Re: [PATCH v1] kbuild: Add KBUILD_VMLINUX_LIBS_PRELINK

Nathan Chancellor
2025-11-21T07:01:45Z

On Wed, Nov 19, 2025 at 12:27:08PM +0800, Tiezhu Yang wrote:
> In order to only link libstub to the final vmlinux, it can not use the
> current KBUILD_VMLINUX_LIBS, just add KBUILD_VMLINUX_LIBS_PRELINK. This
> is preparation for later patch, no functionality change.
>
> Link: https://lore.kernel.org/lkml/pq4h7jgndnt6p45lj4kgubxjd5gidfetugcuf5rcxzxxanzetd@6rrlpjnjsmuy/
> Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
> There is a long discussion in the previous patch:
> https://lore.kernel.org/lkml/20250928085506.4471-1-yangtiezhu@loongson.cn/
>
> This version is based on 6.18-rc6, split the generic parts out
> into a separate patch to avoid merge conflicts, the other parts
> will send out after the merge window.
>
> Makefile | 1 +
> scripts/link-vmlinux.sh | 5 ++---
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index d763c2c75cdb..69485f47b794 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1199,6 +1199,7 @@ KBUILD_VMLINUX_OBJS := built-in.a $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)
> KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
>
> export KBUILD_VMLINUX_LIBS
> +export KBUILD_VMLINUX_LIBS_PRELINK

This variable name is a little confusing to me since they do get added
to vmlinux during linking, not before. I am not sure of a better one
though, maybe KBUILD_VMLINUX_LIBS_FINAL? It may also make sense to
introduce similar syntax to the existing libs-y syntax, maybe

final-libs-y

or something like that?

Also, since these objects are no longer in KBUILD_VMLINUX_LIBS, does
this new variable need to be added to any of the other places in the
build system that use KBUILD_VMLINUX_LIBS for things such as build
dependencies?

> export KBUILD_LDS := arch/$(SRCARCH)/kernel/vmlinux.lds
>
> ifdef CONFIG_TRIM_UNUSED_KSYMS
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 433849ff7529..e72d3254b93f 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -61,12 +61,11 @@ vmlinux_link()
> shift
>
> if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
> - # Use vmlinux.o instead of performing the slow LTO link again.
> objs=vmlinux.o
> - libs=
> + libs="${KBUILD_VMLINUX_LIBS_PRELINK}"
> else
> objs=vmlinux.a
> - libs="${KBUILD_VMLINUX_LIBS}"
> + libs="${KBUILD_VMLINUX_LIBS} ${KBUILD_VMLINUX_LIBS_PRELINK}"
> fi
>
> if is_enabled CONFIG_GENERIC_BUILTIN_DTB; then
> --
> 2.42.0
>