GY28-6661-5 Inital Program Loader and Nucleus Initialization Program Rel21 PLM Mar72

8/20/2019 GY28-6661-5 Inital Program Loader and Nucleus Initialization Program Rel21 PLM Mar72

1/87

File No 5360-36

GY28-6661-5

Program

Logic

OS Release 2

IBM

System 3S0

Operating System

Initial Program Loader and

Nucleus Initialization Program

Program Number 360S CI 535

This publication presents the

interna l

logic

of the

IBM

System/360

Operating

System

In i t ia l

Program

Loader

and Nucleus In i t ia l iza t ion

Program.

The operation of

the

Nucleus In i t ia l iza t ion Program in

each of the

con

t ro l program environments MFT,

MVT)

i s

described in

the

sect ion

dealing with the Nucleus In i t ia l iza t ion

Program. Special in i t ia l iza t ion procedures

for VT

with

Model 65

multiprocessing

systems are

included in

Appendix A.

The

~ a b l e s work

areas

and

control

blocks

are i l lus t ra ted in

the publicat ion

as well as flowcharts

i l lus t ra t ing the logic flow of

the

In i t ia l Program Loader

and the Nucleus In i t ia l iza t ion

Program.

This program logic manual

i s directed to

personnel

responsible for program maintenance. I t can be used to

locate

specif ic areas of the program and

t enables

the reader to

r e la te

these areas to the corresponding

program

l i s t ings

Program

logic

information

i s

not

necessary for program operation and

use.


2/87

Sixth

Edi t ion

March, 1972)

This i s

a major revis ion

of,

and makes

obsolete,

GY28

6661-q and i t s

associated

TNL

GN27-1353. This

edit ion

applies to

Release

21 of

the System/360 Operating

Sys

tem and to a l l

subsequent

re leases unt i l

otherwise

indicated n new edi t ions or Technical

Newslet ters .

A

change

i s

indicated by a ver t ica l l ine to the

l e f t

of

the

change. Changes are cont inual ly being

made

to the

specif ications herein; before using

th is

publ icat ion in

connection with the operat ion of

I M

systems,

consul t

the l a t es t

System/360 SRL

Newsletter, GN20-0360,

for

the edit ions

tha t

are

appl icable and

current .

This

publicat ion was

prepared

for

production using an

I M

update the t ext

and

to control the

page

and l i ne

format.

s ions for photo-offset print ing were

obtained

from

an

I M

using

a special print t ra in .

computer

to

Page

impres-

1Q03

Pr in ter

Copies of th is and other

I M

publ icat ions can be

obtained through

I M

branch off ices .

A

form

for

reader s comments appears

a t the

back

of th is

publ icat ion.

Address any

addit ional

comments concerning the

contents of th is publ ica

t ion to

I M

Corporation,

programming Publicat ions,

Department

636

Neighborhood

Road, Kingston,

New York 12401

Copyright

International

Business

Machines Corporation 1970,1971,1972


3/87

This

publ ica t ion descr ibes

t he

in te rna l

l og ic

and theory of opera t ion

of

the In i -

ti l Program Loader, which br ings in the

programs which become the cont rol

program

nucleus,

and

the Nucleus I n i t i a l i z a t i o n

Program, which prepares those

programs

and

the balance

o f main

s to rage

for

operat ion

of the

con t ro l

program.

The publ ica t ion

cons i s t s

of

e igh t major

sec t ions .

The In t roduct ion p resen t s an

overview of the purpose and

funct ions of

the programs

and in t roduces

t he

major

topics presen ted in the manual. The sec-

t ion ,

I n i t i a l

Program

Loader presen t s a

de ta i l ed discuss ion of t h a t

program s

opera t ion ,

inc lud ing the use of t ab les ,

work areas ,

and

cont rol blocks .

The

address resolut ion procedure

i s

descr ibed

in

d e t a i l as

an adjunct to the l i s t i n g s

o f

the

program.

The

Nucleus I n i t i a l i z a t i o n

Program

sec t ion d i scusses

the operat ion

o f

t ha t

program

and emphasizes the d i f fe rences

t ha t ex i s t for

the d i f f e r e n t

conf igura t ions

o f

t he

con t ro l program. The Routine

L is t s

sec t ion

presen t s a

summary o f each of t he

major IPL and NIP rout ines . The sec t ion

Tables and Work Areas conta ins

i l l u s t r a -

t ions of the t ab les ,

work

areas ,

and

con

t r o l blocks used

by

the

programs o r

i n i -

t i a l i z e d

by the programs. The Flowcharts

sec t ion conta ins cha r t s t h a t diagram the

l og ic f low

o f

the

I n i t i a l Program Loader

and

t he


Program.

Appendix

A:

I n i t i a l i z a t i o n

for MVT with

Model

65

Mult iprocess ing

descr ibes

the

spe-

c i a l i n i t i a l i z a t i o n procedures for the

Model 65

Mult iprocess ing System. Appendix

B:

NIP Inte r face Routine

describes

the

spec ia l

processing necessary to maintain

cor r ec t base addresses

when

NIP uses

subrout ines .

Throughout t h i s publ ica t ion,

re ferences

to con t ro l

program

conf igura t ions a re s imp

l i f i e d by

the use

o f

abbrev ia t ions . When

PREFACE

used in the publ ica t ion, MFT

r e f e r s

to sys -

tems

capable

of multiprogramming with a

f ixed number

o f

t asks ,

and MVT

r e f e r s to

systems capable o f multiprogramming

with a

var iable number of

t a sks .

MVT with Model

65 mult iprocess ing i s not abbrev ia ted in

t h i s publ ica t ion . An appendix

i s

devoted

to a

de ta i l ed

discuss ion

o f

MVT

with Model

65 mult ip rocess ing .

The

r eader o f

t h i s

publ ica t ion should

have a

knowledge of the assembler language

fo r

System/360

and should be

f ami l i a r

with

the

fol lowing

publ ica t ions :

I M

System/360:

pr inc ip l e s

of

Opera

t i on ,

GA22-6821

I M System/360

Operat ing

System:

Int roduct ion,

GC28-6534

Assembler

Language, GC28-6524

MFT Guide, GC27-6939

MVT Guide,

GC28-6720

In

add i t ion , in format ion con ta ined

in

other pub l ica t ions may prove helpful to

understanding

these

programs. These

publ i -

ca t ions

are :

I M

System/360 operat ing

System:

Data

Management

Macro Ins t ruc t ions ,

GC26-3794

Data Management Serv ices Guide,

GC26-3746

Messages and

Codes,

GC28-6631

Opera to r s Reference,

GC28-6691

Programmer s

Guide

to Debugging,

GC28-6670

Serv ice Aids, GC28-6719

Storage

Est imates , GC28-6551

System Control Blocks, GC28-6628

system

Generat ion,

GC28-6554

MFT

superv i sor PLM

GY27-7236

MVT superv i sor PLM GY28-6659


4/87

SUMMARY

OF

AMENDMENTS

Release 2

•

Status Display support

• In i t ia l iza t ion for

the

Generalized Trace aci l i ty

• Relocation of the IPL

program

• Channel

Check

and

Machine Check

Handler

support for

the

System/370

Model 135

•

Operator

Procedures

for loading an

al ternat ive

nucleus

or l imit ing

apparent storage s ize for System/370

machines

Release 20.1

• Time Sharing

Option

• Channel

Check and Machine Check Handler

support for the

System/370

Model

145

Release 20

•

Extended

Precision

Floating Point

Divide

• In i t ia l iza t ion procedures for

the

Block

Multiplexor

channel

•

Locat ing

formatting and i n i t i a l i z ing

the SYS1 DUMP

data se t

v


5/87

INTRODUCTION • • • • • • •

The

I n i t i a l

Program Loader • • • • •

The Nucleus


program

L is t s o f

Rout ines

• •

Tables and Work Areas

• • • • • • •

Flowcharts • • • • • • • • • • • •

CONTENTS

Appendix A: I n i t i a l i z a t i o n fo r

MVT wi th

Appendix B: NIP I n t e r f ace Routine

•

Model 65

Multiprocessing

1

1

1

1

1

2

2

2

THE INITIAL PROGRAM

LOADER

• • • • • • • • • •

3

3

4

4

5

5

5

6

6

6

8

8

8

Loading t h e IPL Program • • • • • • • • • • • • •

Determining t h e

Nucleus • • • • • • •

Clear ing Storage

and

Determining ts Size

• •

Ind ica t ing Size

of Main

Storage • • • •

Finding

t he

Selec ted Nucleus • • • •

Assigning Nucleus

Control

Sect ion

Addresses

Calcu la t ing t he Addresses

• • •

Calcu l a t i n g t h e Relocat ion Factor s

IPL Program Relocat ion • • • • • • •

Loading

t h e

Nucleus

Cont ro l

Sect ions

Replacing

Nucleus Address

Constants

•

Giving Control to t h e


Program

THE NUCLEUS

INITIALIZATION

PROGRAM • • • • • • • • •

Nucleus

Table I n i t i a l i z a t i o n

• • • • • • • • •

I n i t i a l i z i n g t he

Communications

Vector Table

Poin ter

Establ ishing

t he Trace

Table Address Optional : MVT)

Building

t he Dummy

TCB

Table

MFT With Subtasking)

Test ing fo r Extended Prec i s ion

Float ing Po in t Simula t ion

Determining

Size

o f

IBM 2361

Core Storage

Optional :

MFT,

Determining

Console

Readiness

MFT,

MVT

without

MCS)

• • • • • 11

· • 11

. . . • 11

• • 12

•

12

• •

12

MVT) •• 12

• •

12

•

13

Determining the Master Console in a

System

with M ul t ip le

Console

Suppor t Optional :

MFT, MVT)

I n i t i a l i z i n g

Trans ien t Display

Control

Modules

Mul t ip le Console

Support

with

Display Consoles only)

• •

•

13

13

14

• • 14

14

I n i t i a l i z i n g Ready

Direc t

Access UCBS

• • • • • • • • •

I n i t i a l i z i n g t h e System

Residence

UCB • • • •

Crea t ing

and I n i t i a l i z i n g Data Extent Blocks

General System I n i t i a l i z a t i o n

• •

Checking

The Timer

OPTIONAL) • • • • • • • •

Defining

Control Program Areas • . . • • • • • •

I n i t i a l i z i n g t h e

SVC

Table MVT;

Optional : MFT)

Creat ing and


Linkage

Library

DEB.

• • • • • •

16

16

17

•

17

Locat ing, Format t ing,

and


SYS1.DUMP Data

Se t

•

20

Determining User

Options Optional)

• • • • • • • • • •

• • 21

I n i t i a l i z i n g Optional

Control

Program Funct ions

•

22

• 22

• • • • 22

Emulator Warning Message • • • • • • . • • • • • • • • • •


t h e

Parameter Library •• • • • • • • • •

Bui ld ing

the LINKLIB

Lis t PCP,

MFT,

MVT)

•

• • • • • •

23

I n i t i a l i z i n g fo r Genera l ized Trace

F a c i l i t y

•

Estab l i sh ing Block Multiplexer Channel Capabi l i ty •

Building

t he

TCB

Address

Table

MFT) • • • •

Recovery

Management I n i t i a l i z a t i o n

• • • • •

Rebui lding t he System

Queue

Area • • • • • • • • •


fo r Time-Sl ic ing Opt ional )

Allocat ing , Opening,

and Format t ing the Rollout Data

Se t

Optional : MVT

• •

23

• • 23

• •

23

• • 24

• • •

24

• • 24

• 25

I n i t i a l i z a t i o n fo r Machine-Check Handler , Model 65

I n i t i a l i z a t i o n fo r Machine-Check Handler , System/360

Model 85

and

•

27

System/370

I n i t i a l i z a t i o n fo r the

Channel-Check

Handler

Loading Optional Error Recovery

Procedure

Modules • • • • • •

•

27

• •

28

•

30


6/87

I n i t i a l i z a t i o n fo r Dynamic

Device

Reconf igura t ion

SYSRES Support • 30

Rese t t ing Main

Storage D iv is ions

• • • • • • •

32

Expanding t he System Queue Area

Optional)

• • • • •

32

Reloca t ing NIP MVT) •••• • • • • • • • 32

cons t ruc t ing the

Link Pack Area MVT) • • . • • • • • •

32

cons t ruc t ing t h e Resident

Reente rab le Module

Area Optional:

MFT)

•

32

Cons t ruc t ing

t h e Resident BLDL L i s t Optional) • • • 33

Loading the Link Pack Area Modules

MVT)

• • • • • • • • • • • • • 33

Loading t h e Resident Reenterable Module Area Modules Optional :

MFT)

• • • • • • • • • • • • • • • • • • •

IGFMCHFO

Process ing

- -

Stage 2

• • • •

• • . . • • • • • • • •

35

35

Loading Optional Resident Routines MFT) • • • • • • •

• 35

Prepar ing Main

Storage When t h e System Conta ins

Main

Storage

Hierarchy

Support

fo r

IBM

2361 Core Storage MFT) • • • •

35

36

repar ing Main Storage MFT) •••• •••••••

Prepar ing

Main Storage MVT) • • • • • • • • • • • • • •

Estab l i sh ing t h e Final

Master

Scheduler

Region

MVT)

Defin ing

the

Dynamic Area MVT) • • • . • • • • • •

Verifying Hard Copy Requirements fo r MCS Optional) .

Estab l i sh ing

Hard

Copy Output capab i l i ty Optiona l )

NIP

Termina t ion

MFT) •

NIP Terminat ion MVT) •

LISTS

OF

ROUTINES • •

I n i t i a l Program Loader Program Control Sect ion

Nucleus I n i t i a l i z a t i o n Program Control

ect ion

TABLES

AND

WORK

AREAS

• • • •

Scat ter / l r ans la t ion Record

Cont ro l

Record • • • • • •

Relocat ion Dict ionary RLD) Record

Cont ro l

and Reloca t ion Dict ionary Record

Sca t t e r Extent L is t • • • • • •

FLOWCHARTS

APPENDIX A:

INITIALIZATION

FOR MVT WITH

MODEL

65 MULTIPROCESSING

Preliminary I n i t i a l i z a t i o n

a t

Entry to NIP

Checking t he F i r s t Main Storage

Unit

• 36

36

• 37

37

37

37

•

38

39

39

39

41

• 41

• •

42

•

43

44

•

45

• • 46

62

• • • 62

62

Temporary

Pref ixed Storage Area I n i t i a l i z a t i o n • • • • • •

• • 62

62

nit

Control Block I n i t i a l i z a t i o n • • • • • • • • • • • •


Channel

A v ai l ab i l i t y Table


Direc t

Access Device UCBs


Non-Direct

Access Device

UCBs

Pre f ixed

Storage

Area PSA) I n i t i a l i z a t i o n

I n i t i a l i z i n g t h e CPU Sta tus Byte CPUSTAT)

I n i t i a l i z i n g t h e Storage Element Sta tus Map FSSEMAP) •

I n i t i a l i z i n g t h e Pref ix PREFIX2) • •

I n i t i a l i z i n g t h e External

and Machine

New PSWs

Construct ing t h e Second PSA • • • . • •

I n i t i a l i z i n g t h e TCB Poin ter IEATCBP) • • • • •

I n i t i a l i z i n g the PTRIGGER Fie ld • • • • • • • •

I n i t i a l i z i n g t h e Timer Pref ix Fie ld PREFTMRA) ••••

I n i t i a l i z i n g t h e CPU Id en t i f i ca t i o n Bytes • •

I n i t i a l i z i n g t h e Console Id en t i f i ca t i o n Bytes CONSOLID)

I n i t i a l i z i n g the

Channel

A v ai l ab i l i t y Table • • • • • •

Defining

Main Storage

• • • • • • • • . • • • • • • • • •

Determining Unavai lab le Main Storage • • • •

Defining the Free Area

•••

• • • • • • • • • •

Final

ain

Storage

Prepara t ion

• • • •

Second CPU I n i t i a l i z a t i o n • . • .

I n i t i a l i z i n g t h e Channel A v ai l ab i l i t y Table • • • • • •

I n i t i a l i z i n g the Timer • . • • • • • •

Determining

Device

Avai lab i l i ty

• • • •

I n i t i a l i z i n g the TCB Poin ter IEATCBP)

Checking fo r Error Condit ions

NIP Termina t ion • • • • • • . • •

APPENDIX B:

NIP

INTERFACE ROUTINE

INDEX

v i

•

64

65

• • •

65

• • 65

• •

65

• • 67

• •

67

• • • 67

67

67

• 67

• 67

•

68

68

68

68

68

• • • 68

• •

68

•

70

70

• • 70

70

• • 72

• • 72

72

• • 73

· 74


7/87

ILLUSTRATIONS

Figure 1

Wait

St a t e

Error

Codes

• • • • • • • • •

Figure 2. Main

Storage

Layout

Before

IPL Relocat ion •

Figure 3. Main Storage

After IPL Relocat ion • • • •

Figure

4.

Read

Command

Modif icat ions

l

• • 7

7

• • 8

Figure 5. Main

Storage

After Loading F i r s t

Three

Sect ions

Figure 6 . Main

Storage

a t

IPL Terminat ion

9

9

Figure

7.

Regis te r Contents a t

IPL

Terminat ion

Figure

8. Data Extent

Block


Figure 9. Timer Tes t BCT Loop Values

Figure 10.

Nucleus

Dummy Buffer S ize

Figure 11.

Defining Control

Program

Areas

in a System

Without

IBM

2361 Core Storage

MVT) • • • • • • • • • • • • • • • • • •

Figure 12. Defining Cont ro l Program

Areas

in

a

System

With IBM

2361 core Storage MVT)

• • • • • • • • • • • • • • • • • • • •

Fig u r e 13. Defining Control Program Areas

MFT)

Figure 14.

