Difference between ISL and IPL

[Mihails Nikitins]

Hi,

Can anyone explain me the difference between Initial Program Loader (IPL) and Initial System Loader (IPL)? From some docs I see it's the same thing, some docs seem to mention difference.

Points in advance!

BR,
Mihails

[Kent Ostby]

Mihails --

A brief explanation.

IPL stands for "Initial Primary Loader"

ISL stands for "Initial Secondary Loader"

Essentially IPL finds ISL on the boot disk and calls it or at least that is how I have always thought about it.

In usage, they tend to be fixed in the same way. An error related to IPL/ISL usually means that the boot area on the disk (bootlif) has gotten messed up.

In some cases it is a hardware problem.

The most common places where you will see these referenced is during boot time.

I often use:

boot primary isl

then answer "Y" to "Interact with ipl"

You can on most systems I've seen also type:

boot primary ipl

and get to the same dialogue.

Best regards,

Kent M. Ostby

[GK_5]

IPL is Initial Program Loader.
ISL is Initial System Loader.

You have to interact with IPL to go to ISL prompt. At ISL prompt you can change boot parameters, or boot in single user or from alternate disk.

[Donny Jekels · Accepted solution]

IPL is the firmware loaded in eprom, on the motherboard.

ISL is loaded by IPL from the bootlif area.

/usr/sbin/diag/lif/updatediaglif is the ISL

one more thing

/usr/sbin/diag/lif/updatediaglif2 is for 64 bit mode
and
/usr/sbin/diag/lif/updatediaglif is 32 bit.


setboot coomand works on the IPL.

do a #setboot

# setboot
Primary bootpath : 8/4.11.0
Alternate bootpath : 8/4.4.0

Autoboot is ON (enabled)
Autosearch is ON (enabled)
#

this info is read from prom.


hope it helps, and if I am totally off then please let me know.

P->prom
S->software

peace

[Stan Sieler]

Close...

As a quick search of docs.hp.com will show,
IPL = Initial Program Loader and
ISL = Initial System Loader

However, they're sometimes the same thing :)

Here's a great document that defines the
terms:
http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/mpeix/onlinedocs/32650-90908/32650-90908_top.html&con=/mpeix/onlinedocs/32650-90908/00/00/98-con.html&toc=/mpeix/onlinedocs/32650-90908/00/00/98-toc.html&searchterms=PDC&queryid=20030815-115353

It says:

IPL Initial program load is the first code brought into the system and executed from outside the SPU. This code is loaded by the bootstrap code.

ISL Initial system load is a standard code module that is used during the startup of any operating system to provide a standard user interface for booting. On some systems, this code may be the IPL, while on others, IPL may perform some preliminary tasks and then proceed to load the ISL.

On HP-UX machines, ISL is the IPL,
and on MPE/iX machines, MMSAVE is the IPL,
and MMSAVE then loads/launches ISL.

You can see the ISL on your boot disk on
HP-UX:

lifls -l /dev/rdsk/c1t15d0

volume ISL10 data size 7984 directory size 8
filename type start size implement created
===============================================================
...
HPUX -12928 3952 848 0 02/05/10 16:25:44
ISL -12800 4800 306 0 00/11/08 20:49:59
...

Note the type column ... -12800 is "spectrum IPL". (-12928 is "HP-UX kernel")


Here's a portion of the LIF directory on
an MPE/iX system:

:run lifutil

LIFUTIL 20021121 Copyright (c) 2000 Allegro Consultants, Inc.
...

File# LIF File File Type Address Length Vol Created
----- --------- -------------------- ------- ------ --- -----------------
0 MMSAVE spectrum_ipl $30 $60 1 02/09/06 15:09:34
1 ISL spectrum_boot $65ef0 $f0 1 00/09/08 14:34:29
2 START spectrum_boot $4b6460 $7ca8 1 02/09/06 17:02:31 = 30
3 DISCUTIL spectrum_boot $38f8c0 $5598 1 02/09/06 15:09:15
...

("spectrum_ipl" is -12800, "spectrum_boot"
is -12864)

BTW, many people/documents (including some at/from HP), frequently confuse/conflate the two terms.

[Stan Sieler]

Sorry...I forgot that the darn ITRC forum
page wouldn't display in fixed font (as
the *input* displays on my PC :)

Also, my quote from the HP doc was unclear
as to the extent...just the two paragraphs
immediately after "It says" are from the doc,
the rest is from me :)

So...if you want to see the "lifls" or
"lifutil" output better, cut/paste it into
an editor and display it in fixed font.

[Stan Sieler]

(test)

is  this   fixed font?  (I tried entering HTML)

[Stan Sieler]

Argh! The @!#$%^ ITRC forum code is
stripping all multiple blanks out!
(and, although I don't mind, not allowing
user-entered HTML)

The phrase "disgruntled ITRC user" is redundant!

[Stan Sieler]

Ok...my last post on this thread, really! :)

The blanks are there ... they just don't
cut/paste properly (submit bug reports to
your favorite browser vendor, not HP ITRC).

You can see the lifls / lifutil (and other
ITRC posts with mangled column displays)
correctly by doing a "view source" with
your browser.