AMD64 I386 or X64 load?

Matthew R. Dempsky mrd at
Mon Mar 27 05:02:19 UTC 2006

On Mon, Mar 27, 2006 at 02:51:46PM +1100, James Gray wrote:
> Really?  I tested it on an AMD64 machine with a 32bit and a 64bit kernel, and 
> on an Intel Centrino (32bit) system with that code and default compiler 
> options and it generated the correct results.

Did you use the *exact* same compiler with both the 32-bit and 64-bit 

There are three possible combinations:

    1. 32-bit userspace on 32-bit kernel (e.g. i386 port of Ubuntu)

    2. 64-bit userspace on 64-bit kernel (e.g. amd64 port of Ubuntu)

    3. 32-bit userspace on 64-bit kernel (e.g. 32-bit chroot for wine or 
       installing the i386 port but with an amd64 kernel)

Your program's output will tell you how many bits the userspace is.  I 
*suspect* you tested #1 and #2, which lines up with the kernel you were 
using.  However, if the original poster has munged his system into state 
#3, it might give misleading information.

> If you've got a better idea I'm all for it.

The most fullproof way would be to grab an amd64 Live CD and just see if 
it boots successfully.  If not, the system's probably i386.

A quicker way might be checking /proc/cpuinfo.

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