Main Storage

in an

MFT

System After Rebui lding

t he

•

10

• •

15

16

• •

16

18

•

19

20

System

Queue Area

• • • • • • • • • • • • • • • • • • • • • • •

25

Figure 15. Main

Storage

i n an VT sys tem

After

Rebui lding

t h e

System

Queue Area

• • • • • • • • • • • • • • • • • • •

26

Figure

16.

Loading

t h e MCH

Resident

Nucleus

• • • • • •

28

Figure 17.

MCH

Nucleus a t

Conclus ion o f

IGFMCHFO

Stage

1

Process ing 29

Figure

18.

Communications

Scheme

After I n i t i a l i z a t i o n

31

Figure 19. MFT Main Storage A f t e r Resident

BLDL

Li s t cons t ruc t ion

•

34

Figure 20.

MVT

Main Storage A f t e r Resident

BLDL

Cons t ruc t ion 34

Figure 21. MFT

Boundary Box

and Extension fo r

Main

Storage

Hierarchy

Suppor t

• • • • • • • • • • • • • • • • • • • •

•

36

Figure

22.

Fina l MVT Main s t o rag e

• •

36

Figure 23. Shared

Subpool 0 SPQEs

MVT)

Figure 24. Final MFT Main Storage

• • • • •

• • • • •

7

•

38

Figure 25. Main

Storage

After

Mul t ip rocess ing NIP Module Has

Been

Loaded 6

Figure 26.

Channel

Ava i l ab i l i t y

Table At

System

Genera t ion

• •

64

Figure 27.

MVT

with

Model 65 Mul t ip rocess ing

Addit ion to UCB

•

64

Figure 28.

Main

Storage After the Second

PSA

Has Been

Establ ished

•

66

Figure 29.

Main Storage

After Free Area

Has Been

Estab l i shed

69

Figure

30.

Fina l

Main

Storage

Layout

MVT

with

Model

65

Mult ipxocessing)

• • • •

Figure 31.

NIP I n t e r f ace Rout ine

7

73

Chart

AA. I n i t i a l Program

Loader

Control

Flow • • • • • • •

47

Chart AB. Nucleus


Program Control Flow • • • • • • •

48

Chart

AC. Timer


• • • • • • • • • • • • •

49

Chart

AD.

Superv i sor Cal l

SVC)

Table

I n i t i a l i z a t i o n • • • • • • • •

50

Chart

AE.

Machine-Check Handler I n i t i a l i z a t i o n

Model

65) 51

Chart AF.

CCH

I n i t i a l i z a t i o n Rout ine • • • • • • 52

Chart AG.

C C H P G M C K

• • • • • • • • • • • •

53

Chart

AB.

CCH

Move

Module

• • • • • • • • • • • •

54

Chart AI. I n i t i a l i z a t i o n

f o r

Rol lou t /Rol l in

• • • •

55

Chart

AJ. MVT

with

Model

65

Mul t ip rocess ing


56

Chart

AK.

MVT

with

Model 65

Mult iprocess ing

Second

CPU


• • • • • • • • • • • • •

58

Char t AL. I n i t i a l i z a t i o n fo r

SYS1.DUMP

Data se t

• • • •

59

v


8/87


9/87

For t he IBM System/360 Operat ing

System

to

func t ion

i n a computing system, t h e pro-

grams and t he i r assoc ia ted con t r o l blocks

and

work

areas

must be

loaded

in to

main

s to rage and prepared for opera t ion .

Loading t h e con t r o l program modules

i s

the

fUnct ion

o f t he I n i t i a l

Program

Loader,

re fe r red to

as

t he

IPL program.

After the IPL program completes t h e

loading fUnct ion, con t ro l i s passed

to

t h e


Program,

r e f e r r ed t o

as NIP, which

performs

t he funct ions neces-

sary to

i n i t i a t e

opera t ion o f the con t ro l

program.

NIP

a l so loads and i n i t i a l i z e s

opt iona l rou t ines

se l ec t ed by t h e

user .

This publ ica t ion

i s

a

guide

to t h e pro-

gram

l i s t i n g s

o f

IPL and

NIP.

Where

poss-

i b l e

the o rgan iza t ion o f t h e manual fo l -

lows

t he log ica l f low

of

t h e programs

d i s -

cussed and

t he

top ic s appear in t he order

o f t h e i r appearance

in

the program

l st-

ings . Unless otherwise ind ica ted IPL/NIP

processing

i s common

to

both MFT

and

MVT.

Only t h a t

processing

t h a t

i s

unique to one

o r t he o the r or processing

t h a t

i s opt ion-

a l

i s

noted

as

such.

This

s ec t i o n provides

an

overview and genera l

discuss ion of

the

o ther

s ec t i o n s in t he manual . D eta i l ed

informat ion

on

each rou t ine

can

be

found

in

the appropr ia te sec t ion .

THE INITIAL

PROGRAM LOADER

The I n i t i a l Program Loader (IPL) c lea r s

main s t o rag e determines main s to rage s i z e

re loca tes i t s own

i ns t r uc t ions

reads in

the se lec ted con t ro l program nucleus

and

r eso lves address cons tan t s .

When

IPL

has

completed i t s

opera t ions

co n t ro l i s t r a n s -

f e r r ed to the Nucleus I n i t i a l i z a t i o n Pro-

gram. IPL funct ions in the same manner

f o r

both

con t ro l program conf igura t ions ; the

con t ro l program nucleus

which

IPL

loads

governs t h e opt ion

of

the opera t ing system.

The sec t ion The

I n i t i a l

Program

Loader

descr ibes

the

IPL

fUnctions

in

d e t a i l

and

i s

div ided

i n to the fol lowing t op ic s :

• Loading t h e

IPL Program

•

Determining

t h e

Nucleus

•

Clear ing

Storage and Determining

ts

Size

• Finding t h e Selec ted Nucleus

INTRODUCTION

• Assigning Nucleus Control Sec t io n

Addresses

•

IPL

Program

Relocat ion

•

Loading

t h e Nucleus Cont ro l Sec t io n

• Replacing

Nucleus

Address Constants

• Giving

Contro l to the

Nucleus I n i t i a l -

i za t ion Program

THE NUCLEUS INITIALIZATION PROGRAM

The

Nucleus I n i t i a l i z a t i o n Program (NIP)

prepares the co n t ro l program fo r

opera t ion

by

def in ing main s to rage areas

and

i n i t i a l -

i z ing cer ta in t ab les work areas and con-

t r o l

blocks.

These

NIP

funct ions

vary

according to the con t ro l program opt ion

MFT o r MVT , so

t h a t

NIP code fo r an

MVT

system wi l l

conta in rou t ines t h a t do not

appear in

NIP

code fo r an MFT

system.

These

d i f f e r en ces r e su l t from

s e l e c t i v e

process ing o f t he NIP macro

i ns t r uc t ion

dur ing

system genera t ion .

According

to the

system being generated program

swi tches

a re se t which

cause

sec t ions o f

coding to

be

included

in

or de le ted

from, t he NIP

load module produced by

system

genera t ion .

NIP a l so loads and i n i t i a l i z e s o p t i o n a l

rou t ines se l ec t ed

by opera to r command a t

system

i n i t i a l i z a t i o n .

The

NIP sec t ion o f

t h i s

publ ica t ion

i s

organized

in

the o rder of

appearance

o f

rou t ines in t he NIP

macro.

Each rout ine i s

i d e n t i f i e d with the opt ion

o r

opt ions o f

the con t ro l program

in

which

t

i s

included;

f o r example, t h e NIP

Relocat ion

rout ine appears only in

NIP

fo r an MVT

system.

LISTS

OF

ROUTINES

This

s ec t i o n l i s t s

the

IPL and NIP

rou-

t i n e s

by

t h e i r

en t ry

po in t names and gives

a br ie f synops is of

the

rou t ine func t ion

including the t a b l e s work a reas

and con-

t r o l

blocks used

by

the

rou t ine . In

cases

where

a ro u t i n e

i s

embedded

with in

another

rout ine

and

does not

have

a s p e c i f i c en t ry

po in t

name,

the

n ea re s t

en t ry po in t

i s

given in paren theses .

TABLES AND WORK AREAS

This sec t ion

presen t s i l l u s t r a t i o n s

of

t h e t a b l e s work areas con t ro l blocks and

In t roduct ion

1


10/87

record formats r e fe r red to i n t h i s publ ica

t ion .

Many o f

t he con t r o l

blocks used by

IPL

and NIP

are s tandard

system con t ro l

blocks

and

can be found

in

other

pub l ica

t ions . For the convenience o f

the

read e r

however

they

a re

inc luded

i n t h i s

sec t ion .

FLOWCHARTS

This

sec t ion

contains

t he log ic

f low-

char t s for

IPL

and NIP. The char ts a re

arranged to fo l low

t he

same order as the

presen ta t ion

of the top ic

or funct ion

the

char t

represen t s .

