Date: Thu, 17 Mar 2005 23:17:27 -0700 From: Scott Long <scottl@samsco.org> To: David Schultz <das@FreeBSD.org> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/lib/msun/i387 fenv.c fenv.h Message-ID: <423A7277.1000202@samsco.org> In-Reply-To: <20050318061647.GA40922@VARK.MIT.EDU> References: <200503172221.j2HMLkfq017761@repoman.freebsd.org> <20050318055212.GA70385@FreeBSD.org> <20050318061647.GA40922@VARK.MIT.EDU>
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David Schultz wrote: > On Fri, Mar 18, 2005, Alexey Dokuchaev wrote: > >>On Thu, Mar 17, 2005 at 10:21:46PM +0000, David Schultz wrote: >> >>>das 2005-03-17 22:21:46 UTC >>> >>> FreeBSD src repository >>> >>> Modified files: >>> lib/msun/i387 fenv.c fenv.h >>> Log: >>> Make the fenv.h routines work for programs that use SSE for >>> floating-point arithmetic on i386. Now I'm going to make excuses >>> for why this code is kinda scary: >>> >>> - To avoid breaking the ABI with 5.3-RELEASE, we can't change >>> sizeof(fenv_t). I stuck the saved mxcsr in some discontiguous >>> reserved bits in the existing structure. >> >>Why do you care about ABI compatibility between 6-CURRENT and 5.3-RELEASE? >>If you plan to MFC this code at some point, you could use your current >>approach in RELENG_5. This would, of course, mean you'd have to maintain >>two different code sets, but still. > > > The reasons are manifold. For one, I would like the complicated > version to get exposure in -CURRENT before I MFC it. Further, > this only adds a few extra instructions, so it's not a big deal, > particularly compared to the code to support older processors. > You're right that I could just bump the libm version number and > break the ABI, but that inconveniences people, so I would like to > avoid it when possible. You had better bump the version number for libm before 6.0 rolls around!! I've just found a 3rd party binary-only package that supports 'FreeBSD 5.x' but is linked against libm.so.2. Ugh. We need to bury that mistake and NOT make it again. Scott
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