PROPOSAL: Remove 32-bit x86 host support in 4.2 development branch

[Keir Fraser <keir.xen@gmail.com>]

Folks,

There's been discussion in the past about eventually removing support for
32-bit x86 in the development branch of the hypervisor. The reasons being:
 * It takes developer effort to maintain and test
 * Most repackagers are supplying 64-bit only hypervisor binary these days
 * 32-bit target is not supported in any case for various new hypervisor
features (e.g., memory paging, memory sharing, memory access trapping)
 * 64-bit support has been standard in all mainstream x86 processors for
about the last 5 years. With a 64-bit processor there is no reason to run
the 32-bit hypervisor, as the 64-bit hypervisor supports all 32-bit guests.

With 4.1 branched I'd like to raise this topic again. Does anyone have a
strong argument for keeping the 32-bit x86 target alive?

 Thanks,
 Keir