Char ts for

MVT with

Model 65 mult ip rocess ing

are

included.

APPENDIX A:

INITIALIZATION

FOR MVT WITH

MODEL 65 MULTIPROCESSING

In add i t ion

to

i n i t i a l i z a t i o n

f o r MVT


fo r

MVT with

Model 65

mul t i -

2

processing requ i res spec ia l procedures .

These

procedures are

performed

by a spec ia l

module IEAMP650)

and

are

descr ibed n

Appendix A. The reader should unders tand

the

Nucleus

I n i t i a l i z a t i o n Program for MVT

before

using

the appendix.

APPENDIX

B: NIP

INTERFACE ROUTINE

NIP

uses

subrou t ines to perform r e p e t i

t i v e fUnct ions during i n i t i a l i z a t i o n

pro

cess ing. Because

only one base r eg i s t e r i s

ava i lable for executable code NIP uses

in te r face rou t ines assembled in

the

con-

s tan t s area

to

maintain

cor rec t

addressab i

l i t y

in branching to these subrou t ines .


11/87

The I n i t i a l Program Loader IPL) i s a

program which

i n i t i a l i z e s main s torage

and

loads


nucleus.

The IPL

program funct ions

in

exac t ly the same way

regard less of the con t ro l program opt ion to

be

loaded. As a

r e su l t ,

IPL may perform

some

fUnctions which

a re not necessary

fo r

a

p a r t i c u l a r system i n i t i l i z t i o n ~

the

nucleus i n i t i a l i z a t i o n program wil l

not

requi re some of the information. However,

IPL can

i n i t i a l i z e t he same

generated sys

tem

on varying machine

conf igura t ions

and

use ts

work

areas and t ab les to communi

ca te with the nucleus i n i t i a l i z a t i o n pro

gram.

The nucleus i n i t i a l i z a t i o n program

i s ab le to

determine

any r es t r i c t ions , such

as machine s ize , by using these

t ab l e s

and

work areas .

The IPL r ecords , loca ted on the system

res idence volume,

cons i s t

of three r ecords .

The

f i r s t

record i s read in to main s to rage

by

a

hardware fea ture

and causes the second

r ecord

to be read

i n to

main s to rage

above

the a rea to be

occupied by IPL.

A t r a n s f e r

in channel TIC)

command by the f i r s t reco

rd

causes the

execution

o f t he second, o r

boots t rap ,

record.

The boots t rap

record

causes the t h i r d

record , the IPL

program

t ex t , to

be

read

i n t o

main s torage , over

l ay ing

t he

f i r s t record.

The

IPL program:

•

Determines t he

nucleus to be used

( e i the r the

s tandard

nucleus o r an

a l t e r n a t i v e

use r - se l ec t ed

nucleus

can

be

used) .

•

Clear s

main s to rage

and

determines i t s

s ize .

•

Finds t he se l ec t ed nucleus on secondary

s to rage .

•

Assigns main

s to rage addresses

to

the

nucleus con t ro l sec t ions .

• Relocates the unexecuted por t ion

of

ts

own

i ns t r uc t ions and

work

areas

to pre

vent

being

over la id when

the nucleus

cont rol

sec t ions

are read i n to

main

s to rage .

When these p repara t ions a re complete,

the IPL program:

•

Reads

the nucleus i n i t i a l i z a t i o n pro

gram i n t o

a predetermined area of main

s to rage .

• Reads the nucleus con t ro l sec t ions

i n to

main s to rage .

THE

INITIAL

PROGRAM

LOADER

• Estab l i shes

addr e ssab i l i t y among t he

con t ro l sec t ions by reso lv ing address

cons tan t s .

In performing these opera t ions ,

IPL

uses

i t s own inpu t /ou tpu t

r ou t ine IEASTRIO),

and

i n t e r p r e t s

l inkage ed i to r

outpu t

in

order

to reso lve

addresses .

IPL performs these opera t ions for

a l l

of


o p t i o n s ~ t he

d i f

ferences in control

program i n i t i a l i z a t i o n

a re handled by the nucleus i n i t i a l i z a t i o n

program NIP).

When IPL success fu l ly

completes a l l

pro

cess ing ,

t

t r ans fe r s con t r o l to NIP.

I f

an er ro r occurs during

IPL, t he

sys

tem i s placed

in

a wai t s t a t e

and an e r r o r

code i s

s to red in the

program s t a t u s

word.

These

wai t s t a t e codes are expla ined in

Figure 1 . Fur ther discuss ion

and

user

ac t ion requ i red

can be found in

Messages

and Codes.

LOADING THE

IPL

PROGRAM

To

prepare

for i n i t i a l program load ing ,

the opera tor mounts

the

system

res idence

SYSRES) volume on a

d i r e c t

access device

and

se t s the

load uni t

address switches

to

the uni t

address

of

t ha t

device . I n i t i a l

program

loading

i s then i n i t i a t e d by pres

s ing the LOAD key.

Press ing

the

LOAD key

causes

a

system

r ese t , tu rns on the LOAD l i g h t , t u r ns of f

the MANUAL l i g h t , and i n i t i a t e s a r ead

operat ion from

t he se l ec t ed

inpu t device .

When the r ead operat ion

i s

completed s a t i s

f a c t o r i l y , the

IPL

PSW i s

obta ined ,

t he CPU

s t a r t s

opera t ing ,

and t he LOAD

l i g h t

tu rns

of f .

When the read operat ion

i s

i n i t i a t e d ,

t he se l ec t ed inpu t

device

s t a r t s t r a n s f e r

r ing data . The f i r s t 24 bytes are r ead

i n t o s to rage loca t ions 0-23. Storage pro

t ec t ion , program

cont rol led in te r rup t ions ,

and

a poss ib le

i ncor r ec t - leng th ind ica tion

a re ignored. The doubleword r ead i n to

loca t ion 8 i s a channel command

word

CCW)

which causes the

loading

of the

second

IPL

record,

t he

bootstrap record.

The boots t r ap r ecord i s loaded in to

s to rage a t

an

address higher than

t he

s i z e

of

t he

IPL program t e x t ( the t h i r d

record)

to ensure t h a t

the record

wil l

not be over

l a id by t he IPL con t ro l sec t ion . The

The

I n i t i a l Program Loader

3


12/87

t r ans fe r n channel command

a t loca t ion

16

in the f i r s t record)

spec i f i es the

address

of the boots t rap record.

The

boots t rap

record

i s

a chain of

CCWs

t ha t cause the

IPL

con t r o l sec t ion

to be read in to main

s torage , beginning a t loca t ion

O.

When

the device

provides channel end

the l a s t CCW in the chain i s executed),

the u n i t

address i s stored in b i t s 21-31 of

the

f i r s t

word

n

s torage . Bi t s

16-20

are

s e t

to

0, and

b i t s

0-15 remain unchanged.

The CPU

then

fe tches t he doubleword

in

s torage loca t ion 0 as a new

PSW

and pro

ceeds as in a normal operat ion. The LOAD

l i gh t then turns of f .

r----T-----------T------------------------,

ICodelBit PatternlMeaning I

~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

I 01 10000

0001

11/0 not operat ional I

~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

I 02

10000

0010 ICSW

s tored

on

er ro r

I

~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

I

03 10000 0011 11/0 not

i n i t i a t e d

~ - - - - t - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

I 04

10000

0100

IEr ror

on

TIO I

~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

I

05 10000 0101

IUnit-check caused by I

I I Iother than TCC, EOT, I

I I IEOCYL Four Sense bytes I

I I

l a re

moved

to loca t ion

841

I I

I for

stand-alone

dump.

I

~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

I 06

10000

0110 IUndefined

er ro r

I

~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

I

07

10000 0111

INo-console

condi t ion

a t

I

I I IIPL I

~ - - - - t - - - - - - - - - - - t - - - - - - - - - - - - - - - - - - - - - - - - ~

I 17 10001 0111 IUni£-check on Sense I

I I I Command I

~ - - - - t - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

I

18 10001

1000

IAvai lable

s torage

I

I I Iexceeded

for

RLD records

I

~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~

19 10001 1001 IUnexpected Program

check

I

l J

Figure 1. Wait

Sta te

Error Codes

Clear ing Regis te rs

The f i r s t executable

in s t ruc t ion

in IPL

loads

zeros in to

r eg i s t e r s 1 through 14

r eg i s t e r

15 i s used

as a

base r eg i s t e r ) .

The

address

of lEAPCRET i s then

placed

in

r eg i s t e r 10. IEAPCRET

i s

the re turn point

from

the

f i r s t expected program

check.

(Program check in ter rupt ions

are handled

by

IPL. The

program

new

program

s ta tus

word

i s cons t ruc ted po in t ing to IEAINT. lEAINT

i s a

branch

on r eg i s t e r 10; t he contents

o f

r eg i s t e r 10 are modified

by IPL

rout ines to

handle the next

expected

in te r rup t ion . )

IPL

then

determines i

an a l t e rna t ive

nucleus

has

been

se lec ted or

i main

s torage

s i ze

has been l imi ted by

opera to r

ac t ion.

