x32 abi support?

[Alexander Larsson]

On Thu, 2012-05-17 at 02:28 +0200, Kevin Kofler wrote:
> Nicolas Chauvet wrote:
> > So that make me wonder if we really need to built the whole collection
> > as x32 ? Or if we only wants a selection of components to be optimized
> > by x32. For example does it matter to move the whole Xorg server
> > infrastructure as x32 or is it possible to leave it as x86_64 ? or is
> > there any benifit for the move to x32 in this area ?
> 
> As already explained in this thread by others, if you have a mix of x32 and 
> normal x86_64, you end up with both multilibs in memory, negating the memory 
> savings from the bastard x32 ABI.

I don't think this is always the case. Obviously if you run a lot of
both kinds of apps it matters, but if there are a few, small x86-64
processes (say e.g. the xserver, or a database instance) the doubled mem
use from some shared libraries should not affect things overly much. In
most practical uses of computers (i.e. those that actually *do*
something) most memory is used for the users "data", and for that, x32
uses less ram, as all pointers in the ram structures are half the size.

Obviously, it all "depends". But I think x32 makes a lot of sense as an
option, especially in the virtual machine space.