x86 expected to show 2 virtual processors per core, but only shows 1 (Doc ID 2209744.1)

Last updated on DECEMBER 04, 2016

Applies to:

Solaris x64/x86 Operating System - Version 10 3/05 and later
Information in this document applies to any platform.

Symptoms

On x86 systems supporting hyperthreading, psrinfo -pv is expected to show output containing something similar to this:

The physical processor has 8 cores and 16 virtual processors (0-7,16-23)
  The core has 2 virtual processors (0,16)
  The core has 2 virtual processors (1,17)
  The core has 2 virtual processors (2,18)
  The core has 2 virtual processors (3,19)
  The core has 2 virtual processors (4,20)
  The core has 2 virtual processors (5,21)
  The core has 2 virtual processors (6,22)
  The core has 2 virtual processors (7,23)
    x86 (GenuineIntel 306E4 family 6 model 62 step 4 clock 2600 MHz)
      Intel(r) Xeon(r) CPU E5-2650 v2 @ 2.60GHz
The physical processor has 8 cores and 16 virtual processors (8-15,24-31)
  The core has 2 virtual processors (8,24)
  The core has 2 virtual processors (9,25)
  The core has 2 virtual processors (10,26)
  The core has 2 virtual processors (11,27)
  The core has 2 virtual processors (12,28)
  The core has 2 virtual processors (13,29)
  The core has 2 virtual processors (14,30)
  The core has 2 virtual processors (15,31)
    x86 (GenuineIntel 306E4 family 6 model 62 step 4 clock 2600 MHz)
      Intel(r) Xeon(r) CPU E5-2650 v2 @ 2.60GHz

Should the issue happen, psrinfo -pv shows something like this instead:

The physical processor has 8 virtual processors (0-7)
  x86 (GenuineIntel 306E4 family 6 model 62 step 4 clock 2600 MHz)
        Intel(r) Xeon(r) CPU E5-2650 v2 @ 2.60GHz
The physical processor has 8 virtual processors (8-15)
  x86 (GenuineIntel 306E4 family 6 model 62 step 4 clock 2600 MHz)
        Intel(r) Xeon(r) CPU E5-2650 v2 @ 2.60GHz

When the system is booted, messages similar to these appear:

2016-09-03T04:15:35.308322+00:00 hostname acpidev: [ID 850883 kern.warning] WARNING: acpidev: failed to initialize acpica subsystem.
2016-09-03T04:15:35.308326+00:00 hostname acpidev: [ID 287759 kern.warning] WARNING: acpidev: driver disabled due to initalization failure.
2016-09-03T04:15:35.308329+00:00 hostname acpica: [ID 566992 kern.warning] WARNING: isa_enum: init failed
2016-09-03T04:15:35.308333+00:00 hostname isa: [ID 930810 kern.info] NOTICE: Solaris did not detect ACPI BIOS
2016-09-03T04:15:35.308352+00:00 hostname isa: [ID 477837 kern.info] NOTICE: ACPI is off

Cause

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