Le 19/08/2013 03:05, Wookey a écrit : > +++ Henrique de Moraes Holschuh [2013-08-18 21:39 -0300]: >> On Sun, 18 Aug 2013, Adam Borowski wrote: >>> C - ship both versions on i386 and switch between them on runtime >> >> The linker can select at runtime different sets of libraries depending on >> some cpu flags. I think it can do that for SSE2 just fine, you'd build two >> libs: one without interesting intructions, and other with them, and place >> them/name them appropriately for that to work, all in the same binary >> package. > > Right, but be careful not to confuse this functionality with > multiarch. It's called 'multilib'. They both do essentially the same > job (selecting libraries to load by paths), but with different > paths/layouts and selection mechanisms. Multiarch paths are one per > 'arch', which normally means an ABI, not an ISA. multilib paths form a > matrix of all possible options so rapidly get out of hand if you have > more than a couple. Oh, ok, thanks for pointing out the difference between multilib and multiarch. Things get clearer now.
>> I think the glibc package does that, you might want to take a look at it. > > Various packages in debian illustrate the techniques for packaging > multiple ISA flavours. (mplayer, eglibc). I'm not sure that any of > them use multilib paths to do this - they just use package naming so > you choose whether to install 'libc6' or 'libc6-i686' (in the same > paths). They are alternatives, not something than can be installed > side by side in multilib locations and selected at runtime by the > linker. (I haven't actually checked the package contents to confirm > this). > > Things could be packaged using multilib locations if you thought it > was worth the effort. I had a look to eglibc source package. I can tell some dark magic is at work in this package. But as I need only a small fragment of it, I'll probably be able to extract it. The result would be a "lib" package on all architectures, with sse2 enabled only on amd64 arch, and a "lib-sse2" package, recommended by "lib", only present on "i386" arch. The good news for me being that I can easily prepare a first version of the package without multilib, and add the -sse2 version later without breaking anything. Thank you all for your help! -- fabien -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/[email protected]
