| $! | |
| $! This procedure patches the VMB.EXE provided with VAX/VMS V7.3 to | |
| $! support the Boot Block boot functionality provided on all VAX | |
| $! systems which run a ROM based VMB. | |
| $! | |
| $ PATCH /ABSOLUTE /NEW_VERSION /OUTPUT=cp$exe:VMB.EXE cp$src:VMB_orig.EXE | |
| ! The native VMB.EXE program historically supported a Boot Block oriented | |
| ! boot if Bit 3 of the parameter register (R5) was set when VMB was invoked. | |
| ! This Boot Block boot operation reads sector 0 into memory and starts | |
| ! execution at offset 2 of the data block in memory. | |
| ! When portitions of VMB were migrated into ROM to support the earliest | |
| ! MicroVAX system (MicroVAX I) and all subsequent ROM based VMB versions | |
| ! the concept of Boot Block booting was extended in these ROM VMB | |
| ! implementations. The change in boot block booting functionality included | |
| ! several features: | |
| ! 1) If a normal boot attempt to a device failed (due to VMB not being | |
| ! able to locate a secondary bootstrap program), a boot block boot is | |
| ! automatically attempted. If the Bit 3 of R5 was set, then the | |
| ! initial search for a secondary boot block was avoided and a boot | |
| ! block boot was immediately attempted. | |
| ! 2) When performing a boot block boot, the sector 0 contents are examined | |
| ! and if these contents conform to the pattern defined for ROM based | |
| ! (PRA0) booting, the ROM format Offset, Size, and Starting address | |
| ! information is used directly by VMB to load a program into memory | |
| ! and control is transferred to that program. If the contents of | |
| ! sector 0 do not fit the pattern required for ROM based booting, then | |
| ! the code in sector 0 is executed directly starting at offset 2, | |
| ! the same as was originally done with the non ROM based VMB versions. | |
| ! Note that this extended behavior allows sector 0 to contain very little | |
| ! information and quite possibly no actual boot code. | |
| ! Developers of alternate operating systems for VAX computers noticed the ROM | |
| ! based boot block behavior and changed their installation media AND the disk | |
| ! structures to only provide the minimal boot information required on the | |
| ! systems with VMB installed in ROM. | |
| ! | |
| ! Since, when this active development of these alternate operating systems for | |
| ! VAX computers was happening, the vast majority of development and new system | |
| ! deployments were to hardware which had ROM base VMB, no one noticed that | |
| ! older systems which booted with the non ROM based VMB could no longer boot | |
| ! from new install media or disks formatted with these operating systems. | |
| ! | |
| ! This patch addeds the ROM based VMB boot block boot functionality to the | |
| ! original dynamically loaded VMB.EXE used by the older systems to boot. | |
| ! | |
| ! The patch overwrites some VMB code which exists to support NVAX(1302) and | |
| ! Neon-V(1701) systems. If simh simulators for these systems are ever built | |
| ! an alternate location must be found to accomodate this extended logic | |
| ! | |
| define PAA = 08190 ! INIT_ADP_1302 (I think!) | |
| define NEWFIL_OPNERR = PAA+1F ! Replacement to generate File Not Found Error Message | |
| define TRY_BBLOCK = PAA+2B | |
| define OLDFIL_OPNERR = 69A8 ! Original File Not Found Error | |
| define ORIG_BBLOCK_BOOT = 68B6 ! Original code that did Boot Block Boot | |
| define RPB$V_BBLOCK = 3 | |
| define RPB$L_BOOTR5 = 30 | |
