[Bug 1847467] Re: qemu-x86_64 segment prefixes error

[Peter Maydell]

Repro case in comment #1 still demonstrates bug.


** Changed in: qemu
       Status: Incomplete => Confirmed

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https://bugs.launchpad.net/bugs/1847467

Title:
  qemu-x86_64 segment prefixes error

Status in QEMU:
  Confirmed

Bug description:
  qemu-x86_64 version 4.1.0 (qemu-x86_64 version 4.0.0 also have the
  issue)

  In 64-bit mode (x86_64) the DS, ES, SS or CS segment prefixes should
  be ignored; qemu-x86_64 does not ignore them.

  example: an x86_64 instructions preceded by FS DS (0x64 0x26) segment
  prefixes have the linear address of its memory reference flat-mapped
  (as if DS was in action) whereas it should be FS-mapped (offset by
  FS_base, because the DS, ES, SS or CS are just ignored).

  
  I attach a small C++ program that shows this discrepancy.

  $ ./sample
  I'm not in QEMU

  $ qemu-x86_64 ./sample
  I'm in QEMU

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