Downgrading from amd64 to i386

[Sean]

Subhro wrote:
> Andrew P. sat at his 'puter and typed on 9/18/2005 1:49:
> 
>> Hello!
>>
>> I use FreeBSD/amd64 6.0 as the only OS on my desktop
>> PC. Having carefully thought over pros and cons, I decided
>> to downgrade to i386 for the time being.
>>  
>>
> What on earth does this mean? This is simply not possible. amd64 is a 
> completely different platform. i386 is a 32 bit platform and amd64 is a 
> 64 bit one. You can upgrade or downgrade from one version to other 
> provided the platform remains constant. But upgrading from one patform 
> to other involves buying and assembling physically different hardware 
> holding different copies of OS.
> 
> Thanks
> S.
> 

But the AMD hardware, for example I have a dual Opteron, can run in 
64(amd64) or 32(i386) bit mode.
So could you upgrade i386 to amd64 on such a system?
Sounds interesting.