usr/src/sys/vax/mdec/raboot.c

/*      raboot.c        6.1     83/07/29        */

/*
 * UDA50 1st level boot program: loads next 7.5Kbytes from
 * boot sector of file system and sets it up to run.
 */
        .set    RELOC,0x50000
        .set    BOOTLAST,15             /* last boot sector */
        .set    RABPSECT,512            /* bytes per sector */

init:
        .word   0                       /* entry mask for dec monitor */
        nop;nop;nop;nop;nop;nop;nop;nop /* some no-ops for 750 boot to skip */
        nop;nop;
start:
        movl    r1,r7                   /* UNIBUS I/O page address */
        movl    r2,r8                   /* boot device CSR */
        movl    r3,r9                   /* unit number */
        movl    r5,r11                  /* boot flags */
        movl    $RELOC,sp
        moval   init,r10
        movc3   $end,(r10),(sp)
        movl    r7,r1                   /* UNIBUS I/O page address */
        movl    r8,r2                   /* boot device CSR */
        movl    r9,r3                   /* unit number */
        jmp     *$RELOC+start2
/* now running relocated */
/* bring in the boot program */
start2:                                 /* running relocated */
        pushr   $0xffff                 /* BEGIN FIREWALL */
        movl    $1,r4                   /* first boot sector */
        clrl    r5                      /* transfer address */
        clrl    -(sp)                   /* transfer address */
1:
        movl    r4,r8                   /* requested sector # */
        jsb     (r6)                    /* call ROM-based driver */
        blbs    r0,2f
        halt                            /* read error */
2:
        addl2   $RABPSECT,r5            /* bump address */
        movl    r5,(sp)
        aobleq  $BOOTLAST,r4,1b

        .set    PROGSIZE,((BOOTLAST-1)*RABPSECT)
done:
        tstl    (sp)+                   /* pop address */
        popr    $0xffff                 /* END FIREWALL */
        movl    $PROGSIZE,r3
clrcor:
        clrq    (r3)
        acbl    $RELOC,$8,r3,clrcor
/* start loaded program */
        movl    $9,r10                  /* major("/dev/ra0a") */
        calls   $0,*$0
        brw     start2
end: