Merge tag 'kbuild-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux

Pull Kbuild updates from Nicolas Schier:

  - Enable -fms-extensions, allowing anonymous use of tagged struct or
    union in struct/union (tag kbuild-ms-extensions-6.19). An exemplary
    conversion patch is added here, too (btrfs).

    [ Editor's note: the core of this actually came in early through a
      shared branch and a few other trees    - Linus ]

  - Introduce architecture-specific CC_CAN_LINK and flags for userprogs

  - Add new packaging target 'modules-cpio-pkg' for building a initramfs
    cpio w/ kmods

  - Handle included .c files in gen_compile_commands

  - Minor kbuild changes:
     - Use objtree for module signing key path, fixing oot kmod signing
     - Improve documentation of KBUILD_BUILD_TIMESTAMP
     - Reuse KBUILD_USERCFLAGS for UAPI, instead of defining twice
     - Rename scripts/Makefile.extrawarn to Makefile.warn
     - Drop obsolete types.h check from headers_check.pl
     - Remove outdated config leak ignore entries

* tag 'kbuild-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
  kbuild: add target to build a cpio containing modules
  initramfs: add gen_init_cpio to hostprogs unconditionally
  kbuild: allow architectures to override CC_CAN_LINK
  init: deduplicate cc-can-link.sh invocations
  kbuild: don't enable CC_CAN_LINK if the dummy program generates warnings
  scripts: headers_install.sh: Remove two outdated config leak ignore entries
  scripts/clang-tools: Handle included .c files in gen_compile_commands
  kbuild: uapi: Drop types.h check from headers_check.pl
  kbuild: Rename Makefile.extrawarn to Makefile.warn
  MAINTAINERS, .mailmap: Update mail address for Nicolas Schier
  kbuild: uapi: reuse KBUILD_USERCFLAGS
  kbuild: doc: improve KBUILD_BUILD_TIMESTAMP documentation
  kbuild: Use objtree for module signing key path
  btrfs: send: make use of -fms-extensions for defining struct fs_path

Author: torvalds

.mailmap

@@ -589,8 +589,8 @@ Nicolas Pitre <[email protected]> <[email protected]>
 Nicolas Pitre <[email protected]> <[email protected]>
 Nicolas Saenz Julienne <[email protected]> <[email protected]>
 Nicolas Saenz Julienne <[email protected]> <[email protected]>
-Nicolas Schier <[email protected]> <[email protected]>
-Nicolas Schier <[email protected]> <[email protected]>
+Nicolas Schier <[email protected]> <[email protected]>
+Nicolas Schier <[email protected]> <[email protected]>
 Niklas Söderlund <[email protected]>
 Nikolay Aleksandrov <[email protected]> <[email protected]>
 Nikolay Aleksandrov <[email protected]> <[email protected]>

Documentation/kbuild/kbuild.rst

@@ -328,8 +328,14 @@ KBUILD_BUILD_TIMESTAMP
 ----------------------
 Setting this to a date string overrides the timestamp used in the
 UTS_VERSION definition (uname -v in the running kernel). The value has to
-be a string that can be passed to date -d. The default value
-is the output of the date command at one point during build.
+be a string that can be passed to date -d. E.g.::
+
+    $ KBUILD_BUILD_TIMESTAMP="Mon Oct 13 00:00:00 UTC 2025" make
+
+The default value is the output of the date command at one point during
+build. If provided, this timestamp will also be used for mtime fields
+within any initramfs archive. Initramfs mtimes are 32-bit, so dates before
+the 1970 Unix epoch, or after 2106-02-07 06:28:15 UTC will fail.
 
