In this release, corresponding to "pfdisk v 1.3.1", "bootmenu.asm"
and "bootauto.asm" have been trivially modified, to work correctly
with the modified (foreshortened) partition name table, see "pfdisk.2".

Nore important, a new boot program, "bootactv.asm", is included.  This
works very similar to "bootauto.asm", but:

(1)  If there are multiple active fdisk partitions, the last such
is the one booted by default (i.e., after waiting over five seconds
and not hitting any key at the "Boot device: hd0" prompt).  With
"bootauto", the first such is the one booted by default.

(2)  More important, "bootactv" makes some changes to the copy of
the fdisk table in RAM, after the partition to be booted has been
chosen (either from the menu or by timing out).  As with "bootauto",
the partition to be booted is turned active (in the copy of the fdisk
table in RAM).  Unlike "bootauto", all other fdisk partitions are
rendered inactive (in RAM).  Also, all fdisk partitions, other than
the one to be booted, are rendered invalid, by changing their
sysids to decimal 98.  Exception:  ordinary DOS fdisk partitions
(12 bit FAT or 16 bit FAT -- i.e., sysids 1 or 4), do not have
their sysids changed in RAM.  (This is because some versions of
Unix or whatnot may want to mount or access these partitions, and
may have difficulty if the sysids are invalid in RAM).

As with Gordon Ross's original "bootmenu" and "bootauto", THE FDISK
TABLE ON DISK (and all the rest of the boot sector) ARE LEFT
UNCHANGED.  This makes rebooting "safe", since you are not
automatically tampering with your boot sector on every reboot
(unlike some other pd multiple boot programs).

The reason for the extra fiddling with the fdisk table in RAM:
For some fdisk combinations, "bootauto" and "bootmenu", simply
don't work.  E.g., this is so on my system, where I have three
fdisk partitions, containing DOS, ISC Unix SVR3.2.2.1 and ISC
SVR4.0.3.  "booactv" works fine.  However, I have to make
BOTH Unix partitions active in the fdisk tabe on disk.  This
is because most versions of Unix System V/386 also check the
fdisk table on disk, to make sure the the fdisk partition
containing the OS is active, even on disk.  To accomplish this,
the enclosed version of "pfdisk" allows setting multiple active
fdisk partitions (e.g., with a pfdisk command like "a 2 3").

See pfdisk.2

		Oct. 20, 1991
		Saul Lubkin
		lubkin@cs.rochester.edu

