Date: Fri, 7 Sep 2007 00:09:50 -0700 From: Luigi Rizzo <rizzo@icir.org> To: Giorgos Keramidas <keramida@ceid.upatras.gr> Cc: current@freebsd.org Subject: Re: how to tell 64 vs 32 bit architecture ? Message-ID: <20070907000950.A91211@xorpc.icir.org> In-Reply-To: <20070906222647.GB2737@kobe.laptop>; from keramida@ceid.upatras.gr on Fri, Sep 07, 2007 at 01:26:47AM %2B0300 References: <20070906111028.A83649@xorpc.icir.org> <20070906222647.GB2737@kobe.laptop>
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On Fri, Sep 07, 2007 at 01:26:47AM +0300, Giorgos Keramidas wrote: > On 2007-09-06 11:10, Luigi Rizzo <rizzo@icir.org> wrote: > > hi, > > i was wondering what is the proper way to tell a 64 vs 32 bit > > architecture. > > > > I see that some code in sys/ uses ' #ifdef __LP64__ ' but i am not > > sure if this is generic enough (ie not gcc or FreeBSD specific), > > and also suitable for userland (i.e. works on linux or other platforms > > as well). > > This is usually needed to differentiate between a feature "X" which > behaves differently in amd64 vs. i386 vs. sparc vs. sparc64, etc. i am actually looking at pointer sizes, as i need to do some pointer manipulation going through intptr_t, and need to know that in the preprocessor because some constants need to be 32 or 64 bit depending on that, and are not trivial (i.e. not 0, 1 or something i can build with size-agnostic expressions) cheers luigi
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