[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Debian AMD64 Port Ready

* Martin Schulze (joey@infodrom.org) wrote:
> Wouter Verhelst wrote:
> > AIUI, that's not how AMD64 works. If I understood things right, 64bit
> > applications can only use 64 libraries; you can't mix them in one
> > program.

I'm quite confident this is the case.  There are methods out there which
will let you do this kind of nasty library mixing (used in Winbloze and
OS/2 I believe) but as far as I know Linux doesn't support it.  It's
called 'trunking' or something along those lines, iirc.  Basically you
have to mangle the pointers and whatnot to make it work, at the very
least, and it's *really* ugly.

> What's the benefit of a mixed environment then?

Some applications run faster as 32bit binaries, especially on systems
like Sparc64.  Some run faster as 64bit binaries due to lots of 64bit
operations and less pointer work.  Practical examples include:

Sparc64 system:
Most applications 32bit since it's faster and they don't need 64bit.
PostgreSQL, Oracle, home-grown stuff 64bit for additional memory
space and increased speed of 64bit operations.

AMD64 system:
Most applications 64bit since it's generally faster and they get the
benefit of 64bit for 'free' due to the additional registers and whatnot.
Home-grown stuff, non-64bit-clean stuff 32bit for speed of smaller
pointers and so they don't segfault if not 64bit clean.  Also the
ability to run commercial 32bit applications that havn't been ported to
amd64 proper yet.

Hope that helps.


Attachment: signature.asc
Description: Digital signature

Reply to: