Jerone Young jerone.young at canonical.com
Mon Dec 22 03:44:53 GMT 2008

This was actually something that was brought up at an open session at
UDS about Google's internal Ubuntu based distro. They were actually
using a 64bit kernel so they could use all the extra memory past 4 gigs.
32bit kernels can do this using PAE, but there is small performance hit
using PAE. They where honestly a little uncomfortable with this approach
and eventually got everything to move to 64bit. 

On Sat, 2008-12-20 at 20:39 +0100, Tollef Fog Heen wrote:
> ]] "Przemek Kulczycki" 
> | I'm wondering if we really need a full 64-bit OS and all applications at all.
> | In [Open]Solaris, only the kernel and some apps are 64-bit, and the
> | rest is still 32-bit because being 64-bit doesn't give them any
> | advantage.
> Does it give them any advantage being 32 bit?  If not, why not just go
> with a pure 64 bit OS?

It's best to have 64bit userland with x86-64 since it is different from
x86 (mainly more registers & optimal instructions). But for other
architectures, such as PowerPC there is little advantage, where there
isn't such a divergence in the architecture with those that are 64-bit

> | I know it's out of scope of this discussion, but maybe instead of
> | having a separate full 32-bit and 64-bit versions of Ubuntu we could
> | try a Solaris way and make a one hybrid 64-bit/32-bit os?
> Sure, you can do that, and if you want to do that properly, you
> implement multiarch.  That's a bit of work, though.

Why not have Ubuntu/Debian more like Fedora & OpenSuse 64bit distros?
I'm curious why this can't be done with dpkg, if rpm can do it?

You can easily run & install 32bit apps on these distros because the
32-bit libs are placed in /lib & /usr/lib .. while the 64bit libs are
placed in /lib64 & /usr/lib64. This allows their 64bit distros to have
easy 32bit comparability and easily install 32bit packages on top of the
64bit distro. 

This would allow for a migration path for users to move to 64bit without
too much suffering with 32bit apps that they may can't let go of just

Though this is more of an issue around closed apps, since you can
usually get a new version of the open source app to that works with
Ubuntu 64-bit.

> -- 
> Tollef Fog Heen
> UNIX is user friendly, it's just picky about who its friends are
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part
Url : https://lists.ubuntu.com/archives/ubuntu-devel/attachments/20081221/855b23ff/attachment.pgp 

More information about the ubuntu-devel mailing list