| define READFILE = 0120 | |
| define READIN_BOOT = 6A37 | |
| define START_SECOND_HALT = 00BB | |
| define SS$_FILESTRUCT = 08C0 | |
| define SS$_BADCHKSUM = 0808 | |
| define SS$_BADFILEHDR = 0810 | |
| define SS$_BADDIRECTORY = 0828 | |
| dep /long PAA = 0 | |
| dep /long PAA+04 = 0 | |
| dep /long PAA+08 = 0 | |
| dep /long PAA+0C = 0 | |
| dep /long PAA+10 = 0 | |
| dep /long PAA+14 = 0 | |
| dep /long PAA+18 = 0 | |
| dep /long PAA+1C = 0 | |
| dep /long PAA+20 = 0 | |
| dep /long PAA+24 = 0 | |
| dep /long PAA+28 = 0 | |
| dep /long PAA+2C = 0 | |
| dep /long PAA+30 = 0 | |
| dep /long PAA+34 = 0 | |
| dep /long PAA+38 = 0 | |
| dep /long PAA+3C = 0 | |
| dep /long PAA+40 = 0 | |
| dep /long PAA+44 = 0 | |
| dep /long PAA+48 = 0 | |
| dep /long PAA+4C = 0 | |
| dep /long PAA+50 = 0 | |
| dep /long PAA+54 = 0 | |
| dep /long PAA+58 = 0 | |
| dep /long PAA+5C = 0 | |
| dep /long PAA+60 = 0 | |
| dep /long PAA+64 = 0 | |
| dep /long PAA+68 = 0 | |
| dep /long PAA+6C = 0 | |
| dep /long PAA+70 = 0 | |
| dep /long PAA+74 = 0 | |
| dep /long PAA+78 = 0 | |
| dep /long PAA+8C = 0 | |
| dep /long PAA+80 = 0 | |
| dep /long PAA+84 = 0 | |
| dep /long PAA+88 = 0 | |
| dep /long PAA+8C = 0 | |
| dep /long PAA+90 = 0 | |
| dep /long PAA+94 = 0 | |
| dep /long PAA+98 = 0 | |
| dep /long PAA+9C = 0 | |
| dep /ins OLDFIL_OPNERR = ' BRW PAA ' | |
| dep /ins PAA = ' CMPW R0, #SS$_BADCHKSUM ' | |
| dep /ins PAA+05 = ' BEQL TRY_BBLOCK ' | |
| dep /ins PAA+07 = ' CMPW R0, #SS$_FILESTRUCT ' | |
| dep /ins PAA+0C = ' BEQL TRY_BBLOCK ' | |
| dep /ins PAA+0E = ' CMPW R0, #SS$_BADFILEHDR ' | |
| dep /ins PAA+13 = ' BEQL TRY_BBLOCK ' | |
| dep /ins PAA+15 = ' CMPW R0, #SS$_BADDIRECTORY ' | |
| dep /ins PAA+1A = ' BEQL TRY_BBLOCK ' | |
| dep /ins PAA+1C = ' BRW NEWFIL_OPNERR ' | |
| dep /ins NEWFIL_OPNERR = ' PUSHAB L^000069AE ' | |
| dep /ins NEWFIL_OPNERR+6 = ' JMP L^00000294 ' | |
| dep /ins TRY_BBLOCK | |
| ' CLRL R8 ' ! Block to read | |
| ' MOVL #1,R9 ' ! Size to read | |
| ' MOVL R10,R6 ' ! Start of free memory | |
| ' JSB L^READFILE ' ! Read the block to R10 | |
| ' BLBC R0,TRY_OLD_BBLOCK ' ! Br if error | |
| ! | |
| ! validate the boot block | |
| ! | |
| ' MOVZBL B^2(R10),R2 ' ! Get offset to secondary id field | |
| ' CMPB B^3(R10),#1 ' ! Next field a BR instruction | |
| ' BNEQ TRY_OLD_BBLOCK ' ! Br if no | |
| ' MOVAW (R10)[R2],R1 ' ! Address next field | |
| ' CMPW (R1),#^x18 ' ! VAX instruction set id? | |
| ' BNEQ TRY_OLD_BBLOCK ' ! Br if no, error | |
| ' ADDB3 #^x18,B^2(R1),R2 ' ! Get optional value | |
| ' MCOMB R2,R2 ' ! Ones's complement it | |
| ' CMPB R2,B^3(R1) ' ! Check the check sum byte | |
| ' BNEQ TRY_OLD_BBLOCK ' ! Continue if no match | |
| ' ADDL3 B^8(R1),B^0C(R1),R2 ' ! Check other words | |
| ' ADDL B^10(R1),R2 ' ! Get augment to load address | |
| ' CMPL R2,B^14(R1) ' ! Match? | |
| ' BNEQ TRY_OLD_BBLOCK ' ! Br if no | |
| ' ROTL #10,B^4(R10),R8 ' ! Get secondary image LBN | |
| ' MOVL B^8(R1),R9 ' ! Get image size | |
| ' ADDL B^0C(R1),R10 ' ! Compute load address | |
| ' MOVL B^10(R1),R5 ' ! Compute transfer offset | |
| ' BRW READIN_BOOT ' ! Boot block is valid, read file | |
| 'TRY_OLD_BBLOCK:BBS #RPB$V_BBLOCK,B^RPB$L_BOOTR5(R11),OLD_BBLOCK_BOOT' | |
| ' BRW NEWFIL_OPNERR ' ! Report error | |
| 'OLD_BBLOCK_BOOT:MOVL #2,R5 ' ! Transfer address from start of block | |
| ' JMP L^START_SECOND_HALT ' ! Do it. | |
| exit | |
| dep /ins ORIG_BBLOCK_BOOT = ' BRW TRY_BBLOCK ' ! make BOOT /R5:8 work the same way | |
| update | |
| exit |