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IDA disassembled an x86-64 instruction as below:

0000000000000761                 lea     rdx, ds:0[rax*4]

What I know is, segment registers are only relevant in in segmented memory model, while in case of paging they hold an index in GDT/LDT. Why is the above instruction, out of nowhere, referring to the ds segment register?

  • Ubuntu 18.04, 64 bit – Holmes.Sherlock Dec 15 '18 at 15:25
  • The fact that you are not using a segmented memory model doesn’t mean the instruction encoding doesn’t allow you to specify the segment :) Basically on x86_64 the only relevant segment is gs, but a disassembler might still show other segment registers (implicitly) encoded in instructions... – mrexodia Dec 18 '18 at 20:34

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