Hi! Esa Peuha wrote: > kfreebsd-11 currently depends on clang-3.4 which is going to be > removed (see bug #783516), so please update the dependency to a > newer version. Also, if possible, please do the same for kfreebsd-10.
Upstream already builds kfreebsd-11 using clang-3.6, so we should change it to use that anyway. That will be straightforward. For kfreebsd-10 however, upstream stable/10 branch still uses clang-3.4. If we have to choose between clang-3.5 or 3.6, there is a risk we hit some unfixed run-time issue, due to new optimisations or a compiler bug. Both clang-3.5 and 3.6 as packaged in Debian, are already able to build kfreebsd-10. The compiled kernels booted successfully at least within KVM, performed another kernel build, and appeared stable. Successive builds with clang-3.6 produced identical output, so there is no sign of any regression relating to reproducibility of builds. Generated code is very different going from clang-3.4 to 3.5; lots of re-ordering of instructions, likely due to new optimisations. The changes from 3.5 to 3.6 seem to be fewer. Total size of the compiled kernel has increased slightly with each version: kernel built with clang-3.4: 17775248 bytes kernel built with clang-3.5: 17865504 bytes kernel built with clang-3.6: 17911544 bytes clang-3.5 is in kfreebsd-jessie whereas clang-3.6 is not; that might have been a concern for backporting, except we don't use the official backports suite, so that maybe isn't a relevant issue for us. Since kfreebsd-11 is built upstream with clang-3.6, we have a chance of backporting fixes from there if we ever run into compile or run-time issues with future 10.x kernels. So I think we may want to build kfreebsd-10 using clang-3.6, to keep consistency with kfreebsd-11, and so that we rely on fewer clang releases to be maintained simultaneously in Debian. Regards, -- Steven Chamberlain ste...@pyro.eu.org
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