[SOLVED] why i486 not i686?

Mercury305 · 01-17-2013, 02:30 PM

Just wanted to know why most packages are compiled i486 instead of i686? since i686 is a later architecture cpu's.

dugan · 01-17-2013, 02:34 PM

They're i686-optimized, i486-compatible.

Previous discussions:

Mercury305 · 01-17-2013, 03:08 PM

interesting. i think i was about 15 years old or so when i486 was being used. I guess some people collect antique computers and run slackware on them? But as long as its 686 optimized there shouldn't be a problem.

TobiSGD · 01-17-2013, 03:19 PM

Changing Slackware to be compiled for i686 (instead of only being optimized for it) would not only kick i486 CPUs out of the game, but also i586 compatible CPUs (Pentium, Cyrix/IBM 6x86, Winchip CPUs, AMD's K5, K6, K6-II, K6-III and older Geode, some older VIA C3, many embedded designs that I can't mention all here). Many of these are still in use around the world, especially in countries where computer parts aren't cheap or where other things just matter more than upgrading the computer.

Didier Spaier · 01-18-2013, 02:05 AM

Here are three side notes as I like posting in [SOLVED] threads

(1) A similar question, with a poll, was asked a while ago, see this thread
(2) Another question is: "do we still need to support non-smp i486 kernel in Slackware". It was already asked but It would have deserved more reasoned answers, or more developed rationale in the answers IMO
(3) On the other hand don't ask to support back all 386 CPUs as it's probably too late if we are to use a 3.8 or newer kernel, see here...

wildwizard · 01-18-2013, 06:26 AM

Quote:

Originally Posted by Didier Spaier

(3) On the other hand don't ask to support back all 386 CPUs as it's probably too late if we are to use a 3.8 or newer kernel, see here...

i386 was dropped a long time ago by accident, I don't know if it could be done today but back then it would have taken a rebuild of the entire system.

ftp://ftp.slackware.com/pub/slackwar...gcc.SlackBuild

Code:

# Why i486 and not i386?  Because the shared C++ libraries in gcc-3.2.x will
# require 486 opcodes even when a 386 target is used (so we already weren't
# compatible with the i386 for Slackware 9.0, didn't notive, and nobody
# complained :-).  gcc-3.3 fixes this issue and allows you to build a 386
# compiler, but the fix is done in a way that produces binaries that are not
# compatible with gcc-3.2.x compiled binaries.  To retain compatibility with
# Slackware 9.0, we'll have to use i486 (or better) as the compiler target
# for gcc-3.3.