Re: [PATCH 12/23] kbuild: avoid re-running compiler and linker probes

On Wed, Sep 09, 2026 at 09:19:12PM -0700, Nathan Chancellor wrote:

quoted

diff --git a/init/Kconfig b/init/Kconfig
index 8583d9f06c52..3c92c87254a3 100644
--- a/init/Kconfig
+++ b/init/Kconfig

@@ -144,6 +144,44 @@ config CC_HAS_ASSUME
 config CC_HAS_NO_PROFILE_FN_ATTR
 	def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
 
+config CC_HAS_ZERO_INIT_PADDING_BITS
+	def_bool $(cc-option,-fzero-init-padding-bits=all)
+
+config CC_HAS_NO_STACK_CLASH_PROTECTION
+	def_bool $(cc-option,-fno-stack-clash-protection)
+
+config CC_HAS_NO_ADDRSIG
+	def_bool $(cc-option,-fno-addrsig)

I am generally in favor of this proposal since I think these checks
should be cached by Kconfig where possible to clear up running them
twice. That said, I wonder if we should pick a better dumping ground for
these checks other than init/Kconfig. Maybe init/Kconfig.tools or
scripts/Kconfig.tools or something?

Yes, skimming through the patch, I thought about that, too.  Moving more 
cc option checks to Kconfig will make building out-of-tree kmods with a 
different compiler more dangerous.  Maybe we will have to make the 
warning in Makefile's prepare (external kmods) target a bit louder.

I also worry about backsliding and growing cc-option checks. Should we
update the documentation to state that it is preferrable for these
checks to live in Kconfig so that they can be properly cached?

Sounds good, yes.

-- 
Nicolas