Re: linux-next: manual merge of the bpf-next tree with the kbuild tree

[Nathan Chancellor <nathan@kernel.org>]

Hi Mark,

On Sat, Oct 03, 2026 at 12:42:58AM +0200, Mark Brown wrote:
> Today's linux-next merge of the bpf-next tree got a conflict in:
> 
>   init/Kconfig
> 
> between commit:
> 
>   f85147b291e35 ("kbuild: move the toolchain checks into scripts/Kconfig.toolchain")
> 
> from the kbuild tree and commit:
> 
>   eb13a1ff271b0 ("random: vDSO: avoid call to memset() when zeroing reserved parameter")
> 
> from the bpf-next tree.

For the record, this change is from Linus's tree, as it was merged in

  ac7445c28e7a ("Merge tag 'random-7.3-rc6-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random")

but presumably your stable base does not have that merge depending on
whan you started -next so it comes in from the bpf-next merge of Linus's
tree in

  2b5440b31caf ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 7.3-rc5")

I just wanted to make sure the bpf folks didn't think they were on the
hook for this conflict, it is only on me with the Kbuild tree now.

> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.

Thanks, the 'source' line looks correct to me now. Did you also shuffle
CC_OPT_INLINE_MEMSET into scripts/Kconfig.toolchain like below? You had
it right in

  https://lore.kernel.org/ar5-4Yq3wtmXTWnD@sirena.org.uk/

but the patch changed slightly since that resolution ('4294967295' to
'4294967294') due to a problem I reported

  https://lore.kernel.org/20261002094932.GA3435055@ax162/

before the patch was sent upstream, so I wanted to make sure that you
did not reuse the old resolution (and I didn't see a mention of it in
this email).

diff --git a/scripts/Kconfig.toolchain b/scripts/Kconfig.toolchain
index d708a175fe48..c9d2aef4e355 100644
--- a/scripts/Kconfig.toolchain
+++ b/scripts/Kconfig.toolchain
@@ -247,6 +247,11 @@ config CC_HAS_ALLOC_TOKEN
 config CC_HAS_MULTIDIMENSIONAL_NONSTRING
 	def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror)
 
+config CC_OPT_INLINE_MEMSET
+	string
+	default "-finline-stringops=memset" if $(cc-option,-finline-stringops=memset)
+	default "-mllvm -max-store-memset=4294967294" if $(cc-option,-mllvm -max-store-memset=4294967294)
+
 config LD_CAN_USE_KEEP_IN_OVERLAY
 	# ld.lld prior to 21.0.0 did not support KEEP within an overlay description
 	# https://github.com/llvm/llvm-project/pull/130661
-- 
Cheers,
Nathan