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From: Masahiro Yamada <email@example.com> To: Nick Desaulniers <firstname.lastname@example.org> Cc: Nathan Chancellor <email@example.com>, Miguel Ojeda <firstname.lastname@example.org>, Fangrui Song <email@example.com>, Michal Marek <firstname.lastname@example.org>, Arnd Bergmann <email@example.com>, Linux Kernel Mailing List <firstname.lastname@example.org>, Linux Kbuild mailing list <email@example.com>, clang-built-linux <firstname.lastname@example.org>, Geert Uytterhoeven <email@example.com>, Christoph Hellwig <firstname.lastname@example.org>, Linus Torvalds <email@example.com> Subject: Re: [PATCH v3 2/2] Makefile: infer CROSS_COMPILE from SRCARCH for CC=clang LLVM_IAS=1 Date: Sat, 31 Jul 2021 00:15:22 +0900 [thread overview] Message-ID: <CAK7LNATbbHosb7uB53HPo3BpdFH_g5YAKkn1ouL=ymHb5nkEXw@mail.gmail.com> (raw) In-Reply-To: <CAKwvOdm0xs4ikb0K0_b8Az0T=Kxu_-6AHjWHOhjsKZb3hTrH2A@mail.gmail.com> On Fri, Jul 30, 2021 at 9:19 AM Nick Desaulniers <firstname.lastname@example.org> wrote: > > On Thu, Jul 29, 2021 at 2:00 PM Nathan Chancellor <email@example.com> wrote: > > > > While I understand that the LLVM=1 LLVM_IAS=1 case works perfectly fine > > with this series, I am of the belief that making it work for CC=clang > > LLVM_IAS=1 is a mistake because there is no way for that configuration > > to work for cross compiling without CROSS_COMPILE. > > So with v3 of this change, rather than: > > $ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make CC=clang -j72 > > If you wanted to omit CROSS_COMPILE, you'd need: > > $ ARCH=arm64 make CC=clang LLVM_IAS=1 LD=ld.lld OBJCOPY=llvm-objcopy > STRIP=llvm-strip > > or > > $ ARCH=arm64 make CC=clang LLVM_IAS=1 LD=aarch64-linux-gnu-ld > OBJCOPY=aarch64-linux-gnu-objcopy STRIP=aarch64-linux-gnu-strip or $ ARCH=arm64 make LLVM=1 LLVM_IAS=1 still works. > That's straight up worse IMO and defeats the purpose of "shortening > the command line," which should be the goal. Not "making CC=clang > maximally flexible." We don't want folks generally using CC=clang; > preferably they'd use LLVM=1. I need to rewrite our docs to make that > more explicit and straightforward. And if folks would prefer to use > CC=clang for whatever reason, let them explicitly state CROSS_COMPILE > then. > > So I agree with Nathan, and hope Masahiro will reconsider that perhaps > the v2 variant that required LLVM=1 maybe makes more sense. We can always infer the target triple from ARCH unless CROSS_COMPILE is given. Doing this all the time makes nothing wrong. "Whether CROSS_COMPILE is unneeded" is a different thing. > Either way, I need to fix the comment in the new script, commit > message, and docs, so v4 is necessary. > > I'm tempted to add a rewrite of our docs to say "just use LLVM=1" > front and center, then get into finer grain details below, moving this > second patch to be the third in a series. Let's see what Masahiro's > thoughts are though first. (I do appreciate them, even when I > disagree). I am not sure about that. LLVM=1 is a very strong all-or-nothing flag, but technically there is no reason to force it. (At least, target-tools and host-tools look independent to each other to me) When you send v4, one more request: Please drop LLVM_IAS=1 check as well. -- Best Regards Masahiro Yamada
next prev parent reply other threads:[~2021-07-30 15:16 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-29 16:50 [PATCH v3 0/2] infer CROSS_COMPILE from SRCARCH for CC=clang LLVM_IAS=1 Nick Desaulniers 2021-07-29 16:50 ` [PATCH v3 1/2] Makefile: move initial clang flag handling into scripts/Makefile.clang Nick Desaulniers 2021-07-29 16:50 ` [PATCH v3 2/2] Makefile: infer CROSS_COMPILE from SRCARCH for CC=clang LLVM_IAS=1 Nick Desaulniers 2021-07-29 19:40 ` Arnd Bergmann 2021-07-29 21:00 ` Nathan Chancellor 2021-07-30 0:19 ` Nick Desaulniers 2021-07-30 6:50 ` Miguel Ojeda 2021-07-30 15:15 ` Masahiro Yamada [this message] 2021-07-30 15:10 ` Masahiro Yamada
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