GATE CSE 1998 | Question: 1.28

Question

A linker reads four modules whose lengths are $200, 800, 600$ and $500$ words, respectively. If they are loaded in that order, what are the relocation constants?

• A. $0, 200, 500, 600$
• B. $0, 200, 1000, 1600$
• C. $200, 500, 600, 800$
• D. $200, 700, 1300, 2100$

Answer 1

answer - B

first module loaded starting at address $0$. Size is $200$. hence it will occupy first $200$ address (last address being $199$). Second module will be present from $200$ and so on.

Comments

@Ayush+Upadhyaya

Is it always the case that ..linker will place module 2 after module 1 ..then module 3 after module 2

(Here I mean module -> Object code(.o) )

What if it place module 2 before 1...?? m confused now :(

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If they are loaded in that order

@jatin khachane 1  it is mentioned. Otherwise linker will ask OS for free slot in memory and suppose OS provides address x then in base register of that module x will be stored and relative addresses will be converted to absolute accordingly.

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What if it place module 2 before 1...??

Yes it is possible. But during program execution MMU will take care of it using page tables. 

Answer 2

1. Module 1 (Length: 200 words):

   • Starting Address: 0 (No preceding modules)

2. Module 2 (Length: 800 words):

   • Starting Address: 200 (Length of Module 1)

3. Module 3 (Length: 600 words):

   • Starting Address: 1000 (Sum of lengths of Modules 1 and 2)

4. Module 4 (Length: 500 words):

   • Starting Address: 1600 (Sum of lengths of Modules 1, 2, and 3)

Therefore, the relocation constants for each module are as follows:

1. Module 1: 0
2. Module 2: 200
3. Module 3: 1000
4. Module 4: 1600