .Ql *Configure Language .
111 .Ss Screen display
112 .\" From <URL:http://mail-index.NetBSD.org/port-arm26/2000/05/02/0001.html>
113 When it starts up,
114 .Nm
115 displays the current memory map.
116 Each character in the map represents one page of (physical) RAM. The
117 ticks along the top are to stop you getting lost. The characters in the
118 map indicate what the memory's being used for (actually where it's
119 logically mapped):
120 .Pp
121 .Bd -literal -offset indent
122 0 -\*[Gt] zero-page
123 + -\*[Gt] boot26 workspace
124 * -\*[Gt] Free space (boot26 wants to put the kernel here)
125 d -\*[Gt] RAM disc
126 s -\*[Gt] System sprite area
127 m -\*[Gt] RMA
128 h -\*[Gt] System heap/stack
129 f -\*[Gt] Font cache
130 S -\*[Gt] Screen memory
131 .Ed
132 .Pp
133 On a machine with 32k pages (which is all
134 .Nx Ns /acorn26
135 supports), the left
136 half of the first line is potential screen memory, and hence not used by
137 .Nm .
138 The next page is usually zero page under RISC OS, and is used for
139 zero page under
140 .Nx
141 as well. The next is usually the system heap under RISC OS,
142 and is used for process 0's kernel stack under
143 .Nx .
144 The next is used for the message buffer under
145 .Nx .
146 Pages from there on are used to load
147 the kernel, and must be free if
148 .Nm
149 is to do so successfully. Future
150 bootloaders should load the kernel into whatever pages are free, then kick
151 out RISC OS and shuffle them into the right shape. This is left as an
152 exercise for the enthusiastic reader.
153 .Sh FILES
154 .Bl -tag -width Pa
155 .It Pa /usr/mdec/boot26,ffa
156 The location of
157 .Nm
158 in the
159 .Nx
160 filesystem.
161 .El
162 .Sh SEE ALSO
163 .Xr gzip 1 ,
164 .Xr reboot 2 ,
165 .Xr ddb 4 ,
166 .Xr userconf 4 ,
167 .Xr init 8 ,
168 .Xr boothowto 9
169 .Sh HISTORY
170 .Nm
171 was introduced in
172 .Nx 1.6
173 as a replacement for the original
174 .Nx Ns /arm26
175 bootloader, which was written in BBC BASIC.
176 .Sh BUGS
177 .Nm
178 cannot load kernels from a
179 .Nx
180 filesystem.