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    SubjectRe: [PATCH v2 2/2] Makefile: infer CROSS_COMPILE from SRCARCH for LLVM=1 LLVM_IAS=1
    On Tue, Jul 20, 2021 at 10:43 AM Linus Torvalds
    <torvalds@linux-foundation.org> wrote:
    >
    > But clang has become a primary compiler for some kernel communities,
    > and I think it might be time to just re-visit that entirely.
    >
    > In particular, I think we should just make it a Kconfig option. I hate
    > the command flag stuff so much, that my clang tree literally has this
    > patch in it:
    >
    > -CC = $(CROSS_COMPILE)gcc
    > +CC = $(CROSS_COMPILE)clang
    >
    > so that I can just do the same "make -j128" in both my gcc tree and my
    > clang tree.
    >
    > But each build tree already has its own .config file, so it would be a
    > lot more convenient if that was how the compiler was chosen, and then
    > "make oldconfig" would just DTRT.
    >
    > We do most of the other heavy lifting in this area in Kconfig anyway,
    > why not add that compiler choice?
    >
    > Obviously it would be gated by the tests to see which compilers are
    > _installed_ (and that they are valid versions), so that it doesn't ask
    > stupid things ("do you want gcc or clang" when only one of them is
    > installed and/or viable).
    >
    > Hmm? So then any "LLVM=1" thing would be about the "make config"
    > stage, not the actual build stage.
    >
    > (It has annoyed me for years that if you want to cross-compile, you
    > first have to do "make ARCH=xyz config" and then remember to do "make
    > ARCH=xyz" for the build too, but I cross-compile so seldom that I've
    > never really cared).
    >
    > Let the flame wars^H^Hpolite discussions ensue..

    I will concede that "why do I need to respecify all of my command line
    args/env vars to make when I already did so for a configure step?" is
    a reasonable question to ask, and may be worth pursuing.

    There's still some that we can eliminate for BOTH configure and actual
    build, like CROSS_COMPILE. :^)
    --
    Thanks,
    ~Nick Desaulniers

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