Migrating i386 to amd64

[David O'Brien]

On Fri, Dec 31, 2004 at 10:17:17PM +0100, Michael Reifenberger wrote:
> On Fri, 31 Dec 2004, Ade Lovett wrote:
> ...
> >>Do my old i386 ports (like X etc) work under amd64?
> >
> >Simple answer.  No.  Steps (1) and (2) above are implying a complete 
> >binary system reinstall.  Part of the data you should probably be backing 
> >up is a list of installed packages so you can put the amd64 ones back in 
> >after installing kernel+userland.
> >
> 
> Autsch.
> Thats what I didn't want to hear.
> Thanks anyway!
> 
> BTW: Do I have any benefit of using this hardware (2GB RAM) with amd64
> in favour of i386 (besides a bigger virtual address space)?

Yes.  A 64-bit kernel is often more efficient because so many of the
kernel data structures these days are 64-bit counters, etc..  Also the
AMD64 ABI has 8 more general purpose registers, which gives the compiler
a lot more to work with in optimizing and allows parameters to be passed
thru registers vs. the slower memory stack.  I also would not dismiss the
benefits of the larger virtual address space.  There are applications
where the kernel really benefits from not being constrained to its
limited amount of VA in 32-bit mode.

-- 
-- David  (obrien at FreeBSD.org)