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

/*
**      @(#)rdboot.c    7.1 (Berkeley) %G%
*/

/*
** This is a VMB boot block for microvax.  For more info, see
** the KA-630 User's manual.
*/

/*
**          ---------------------------------------------------
** BB + 0: |      1     |      N     |      any value          |
**          ---------------------------------------------------
*/
xxx:    .long   0x001040000
/*
**          ---------------------------------------------------
**      4: |        low  lbn         |      high lbn           |
**          ---------------------------------------------------
*/
        .long   0x000010000
/*
** BB + 2*N
**          ---------------------------------------------------
**    + 0: | check byte |      K     |     0     |   18 (HEX)  |
**          ---------------------------------------------------
*/
        .long   0x0e7000018
/*
**          ---------------------------------------------------
**    + 4: |     any  value          |  1 or 81  |      0      |
**          ---------------------------------------------------
*/
        .long   0x000008100
/*
**          ---------------------------------------------------
**    + 8: |     size in blocks of the image                   |
**          ---------------------------------------------------
*/
        .long   0x00000000f
/*
**          ---------------------------------------------------
**    +12: |     load offset from default load address         |
**          ---------------------------------------------------
*/
        .long   0x000000000
/*
**          ---------------------------------------------------
**    +16: |     offset into image to start execution          |
**          ---------------------------------------------------
*/
        .long   0x000000002
/*
**          ---------------------------------------------------
**    +20: |     sum of previous three longwords               |
**          ---------------------------------------------------
*/
        .long   0x000000011
/*
**
** BB +0:       These two bytes can have any value
**
** BB+2:        This value is the word offset from the start of the
**              bootblock to the identification area described below.
**
** BB+3:        This byte must be one.
**
** BB+4:        This longword contains the logical block number
**              (word swapped) of the secondary image.
**
** BB+(2*n)+0:  This byte defines the expected instruction set.
**              18(hex) means VAX.
**
** BB+(2*n)+1:  This byte defines the expected controller type, 0
**              means unknown.
**
** BB+(2*n)+2:  This byte defines the file structure on the volume,
**              it may be any value.
**
** BB+(2*n)+3:  This byte must be the ones complement of the sum of
**              the previous three bytes.
**
** BB+(2*n)+4:  This byte must be zero.
**
** BB+(2*n)+5:  This byte must be 1 or 81 (hex).  This byte defines
**              the version number of the format standard and the
**              type of disk.  The version is one, the high bit is 0
**              for single sided, 1 for double sided.
**
** BB+(2*n)+6:  These two bytes may be any value, but generally they
**              are zero.
**
** BB+(2*n)+8:  This entry is a longword containing the size in
**              blocks of the secondary bootstrap image.
**
** BB+(2*n)+12: This entry is a longword containing a load offset
**              (usually zero) from the default load address of the
**              secondary bootstrap.
**
** BB+(2*n)+16: This entry is a longword containing the byte offset
**              into the secondary bootstrap where execution is to
**              begin.
**
** BB+(2*n)+20: This entry is a longword containing the sum of the
**              previous three longwords.
*/