startit.s revision 1.6
1 /* $NetBSD: startit.s,v 1.6 2001/02/26 14:58:37 is 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 1.6 2001/02/26 14:58:37 is Exp $ 35 */ 36 #include <machine/asm.h> 37 38 .set ABSEXECBASE,4 39 40 .text 41 42 ENTRY_NOPROFILE(startit) 43 #if TESTONAMIGA 44 movew #0x999,0xdff180 | gray 45 #endif 46 #if TESTONDRACO 47 moveb #0,0x200003c8 48 moveb #31,0x200003c9 49 moveb #31,0x200003c9 50 moveb #31,0x200003c9 51 #endif 52 movel sp,a3 53 movel 4:w,a6 54 lea pc@(start_super:w),a5 55 jmp a6@(-0x1e) | supervisor-call 56 57 start_super: 58 #if TESTONAMIGA 59 movew #0x900,0xdff180 | dark red 60 #endif 61 movew #0x2700,sr 62 63 | the BSD kernel wants values into the following registers: 64 | a0: fastmem-start 65 | d0: fastmem-size 66 | d1: chipmem-size 67 | d3: Amiga specific flags 68 | d4: E clock frequency 69 | d5: AttnFlags (cpuid) 70 | d6: boot partition offset 71 | d7: boothowto 72 | a4: esym location 73 | a2: Inhibit sync flags 74 | All other registers zeroed for possible future requirements. 75 76 lea pc@(_startit:w),sp | make sure we have a good stack *** 77 78 movel a3@(4),a1 | loaded kernel 79 movel a3@(8),d2 | length of loaded kernel 80 | movel a3@(12),sp | entry point in stack pointer 81 movel a3@(12),a6 | entry point *** 82 movel a3@(16),a0 | fastmem-start 83 movel a3@(20),d0 | fastmem-size 84 movel a3@(24),d1 | chipmem-size 85 movel a3@(28),d7 | boothowto 86 movel a3@(32),a4 | esym 87 movel a3@(36),d5 | cpuid 88 movel a3@(40),d4 | E clock frequency 89 movel a3@(44),d3 | Amiga flags 90 movel a3@(48),a2 | Inhibit sync flags 91 movel a3@(52),d6 | boot partition offset 92 93 cmpb #0x7D,a3@(36) | is it DraCo? 94 movel a3@(56),a3 | Load to fastmem flag 95 jeq nott | yes, switch off MMU later 96 97 | no, it is an Amiga: 98 99 #if TESTONAMIGA 100 movew #0xf00,0xdff180 |red 101 #endif 102 #if TESTONDRACO 103 moveb #0,0x200003c8 104 moveb #63,0x200003c9 105 moveb #0,0x200003c9 106 moveb #0,0x200003c9 107 #endif 108 109 movew #(1<<9),0xdff096 | disable DMA on Amigas. 110 111 | ------ mmu off start ----- 112 113 btst #3,d5 | AFB_68040,SysBase->AttnFlags 114 jeq not040 115 116 | Turn off 68040/060 MMU 117 118 subl a5,a5 119 .word 0x4e7b,0xd003 | movec a5,tc 120 .word 0x4e7b,0xd806 | movec a5,urp 121 .word 0x4e7b,0xd807 | movec a5,srp 122 .word 0x4e7b,0xd004 | movec a5,itt0 123 .word 0x4e7b,0xd005 | movec a5,itt1 124 .word 0x4e7b,0xd006 | movec a5,dtt0 125 .word 0x4e7b,0xd007 | movec a5,dtt1 126 jra nott 127 128 not040: 129 lea pc@(zero:w),a5 130 pmove a5@,tc | Turn off MMU 131 lea pc@(nullrp:w),a5 132 pmove a5@,crp | Turn off MMU some more 133 pmove a5@,srp | Really, really, turn off MMU 134 135 | Turn off 68030 TT registers 136 137 btst #2,d5 | AFB_68030,SysBase->AttnFlags 138 jeq nott | Skip TT registers if not 68030 139 lea pc@(zero:w),a5 140 .word 0xf015,0x0800 | pmove a5@,tt0 (gas only knows about 68851 ops..) 141 .word 0xf015,0x0c00 | pmove a5@,tt1 (gas only knows about 68851 ops..) 142 143 nott: 144 | ---- mmu off end ---- 145 #if TESTONAMIGA 146 movew #0xf60,0xdff180 | orange 147 #endif 148 #if TESTONDRACO 149 moveb #0,0x200003c8 150 moveb #63,0x200003c9 151 moveb #24,0x200003c9 152 moveb #0,0x200003c9 153 #endif 154 155 156 | ---- copy kernel start ---- 157 158 | removed Z flag 159 | tstl a3 | Can we load to fastmem? 