 KBUILD_BUILD_USER, KBUILD_BUILD_HOST
 ------------------------------------

MAINTAINERS

@@ -13498,7 +13498,7 @@ F:	fs/autofs/
 
 KERNEL BUILD + files below scripts/ (unless maintained elsewhere)
 M:	Nathan Chancellor <[email protected]>
-M:	Nicolas Schier <[email protected]>
+M:	Nicolas Schier <[email protected]>
 L:	[email protected]
 S:	Odd Fixes
 Q:	https://patchwork.kernel.org/project/linux-kbuild/list/

Makefile

@@ -1084,7 +1084,7 @@ KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srcroot)/=)
 endif
 
 # include additional Makefiles when needed
-include-y			:= scripts/Makefile.extrawarn
+include-y			:= scripts/Makefile.warn
 include-$(CONFIG_DEBUG_INFO)	+= scripts/Makefile.debug
 include-$(CONFIG_DEBUG_INFO_BTF)+= scripts/Makefile.btf
 include-$(CONFIG_KASAN)		+= scripts/Makefile.kasan
@@ -1137,8 +1137,17 @@ ifneq ($(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS),)
 LDFLAGS_vmlinux	+= --emit-relocs --discard-none
 endif
 
-# Align the bit size of userspace programs with the kernel
-USERFLAGS_FROM_KERNEL := -m32 -m64 --target=%
+# Align the architecture of userspace programs with the kernel
+USERFLAGS_FROM_KERNEL := --target=%
+
+ifdef CONFIG_ARCH_USERFLAGS
+KBUILD_USERCFLAGS += $(CONFIG_ARCH_USERFLAGS)
+KBUILD_USERLDFLAGS += $(CONFIG_ARCH_USERFLAGS)
+else
+# If not overridden also inherit the bit size
+USERFLAGS_FROM_KERNEL += -m32 -m64
+endif
+
 KBUILD_USERCFLAGS  += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
 KBUILD_USERLDFLAGS += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
 

drivers/gpu/drm/Makefile

@@ -6,7 +6,7 @@
 CFLAGS-$(CONFIG_DRM_USE_DYNAMIC_DEBUG)	+= -DDYNAMIC_DEBUG_MODULE
 
 # Unconditionally enable W=1 warnings locally
-# --- begin copy-paste W=1 warnings from scripts/Makefile.extrawarn
+# --- begin copy-paste W=1 warnings from scripts/Makefile.warn
 subdir-ccflags-y += -Wextra -Wunused -Wno-unused-parameter
 subdir-ccflags-y += $(call cc-option, -Wrestrict)
 subdir-ccflags-y += -Wmissing-format-attribute

fs/btrfs/send.c

@@ -47,28 +47,30 @@
  * It allows fast adding of path elements on the right side (normal path) and
  * fast adding to the left side (reversed path). A reversed path can also be
  * unreversed if needed.
+ *
+ * The definition of struct fs_path relies on -fms-extensions to allow
+ * including a tagged struct as an anonymous member.
  */
+struct __fs_path {
+	char *start;
+	char *end;
+
+	char *buf;
+	unsigned short buf_len:15;
+	unsigned short reversed:1;
+};
+static_assert(sizeof(struct __fs_path) < 256);
 struct fs_path {
-	union {
-		struct {
-			char *start;
-			char *end;
-
-			char *buf;
-			unsigned short buf_len:15;
-			unsigned short reversed:1;
-			char inline_buf[];
-		};
-		/*
-		 * Average path length does not exceed 200 bytes, we'll have
-		 * better packing in the slab and higher chance to satisfy
-		 * an allocation later during send.
-		 */
-		char pad[256];
-	};
+	struct __fs_path;
+	/*
+	 * Average path length does not exceed 200 bytes, we'll have
+	 * better packing in the slab and higher chance to satisfy
+	 * an allocation later during send.
+	 */
+	char inline_buf[256 - sizeof(struct __fs_path)];
 };
 #define FS_PATH_INLINE_SIZE \
-	(sizeof(struct fs_path) - offsetof(struct fs_path, inline_buf))
+	sizeof_field(struct fs_path, inline_buf)
 
 
 /* reused for each extent */
@@ -305,7 +307,6 @@ struct send_ctx {
 	struct btrfs_lru_cache dir_created_cache;
 	struct btrfs_lru_cache dir_utimes_cache;
 
