Merge tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:
 "Build system:

   - add CONFIG_UNUSED_KSYMS_WHITELIST, which will be useful to define a
     fixed set of export symbols for Generic Kernel Image (GKI)

   - allow to run 'make dt_binding_check' without .config

   - use full schema for checking DT examples in *.yaml files

   - make modpost fail for missing MODULE_IMPORT_NS(), which makes more
     sense because we know the produced modules are never loadable

   - Remove unused 'AS' variable

  Kconfig:

   - sanitize DEFCONFIG_LIST, and remove ARCH_DEFCONFIG from Kconfig
     files

   - relax the 'imply' behavior so that symbols implied by 'y' can
     become 'm'

   - make 'imply' obey 'depends on' in order to make 'imply' really weak

  Misc:

   - add documentation on building the kernel with Clang/LLVM

   - revive __HAVE_ARCH_STRLEN for 32bit sparc to use optimized strlen()

   - fix warning from deb-pkg builds when CONFIG_DEBUG_INFO=n

   - various script and Makefile cleanups"

* tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
  Makefile: Update kselftest help information
  kbuild: deb-pkg: fix warning when CONFIG_DEBUG_INFO is unset
  kbuild: add outputmakefile to no-dot-config-targets
  kbuild: remove AS variable
  net: wan: wanxl: refactor the firmware rebuild rule
  net: wan: wanxl: use $(M68KCC) instead of $(M68KAS) for rebuilding firmware
  net: wan: wanxl: use allow to pass CROSS_COMPILE_M68k for rebuilding firmware
  kbuild: add comment about grouped target
  kbuild: add -Wall to KBUILD_HOSTCXXFLAGS
  kconfig: remove unused variable in qconf.cc
  sparc: revive __HAVE_ARCH_STRLEN for 32bit sparc
  kbuild: refactor Makefile.dtbinst more
  kbuild: compute the dtbs_install destination more simply
  Makefile: disallow data races on gcc-10 as well
  kconfig: make 'imply' obey the direct dependency
  kconfig: allow symbols implied by y to become m
  net: drop_monitor: use IS_REACHABLE() to guard net_dm_hw_report()
  modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n
  modpost: rework and consolidate logging interface
  kbuild: allow to run dt_binding_check without kernel configuration
  ...

1 files changed, 14 insertions, 2 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 697d109387ed..f11846c06176 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -6,8 +6,7 @@ config DEFCONFIG_LIST
 	default "/lib/modules/$(shell,uname -r)/.config"
 	default "/etc/kernel-config"
 	default "/boot/config-$(shell,uname -r)"
-	default ARCH_DEFCONFIG
-	default "arch/$(ARCH)/defconfig"
+	default "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)"
 
 config CC_IS_GCC
 	def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
@@ -2211,6 +2210,19 @@ config TRIM_UNUSED_KSYMS
 
 	  If unsure, or if you need to build out-of-tree modules, say N.
 
+config UNUSED_KSYMS_WHITELIST
+	string "Whitelist of symbols to keep in ksymtab"
+	depends on TRIM_UNUSED_KSYMS
+	help
+	  By default, all unused exported symbols will be un-exported from the
+	  build when TRIM_UNUSED_KSYMS is selected.
+
+	  UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
+	  exported at all times, even in absence of in-tree users. The value to
+	  set here is the path to a text file containing the list of symbols,
+	  one per line. The path can be absolute, or relative to the kernel
+	  source tree.
+
 endif # MODULES
 
 config MODULES_TREE_LOOKUP