[OpenIndiana-discuss] Tribblix update

[Peter Tribble]

On Mon, Dec 17, 2012 at 11:41 AM, Jim Klimov <jimklimov at cos.ru> wrote:
> On 2012-12-17 06:59, Alan Coopersmith wrote:
>>
>> Oh, and it assumes no one needs 32-bit binaries any more,
>> [...]
>
> Well, I may probably get corrected (and should, if need be) - but
> in such discussions I've always thought (and heard) that these are
> two different things. 64-bit kernel is for optimal harnessing of
> hardware with large (>4gb) memory and perhaps wider instructions
> on CPU.
>
> 64-bit or 32-bit userspace programs is about addressing virtual
> memory again and large files to an extent (AFAIK the latter can
> be used with 32-bit programs too). 64-bit userspace with "small"
> programs like many UNIX command-line tools, GUI applets, etc.
> which don't feasibly need to juggle gigabytes of data at once -
> now, that would also be about wasting RAM and CPU cycles on
> pushing around more bytes of pointers and other increased
> structures with no practical gain.
>
> Am I wrong to maintain this point of view?

It's a trade-off. Certainly on x86, 64-bit code is significantly quicker
(it's much more modern). On SPARC, it's probably so-so.

If you have to support a 32-bit system, then you're forced to ship
32-bit userspace binaries. You could ship both 32- and 64-bit,
and use isaexec, but that's additional work to build, more bytes
to ship, and a slight performance hit to go through isaexec. If you
don't have to support 32-bit at all, then you don't have to worry
about those compromises and can just ship 64-bit applications
and be done with it.

-- 
-Peter Tribble
http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/