4

DETERMINING

THE

NUCLEUS

The user has the opt ion

of se lec t ing the

nucleus to

be

loaded. The

opera tor

oom

mUnicates t h i s

information

to the

IPL pro

gram by

stopping a t

loca t ion

80 (hex), and

s tor ing

the su f f ix for

the a l t e rna t ive

nuc

leus

i n to loca t ion 8.

On

System/360

CPU

models, the s topping

i s

accomplished by

se t t ing the ADDRESS COMPARE switches to 80.

On

System/370

CPU

models,

the

RATE switch

i s s e t

to INSTRUCTION STEP before

the

opera to r p resses the LOAD key. (The

pr i -

mary nucleus

name i s IEANUC01; user a l t e r -

nat ive

nuc le i

a re

given unique names

by

appending

2

through

9 to

the

base name

IEANUCO.)

For fur ther

information

about

nucleus generat ion,

see

System Generat ion.

As i t s f i r s t opera t ion a f te r c lear ing

r eg i s t e r s ,

IPL

t es t s

loca t ion

8. I f

loca-

t ion

8 i s not zero, the

charac te r found i s

appended to the nucleus name and the name

thus formed

i s s tored

a t

IEANUCY

for l a t e r

use.

I f loca t ion

8 s zero, the

primary

nucleus

IEANUC01) i s

used.

At t h i s t ime, the opera tor may a lso

l im i t

apparent s to rage s i ze ,

by

s tor ing a

hexadecimal charac te r

i n to loca t ion

9.

CLEARING

STORAGE AND DETERMINING ITS

SIZE

After the

IPL

program has

determined

the

nucleus,

i t s next opera t ion i s to determine

i a

l i m i t

has

been se t

on main

s torage

s i ze . Locat ion 9

(hex)

i s

t e s ted fo r

zero.

I f not

zero,

the maximum s torage

s i ze

i s

se t according

to

the

charac te r

which has

been

loaded

in to

loca t ion

9.

The

val id

characters

and

t he i r

meanings

are:

• X C6

i nd ica t e s

maximum

s torage

of

64K.

• X C7 indicates maximum s torage of

128K.

• X A7

indica tes

maximum

s torage of

192K.

•

X C8

indicates maximum s torage of

256K.

• X A8 indica tes maximum s torage of

384K.

•

X C9 i nd ica t e s

maximum

s torage

of

512K.

• X DO

indica tes

maximum

s torage

of

768K.

• X Dl indicates maximum s torage of

1024K.


13/87

IPL l a t e r c lea r s s to rage , up

to

the

indica ted l im i t ,

by

moving

zeros . Even

though

more

main s to rage might

be

ava i l ab le

on the machine

sys tem,

any addresses above

t he spec i f i ed l i m i t w i l l

be ignored

by the

con t ro l

program, and any l a t e r

at tempts to

address s to rage above t he l im i t may

r e s u l t

in

a protec t ion v io la t ion

i n t e r r up t ion .

Clearing Float ing Point Regis ters

IPL next loads zeros

i n t o

the

f loa t ing

point

r e g i s t e r s ,

using a se r ies of LDR

i ns t r uc t ions . I f

the system i s not

equipped with f loa t ing- po in t r eg i s te r s , a

program

check in te r rup t ion occurs . The

program

new

PSW ( loca t ion 60 hex) poin t s to

lEAINT

which

i s

a branch in s t ruc t ion BR

10).

Since

r eg i s t e r 10 was prev ious ly

loaded

with the

address of lEAPCRET, con

t r o l i s re tu rned t o tha t poin t . lEAPCRET

i s

the in s t ruc t ion

fol lowing

the

s e r i e s

o f

LDR in s t ruc t ions .

Regis te r

10 i s then

loaded

with

the address o f lEAROUND, the

rout ine

which

i s to gain con t ro l

a f t e r

t he

next expected

program

i n t e r r up t ion .

INDICATING SIZE OF MAIN STORAGE

IPL c lears

main s to rage using

an

MVC

in s t ruc t ion in a loop, moving 256

zeros

a t

a

t ime.

This cont inues

u n t i l

an address ing

i n t e r r up t ion

occurs . The rou t ine t h a t

c lea r s s to rage i s i d e n t i f i e d

on

t he

program

l i s t i n g s by

the

name lEAZRLP3.

The

expected in te r rup t ion i s handled

(via pro

gram

new PSW

and

IEAINT)

by IEAROUND.

IEAROUND rounds

main

s to rage

s i z e ( in

r e g i s t e r 9)

to

a

doubleword

boundary and

s to r e s t h i s rounded value a t lEAMAXC. The

rou t ine IEAKYLP then se t s the s to rage

key

fo r

each

2K block of s to rage to the super

vi sor key of

o.

FINDING THE SELECTED

NUCLEUS

The IPL nucleus loca t ion

rou t ine

IEAPC

KEY searches fo r t he chosen nucleus name

on

the pr imary sys tem r es idence volume and

determines the

l oca t ion

of

t he

nucleus data

se t . To

l oca t e t he cor r ec t

nucleus, the

rou t ine :

1. Passes

t he

address of the system r e s i

dence device ,

s to r ed

a t l oca t ion 2,

to

the

I/O

subrou t ine

IEASTRIO).

This

device

conta ins t he system

res idence

volume.)

2.

Reads

the

l abe l

o f

the

sys tem

r e s i

dence

volume to

f ind the

address of

t he VTOC, which

con ta ins the

data

s e t

cont rol block fo r the nucleus data

se t .

3.

Reads

t h e

data

se t

con t ro l

block for

the

VTOC

to determine

the

number

of

t racks

per

log ica l cy l inder o f t he

system

r es idence dev ice . IPL obta ins

t h i s

value ,

s ince

d i f f e r e n t types o f

d i rec t

access devices

may

be

used.)

4. Reads the SYS1.NUCLEUS DSCB

to de te r

mine the

loca t ion o f

the par t i t ioned

data s e t

di r ec to r y .

5. Determines the

l oca t ion

o f

the f i r s t

sca t t e r / t r ans la t ion record fo r the

nucleus data s e t member from

t he pa r

t i t i o n e d data se t di rec tory r ecord

conta in ing t he nucleus name.

6. Reads

the

sc a t t e r / t r a n s l a t i o n

record

i n to

main

s torage above

the t e x t

of

the IPL

program.

ASSIGNING

NUCLEUS

CONTROL SECTION ADDRESSES

For each nucleus cont rol

sec t ion , t he

IPL program

ass igns

an

address

in

main

s torage and

ca lcu la t e s a r e loca t ion

fac tor .

The re loca t ion fac tors a re

used

to conver t

address cons tan t s

to

the ac tua l main

s torage

addresses .

Since IPL obta ins t h e nucleus s t ruc tu re

from the sc a t t e r / t r a n s l a t i o n record ,

IPL

can

only ca lcu la t e

con t ro l

sec t ion

addresses a f t e r

t h i s r ecord has been read

i n t o

main

s torage . The

composit ion

of the

nucleus cannot

be

known

in

advance because

severa l opt ions t h a t a f f e c t nucleus s ize

a re

avai l ab le a t sys tem

genera t ion . )

More

information

about sys tem genera t ion

i s

avai l ab le in

System

Genera t ion.

The sc a t t e r / t r a n s l a t i o n r ecord contains

the sca t te r l st and the

t r ans la t ion

t ab le ,

which

are

provided y

l inkage

ed i to r to a id

in

the assignment of CSECT addresses . The

sc a t t e r l st conta ins suggested r e l a t i v e

load addresses

for

the S E T s ~ the t r ans la

t i o n

tab le

gives indexes for the displace

ment of each cont rol

se c t i o n s

s c a t t e r l st

entry

from

the

s t a r t o f

the

l i s t .

Note: In

aSSigning

and

ca lcu la t ing

addresses for

the nucleus con t ro l

sec t ions ,

IPL expects

t ha t

t he

f i r s t

two cont rol

sec

t ions in the

nucleus

member data se t

a r e

the

nucleus


program

con t ro l

sec t ion and the I /O in te r rup t ion handler

con t ro l

sec t ion . The f i r s t CSECT NIP) i s

loaded ad jacen t to the re loca ted IPL t e x t

in high-address s to rage ,

t he second

CSECT

i s loaded a t abso lu te

loca t ion

0, as

t he

I/O i n t e r r up t ion handler CSECT

def ines

t he

permanent

s to rage

area

f o r

the

cont rol pro

gram. I f

t he se

two CSECTS a re not

in

t h i s

order , i n i t i a l i z a t i o n and

subsequent

opera

t i o n i s

unpred ic tab le .

