Re: pre egcs-1.1 testing and Linux 2.1.x

David S. Miller (davem@dm.cobaltmicro.com)
Sun, 23 Aug 1998 13:10:21 -0700


Date: Sun, 23 Aug 1998 12:52:30 -0700 (PDT)
From: Linus Torvalds <torvalds@transmeta.com>

NOBODY said "we don't recommend using the feature, because we know
it has problems but we hope to fix them"

Jeff said precisely this pinhead, you must have missed it. Since you
have, let me quote him:

------------------------------------------------------------
No code using regparm is safe. Again, you might get away with it for
a while, but in the end, it's going to generate incorrect code. And
(of course) the places where incorrect code is generated will vary
from one version of the compiler to the next due to subtle differences
in the generated code.

I strongly recommend against using regparm until such time as someone
can rewrite reload to deal with machines with small register classes
like the x86.
------------------------------------------------------------

Translates to me info: "We don't recommend using this feature"

Furthermore a long discussion has been happening on the egcs list
about how to begin tackling this problem, yet at the same time
acknowledging the fact that it is a long term job.

Instead, people said "we're going to make the problem go away by hiding
the feature".

Nobody has said this, instead they have said that it should be turned
off by default for everyone, for the purposes of ensuring (in all
cases, and with a change that is simple to verify right now) people
don't get incorrect code-gen until we fix it. Everyone has expressed
the full intention of fixing the problem.

And THAT in turn means that we can't compile the kernel with such a
compiler.

No, it means nobody who uses regparm will get them. In this view, the
fact that the kernel depends upon it is a moot point. Don't use the
fact that Linux happens to depend upon it now as a way to force your
wishes on the egcs team (Linux needs it, don't disable it dammit),
that's impolite.

Later,
David S. Miller
davem@dm.cobaltmicro.com

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