[CentOS] Re: 64 Bit?

[Scott Lamb]

On May 21, 2007, at 10:30 AM, drew einhorn wrote:

> Thanks, Is there a guide somewhere on how to read the cpu info.

Not that I know of, but there's always the source:

* http://lxr.linux.no/ident?i=cpuinfo_op
* http://lxr.linux.no/source/arch/i386/kernel/cpu/proc.c#L11
* http://lxr.linux.no/source/include/asm-i386/cpufeature.h

In particular, "lm" (a.k.a. X86_FEATURE_LM) appears to indicate 64- 
bit support.

> I do remember seeing stuff about hyperthreading on this box.
> Does hyperthreading imply 64 bit.

No.

> Here's the cpu from another box that has hyperthreading, but I
> was assuming it was not 64 bit.  Can I run a 64-bit kernel on this  
> one?
> processor       : 0
> vendor_id       : GenuineIntel
> cpu family      : 15
> model           : 2
> model name      : Intel(R) Pentium(R) 4 CPU 3.40GHz
> stepping        : 5
> cpu MHz         : 3392.058
> cache size      : 2048 KB
> fdiv_bug        : no
> hlt_bug         : no
> f00f_bug        : no
> coma_bug        : no
> fpu             : yes
> fpu_exception   : yes
> cpuid level     : 2
> wp              : yes
> flags           : 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 ht tm pbe up

No. It doesn't have "lm", so it must not support 64-bit.

-- 
Scott Lamb <http://www.slamb.org/>