disabling hyperthreading when no access to bios in freebsd8

Hi

on freebsd7 I see the following sysctl.

Code:
machdep.hlt_logical_cpus

on freebsd8 its missing, any ideas? the docs indicate it still should be there and SMP is enabled.

processor is an i7 and hyperthreading is on.
 
The sysctl and kernel tunable are still there, so I think that the logic for determining whether or not a CPU is logical is incorrect for i7 (even on 9-CURRENT). I'll talk to jhb@ about this and see if it can get resolved and MFCed.
 
I've done some more poking around and it appears that it does properly detect that they're logical processors (note SMT):

Code:
CPU: Intel(R) Xeon(R) CPU           W3520  @ 2.67GHz (2694.12-MHz K8-class CPU)
  Origin = "GenuineIntel"  Id = 0x106a5  Family = 6  Model = 1a  Stepping = 5
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x9ce3bd<SSE3,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,DCA,SSE4.1,SSE4.2,POPCNT>
  AMD Features=0x28100800<SYSCALL,NX,RDTSCP,LM>
  AMD Features2=0x1<LAHF>
  TSC: P-state invariant
real memory  = 12884901888 (12288 MB)
avail memory = 12379992064 (11806 MB)
ACPI APIC Table: <091109 APIC2100>
FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs
FreeBSD/SMP: 1 package(s) x 4 core(s) x 2 SMT threads
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP): APIC ID:  1
 cpu2 (AP): APIC ID:  2
 cpu3 (AP): APIC ID:  3
 cpu4 (AP): APIC ID:  4
 cpu5 (AP): APIC ID:  5
 cpu6 (AP): APIC ID:  6
 cpu7 (AP): APIC ID:  7

I'm emailing jhb@ to see if this is a known issue or the implementation was done this way on purpose.
 
ok thanks for the response.

here is confirmation of the SMT also.

Code:
CPU: Intel(R) Core(TM) i7 CPU         920  @ 2.67GHz (2684.00-MHz K8-class CPU)
  Origin = "GenuineIntel"  Id = 0x106a5  Stepping = 5
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x98e3bd<SSE3,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1,SSE4.2,POPCNT>
  AMD Features=0x28100800<SYSCALL,NX,RDTSCP,LM>
  AMD Features2=0x1<LAHF>
  TSC: P-state invariant
real memory  = 12889096192 (12292 MB)
avail memory = 12312739840 (11742 MB)
ACPI APIC Table: <7522MS A7522800>
FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs
FreeBSD/SMP: 1 package(s) x 4 core(s) x 2 SMT threads
 
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