[Qemu-devel] [Bug 1693649] [NEW] x86 pause misbehaves with -cpu haswell

[Paul Goyette]

Public bug reported:

Using qemu-2.9.0

When booting NetBSD using '-cpu haswell -smp 4', the system fails to
initialize the additional CPUs.  It appears as though the "application
processor" enters routine x86_pause() but never returns.

x86_pause() is simply two assembler instructions: 'pause; ret;'

Replacing the routine with 'nop; nop; ret;' allows the system to
proceed, of course without the benefit of the pause instruction on spin-
loops!

Additionally, booting with '-cpu phenom -smp 4' also works, although the
system does seem confused about the type of CPU being used.

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1693649

Title:
  x86 pause misbehaves with -cpu haswell

Status in QEMU:
  New

Bug description:
  Using qemu-2.9.0

  When booting NetBSD using '-cpu haswell -smp 4', the system fails to
  initialize the additional CPUs.  It appears as though the "application
  processor" enters routine x86_pause() but never returns.

  x86_pause() is simply two assembler instructions: 'pause; ret;'

  Replacing the routine with 'nop; nop; ret;' allows the system to
  proceed, of course without the benefit of the pause instruction on
  spin-loops!

  Additionally, booting with '-cpu phenom -smp 4' also works, although
  the system does seem confused about the type of CPU being used.

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