On 29/11/12 17:54, Gilles Dartiguelongue wrote: > Le jeudi 29 novembre 2012 à 10:07 +0100, justin a écrit : >> On 29/11/12 09:48, Gilles Dartiguelongue wrote: >>> Le jeudi 29 novembre 2012 à 08:52 +0100, justin a écrit : >>>> Currently we have an eselect module to switch between different >>>> implementations by setting /usr/lib/lib[blas,lapack].so to the selected >>>> implementation. >>>> >>>> This has two drawbacks, which some of you might already of hit: >>>> 1. They seem to be not completely API/ABI compatible (I don't which one >>>> is correct here. And please don't be nitpicking on this point). So >>>> switching would mean recompilation of all packages linked against it >>>> before, otherwise you might get runtime errors. This takes time and >>>> triggers point 2. >>>> >>>> 2. As andy showed we should stick with specific implementations for >>>> specific tasks. The current way flattens this out to be optimal for some >>>> and suboptimal for others. >>>> >>>> Now, there has been a lot of effort around Andy and Sebastien to solve >>>> this problem. The solution is simple: don't install any libblas.so or >>>> liblapack.so in libdir, but instead make the pkg-config module >>>> eselectable and force packages to used pkg-config. Nearly (I think its >>>> 100%) of the packages in the tree already use pkg-config to detect >>>> blas/lapack. >>> >>> I think I understand the problem now. You should not patch/generate .pc >>> files but install them to an implementation specific subdirectory. >>> >> >> If I get you correctly you are assuming that we have pkgconfig files for >> all implementations coming from upstreams. That's not correct, we have >> nearly none. So we need to generate them our own. And yes this need to >> be sent upstream. >> >> That's the reason for the eclass. >> >>> That way, you just have to append that path to PKGCONFIG_PATH when >>> configuring your package using blas and you should be able to >>> transparently select which implementation to get without further >>> patching of either upstream or downstream packages. >>> >> >> This would mean that the pkg maintainer decides the implementation. But >> we leave this choice to the user which works fine. And we have a working >> eselect based solution. > > No, this means you can then use USE flags to select it which is package > manager controlled and usually easier to deal with than eselected stuff. >
So you mean adding a USE for each implementation to each package which is using one fo blas/cblas/lapack/clapack/lapacke and all the others which I forgot? And in the end, we still would need pc files, because version A of implementation X could have different library names then version B.
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