[Qemu-devel] [Bug 1693667] [NEW] -cpu haswell / broadwell have no MONITOR in features1

[Paul Goyette]

Public bug reported:

In qemu 2.9.0 if you run

    qemu-system-x86_64 -cpu Broadwell (or Haswell)

then the CPU features1 flag include the SSE3 bit, but do NOT include the
MONITOR/MWAIT bit.  This is so even when the host includes the features.


Additionally, running qemu in this manner results in several error messages:

warning: TCG doesn't support requested feature: CPUID.01H:ECX.fma [bit 12]
warning: TCG doesn't support requested feature: CPUID.01H:ECX.pcid [bit 17]
warning: TCG doesn't support requested feature: CPUID.01H:ECX.x2apic [bit 21]
warning: TCG doesn't support requested feature: CPUID.01H:ECX.tsc-deadline [bit 
24]
warning: TCG doesn't support requested feature: CPUID.01H:ECX.avx [bit 28]
warning: TCG doesn't support requested feature: CPUID.01H:ECX.f16c [bit 29]
warning: TCG doesn't support requested feature: CPUID.01H:ECX.rdrand [bit 30]
warning: TCG doesn't support requested feature: CPUID.07H:EBX.hle [bit 4]
warning: TCG doesn't support requested feature: CPUID.07H:EBX.avx2 [bit 5]
warning: TCG doesn't support requested feature: CPUID.07H:EBX.invpcid [bit 10]
warning: TCG doesn't support requested feature: CPUID.07H:EBX.rtm [bit 11]
warning: TCG doesn't support requested feature: CPUID.07H:EBX.rdseed [bit 18]
warning: TCG doesn't support requested feature: 
CPUID.80000001H:ECX.3dnowprefetch


(Among possible other uses, the lack of the MONITOR feature bit causes NetBSD 
to fall-back on a
check-and-pause loop while an application CPU is waiting to be told to proceed 
by the boot CPU.)

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1693667

Title:
  -cpu haswell / broadwell have no MONITOR in features1

Status in QEMU:
  New

Bug description:
  In qemu 2.9.0 if you run

      qemu-system-x86_64 -cpu Broadwell (or Haswell)

  then the CPU features1 flag include the SSE3 bit, but do NOT include
  the MONITOR/MWAIT bit.  This is so even when the host includes the
  features.

  
  Additionally, running qemu in this manner results in several error messages:

  warning: TCG doesn't support requested feature: CPUID.01H:ECX.fma [bit 12]
  warning: TCG doesn't support requested feature: CPUID.01H:ECX.pcid [bit 17]
  warning: TCG doesn't support requested feature: CPUID.01H:ECX.x2apic [bit 21]
  warning: TCG doesn't support requested feature: CPUID.01H:ECX.tsc-deadline 
[bit 24]
  warning: TCG doesn't support requested feature: CPUID.01H:ECX.avx [bit 28]
  warning: TCG doesn't support requested feature: CPUID.01H:ECX.f16c [bit 29]
  warning: TCG doesn't support requested feature: CPUID.01H:ECX.rdrand [bit 30]
  warning: TCG doesn't support requested feature: CPUID.07H:EBX.hle [bit 4]
  warning: TCG doesn't support requested feature: CPUID.07H:EBX.avx2 [bit 5]
  warning: TCG doesn't support requested feature: CPUID.07H:EBX.invpcid [bit 10]
  warning: TCG doesn't support requested feature: CPUID.07H:EBX.rtm [bit 11]
  warning: TCG doesn't support requested feature: CPUID.07H:EBX.rdseed [bit 18]
  warning: TCG doesn't support requested feature: 
CPUID.80000001H:ECX.3dnowprefetch

  
  (Among possible other uses, the lack of the MONITOR feature bit causes NetBSD 
to fall-back on a
  check-and-pause loop while an application CPU is waiting to be told to 
proceed by the boot CPU.)

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