startit.s revision 1.2
1 /* $NetBSD: startit.s,v 1.2 1997/02/01 01:46:27 mhitch Exp $ */ 2 3 /* 4 * Copyright (c) 1996 Ignatios Souvatzis 5 * Copyright (c) 1994 Michael L. Hitch 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Michael L. Hitch. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 * 33 * 34 * From: $NetBSD: startit.s,v 1.2 1997/02/01 01:46:27 mhitch Exp $ 35 */ 36 37 .set ABSEXECBASE,4 38 39 .text 40 41 .globl _startit 42 .globl _startit_end 43 44 _startit: 45 #if TESTONAMIGA 46 movew #0x999,0xdff180 | gray 47 #endif 48 movel sp,a3 49 movel 4:w,a6 50 lea pc@(start_super:w),a5 51 jmp a6@(-0x1e) | supervisor-call 52 53 start_super: 54 #if TESTONAMIGA 55 movew #0x900,0xdff180 | dark red 56 #endif 57 movew #0x2700,sr 58 59 | the BSD kernel wants values into the following registers: 60 | a0: fastmem-start 61 | d0: fastmem-size 62 | d1: chipmem-size 63 | d3: Amiga specific flags 64 | d4: E clock frequency 65 | d5: AttnFlags (cpuid) 66 | d6: boot partition offset 67 | d7: boothowto 68 | a4: esym location 69 | a2: Inhibit sync flags 70 | All other registers zeroed for possible future requirements. 71 72 lea pc@(_startit:w),sp | make sure we have a good stack *** 73 74 movel a3@(4),a1 | loaded kernel 75 movel a3@(8),d2 | length of loaded kernel 76 | movel a3@(12),sp | entry point in stack pointer 77 movel a3@(12),a6 | entry point *** 78 movel a3@(16),a0 | fastmem-start 79 movel a3@(20),d0 | fastmem-size 80 movel a3@(24),d1 | chipmem-size 81 movel a3@(28),d7 | boothowto 82 movel a3@(32),a4 | esym 83 movel a3@(36),d5 | cpuid 84 movel a3@(40),d4 | E clock frequency 85 movel a3@(44),d3 | Amiga flags 86 movel a3@(48),a2 | Inhibit sync flags 87 movel a3@(52),d6 | boot partition offset 88 89 cmpb #0x7D,a3@(36) | is it DraCo? 90 movel a3@(56),a3 | Load to fastmem flag 91 jeq nott | yes, switch off MMU later 92 93 | no, it is an Amiga: 94 95 #if TESTONAMIGA 96 movew #0xf00,0xdff180 |red 97 #endif 98 | moveb #0,0x200003c8 99 | moveb #63,0x200003c9 100 | moveb #0,0x200003c9 101 | moveb #0,0x200003c9 102 103 movew #(1<<9),0xdff096 | disable DMA on Amigas. 104 105 | ------ mmu off start ----- 106 107 btst #3,d5 | AFB_68040,SysBase->AttnFlags 108 jeq not040 109 110 | Turn off 68040/060 MMU 111 112 subl a5,a5 113 .word 0x4e7b,0xd003 | movec a5,tc 114 .word 0x4e7b,0xd806 | movec a5,urp 115 .word 0x4e7b,0xd807 | movec a5,srp 116 .word 0x4e7b,0xd004 | movec a5,itt0 117 .word 0x4e7b,0xd005 | movec a5,itt1 118 .word 0x4e7b,0xd006 | movec a5,dtt0 119 .word 0x4e7b,0xd007 | movec a5,dtt1 120 jra nott 121 122 not040: 123 lea pc@(zero:w),a5 124 pmove a5@,tc | Turn off MMU 125 lea pc@(nullrp:w),a5 126 pmove a5@,crp | Turn off MMU some more 127 pmove a5@,srp | Really, really, turn off MMU 128 129 | Turn off 68030 TT registers 130 131 btst #2,d5 | AFB_68030,SysBase->AttnFlags 132 jeq nott | Skip TT registers if not 68030 133 lea pc@(zero:w),a5 134 .word 0xf015,0x0800 | pmove a5@,tt0 (gas only knows about 68851 ops..) 135 .word 0xf015,0x0c00 | pmove a5@,tt1 (gas only knows about 68851 ops..) 136 137 nott: 138 | ---- mmu off end ---- 139 #if TESTONAMIGA 140 movew #0xf60,0xdff180 | orange 141 #endif 142 | moveb #0,0x200003c8 143 | moveb #63,0x200003c9 144 | moveb #24,0x200003c9 145 | moveb #0,0x200003c9 146 147 | ---- copy kernel start ---- 148 149 tstl a3 | Can we load to fastmem? 150 jeq L0 | No, leave destination at 0 151 movl a0,a3 | Move to start of fastmem chunk 152 addl a0,a6 | relocate kernel entry point 153 L0: 154 movl a1@+,a3@+ 155 subl #4,d2 156 bcc L0 157 158 lea pc@(ckend:w),a1 159 movl a3,sp@- 160 pea pc@(_startit_end:w) 161 L1: 162 movl a1@+,a3@+ 163 cmpl sp@,a1 164 bcs L1 165 addql #4,sp 166 167 btst #3,d5 168 jeq L2 169 .word 0xf4f8 170 L2: movql #0,d2 | switch off cache to ensure we use 171 movec d2,cacr | valid kernel data 172 173 #if TESTONAMIGA 174 movew #0xFF0,0xdff180 | yellow 175 #endif 176 | moveb #0,0x200003c8 177 | moveb #63,0x200003c9 178 | moveb #0,0x200003c9 179 | moveb #0,0x200003c9 180 181 rts 182 183 | ---- copy kernel end ---- 184 185 ckend: 186 #if TESTONAMIGA 187 movew #0x0ff,0xdff180 | petrol 188 #endif 189 | moveb #0,0x200003c8 190 | moveb #0,0x200003c9 191 | moveb #63,0x200003c9 192 | moveb #63,0x200003c9 193 194 movl d5,d2 195 roll #8,d2 196 cmpb #0x7D,d2 197 jne noDraCo 198 199 | DraCo: switch off MMU now: 200 201 subl a5,a5 202 .word 0x4e7b,0xd003 | movec a5,tc 203 .word 0x4e7b,0xd806 | movec a5,urp 204 .word 0x4e7b,0xd807 | movec a5,srp 205 .word 0x4e7b,0xd004 | movec a5,itt0 206 .word 0x4e7b,0xd005 | movec a5,itt1 207 .word 0x4e7b,0xd006 | movec a5,dtt0 208 .word 0x4e7b,0xd007 | movec a5,dtt1 209 210 noDraCo: 211 moveq #0,d2 | zero out unused registers 212 movel d2,a1 | (might make future compatibility 213 movel d2,a3 | would have known contents) 214 movel d2,a5 215 movel a6,sp | entry point into stack pointer 216 movel d2,a6 217 218 #if TESTONAMIGA 219 movew #0x0F0,0xdff180 | green 220 #endif 221 | moveb #0,0x200003c8 222 | moveb #0,0x200003c9 223 | moveb #63,0x200003c9 224 | moveb #0,0x200003c9 225 226 jmp sp@ | jump to kernel entry point 227 228 229 | A do-nothing MMU root pointer (includes the following long as well) 230 231 nullrp: .long 0x7fff0001 232 zero: .long 0 233 234 _startit_end: 235
Indexes created Wed Oct 22 06:10:02 GMT 2025