Message-ID: <CAF1bQ=Q-97ovXXQgtXq75zZUL_FtXo4LHoATHHYLgL-cPi5CdQ@mail.gmail.com>
Date: Tue, 28 Oct 2025 10:07:31 -0700
From: Rong Xu <xur@...gle.com>
To: Piotr Gorski <piotrgorski@...hyos.org>
Cc: Masahiro Yamada <masahiroy@...nel.org>, Nathan Chancellor <nathan@...nel.org>, 
	Nicolas Schier <nicolas.schier@...ux.dev>, 
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, Miguel Ojeda <ojeda@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Alice Ryhl <aliceryhl@...gle.com>, 
	Sami Tolvanen <samitolvanen@...gle.com>, "Mike Rapoport (Microsoft)" <rppt@...nel.org>, 
	Rafael Aquini <aquini@...hat.com>, Michael Ellerman <mpe@...erman.id.au>, 
	Stafford Horne <shorne@...il.com>, Christophe Leroy <christophe.leroy@...roup.eu>, 
	Teresa Johnson <tejohnson@...gle.com>, linux-kernel@...r.kernel.org, 
	linux-kbuild@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH v4 0/2] kbuild: distributed build support for Clang ThinLTO

Thanks for testing this!

The culprit was the string -D'pr_fmt(fmt)=KBUILD_MODNAME ": " fmt'.

The previous patch parsed c_flags and removed -D% and a bunch of other
FE flags. Masahiro suggested using _c_flags instead.
I erroneously assumed there were no -D% in _c_flags. But this is
wrong. It seems that we do need to filter out -D% even using _c_flags.

I'll send an updated patch shortly.

Best regards,

-Rong


On Tue, Oct 28, 2025 at 3:43 AM Piotr Gorski <piotrgorski@...hyos.org> wrote:
>
> I tried using this on kernel 6.17.5, but unfortunately I get this error.
> I previously tested the version in CachyOS:
> https://github.com/CachyOS/linux/commit/68984063b5e27854272241549e47cb2930ef9710
> and https://github.com/CachyOS/linux/
> commit/00a3ff73a566b7e27b4ced46af4ce27177d9fc37 and everything works fine.
>
> /bin/sh: -c: line 1: syntax error near unexpected token `('
> /bin/sh: -c: line 1: `set -e;    trap 'rm -f
> drivers/net/wireguard/main.o; trap - HUP; kill -s HUP $$' HUP; trap 'rm
> -f drivers/net/wireguard/main.o; trap - INT; kill -s INT $$' INT;  trap
> 'rm -f drivers/net/wireguard/main.o
> ; trap - QUIT; kill -s QUIT $$' QUIT;  trap 'rm -f
> drivers/net/wireguard/main.o; trap - TERM; kill -s TERM $$' TERM; trap
> 'rm -f drivers/net/wireguard/main.o; trap - PIPE; kill -s PIPE $$' PIPE;
> printf '\n%s\n' 'saved_c_flag
> s_drivers/net/wireguard/main.o := -D__KERNEL__ --target=x86_64-linux-gnu
> -fintegrated-as -Werror=ignored-optimization-argument
> -Werror=option-ignored -std=gnu11 -fshort-wchar -funsigned-char
> -fno-common -fno-PIE -fno-strict-a
> liasing -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
> -fcf-protection=branch -fno-jump-tables -m64 -falign-loops=1 -mno-80387
> -mno-fp-ret-in-387 -mstack-alignment=8 -mskip-rax-setup -march=znver4
> -mno-red-zone -mcmodel=kern
> el -mstack-protector-guard-reg=gs
> -mstack-protector-guard-symbol=__ref_stack_chk_guard -Wno-sign-compare
> -fno-asynchronous-unwind-tables -mretpoline-external-thunk
> -mindirect-branch-cs-prefix -mfunction-return=thunk-extern -m
> harden-sls=all -fpatchable-function-entry=16,16
> -fno-delete-null-pointer-checks -O3 -fstack-protector-strong
> -ftrivial-auto-var-init=zero -fno-stack-clash-protection -pg -mfentry
> -DCC_USING_NOP_MCOUNT -DCC_USING_FENTRY -fno-l
> to -flto=thin -fsplit-lto-unit -fvisibility=hidden -falign-functions=16
> -fstrict-flex-arrays=3 -fno-strict-overflow -fno-stack-check
> -fno-builtin-wcslen -Wall -Wextra -Wundef
> -Werror=implicit-function-declaration -Werror=impl
> icit-int -Werror=return-type -Wno-format-security -Wno-trigraphs
> -Wno-frame-address -Wno-address-of-packed-member -Wmissing-declarations
> -Wmissing-prototypes -Wframe-larger-than=2048 -Wno-gnu
> -Wno-format-overflow-non-kprintf
> -Wno-format-truncation-non-kprintf -Wno-default-const-init-unsafe
> -Wno-pointer-sign -Wcast-function-type
> -Wno-unterminated-string-initialization -Wimplicit-fallthrough
> -Werror=date-time -Wenum-conversion -Wunused -Wno-unused-
> but-set-variable -Wno-unused-const-variable -Wno-format-overflow
> -Wno-override-init -Wno-pointer-to-enum-cast
> -Wno-tautological-constant-out-of-range-compare -Wno-unaligned-access
> -Wno-enum-compare-conditional -Wno-missing-fi
> eld-initializers -Wno-type-limits -Wno-shift-negative-value
> -Wno-enum-enum-conversion -Wno-sign-compare -Wno-unused-parameter -g
> -gdwarf-5 -D'pr_fmt(fmt)=KBUILD_MODNAME ": " fmt'' >>
> drivers/net/wireguard/.main.o.cmd'
> make[5]: *** [scripts/Makefile.build:287: drivers/net/wireguard/main.o]
> Error 2
> make[5]: *** Deleting file 'drivers/net/wireguard/main.o'
> make[4]: *** [scripts/Makefile.build:556: drivers/net/wireguard] Error 2
>
> LLVM/CLANG: 21.1.4
>
> If necessary, I can send more logs.
>
> Best regards,
>
> Piotr
>
> W dniu 27.10.2025 o 23:09, xur@...gle.com pisze:
> > From: Rong Xu <xur@...gle.com>
> >
> > This V4 is based on the reimplementation provided by Masahiro Yamada
> > on May 26. The difference is that this version now saves the compiler
> > flags (_c_flags) from the Front-End (FE) compilation and re-uses them
> > for the subsequent Back-End (BE) compilation.
> >
> > Rong Xu (2):
> >    kbuild: move vmlinux.a build rule to scripts/Makefile.vmlinux_a
> >    kbuild: distributed build support for Clang ThinLTO
> >
> >   .gitignore                 |  2 +
> >   Makefile                   | 25 +++++-------
> >   arch/Kconfig               | 19 +++++++++
> >   scripts/Makefile.lib       |  7 ++++
> >   scripts/Makefile.thinlto   | 40 ++++++++++++++++++
> >   scripts/Makefile.vmlinux_a | 83 ++++++++++++++++++++++++++++++++++++++
> >   scripts/mod/modpost.c      | 15 +++++--
> >   7 files changed, 174 insertions(+), 17 deletions(-)
> >   create mode 100644 scripts/Makefile.thinlto
> >   create mode 100644 scripts/Makefile.vmlinux_a
> >
> >
> > base-commit: dcb6fa37fd7bc9c3d2b066329b0d27dedf8becaa

Powered by blists - more mailing lists