[Qemu-devel] [Bug 672934] Re: FPU incorrect on Mac OS X

[T. Huth]

Looks like the ISO from comment #4 (thanks for attaching that one!)
shows the correct behavior with up to date QEMU 2.7. Also, the affected
softfloat code has been completely reworked in between (e.g. with commit
cf67c6bad56d43e6d60), so I assume this has been fixed sometimes in the
past years.

** Changed in: qemu
       Status: New => Fix Released

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https://bugs.launchpad.net/bugs/672934

Title:
  FPU incorrect on Mac OS X

Status in QEMU:
  Fix Released

Bug description:
  I am using the 0.13.0 release version of QEMU on Mac OS X 10.6.4. I
  work for a university and the affected guest OS is our own research
  OS. I believe I found a bug in QEMU's FPU emulation, which only
  triggers on the Mac. You can reproduce the problem by booting the
  attached ISO image.

  Investigating the problem, I found that the lua interpreter in our
  loader component (called "ned") internally uses doubles to represent
  all lua-numbers. These doubles are showing completely wrong values on
  QEMU/Mac, resulting in the lua code not processing properly.

  I also attached a patch which fixes the problem for me. The attached
  ZIP-file also contains "before" and "after" screenshots. Note that
  booting the ISO on a real machine or on a Linux-QEMU always shows the
  correct "after" behavior. Only QEMU on the Mac exhibits the wrong
  "before" behavior without my patch. The patch might break other
  systems setting the CONFIG_BSD flag, so maybe the preprocessor should
  check for __APPLE__ instead to make the fix Mac-only.

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