Re: [RFC] POSIX personality

[Linus Torvalds]

On Thu, 23 May 2002, Bill Davidsen wrote:
>
> I think the reason which comes to mind is avoiding future problems. By
> having a single POSIX mode flag not only does the program not have to know
> about setting the "right" other bits today, but if we find that POSIX
> behaviour is needed in some other area in the future, the program doesn't
> need to be modified and recompiled, because the POSIX behaviour "is in
> there" for all things.

That's a nice argument in theory, but if you change the behaviour of
existing flags, you might fix some program for the real semantics, but you
might equally well _break_ some program that unwittingly depended on the
old semantics.

So I think your argument is fundamentally flawed. The binary has been
tested with the old behaviour, and assuming that you can "fix" existing
binaries by changing kernel behaviour is a seriously flawed argument.

Yes, it might work for some programs, but basically you're on very thin
ice.

Does Linux break stuff when absolutely required? Sure. But designing an
interface that _plans_ on changing semantics is just incredibly stupid,
and should absolutely not be done. Ever.

			Linus