Re: Debian AMD64 and Intel CPUs
On Sun, Jul 12, 2009 at 20:22, David Fox <dfox94085@gmail.com> wrote:
>
> On Sun, Jul 12, 2009 at 2:24 PM, T o n g<mlist4suntong@yahoo.com> wrote:
>
> > Can someone tell me what kind of Intel CPUs have that EM64T? Any easy
> > rule of thumb? E.g., can I safely assume all those Intel 64 Duecore are
>
> One needs to be careful with Intel nomenclature. Some CoreDuos are 32
> bit only, but most if not all core 2 duos can do 64bit. Actually, 64
> bit is pretty commonplace these days, unless you have a fairly old
> processor.
All Core 2 and higher CPUs are 64 bit. In fact all current Intel CPUs
(except the ultra-low power Atom) are 64 bit. Even the low-end current-gen
Celeron and so-called "Intel Pentium" are 64 bit.
On the other hand, none of the now-retired Core Solo/Core Duo (Yonah)
or older Pentium M line where 64 bit.
The P4 and Pentium D had some 32 bit chips and later some 64 bit chips.
> But to be certain, the rule of thumb is to do a 'cat /proc/cpuinfo'
> and look for the lm (long mode) flag. The presence of that flag
> indicates 64 bit capability.
>
>
> Another caveat relating somewhat to Intel chips - it is best to query
> intel directly regarding the feature set of the intended processor
> model number, not only for 64 bit (which most will have) but for
> virtualization capability, which some will not have. I pointed this
> out at a gathering yesterday -- if you look at the more recent
> offerings from intel, some of the lower end CPUs will have VT
> capability, but other newer ones will not, and then later on, VT
> capability resumes. It's as if the feature is disabled in some of
> their processors.
>
> I surmise this only affects some virtualizattion. For instance, on my
> Q6600 (core 2 quad, not the most screamingly fast cpu, but more than
> adequate for my needs) I can do Virtualbox fine, but on my laptop
> (Core2Duo T5800) virtualization is not supported, at least not by
> Virtualbox, as the CPU seems to omit this feature.
It is true that VT is not in all current Intel chips, and it is hard to
predict which ones have it. However, VirtualBox should still run fine,
just without that special acceleration. KVM and some others, however
require VT.
Cheers,
Kelly Clowers
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