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Date:      Tue, 16 Dec 2008 22:27:46 +0100
From:      Roman Divacky <rdivacky@freebsd.org>
To:        "M. Warner Losh" <imp@bsdimp.com>
Cc:        arch@freebsd.org
Subject:   Re: Removing some cruft...
Message-ID:  <20081216212746.GA28834@freebsd.org>
In-Reply-To: <20081216.131845.-1739986974.imp@bsdimp.com>
References:  <20081216.131845.-1739986974.imp@bsdimp.com>

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On Tue, Dec 16, 2008 at 01:18:45PM -0700, M. Warner Losh wrote:
> I was looking at the MIPS elf stuff based on a submission of some
> 64-bit support.  In doing so, I discovered a number of 'unused' types
> that appear to have comments that indicate that they can be removed
> now and were just slavishly copied from arch to arch to arch.
> 
> /*
>  * The following non-standard values are used for passing information
>  * from John Polstra's testbed program to the dynamic linker.  These
>  * are expected to go away soon.
>  *
>  * Unfortunately, these overlap the Linux non-standard values, so they
>  * must not be used in the same context.
>  */
> #define	AT_BRK		10	/* Starting point for sbrk and brk. */
> #define	AT_DEBUG	11	/* Debugging level. */
> 
> These have be slavishly copied to arm, powerpc, sparc64, ia64, mips,
> sun4v and amd64.  All these files have nearly identical comments
> (except powerpc, which changes the value).
> 
> The only place these are used in the kernel is in the Linux!
> emulation in i386/linux/linux_sysvec.c and
> amd64/linux32/linux32_sysvec.c:
> 
> 	if (args->trace)
> 		AUXARGS_ENTRY(pos, AT_DEBUG, 1);
> 
> Since AT_DEBUG and AT_UID have the same value, and we look at AT_UID
> later, we wind up passing the wrong value for AT_UID.  Fortunately, we
> don't use AT_UID for anything in the tree....

I cannot find any reference of AT_DEBUG in linux 2.6.16 sources and it
indeed looks bogus...



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