On Tue, Feb 25, 2020 at 12:59:25PM -0800, Nick Desaulniers wrote: > On Mon, Feb 24, 2020 at 8:16 PM Nathan Chancellor > <natechancellor@xxxxxxxxx> wrote: > > > Should this also include an update to Documentation/process/changes.rst > > > with the minimum version required? (I would expect this to be "9" for Clang, > > > and "11" for ld.lld.) > > > > I think the clang one should be added in a separate patch that > > solidifies that in include/linux/compiler-clang.h with a CLANG_VERSION > > macro and version check, like in include/linux/compiler-gcc.h. > > > > ld.lld's minimum version should also be 9, what is the blocking issue > > that makes it 11? > > I'm super hesitant to put a minimally required version of Clang, since > it really depends on the configs you're using. Sure, clang-9 will > probably work better than clang-4 for some configs, but I would say I think it's not unreasonable to say clang-9 due to x86 not building prior to clang-9. (Yes, other archs can build with earlier clang, but that's true for earlier gccs too.) > ToT clang built from source would be even better, as unrealistic as > that is for most people. The question of "what's our support model" > hasn't realistically come up yet, so I don't really want to make a > decision on that right now and potentially pigeonhole us into some > support scheme that's theoretical or hypothetical. We need to expand > out the CI more, and get more people to even care about Clang, before > we start to concern ourselves with providing an answer to the question > "what versions of clang are supported?" But it's just a strong > opinion of mine, held loosely. "Supported" is hand-wavey anyway. I would say, "this version is _expected_ to build the kernel", etc. > Either way, it can be done (or not) in a follow up patch. I would > like to land some Documentation/ even if it's not perfect, we can go > from there. Sounds fine, but I think we should take a specific version stand as the "minimum" version. Being able to build x86 defconfig is a good minimum IMO. -- Kees Cook
