[FUG-BR] Fw: i386 port no longer bootable on non-SSE CPUs

[Nilton Jose Rizzo]

  Não sei se isso é idiotisse ou realmente eles não querem
mais sistemas legados ...... mas acho que luita gente irá ficar chateada
por não poder contar com o FreeBSD para um hardware de roteamento.



---------- Mensagem Encaminhada -----------
De:"Andrew Wilcox" <AWilcox at Wilcox-Tech.com>
Para:"freebsd-current" <freebsd-current at freebsd.org>
Enviada:Fri, 20 Feb 2015 15:09:49 -0600
Assunto:i386 port no longer bootable on non-SSE CPUs

Hello,

The i386 port, both 10-STABLE and 11-CURRENT, will not boot on systems without
SSE support.  This is caused by r273995, as using `svn merge -c -273995` (and
hacking-and-sloshing through the few compiler errors afterwards) makes it once
again bootable.

This crash happens very early on in boot, before even mi_startup (as the
author line is never even printed): http://i.imgur.com/SAty1mT.jpg

This breaks support for all i486, Pentium, Pentium Pro, and Pentium II-based
CPUs and computers.  These are not only found in older computers that are
useful as routers and file servers, but there are some new SoCs still using
these chips:

Intel Galileo board
http://www.frys.com/product/8080584
Pentium core, no MMX/SSE whatsoever.  Released late 2014.

AMD Elan SC520, Geode series
http://www.eurotech.com/en/products/CPU-1421
http://www.amd.com/en-us/products/embedded/processors/lx
While the Elan is no longer manufactured, it still remains popular.  The new
Geode LX series of processors only implement MMX (so are roughly equivalent to
a Pentium Pro in terms of instruction set).

Backing out r273995 allows boot to proceed normally, as shown here:
http://imgur.com/a/WWsa5

I attempted to revert locore.S to see if it was related to the stack setup
changes found in that commit and it made no difference; the panic was the same.

I would be willing to test any patches/diffs on any or all of the systems I
have, but unfortunately I'm in a bit over my head trying to figure out which
part of this commit is causing it.

Best,
Andrew

--
Andrew Wilcox, C/C++/Python developer, kernel hacker
Blog:   http://blog.foxkit.us/  WWW: http://foxkit.us/
GitHub:  https://github.com/awilfox

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**Nilton José Rizzo            UFRRJ
**http://www.rizzo.eng.br      http://www.ufrrj.br
**http://lattes.cnpq.br/0079460703536198
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