[ubuntu-us-nm] Building own system and 64-bit

Joe Pfeiffer joseph at pfeifferfamily.net
Mon Apr 21 15:30:51 BST 2008

Some answers but not all:

Andrew Parker writes:
>Now the 64-bit questions.  
>     1. Do I gain any advantage getting a 64-bit processor if Windows XP
>        (in a VM) runs on 32-bit, other than upgradability?

No.  If you're running 32-bit, having a 64-bit processor makes no

>     2. The processors that I am looking at say they support 64-bit.
>        But are they really 64-bit?  For example, are the Intel Core 2
>        Quad, Core 2 Duo and the Dual Core all 64-bit?  I do not think
>        so.

Yes.  Everything Intel calls "Core 2" is 64-bit.  I'm not sure about
"Dual Core"; if you mean "Pentium Dual Core", the answer is yes for
that as well.  See


>     3. If I get a 64-bit chip, can I run a 32-bit Ubuntu?

Yes.  My wife has a 64-bit AMD laptop, which we run 32-bit Debian on.

>     4. But, if I run 64-bit Ubuntu can I run software built for 32-bit?
>        Looking at the Grass website, there is a AMD64 version and an
>        I386.  Does the AMD64 apply to Intel 64-bit too?  And the I386
>        the 32-bit version?

Yes, though here you're reaching the limits of what I know about.
Apparently you can run a 32-bit kernel and 64-bit applications, or the
other way around, but it involves some sort of magic with putting the
right libraries in the right places.  Haven't tried it...

>     5. What about VMware. If I run 64-bit Ubuntu, 64-bit Vmware, can I
>        run my 32-bit Windows XP?  And, if I run the 64-bit VWmware, can
>        I transfer my existing VM running on a 32-bit Ubuntu to the
>        64-bit VMware Version?

No idea.

>     6. If I go with a 64-bit processor and a 32-bit Ubuntu, will I be
>        able to utilize 8GB of RAM?

Assuming Ubuntu's kernel is compiled with HIGHMEM enabled (which I
would guess to be a pretty safe assumption), yes.

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