start.S revision 1.7
1 /* $NetBSD: start.S,v 1.7 2020/04/06 01:43:26 snj Exp $ */ 2 /* 3 * Copyright (c) 1995 Ludd, University of Lule}, Sweden. 4 * All rights reserved. 5 * 6 * This code is derived from software contributed to Ludd by 7 * Bertram Barth. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 /* All bugs are subject to removal without further notice */ 31 32 33 #define _LOCORE 34 35 #define __HAVE_OLD_DISKLABEL /* not automatically added due to _LOCORE */ 36 #define OMIT_DKTYPENUMS 37 #define OMIT_FSTYPENUMS 38 #include "sys/disklabel.h" 39 40 #include "../include/mtpr.h" 41 #include "../include/asm.h" 42 43 _C_LABEL(_start): 44 _C_LABEL(start): 45 .globl _C_LABEL(start) # this is the symbolic name for the start 46 .globl _C_LABEL(_start) # of code to be relocated. We can use this 47 # to get the actual/real address (pc-rel) 48 # or to get the relocated address (abs). 49 50 .org 0x00 # uVAX booted from TK50 starts here 51 brb from_0x00 # continue behind dispatch-block 52 53 # At offset 0x02 we have a dual used area: VMB.EXE starts execution here, 54 # and uVAX-ROM looks for a pointer to a parameter block. We arrange for 55 # the parameter block offset to disassemble as a CASEL instructions which 56 # falls through to 0x08. 57 .org 0x02 # information used by uVAX-ROM 58 .byte 0xcf # offset in words to identification area 59 .byte 1 # this byte must be 1 60 .word 0 # logical block number (word swapped) 61 .word 0 # of the secondary image 62 63 .org 0x08 # 64 brb from_0x08 # skip ... 65 66 .org 0x0C # 11/750 & 8200 starts here 67 movzbl $1,_C_LABEL(from)# We booted from "old" rom. 68 brw cont_750 69 70 71 from_0x00: # uVAX from TK50 72 brw start_uvax # all uVAXen continue there 73 74 from_0x08: # Any machine from VMB 75 movzbl $4,_C_LABEL(from) # Booted from full VMB 76 /* 77 * Read in block 1-15. 78 */ 79 movl 52(%r11), %r7 # load iovec/bqo into %r7 80 addl3 (%r7), %r7, %r6 # load qio into %r6 81 pushl %r11 # base of rpb 82 pushl $0 # virtual-flag 83 pushl $33 # read-logical-block 84 pushl $1 # lbn to start reading 85 pushl $7680 # number of bytes to read 86 pushab start_uvax # buffer-address 87 calls $6, (%r6) # call the qio-routine 88 brw start_uvax 89 90 # the complete area reserved for label 91 # must be empty (i.e. filled with zeroes). 92 # disklabel(8) checks that before installing 93 # the bootblocks over existing label. 94 95 .org LABELOFFSET 96 .globl _C_LABEL(romlabel) 97 _C_LABEL(romlabel): 98 .long 0 99 100 .org LABELOFFSET + d_end_ 101 # Make sure the parameter block is past the disklabel. 102 # If not, the next .org would try to move backwards. 103 104 /* 105 * Parameter block for uVAX boot. 106 */ 107 #define VOLINFO 0 /* 1=single-sided 81=double-sided volumes */ 108 #define SISIZE 16 /* size in blocks of secondary image */ 109 #define SILOAD 0 /* load offset (usually 0) from the default */ 110 #define SIOFF 0x200 /* byte offset into secondary image */ 111 112 .org 0x19e # do not move, see comment earlier about CASEL 113 .byte 0x18 # must be 0x18 114 .byte 0x00 # must be 0x00 (MBZ) 115 .byte 0x00 # any value 116 .byte 0xFF - (0x18 + 0x00 + 0x00) 117 /* 4th byte holds 1s' complement of sum of previous 3 bytes */ 118 119 .byte 0x00 # must be 0x00 (MBZ) 120 .byte VOLINFO 121 .byte 0x00 # any value 122 .byte 0x00 # any value 123 124 .long SISIZE # size in blocks of secondary image 125 .long SILOAD # load offset (usually 0) 126 .long SIOFF # byte offset into secondary image 127 .long (SISIZE + SILOAD + SIOFF) # sum of previous 3 128 129 130 .align 2 131 .globl _C_LABEL(from) 132 _C_LABEL(from): 133 .long 0 134 135 /* 136 * After bootblock (LBN0) has been loaded into the first page 137 * of good memory by 11/750's ROM-code (transfer address 138 * of bootblock-code is: base of good memory + 0x0C) registers 139 * are initialized as: 140 * R0: type of boot-device 141 * 0: Massbus device 142 * 1: RK06/RK07 143 * 2: RL02 144 * 17: UDA50 145 * 35: TK50 146 * 64: TU58 147 * R1: (UBA) address of UNIBUS I/O-page 148 * (MBA) address of boot device's adapter 149 * R2: (UBA) address of the boot device's CSR 150 * (MBA) controller number of boot device 151 * R6: address of driver subroutine in ROM 152 * 153 * cont_750 reads in LBN1-15 for further execution. 154 */ 155 cont_750: 156 movl $_C_LABEL(start), %sp # move stack to avoid clobbering the code 157 pushr $0x131 # save clobbered registers 158 clrl %r4 # %r4 == # of blocks transferred 159 movab _C_LABEL(start),%r5 # %r5 have base address for next transfer 160 pushl %r5 # ...on stack also (Why?) 161 1: incl %r4 # increment block count 162 movl %r4,%r8 # LBN is in %r8 for rom routine 163 addl2 $0x200,%r5 # Increase address for next read 164 cmpl $16,%r4 # read 15 blocks? 165 beql 2f # Yep 166 movl %r5,(%sp) # move address to stack also 167 jsb (%r6) # read 512 bytes 168 blbs %r0,1b # jump if read succeeded 169 halt # otherwise die... 170 2: tstl (%sp)+ # remove boring arg from stack 171 popr $0x131 # restore clobbered registers 172 brw start_all # Ok, continue... 173 174 /* uVAX main entry is at the start of the second disk block. This is 175 * needed for multi-arch CD booting where multiple architecture need 176 * to shove stuff in boot block 0. 177 */ 178 .org 0x200 # uVAX booted from disk starts here 179 180 start_uvax: 181 movzbl $2,_C_LABEL(from) # Booted from subset-VMB 182 brb start_all 183 184 /* 185 * start_all: stack already at RELOC, we save registers, move ourself 186 * to RELOC and loads boot. 187 */ 188 start_all: 189 movl $_C_LABEL(start), %sp # move stack to a better 190 pushr $0x1fff # save all regs, used later. 191 192 subl3 $_C_LABEL(start), $_C_LABEL(edata), %r0 193 # get size of text+data (w/o bss) 194 moval _C_LABEL(start), %r1 # get actual base-address of code 195 subl3 $_C_LABEL(start), $_C_LABEL(end), %r2 196 # get complete size (incl. bss) 197 movl $_C_LABEL(start), %r3 # get relocated base-address of code 198 movc5 %r0, (%r1), $0, %r2, (%r3) # copy code to new location 199 200 movpsl -(%sp) 201 movl $relocated, -(%sp) # return-address on top of stack 202 rei # can be replaced with new address 203 relocated: # now relocation is done !!! 204 movl %sp, _C_LABEL(bootregs) 205 calls $0, _C_LABEL(Xmain) # call Xmain (gcc workaround)which is 206 halt # not intended to return ... 207 208 /* 209 * hoppabort() is called when jumping to the newly loaded program. 210 */ 211 ENTRY(hoppabort, 0) 212 movl 4(%ap),%r6 213 movl _C_LABEL(rpb),%r11 214 mnegl $1,%ap # Hack to figure out boot device. 215 movpsl -(%sp) 216 pushab 2(%r6) 217 mnegl $1,_C_LABEL(vax_load_failure) 218 rei 219 # calls $0,(%r6) 220 halt 221 222 ENTRY(unit_init, R6|R7|R8|R9|R10|R11) 223 mfpr $17,%r7 # Wanted bu KDB 224 movl 4(%ap),%r0 # init routine address 225 movl 8(%ap),%r9 # RPB in %r9 226 movl 12(%ap),%r1 # VMB argument list 227 callg (%r1),(%r0) 228 ret 229 230 # A bunch of functions unwanted in boot blocks. 231 ENTRY(getchar, 0) 232 halt 233 234 #ifndef USE_PRINTF 235 ENTRY(putchar, 0) 236 ret 237 238 ENTRY(printf, 0) 239 ret 240 #endif 241 242 ENTRY(panic, 0) 243 halt 244
Indexes created Sun Sep 28 16:09:52 GMT 2025