The

I n i t i a l

Program

Loader 5


14/87

C LCUL TING THE ADDRESSES

Using the r e l a t i v e or igins obtained

from

the s c a t t e r

list

IPL determines

t he

main

s to rage a rea requ i red by each con t ro l sec

t ion . IPL

cons t r uc t s

a

t ab l e

of these

s i ze s

and

uses it

to ass ign

CSECT loading

addresses ,

which

it

places

in

an

address

t ab le .

The

IPL-constructed t ab l e s a re of the

same s t ruc tu re as the s c a t t e r t a b l e ,

and

the e n t r i e s assoc ia ted with a given CSECT

have

t he

same r e l a t i v e posi t ion

in

each

IPL

t ab le as in

t he

s c a t t e r t ab le .

Building

the Size Table SIZTABLE)

Using the

sc a t t e r t ab le

information to

ca lcu la t e t he

s i z e

of every

con t ro l

sec t ion

but the l a s t , IPL:

1 .

Subt rac t s the con t ro l

sec t ion

or ig in

from t he

next higher

cont ro l sec t ion

or ig in . This

gives the

area

s i ze

requ i red

f o r

the former CSECT.

2 .

Stores

the di f fe rence in t he

s ize

tab le

in

a pos i t i on corresponding to

t h a t o f the cont rol sec t ion en t ry in

t he

sc a t t e r

t a b l e .

To ca lcu la te the s i z e of

the

l a s t

CSECT,

IPL

sub t r ac t s

t h a t CSECT s r e l a t ive

or ig in

from the s i z e of the

e n t i r e

nucleus , which

was obta ined

from

t he pa r t i t i oned data se t

di r ec to r y

record.

Building the Address Table ADRTABLE)

IPL

makes address

assignments

f i r s t f o r

the NIP and I/O


handler con

t r o l

sec t ions ,

which have

the t r a n s l a t i o n

tab le en t r i es

immediate ly

fol lowing

t he

i n i t i a l

dummy

ent ry .

Since NIP remains

in s torage

only tem

por a r i ly ,

IPL loads it

adjacent

to the por

t ion of IPL

t h a t has

been re loca ted (which

a l so

i s in

s to rage t emporar i ly ) .

This

address

i s

obta ined by sub t rac t ing the s i z e

o f t he

area

needed by

the

NIP con t ro l sec

t ion from

t he r e loca t ion

address o f IPL.

The

di f fe rence i s

s tored in

NIP s ent ry

in

the address t a b l e .

IPL then ass igns the I /O


handler an address

o f 0 s ince it

con ta ins

the

pre-assembled

Program

Sta tus

Words

(PSWs), which are not re loca table .

Since

other nucleus

con t ro l sec t ions

may

be placed in main

s to rage

in random

order ,

t h e i r addresses in s t o rag e have t he same

numerical

r e l a t i o n as t h e i r

en t r ies in

t he

t r a n s l a t i o n

tab le . (The t r ans la t ion

t a b l e

is

an

a l t e r n a t i v e

suggest ion

of

loading

order from

l inkage ed i to r . ) IPL

ca lcu la t e s

these addresses by:

6

1. Adding to the preceding en t ry

i n t he

address

t ab le the

assoc ia ted

en t ry in

t he s ize t ab le . For

example,

t he

second

address p laced

in

the t a b l e

w i l l be equal to the s i ze o f the I /O

in te r rup t ion handler , which

has

an

address o f zero .

2. Stores the sum

in

the address t a b l e

in

a l oca t ion corresponding to t h a t con

t r o l s e c t i o n s e n t r i e s

in the

sc a t t e r

and s i z e

t ab les .

C LCUL TING THE RELOCATION F CTORS

The IPL program uses the addresses it

has ass igned to

t he

control sec t ions to

ca lcu la t e t he corresponding r e loca t ion

fac

t o r s . For each

control

sec t ion, IPL

sub

t r a c t s

the suggested r e l a t ive or ig in found

in

t he

s c a t t e r

t a b l e

from

t he

ass igned main

s to rage

address .

The

di f fe rence ,

which

may

be pos i t i ve

o r

negat ive , i s s to r ed in the

re loca t ion f ac to r

t ab l e

RLFTABLE). For

example,

cons ider the re loca t ion

f ac to r

fo r

the I/O


handler CSECT. The

ass igned address

i s loca t ion

0,

but

the

r e l a t ive or ig in may be 2000. The r e loca

t i on f ac to r i s then -2000.

The CSECT en t r ies

in the

RLFTABLE are in

the

same

order as

in t he sc a t t e r , s i z e ,

and

address

t a b l e s .

Therefore, RLFTABLE

en t r ies a lso a re access ible through t he

t r a n s l a t io n t a b l e .

IPL PROGR M RELOC TION

IPL, Which was

loaded beginning

a t loca

t ion 0,

must

load the nucleus t ex t i n to

the

area o f s to rage it now

occupies.

To make

room f o r

the

nucleus t e x t , IPL r e loca t e s

i t s t ab l e s and

the

unexecuted por t ion of

code

to upper main s to rage . The r e loca t ion

address

i s

determined by the s i z e of

s to rage

and

the s i z e o f the

IPL

t ab les and

code to

be re loca ted.

The

s ize

o f

unex

ecuted

IPL code

and

IPL t ab l e s i s sub

t r ac ted from an address determined by

s to rage

s i z e .

The r e su l t o f

t he

subt rac

t i on gives the

beginning address

o f

the

re loca ted

IPL.

For

s to rage

s izes

S12K

and

grea te r , IPL s i z e i s sub t rac ted from

SOaK.

For

s torage s ize 256, IPL s iz

i s

sub

t r a c t e d

from

252K.

For

other

s izes

l e s s

than

512K

IPL s i ze i s

sub t rac ted

from the

highest

ava i l ab le s to rage address . The

re loca ted por t ion of IPL w i l l

never

occupy

s to rage above SOaK. Relocat ion i s accomp

l i shed

using the

IE DDR rou t ine . After

IPL re loca tes

i t s

t ab les

and

unexecuted

in s t ruc t ions , it moves zeros i n t o the

s to rage it occupied before

re loca t ion.

Figures

2

and

3 i l l u s t r a t e

main s to rage

before and

a f t e r IPL re loca t ion.


15/87

Cleared

Storage

Highest

Address

for

IPL/NIP

Relocation Factor Table RLFTABLE)

low Address

Figure

2

Address Tab Ie

ADRT

ABLE)

Size

Table

Scatter list

Translation

Table

PL Program

Main

Storage

Layout

Before

IPL

Relocation

Relocation Factor Table

RLFTABLE)

Highest

Address

for

IPL/NIP

low

Address

Figure

3

Address

Table

ADRTABLE)

Size Table

Scatter

List

Translation Table

PL Program

Available Main

Storage

Cleared to all 0

Main

Storage

After

IPL

Relocation

The

n i t i a l

Program Loader


16/87

LOADING

THE

NUCLEUS

CONTROL SECTIONS

The IPL

program

reads in nucleus CSECTs

in any

sequence

tha t it encounters them in

the

load

module.

Firs t , the

IPL program

in i t ia l izes a 260-byte buffer in

main

storage. t uses t h i s buffer to read in

control , RLD,

and control/RLD records. IPL

reads the f i r s t nucleus control record

in to

the buffer . Then,

to load

each control

sect ion, the

IPL

program:

1. Determines, from

the

record

in

the

buffer ,

the length of the

following

t ex t record and

the

external symbol

dict ionary

iden t i f ica t ion number

ESDID) of the control

sect ion

con

ta in ing the t ex t record.

2.

Finds the

proper

t rans la t ion table

entry, so tha t it can obtain the re lo -

cation factor. The

control

sect ion

ident i f ica t ion number

i s

also the dis-

placement

of

the

corresponding

entry

from

the

s t a r t of

the

transla t ion

table . The IPL program uses th i s

value as

an

index

to

the

tab le to

f ind

the

appl icable entry.)

3. Finds

the

re locat ion factor for

the

control sect ion by

using

the

t rans la-

t ion table entry multiplied by four)

as

a displacement within

the

re loca

fac tor tab le . All text records in

the

same control

sect ion

have the same

re locat ion fac tor . )

4.

Modifies

a

preassembled READ

command

in the

control

record by

adding the

relocation fac tor

to

the

operand

of

the command,

which has

been

se t

by

linkage edi tor

to

the

re la t ive

or ig in

of

the

CSECT

in

the

load

module.

Figure 4

shows

the

modification

of

the

read commands for the

text

records of

a Single CSECT.

Name

Operation

Operand

Preassemb led

RDRCDI

RD

100

{256 Bytes}

Read

Commands

RDRCD2

RD 356

{256 Bytes}

RDRCD3

RD

612

{20 Bytes}

Read

Commands

RDRCDI RD

80

{256 Bytes}

With

RLF -20

RDRCD2 RD

336

{256 Bytes}

added

to

Relative

RDRCD3

RD

592

{20 Bytes}

Origin

Note:

CSECT

with

assigned s t o r ~ g address of 80

and

relative

origin of 100 is assumed. This

table

shows modification o f

commands to read first three records

of CSECT

•

Figure 4. Read

Command Modifications

8

5. Passes

the preassembled READ

command

to

the

I/O subroutine

IEASTRIO),

which then reads the t ex t record in to

the

loading address.

