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Date: Fri, 2 Nov 2001 05:55:43 +0000
From: Pavel Machek <pavel@suse.cz>
To: Ingo Molnar <mingo@elte.hu>
Cc: Jamie Lokier <lk@tantalophile.demon.co.uk>,
       Linus Torvalds <torvalds@transmeta.com>, linux-kernel@vger.kernel.org
Subject: Re: [patch] complain about unknown CLONE_* flags
Message-ID: <20011102055542.N35@toy.ucw.cz>
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Hi!

> > Ingo, how do you handle this sort of backward compatibility in your
> > latest pthreads library, or don't you do backward compatibility?
> 
> [btw., it's not me doing it but Ulrich Drepper. I'm mostly doing the 'lets
> find out how the kernel could help' side of things.]
> 
> the proper way of doing this is a way of getting fundamental kernel
> capabilities, not the 'probing' of the kernel in various ways. Glibc
> starts looking like old ISA drivers trying to do nonintrusive
> autodetection: 'lets try this port carefully without disturbing state,
> perhaps this feature is there'.
> 
> one way to handle this cleanly would be to add a kernel capabilities
> bitmask to sysconf(), and backport this to all mainstream Linux kernels

I'm afraid that bitmask will get out-of-date. Doing EINVAL seems like a good
way to do this. [Hmm, perhaps we need CLONE_DONT which only checks capabilities
and returns? It still seems better than sysconf...]
									Pavel
-- 
Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt,
details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html.

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