[Bug 572215] [NEW] too many cores detected on intel i7

[Bernhard Neuhofer]

Public bug reported:

Binary package hint: linux-image

I upgraded my 32-bit ubuntu 9.10 to ubuntu 10.04 and the kernel 2.6.32 won't boot. 
Only the old kernel from ubuntu 9.10.

If I disable the quiet and splash screen option in grub I can see that
the kernel crashes while detecting/ initializing the cpu cores:


 CPU 1 irqstacks, hard=c03dc000 soft=c03bc000
Not responding.
Inquiring remote APIC #1...
... APIC #1 ID: failed
... APIC #1 VERSION: failed
... APIC #1 SPIV: failed
CPU #1 not responding - cannot use it.
... for 8!! cpus. Which results in 8+8 = 16 Cores!!!


I can only boot with the option noht (hyperthreading disabled) wich results in 8 cpu cores, which is wrong because the i7 has 4 real und 4 hyperthreading cores. Strangely this seems to work. An other way is to disable hyperthreading in the bios which results in 4 useable cores.

The same error appears with the generic and the generic-pae image.

My System:
Intel Core i7-860
4GB RAM
Gigabyte P55M-UD4 with latest F8 Bios
Geforce 8800GTS
SATA AHCI Samsung 500GB

** Affects: linux-meta (Ubuntu)
     Importance: Undecided
         Status: New

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too many cores detected on intel i7
https://bugs.launchpad.net/bugs/572215
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