6.

Reads

in to

the

buffer the control ,

control/RLD, or

RLD record following

the

t ex t record.

7. Moves any re locat ion information for

the

control

sect ion

from

the

record

in

the buffer

into

the relocation

dic

t ionary RLD)

area above the high

end

of the

nucleus.

Figure 5

i l l u s t r a t e s

the placement of

RLD

information.

I f

the

record

i s

an RLD record, which

contains only

relocation

information,

IPL

reads and t ransfers RLD

informa

t ion

unt i l it encounters a control or

control/RLD record

on

the

data se t

member).

8.

Repeats the procedure from the f i r s t

s tep

un t i l

a l l

of

the

nucleus t ex t

has

been

read into main

storage.

Figure

5

shows

the

arrangement of

storage af te r three control sections are

loaded. IPL loads the CSECTs in

the

order

in which it encounters them on

disk and

not

n the order of the i r main

storage

addresses.

REPLACING NUCLEUS

ADDRESS CONSTANTS

IPL establishes

addressabi l i ty

among

the

control sections by

converting nucleus

address constants to the i r main storage

equivalents .

The IEARELOC routine uses the

address tab le and the RLD

information

to

make

the

conversions.

From

the

address

tab le ,

IPL

obtains the

location

of

each

control sect ion: then

from

the

RLD information,

IPL

findS the

length and

displacement

from

the

control

sect ion orig in

of each

address

constant in

the CSECT.

IPL adds to each of these

address

con

s tants

the relocation

factor for

the CSECT

refer red to by the constant. Final ly , IPL

replaces each

address

constant

with

the

corresponding sum

it

has computed, which i s

the actual

main storage

address.

Figure 6 shows the

layout of

storage

af te r

a l l

CSECTs

have been

loaded

and

address constants

have been replaced.

GIVING CONTROL

TO

THE NUCLEUS

INITIALIZATION

PROGRAM

When it

gives control to

NIP,

the

IPL

program

loads,

into general regis ters ,

the

s ize of

main

s torage, the address

of

the

system

residence device,

the

address

of the


17/87

s i ze tab l e

the address of the

address

tab le

the

number

of

entr ies per tab le and

the address

of the

next doubleword above

the

end of the

nucleus. The

contents of

general

regis ters at IPL

termination i s

shown in Figure

7.

The

IPL

program then


RLFTABLE)

Address Table

ADRTABLE)

Size

Table

Scatter List

Translation

Table

Re

located

portion

of

IP L program

First loaded CSECT text

N IP Program)

Zeros)

RLD

Data - 3rd CSECT

RLD Data - 2nd CSECT

RLD Data - 1st CSECT

Zeros)

Third loaded CSECT

Zeros)

Second loaded CSECT text

I/O Supervisor)

ow Address

Figure

5. Main

Storage After

Loading

Firs t

Three Sections

Highest

Address

for

IPVNIP

branches to absolute

locat ion 6C

hex).

This

locat ion

contains an ins truct ion to

load

the

program s tatus word from

locat ion

170 hex), which contains the s tart ing

address

of the

Nucleus In i t ia l i za t ion

Program.


RLFTABLE)

Address Tab Ie ADRTAB LE)

Size Table

Scatter List

Translation

Table

Relocated

Portion

of

IPL

Executed)

NIP Program

Text

Available Main Storage

zeros)

Used

RLD Data

Nucleus Text

ow

Address

Highest

Address

for

IPVNIP

Figure 6.

Main

Storage at

IPL

Termination

The

I n i t i a l Program

Loader 9


18/87

Reg

ontent

Reg

ontent

0 aries

B

Address of ADRTABLE excluding Dummy Entry)

Varies

9

Number of Entries per table number of CSECTS)

2

aries

1

SYSRES Device Address

3 Varies

Varies

4 Address of SI ZT AB L excluding Dummy Entry)

12

Varies

5 Varies

13

Varies

6

Storage

Size

14

Varies

7 Address of End of Nucleus 15

aries

Figure 7

Register

Contents

t IPL

Termination

10


19/87

The Nucleus I n i t i a l i z a t i o n

Program (NIP)

i s

assembled

a t system

genera t ion from

a

system genera t ion SYSGEN) macro SGIEA2NP)

according

to

the

opt ions

se lec ted for the

system being genera ted . Therefore, the

order

of

the rou t ines in NIP i s

t he

same

fo r a l l l eve l s o f

the

con t ro l program, but

NIP

fUnctions

vary according to t he con t ro l

program

se l ec t ed

- - some funct ions may be

dropped from the assembly en t i r e ly ,

e i t h e r

because

they are no t supported by a

cont rol

program

l eve l o r not

se l ec t ed

as a SYSGEN

opt ion.

This sec t ion

descr ibes

the

organ iza t ion

and

funct ions

o f

NIP

in

the order

of

the

appearance

o f

rou t ines

in the NIP

macro

i ns t r uc t ion .

Each func t ion

i s i d e n t i f i e d

by:

1 . The con t ro l

program

l eve l MFT, MVT

to

which

t app l i e s .

2. A rou t ine o r

en t ry

poin t

name

to

a s s i s t the

reader

in r e la t ing the

descr ipt ion to

t he

program l i s t i n g . A

l st o f

NIP

r ou t ine s and t h e i r en t ry

po in t s

i s

inc luded in the

sec t ion

Lis ts of Routines .

I f the con t ro l program i s to be MVT with

Model

65

mult ip rocess ing ,

a

spec ia l

module

IEAMP650) must perform

some

of the

i n i

t i a l i z a t i o n

procedure .

The add i t iona l i n i

t i a l i z a t i o n for MVT

with

Model 65 mu l t i

processing

i s discussed

in Appendix

A.

NIP crea tes some cont rol blocks

and

t ab l e s

which a re used l a t e r by con t ro l

p ro

gram

rout ines . NIP a lso uses

con t ro l

blocks

and

t ab les

which

are assembled

as

pa r t of nucleus cont rol sec t ions . These

con t ro l

blocks and t ab les a re discussed no t

only from the s tandpoin t o f NIP's

use ,

but

a l so the l a t e r

use

by con t ro l program rou

t ines .

The

cont rol

blocks and

t ab les

which

a re

used

o r

i n i t i a l i z e d by

NIP are

descr ibed

in more d e t a i l i n

the sec t ion

Tables and Work Areas . Detai led d es c r i p

t i ons

of

major sys tem

con t ro l blocks can be

found

in

System Control

Blocks .

I l lu s t r a t ions o f main s torage layout

during var ious s tages

of

NIP

execut ion

are

included i n t h i s sec t ion . Where necessary ,

each con t ro l program l eve l i s i l l u s t r a t e d

separa te ly .

THE NUCLEUS

INITIALIZATION

PROGRAM

NUCLEUS TABLE INITIALIZATION

The nucleus i n i t i a l i z a t i o n program

f i r s t

i n i t i a l i z e s

system

t ab les

which

a re

used

by

NIP

and

then l a t e r used y con t ro l

program

rout ines . Some of these

t ab l e s

are opt ion

a l , other s vary s l i g h t l y according to

con

t r o l

program opt ion. The i n i t i a l i z a t i o n ,

there fore ,

depends

on the

con t ro l program

opt ion and the opt ions se lec ted a t

sys tem

genera t ion .

INITIALIZING

THE

COMMUNICATIONS

VECTOR

TABLE POINTER

The f i r s t funct ion

o f NIP,

a f t e r es tab

l i sh ing addr e ssab i l i t y , i s to i n i t i a l i z e

the

po in ter

to the

communications

vec tor

t ab le

(CVT).

The

CVT i s

brought

i n to

s to rage as

p a r t

of the I /O Superv isor

con

t r o l sec t ion,

and

NIP

obta ins

t he CVT

address by means of an ex te r na l re ference

(V-type

address

constant ) . NIP then

s to r e s

the address of the

CVT

a t

l oca t ion

10

(hex.) , so t h a t t h i s address

may

l a t e r be

used to place e n t r i e s i n

the

CVT or to

r e t r i eve

information from t he CVT.

CVT-Related I n i t i a l i z a t i o n

NIP s to res ,

in

ts own

cons tan t a rea ,

the

s i ze

of s t o rag e and t he poin ter t o t he

end of the nucleus . IPL passes t h i s i n f o r

mation to

NIP

i n r eg i s t e r s 6

and 7, r espec

t ive ly .

I f ,

in

a

system

with MVT,

the

r o l lou t

opt ion has been se lec ted, the

main

s to rage

s i ze

i s

a l so

placed in the

r o l l o u t

parameter l st ( see

I n i t i a l i z in g

the Rol l

ou t

Data

Set ) .

The address of the dev ice

which

was used

for IPL loading i s saved for l a t e r use by

NIP to

determine the

sys tem

res idence

(SYS

RES) device.

