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During exception entry, a programmer forgets to save the Link Register (LR). What problem will most likely occur?

medium📝 Analysis Q7 of 15
ARM Architecture - Exception and Interrupt Model
During exception entry, a programmer forgets to save the Link Register (LR). What problem will most likely occur?
AReturn address is lost, causing incorrect return after exception
BProcessor will not switch to exception mode
CException handler will not execute
DProcessor will reset automatically
Step-by-Step Solution
Solution:

  1. Step 1: Purpose of saving LR

    LR stores return address to resume after exception.

  2. Step 2: Consequence of not saving LR

    Without LR saved, return address is lost, causing wrong return.

  3. Final Answer:

    Return address is lost, causing incorrect return after exception -> Option A

  4. Quick Check:

    Not saving LR loses return address [OK]
Quick Trick: Always save LR to preserve return address [OK]
Common Mistakes:
  • Thinking processor won't switch mode
  • Assuming handler won't run
  • Believing processor resets automatically

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