From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,eeee56c19a542f8d X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,UTF8 Path: g2news2.google.com!news4.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca.giganews.com!nntp.scarlet.biz!news.scarlet.biz.POSTED!not-for-mail NNTP-Posting-Date: Sat, 20 May 2006 06:27:00 -0500 From: Ludovic Brenta Newsgroups: comp.lang.ada Subject: Re: Multi-arch References: <1147857777.703653.268610@j33g2000cwa.googlegroups.com> <1148023421.378001.90560@j33g2000cwa.googlegroups.com> Date: Sat, 20 May 2006 13:18:46 +0200 Message-ID: <877j4h54h5.fsf@ludovic-brenta.org> User-Agent: Gnus/5.110004 (No Gnus v0.4) Emacs/21.4 (gnu/linux) Cancel-Lock: sha1:AO8Q1SJbLnztUces8WPISmD+BDU= MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit NNTP-Posting-Host: 62.235.55.89 X-Trace: sv3-k49zhLAs8XwbSz9+WbJW758RKZf75w0zvoH++9CUTBvh3DBizv/GM3grk8JKE2CxqIs7FpEKWMAc6BY!N9QctbsEbyrHk1Lqb4yhXEQPpaNth5edTNjT3cfPiGE42fepltiaySk2fvPk6j8qRwyLCOiE X-Complaints-To: abuse@scarlet.be X-DMCA-Complaints-To: abuse@scarlet.biz X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.32 Xref: g2news2.google.com comp.lang.ada:4312 Date: 2006-05-20T13:18:46+02:00 List-Id: Björn Persson writes: > Ludovic Brenta skrev: >> Björn Persson a écrit : >>> Is multi-arch useful in an altogether free system in some way that >>> eludes me? >> Yes. >> Today, for example, OpenOffice works only on 32-bit architectures; if >> you want to run it on an amd64 machine, you need biarch or multiarch. >> There are probably other cases where compiling for one of the >> architectures in a multi-arch system is problematic. > > That sounds like a defect in OpenOffice, so in that case multi-arch > support functions as a workaround for a buggy program. I think it's a bit more complex than that; it may well be a defect in OpenOffice, but also in the compiler or in any of the numerous libraries that OpenOffice uses. But I agree, in this case multi-arch is a workaround; this does not make multi-arch a bad idea, though. >> Also, 32-bit binaries use less memory than 64-bit binaries do. It makes >> sense to run 32-bit binaries on 64-bit machines, if those binaries do >> not benefit from the larger address space or 64-bit instructions. > > Ah. Yes, that's a good reason if the difference in memory usage is > significant. (A factor two perhaps?) A factor two for pointers and integers, yes, but not for Strings or other data structures. If you have many pointers, the increase in memory usage is quite significant. >> Another benefit of multiarch is that you can e.g. compile i386 binaries >> on an amd64 machine and run them on i386 machines. > > And then the compiler would also be an i386 program I presume. What > are the benefits of that over an AMD64 to i386 cross compiler? On the amd64 machine, you need either an amd64-to-i386 cross-compiler (gcc -m32 does just that), or a native i386 compiler. Either will do, but then you also need the i386 libraries to link against. A proper multi-arch design allows you to have these libraries alongside the amd64 libraries, in a clean way as opposed to local hacks. -- Ludovic Brenta.