On Mon, May 28, 2012 at 02:43:47PM +0000, Andy Smith wrote: I've encountered an interesting reason for 64bit recently - apparently go (http://golang.org/) has problems with long running 32 bit server processes that go away on 64bit. Not that I have any code that actually qualifies. Michael

On 28/05/2012 15:43, Andy Smith wrote: Another thought to throw in to the mix here is the x32 ABI, introduced with linux 3.4: this essentially uses all of the architectural features of x86-64 (thus gaining the benefit of the extra registers and other improvements over vanilla x86-32), but uses 32-bit addressing. This gives you much of the benefit of the x86-64 arch without the memory overhead of 64-bit pointers, and is ideal for circumstances where the 32-bit address space is never going to be exceeded (e.g. the vast majority of customer VPSes at present). As I understand it (i.e. correct me if I'm wrong), the kernel itself would still be x86-64, so from a hosting point of view guests would look & work exactly the same as regular 64-bit guests. OS support is some way off yet, for Debian we're probably looking at the release after Wheezy (i.e. sometime in 2015), by which time the point may be moot if there is a sufficient abundance of memory. That said, even with a doubling of RAM I imagine there will still be a decent proportion of customers with < 2GiB memory at that time for whom an x32 userspace might make sense. -- Phil