egcs: Problems compiling recen Linux kernels on intel

Horst von Brand vonbrand@inf.utfsm.cl
Thu Dec 4 10:12:00 GMT 1997


Joe Buck <jbuck@synopsys.com> said:
> "Horst von Brand" at Dec 4, 97 10:31 am said:

> > The FAQ mentions a problem with linux/arch/i386/kernel/process.c. This
> > can be worked around (without bad effects I can see) by specifying
> > -fno-strength-reduce for that file. Works up to linux-2.1.70 and
> > egcs-971201, at least.

> Please don't get the Linux people starting using -fno-strength-reduce
> again.  You're just saying "I want my kernel to run more slowly".
> That workaround is inferior to using the patch.

What patch? The FAQ asks for a workaround, this is one.

> > Somebody on linux-kernel@vger.rutgers.edu mentioned that, I've no way to
> > know who it was now.

> The bug is in Linux and should be patched there.  Historically, Linux has
> often used unsafe assembly language code that was experimentally verified
> to work with particular gcc versions (as in: this code is OK if we trick
> gcc into not optimizing it).  New gcc versions have broken this code.
> This happened when 2.7.x came out, and it's happening again with egcs and
> 2.8.0.

You are of course absolutely right; I'm going to take a closer look at this
(and hopefully propose a patch to linux). Just haven't got the time just
now...  But what do you propose to do in the meantime?
-- 
Dr. Horst H. von Brand                       mailto:vonbrand@inf.utfsm.cl
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513




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