Regis ter 6, which

contains

t he value

found

by IPL

for

main s to rage s i z e , i s

decremented by one

and

t he

r e su l t (highest

addressable byte in main

s to rage) s tored in

the CVT a t o f f s e t 164. In systems

with

MFT,

t h i s

address

i s

a l s o

s tored

in

the

superv isor val id i ty-check rou t ine which i s

res iden t in

the

nucleus .

The communications vector

t a b l e conta ins

addresses of cont rol blocks and t ab les

which

a re used

by

con t r o l

program

rout ines .

Many

of

these addresses are

reso lved during

the t ime t h a t IPL r eads in the nucleus , but

NIP

must

ad jus t some of the addresses

because

NIP processing changes the l o ca -

The

Nucleus I n i t i a l i z a t i o n Program

11


20/87

t i ons o f

c e r t a i n boundaries

and

con t ro l

blocks. A

d e t a i l e d

l ayout and d es c r i p t i o n

of

the

CVT

can be found

in

System Control

Blocks .

ESTABLISHING

THE

TRACE TABLE ADDRESS

OPTIONAL: MVT

I f system genera t ion inc luded t h e t r a c e

t ab l e

opt ion ,

NIP r e t r i eves

t he th r ee

poin ters cur ren t en t ry po in ter , s t a r t - o f

t ab l e po in t e r , end-of - t ab le

po in ter ) and

rounds them

to

eight -word boundaries .

The

address

o f

t h e list of

poin ters

i s

a t l o ca

t i o n

84 dec) .

NIP only

ad jus t s the bound

a r i e s o f t h e t r a c e t a b l e ; no c l ea r i n g o f

t r a c e t a b l e

s to rage

i s performed.

The t r a c e t a b l e i s pr imar i ly a debugging

too l ;

en t r i es are

made in

t h i s t a b l e for

a l l I /O and

SVC

i n t e r r up t ions . For a

d e t a i l e d

desc r ip t ion o f the

t r a ce t ab l e

and

an explanat ion o f

its

use in debugging, see

Programmer 's Guide

to

Debugging.

BUILDING THE DUMMY

TCB TABLE MFT

WITH

SUBTASKING)

NIP

cons t ruc t s

a dummy TCB t a b l e a t

l oca t ion ATCHLOP2. This t able

holds

a

maximum o f 15 en t r ies ,

and

i s

used

by

NIP

un t i l t h e

sys tem

queue area i n i t i a l i z a t i o n

i s

c o m p l e t ~ d After

t he

system queue area

i s

i n i t i a l i z e d ,

t he t ab l e i s

r ebu i l t

in its

permanent l oca t ion see Building t h e TCB

Address Table (MFT) ).

TESTING FOR EXTENDED PRECISION FLOATING

POINT SIMULATION

The Nucleus I n i t i a l i z a t i o n Program t e s t s

to determine i t he

Extended Prec i s ion

Float ing Po in t Divide fea tu re

i s

p a r t o f

the system hardware. I f the fea ture s

presen t , a

f l ag s

se t in t h e CVTOPTA f i e l d

of the Communicat ions Vector

Table .

The Program Check New PSW address i s

r ep laced wi th

t h e address o f

t he r ou t ine

EPFPRET. NIP

then i s sues an

extended

p re

c i s i o n in s t ruc t ion . I f t he opera t ion i s

success fu l ,

b i t 7

o f

t h e CVTOPTA f i e l d o f

the CVT is s e t and process ing cont inues .

Unsuccessful execution

of

the extended p re

c i s i o n i n s t r u c t i o n causes a

program

check,

and

con t ro l

goes

to

EPFPRET

to

determine

the type o f

program check

by

examining

t h e

Program Check Old PSW. An opera t ions

i n t e r r up t ion ind ica t e s

t h a t

t he r e

are no

f loa t ing

poin t

r e g i s t e r s

in

t he hardware,

and

the extended prec is ion fea ture i s

not

included.

The f l ag a t b i t 7 of CVTOPTA in t he CVT

i s

se t for l a t e r

use

by the i n i t i a l

12

Extended

Prec i s ion Simula tor Rout ine (IEAE

PSIM). A b i t

se t t ing

of 1 i s used

to ind

i c a t e t he presence of the

Extended

Pr ec i

s ion

Floa t ing

Poin t Divide fea ture ; only

t he div ide s imula to r i s needed. A b i t se t

t i ng o f

0

i nd ica t e s t h a t

a l l extended pre

c i s ion

ins t r uc t ions

a re to be s imula ted .

DETERMINING

SIZE OF IBM

2361 CORE

STORAGE

OPTIONAL: MFT,

MVT

Main

s to rage

may

be

expanded

by inc lud

ing IBM 2361 Core Storage in the system.

Main

Storage

Hierarchy Suppor t f o r IBM 2361

Models 1 and 2 permits se lec t ive access

to

e i ther processor s to rage

(known

as

h i e r a r

chy 0) o r the add i t iona l s to rage added by

including 2361 Core

Storage

the

ad d i t i o n a l

s to rage s

known

as hierarchy

1) .

NIP

determines

i

2361

Core Storage

i s

i n t h e

system by

comparing

t o t a l s to rage s i z e

(determined by

IPL) with

1024K.

I f the

s i z e i s

l a rger

t h an 1024K, NIP

div ides the

l a s t

s to rage

address

by

1024K.

The

remainder in t h e div i s ion

in

r eg i s t e r 0)

i s

placed

in

IEAHOH1

as

the s i ze of

h ie ra r

chy o.

I f t he r e

i s no remainder , processor

s i ze i s assumed to be 1024K.

DETERMINING CONSOLE READINESS MFT, MVT

WITHOUT MCS

Before NIP

can communicate

with

the

opera to r ,

it

must

determine whether t h e

console i s ready. To

do

t h i s , t he console

i n i t i a l i z a t i o n rou t ine IEACONS1)

f inds

t h e

pr imary

console

and

checks i t s

r ead i n es s .

I f

the

pr imary

console is not ready,

NIP

f inds t he a l t e r n a t i v e console , checks it

fo r read iness , and es t ab l i she s it as t he

primary

conso le .

I f

ne i the r

t h e primary

nor the

a l t e r n a t i v e console i s

ready,

NIP

i s sues an LPSW

i ns t r uc t ion , plac ing

t h e

system in a wait s t a t e with an er ro r

code

of 07 (hexadecimal) i n t he

curren t

Program

Sta tus Word (PSW). To r ecover , t he console

must be

made ready

and

t he IPL procedure

r epeated .

NIP

f inds the conso les

by comparing

names in

t he

UCB t a b l e with t h e names pro

vided fo r the

pr imary

and

a l t e r n a t i v e con

so le s

by

t he

system

genera t ion

program.

Two names a r e given f o r each console: an

inpu t name

and

an outpu t name.

For

a s t an

dard, noncomposite

console ,

the opera t ion

of the

conso le

search rou t ine

i s

s i mp l i f i ed

s ince

only inpu t names need be compared, as

both inpu t

and

outpu t names r e f e r t o

t he

same console.

For

composi te consoles ,

NIP

f i r s t f inds the inpu t

console

and repea t s

i t s search

t o

f ind

t he

output console.


21/87

DETERMINING

THE MASTER CONSOLE

IN A SYSTEM

WITH MULTIPLE CONSOLE SUPPORT OPTIONAL:

MFT, MVT)

I f t h e system was genera ted with Mul

t i p l e

Console

Support

MCS),

NIP

obta ins

t he

po in t e r t o t h e master console entry

in

the

Unit

Cont ro l

Module UCM).

The

p o i n t e r

i s conta ined

in

t he MCS Pre f i x

to

t he

UCM.

NIP then t e s t s t he master console f o r ava i

l a b i l i t y . I f t h e

master console

i s

ava i l

ab le ,

t he

UCB fo r t h a t u n i t

i s

f lagged t o

i nd ica t e

t h a t it

i s t he

master

console , and

t h e master console f lag in

the

UCMDISP

f i e l d

of

t he u n i t ' s UCM en t ry i s se t

to

1 .

A complete descr ip t ion

and

diagram

of

t h e

UCM, inc lud ing

t he

MCS Pref ix ,

can be found

i n t he MFT Superv i sor

and

MVT

superv i sor

Proqram

Loqic Manuals.

NIP t h en determines whether t he

hard

copy

log

i s

necessary . The

hard

copy log

i s

requ i red

i t he master console i s a

graphic device.

I f

t he master console i s a

graphic device, or

i a second

console

i s

found ava i lable , the hard copy

requ i red

f lag i s s e t to 1 .

I f

t h e master console

i s found to

be

unavai lab le , NIP

se t s

t h e

·p rev iou

GY28-6661-5 Inital Program Loader and Nucleus Initialization Program Rel21 PLM Mar72

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Transcript of GY28-6661-5 Inital Program Loader and Nucleus Initialization Program Rel21 PLM Mar72