-	/* Must be last as it ends in a flexible-array member. */
 	struct fs_path cur_inode_path;
 };
 

init/Kconfig

@@ -82,10 +82,14 @@ config RUSTC_LLVM_VERSION
 	int
 	default $(rustc-llvm-version)
 
+config ARCH_HAS_CC_CAN_LINK
+	bool
+
 config CC_CAN_LINK
 	bool
-	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
-	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
+	default ARCH_CC_CAN_LINK if ARCH_HAS_CC_CAN_LINK
+	default $(cc_can_link_user,$(m64-flag)) if 64BIT
+	default $(cc_can_link_user,$(m32-flag))
 
 # Fixed in GCC 14, 13.3, 12.4 and 11.5
 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921

scripts/Kconfig.include

@@ -65,6 +65,9 @@ cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$
 m32-flag := $(cc-option-bit,-m32)
 m64-flag := $(cc-option-bit,-m64)
 
+# Test whether the compiler can link userspace applications
+cc_can_link_user = $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(1))
+
 rustc-version := $(shell,$(srctree)/scripts/rustc-version.sh $(RUSTC))
 rustc-llvm-version := $(shell,$(srctree)/scripts/rustc-llvm-version.sh $(RUSTC))
 

scripts/Makefile.modinst

@@ -100,7 +100,7 @@ endif
 # Don't stop modules_install even if we can't sign external modules.
 #
 ifeq ($(filter pkcs11:%, $(CONFIG_MODULE_SIG_KEY)),)
-sig-key := $(if $(wildcard $(CONFIG_MODULE_SIG_KEY)),,$(srctree)/)$(CONFIG_MODULE_SIG_KEY)
+sig-key := $(if $(wildcard $(CONFIG_MODULE_SIG_KEY)),,$(objtree)/)$(CONFIG_MODULE_SIG_KEY)
 else
 sig-key := $(CONFIG_MODULE_SIG_KEY)
 endif

scripts/Makefile.package

@@ -189,6 +189,25 @@ tar-pkg: linux-$(KERNELRELEASE)-$(ARCH).tar
 tar%-pkg: linux-$(KERNELRELEASE)-$(ARCH).tar.% FORCE
 	@:
 
+# modules-cpio-pkg - generate an initramfs with the modules
+# ---------------------------------------------------------------------------
+
+.tmp_modules_cpio: FORCE
+	$(Q)$(MAKE) -f $(srctree)/Makefile
+	$(Q)rm -rf $@
+	$(Q)$(MAKE) -f $(srctree)/Makefile INSTALL_MOD_PATH=$@ modules_install
+
+quiet_cmd_cpio = CPIO    $@
+      cmd_cpio = $(CONFIG_SHELL) $(srctree)/usr/gen_initramfs.sh -o $@ $<
+
+modules-$(KERNELRELEASE)-$(ARCH).cpio: .tmp_modules_cpio
+	$(Q)$(MAKE) $(build)=usr usr/gen_init_cpio
+	$(call cmd,cpio)
+
+PHONY += modules-cpio-pkg
+modules-cpio-pkg: modules-$(KERNELRELEASE)-$(ARCH).cpio
+	@:
+
 # perf-tar*-src-pkg - generate a source tarball with perf source
 # ---------------------------------------------------------------------------
 
@@ -245,6 +264,7 @@ help:
 	@echo '  tarbz2-pkg          - Build the kernel as a bzip2 compressed tarball'
 	@echo '  tarxz-pkg           - Build the kernel as a xz compressed tarball'
 	@echo '  tarzst-pkg          - Build the kernel as a zstd compressed tarball'
+	@echo '  modules-cpio-pkg    - Build the kernel modules as cpio archive'
 	@echo '  perf-tar-src-pkg    - Build the perf source tarball with no compression'
 	@echo '  perf-targz-src-pkg  - Build the perf source tarball with gzip compression'
 	@echo '  perf-tarbz2-src-pkg - Build the perf source tarball with bz2 compression'