160 | jeq L0 | No, leave destination at 0 161 movl a0,a3 | Move to start of fastmem chunk 162 addl a0,a6 | relocate kernel entry point 163 164 addl #3,d2 165 andl #0xfffffffc,d2 | round up. 166 167 | determine if the kernel need be copied upwards or downwards 168 169 cmpl a1,a3 | a3-a1 170 bcs above | source is above 171 172 movl a0,sp 173 addl d0,sp | move the stack to the end of segment 174 175 | copy from below upwards requires copying from end to start. 176 177 addl d2,a3 | one long word past 178 addl d2,a1 | one long word past 179 180 subl #4,sp | alloc space 181 movl a1,sp@- | save source 182 movl a3,sp@- | save destination 183 184 | copy copier to end of segment 185 186 movl sp,a3 187 subl #256,a3 | end of segment save our stack 188 189 lea pc@(_startit_end:w),a1 190 movl a0,sp@- | save segment start 191 lea pc@(below:w),a0 192 193 L0: movw a1@-,a3@- 194 cmpl a0,a1 195 bne L0 196 movl sp@,a0 | restore segment start 197 movl a3,sp@ | address of relocated below 198 addl #(ckend - below),a3 199 movl a3,sp@(12) | address of ckend for later 200 | ---- switch off cache ---- 201 bra Lchoff | and to relocated below 202 203 204 below: movl sp@+,a3 | recover destination 205 movl sp@+,a1 | recover source 206 207 L1: movl a1@-,a3@- | copy kernel 208 subl #4,d2 209 bne L1 210 211 | ---- switch off cache ---- 212 bra Lchoff | and to relocated ckend 213 214 above: movl a1@+,a3@+ 215 subl #4,d2 216 bne above 217 218 lea pc@(ckend:w),a1 219 movl a3,sp@- 220 pea pc@(_startit_end:w) 221 L2: 222 movl a1@+,a3@+ 223 cmpl sp@,a1 224 bcs L2 225 addql #4,sp 226 227 #if TESTONAMIGA 228 movew #0xFF0,0xdff180 | yellow 229 #endif 230 #if TESTONDRACO 231 moveb #0,0x200003c8 232 moveb #63,0x200003c9 233 moveb #63,0x200003c9 234 moveb #0,0x200003c9 235 #endif 236 237 | ---- switch off cache ---- 238 Lchoff: btst #3,d5 239 jeq L3c 240 .word 0xf4f8 241 L3c: movl d2,sp@- | save d2 242 movql #0,d2 | switch off cache to ensure we use 243 movec d2,cacr | valid kernel data 244 movl sp@+,d2 | restore d2 245 rts 246 247 | ---- copy kernel end ---- 248 249 ckend: 250 #if TESTONAMIGA 251 movew #0x0ff,0xdff180 | petrol 252 #endif 253 #if TESTONDRACO 254 moveb #0,0x200003c8 255 moveb #0,0x200003c9 256 moveb #63,0x200003c9 257 moveb #63,0x200003c9 258 #endif 259 260 movl d5,d2 261 roll #8,d2 262 cmpb #0x7D,d2 263 jne noDraCo 264 265 | DraCo: switch off MMU now: 266 267 subl a5,a5 268 .word 0x4e7b,0xd003 | movec a5,tc 269 .word 0x4e7b,0xd806 | movec a5,urp 270 .word 0x4e7b,0xd807 | movec a5,srp 271 .word 0x4e7b,0xd004 | movec a5,itt0 272 .word 0x4e7b,0xd005 | movec a5,itt1 273 .word 0x4e7b,0xd006 | movec a5,dtt0 274 .word 0x4e7b,0xd007 | movec a5,dtt1 275 276 noDraCo: 277 moveq #0,d2 | zero out unused registers 278 movel d2,a1 | (might make future compatibility 279 movel d2,a3 | would have known contents) 280 movel d2,a5 281 movel a6,sp | entry point into stack pointer 282 movel d2,a6 283 284 #if TESTONAMIGA 285 movew #0x0F0,0xdff180 | green 286 #endif 287 #if TESTONDRACO 288 moveb #0,0x200003c8 289 moveb #0,0x200003c9 290 moveb #63,0x200003c9 291 moveb #0,0x200003c9 292 #endif 293 294 jmp sp@ | jump to kernel entry point 295 296 297 | A do-nothing MMU root pointer (includes the following long as well) 298 299 nullrp: .long 0x7fff0001 300 zero: .long 0 301 302 ENTRY_NOPROFILE(startit_end) 303
Indexes created Wed Oct 22 13:09:56 GMT 2025