Sometimes we need to trigger a global rebuild of the kernel tree - for instance, when any of the GCC plugins changes. [1]
This commit provides a simple mechanism to force a global rebuild using a single header file. The top-level Makefile creates include/generated/global-rebuild.h if it does not exist, and this file is included by all kernel sources. You can touch it in a build rule when a global rebuild is required. The following is an example change to the GCC plugin build rule. quiet_cmd_plugin_cxx_so_c = HOSTCXX $@ - cmd_plugin_cxx_so_c = $(HOSTCXX) $(plugin_cxxflags) $(plugin_ldflags) -o $@ $< + cmd_plugin_cxx_so_c = $(HOSTCXX) $(plugin_cxxflags) $(plugin_ldflags) -o $@ $<; touch include/generated/global-rebuild.h Link: https://lore.kernel.org/linux-kbuild/cak7lnatdbxc+3hq6zosk9t-lkf4msnmeun6s5eqovwnbqw_...@mail.gmail.com/T/#me069145443a17f0b464c13814424dbba0d970863 [1] Cc: Kees Cook <k...@kernel.org> Signed-off-by: Masahiro Yamada <masahi...@kernel.org> --- Makefile | 9 ++++++++- arch/um/Makefile | 3 ++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 5aa9ee52a765..64811eebd549 100644 --- a/Makefile +++ b/Makefile @@ -558,7 +558,8 @@ USERINCLUDE := \ -I$(srctree)/include/uapi \ -I$(objtree)/include/generated/uapi \ -include $(srctree)/include/linux/compiler-version.h \ - -include $(srctree)/include/linux/kconfig.h + -include $(srctree)/include/linux/kconfig.h \ + -include $(objtree)/include/generated/global-rebuild.h # Use LINUXINCLUDE when you must reference the include/ directory. # Needed to be compatible with the O= option @@ -1257,6 +1258,11 @@ endif include/config/kernel.release: FORCE $(call filechk,kernel.release) +filechk_empty = printf '' + +include/generated/global-rebuild.h: FORCE + $(call filechk,empty) + # Additional helpers built in scripts/ # Carefully list dependencies so we do not try to build scripts twice # in parallel @@ -1273,6 +1279,7 @@ scripts: scripts_basic scripts_dtc PHONY += prepare archprepare archprepare: outputmakefile archheaders archscripts scripts include/config/kernel.release \ + include/generated/global-rebuild.h \ asm-generic $(version_h) include/generated/utsrelease.h \ include/generated/compile.h include/generated/autoconf.h \ include/generated/rustc_cfg remove-stale-files diff --git a/arch/um/Makefile b/arch/um/Makefile index 1d36a613aad8..f564a26c1364 100644 --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -73,7 +73,8 @@ USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \ -D_FILE_OFFSET_BITS=64 -idirafter $(srctree)/include \ -idirafter $(objtree)/include -D__KERNEL__ -D__UM_HOST__ \ -include $(srctree)/include/linux/compiler-version.h \ - -include $(srctree)/include/linux/kconfig.h + -include $(srctree)/include/linux/kconfig.h \ + -include $(objtree)/include/generated/global-rebuild.h #This will adjust *FLAGS accordingly to the platform. include $(srctree)/$(ARCH_DIR)/Makefile-os-Linux -- 2.43.0
