[ubuntu-uk] 64 vs 32bit Applications

[Paul Waring]

On Wed, Jun 01, 2016 at 11:33:11AM +0100, Nigel Verity wrote:
>    I don't have a technical issue but I'd welcome a bit of enlightenment.....
> 
>    I've recently gone over to 64bit Ubuntu versions on all my boxes and this
>    raised a question. Does every binary object in the repositories have to be
>    compiled twice - once for 32 and again for 64bit architectures - or can
>    32bit compilations run on a 64bit host?

In theory 32 bit software should run on a 64 bit architecture (assuming
x86) as 64 bit CPUs can still run 32 bit code.

>    If they are separate versions is there a likelihood that some particularly
>    obscure packages will fall by the wayside simply through being considered
>    not worth compiling for 64bit? Perhaps there is a formal policy on this.

There's an Ask Ubuntu topic about this very question:

http://askubuntu.com/questions/359156/how-do-you-run-a-32-bit-program-on-a-64-bit-version-of-ubuntu

The short answer seems to be that if you install software via the
official repositories it will 'just work'. If you want to run unpackaged
software then you need to do a bit of fiddling to ensure that you get
the right versions of the relevant libraries (it took me several days to
get a piece of legacy 32 bit software to run on Scientific Linux when
they dropped out of the box support for 32 bit).

-- 
Paul Waring
Freelance consultant
http://www.pwaring.com