PROTECTION

 

 

 

 

CPU

 

 

I'

MEMORY

 

 

 

15

 

 

0

 

·

 

 

23

I

 

 

I --

I

 

 

 

GOT LIMIT

 

·

 

 

 

 

 

 

LIT-

 

GOTR

 

I

GOT BASE

 

 

1

 

 

--

15

 

 

0 --

 

 

 

 

 

I

LOT

 

 

-r

LOT,

 

r

-

SELECTOR

"0 -,

 

 

- 15 - - -

I

CURRENl

 

I

 

J LOT LIMIT

 

I

I

LOT

 

 

 

I

 

I

23

 

r-;

-I

· I

 

I

l

 

 

 

I

..J

 

 

I

 

 

 

 

LOTR

 

 

LOT BASE

 

~

 

 

I

 

 

 

 

I

 

LOTn

 

I

PROGRAM INVISIBLE

 

·

 

L ________ ....I

 

 

 

 

 

 

 

 

 

G30108

Figure 7-4. Local and Global Descriptor Table Definitions

15

3 2

 

o

 

INDEX

T

I

E

means that an event external to

I

0

X

the program caused the exception

 

T

T

 

 

(i.e., external interrupt, single step,

 

 

 

 

processor extension error)

,

I

 

L

o means that an exception occurred

 

 

while processing the instructloft at

 

 

 

CS:IP saved on stack.

 

 

 

 

1 means use lOT and ignore bit 2.

 

 

~ o means bit 2 indicates table usage

 

 

 

 

1 means use LOT

 

 

 

:

o means use GOT

' ------------- _Entry in lOT, GOT, or LOT

G30108

Figure 7-5. Error Code Format (on the stack)

7-7

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