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Date:      Fri, 5 Sep 2003 02:59:22 +0200
From:      Marius Strobl <marius@alchemy.franken.de>
To:        Marcel Moolenaar <marcel@xcllnt.net>
Cc:        current@freebsd.org
Subject:   Re: Question about genassym, locore.s and 0-sized arrays (showstopper for an icc compiled kernel)
Message-ID:  <20030905025922.A68885@newtrinity.zeist.de>
In-Reply-To: <20030904224709.GA48780@ns1.xcllnt.net>; from marcel@xcllnt.net on Thu, Sep 04, 2003 at 03:47:09PM -0700
References:  <20030904180448.021a1b6b.Alexander@Leidinger.net> <20030904162858.GI98381@dan.emsphone.com> <20030905001411.3a9030b3.Alexander@Leidinger.net> <20030904224709.GA48780@ns1.xcllnt.net>

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On Thu, Sep 04, 2003 at 03:47:09PM -0700, Marcel Moolenaar wrote:
> 
> We use the size of the symbol (ie the size of the object identified
> by the symbol) to pass around values. This we do by creating arrays.
> If we want to export a C constant 'FOOBAR' to assembly and the constant
> is defined to be 6, then we create an array for the sign, of which the
> size is 1 for negative numbers and 0 otherwise. In this case the array
> will be named FOOBARsign and its size is 0. We also create 4 arrays (*w0,
> *w1, *w2 and *w3), each with a maximum of 64K and corresponding to the
> 4 16-bit words that constitutes a single 64-bit entity.
> In this case
> 	00000006 C FOOBARw0
> 	00000000 C FOOBARw1
> 	00000000 C FOOBARw2
> 	00000000 C FOOBARw3
> 
> If the compiler creates arrays of size 1 for arrays we define as a
> zero-sized array, you get exactly what you've observed.
> 

Is this rather complex approach really necessary? I have successfully
generated assyms.s' using genassym.sh(8) from NetBSD and both ICC and
GCC on i386 which have exactly the same values as one generated with
sys/kern/genassym.sh from FreeBSD. The genassym.sh(8) of NetBSD kind
of directly exports the C-constants so it just needs one symbol per
constant and doesn't require zero sized arrays. Given that it's from
NetBSD their approach also should be very MI.



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