How does the first stage of LILO locate the second stage?



First stage
===========
It's located in the 446 bytes of the MBR.


Second stage
============
It's located in a file usually named /boot/boot.b.



How does the first stage find the second stage?
===============================================
The physical disk location of "boot.b" is stored in an embedded variable within the first stage.

There's something about a "map file" that is included in the MBR too...  I don't understand this part.



Source code
===========

- first.S is stage 1, and second.S is stage 2

- first.S has these embedded variables:

        raid:   .long   0               ! raid sector offset
        tstamp: .long   0               ! timestamp
        map_serial_no:  .long   0       ! volume S/N containing map file
        prompt: .word   0               ! indicates whether to always enter prompt
                                        ! contains many other flags, too

        d_dev:  .byte   0x80            ! map file device code
        d_flag: .byte   0               ! disk addressing flags
        d_addr: .long   0               ! disk addr of second stage index sector






References
==========

http://giraffe-data.com/~bryanh/giraffehome/d/note/lilo
http://snow.nl/dist/xhtmlc/ch14s03.html
http://linux-sxs.org/administration/liloexpl2.html