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.home | help
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