SMP in 5.1 cant deactivate hyperthreading

[Steven Hartland]

sysctl machdep.hlt_logical_cpus:
machdep.hlt_logical_cpus: 1

Relevant sections from dmesg:
Programming 24 pins in IOAPIC #0
IOAPIC #0 intpin 2 -> irq 0
Programming 24 pins in IOAPIC #1
Programming 24 pins in IOAPIC #2
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
 cpu0 (BSP): apic id:  0, version: 0x00050014, at 0xfee00000
 cpu1 (AP):  apic id:  6, version: 0x00050014, at 0xfee00000
 cpu2 (AP):  apic id:  1, version: 0x00050014, at 0xfee00000
 cpu3 (AP):  apic id:  7, version: 0x00050014, at 0xfee00000
 io0 (APIC): apic id:  2, version: 0x00178020, at 0xfec00000
 io1 (APIC): apic id:  3, version: 0x00178020, at 0xfec80000
 io2 (APIC): apic id:  4, version: 0x00178020, at 0xfec80400

acpi_timer0: <24-bit timer at 3.579545MHz> port 0x1008-0x100b on acpi0
acpi_cpu0: <CPU> on acpi0
acpi_cpu1: <CPU> on acpi0

acpi_cpu: throttling enabled, 8 steps (100% to 12.5%), currently 100.0%
ad0: 38166MB <WDC WD400JB-00ENA0> [77545/16/63] at ata0-master UDMA100
SMP: AP CPU #2 Launched!
SMP: AP CPU #1 Launched!
SMP: AP CPU #3 Launched!


mptable:
===============================================================================
MPTable, version 2.0.15
-------------------------------------------------------------------------------
MP Floating Pointer Structure:
  location:                     BIOS
  physical address:             0x000f7190
  signature:                    '_MP_'
  length:                       16 bytes
  version:                      1.4
  checksum:                     0x2b
  mode:                         Virtual Wire
-------------------------------------------------------------------------------
MP Config Table Header:
  physical address:             0x0009fc70
  signature:                    'PCMP'
  base table length:            372
  version:                      1.4
  checksum:                     0x9e
  OEM ID:                       ' '
  Product ID:                   'Kings Canyon'
  OEM table pointer:            0x00000000
  OEM table size:               0
  entry count:                  35
  local APIC address:           0xfee00000
  extended table length:        0
  extended table checksum:      0
-------------------------------------------------------------------------------
MP Config Base Table Entries:
--
Processors:     APIC ID Version State           Family  Model   Step    Flags
                 0       0x14    BSP, usable     15      2       7       0xbfebfbff
                 6       0x14    AP, usable      15      2       7       0xbfebfbff
                 1       0x14    AP, usable      15      2       7       0xbfebfbff
                 7       0x14    AP, usable      15      2       7       0xbfebfbff

systat:
                    /0   /10  /20  /30  /40  /50  /60  /70  /80  /90  /100
root     idle: cpu1 XXXXXXXXXX
root     idle: cpu2 XXXXXXXXXX
root     idle: cpu3 XXXXXXXXXX
root     idle: cpu0 XXXXXXXXXX
             <idle> XXXXXXXX