From nobody Sun Feb 8 15:58:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C110717A2FC; Sat, 3 May 2025 08:41:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746261716; cv=none; b=BjgfkHCd6Tgq01bjqRAjaUxORccdUD0kw6N6rPybWcwlOTKgQOnIYvoOhBLfsog+5rUdF4PFtMUaZZX6YuJ5sGnO4qUn7hJ2KtELn/bHwyWAvXIh3pX+kBkajvv6VP9KC5n30VUIVpCjW5gGhRUfchExCNIzHPmE4fGmtCOLrhg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746261716; c=relaxed/simple; bh=+PcCraay1DizFcXkGnQrr4jLbEi5SeYlgRLvxR87H1w=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=j8Nt2kfZrmO4XU+HRj5EmJZHy4GOU7jvfGUUB4kCY16pTY/eWv/pyLIcIiJKcDaIz30ZIp4DMhkrpxuXnM4R+hq6KAEeq8NfMyORGa/8v8cHWPDj9JCQTXpjh6adz+iKMC96HCVq3XnkCb2D/Ns6mIQo6JIzUQawJKHUS0ikGWc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=icAiLkvx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="icAiLkvx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4ABD6C4CEE9; Sat, 3 May 2025 08:41:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746261716; bh=+PcCraay1DizFcXkGnQrr4jLbEi5SeYlgRLvxR87H1w=; h=From:To:Cc:Subject:Date:From; b=icAiLkvxWq3doiPO+t5E/kfc2c/7ZDNGG4rWvNXdbSKcmAxQsX3Yylbo/wVxa4HQL Ld/txHQM0xF3Hue7oRrEiwvy+OB8cA3xyG+QPqBQGoCWWy+KXP7KXSoMa6n6S9V2fK JKVSuN4CHm9rpF0D/SEghlW2o8o5ayOvKy++D0rP3YCIxr4kox+L2tVJaAVlgoYIgp al1/rA1hZGr5QwLfniQIvAYf8U9coCjZpxhQ/BeUCFNItMlCeh5JQPQgQ7fr2Py8qc FKLZ33ZsB7I8ENpp7IaqN7ZkB1C8SzWfniK/PAdfFWqetqYlAudr/dKhLYo5+5kVGY ZXr2leGqB6yrw== From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Masahiro Yamada , Kees Cook , Anton Ivanov , Johannes Berg , Nathan Chancellor , Nicolas Schier , Richard Weinberger , linux-um@lists.infradead.org Subject: [PATCH] kbuild: introduce include/generated/global-rebuild.h Date: Sat, 3 May 2025 17:41:43 +0900 Message-ID: <20250503084145.1994176-1-masahiroy@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 =3D HOSTCXX $@ - cmd_plugin_cxx_so_c =3D $(HOSTCXX) $(plugin_cxxflags) $(plugin_ldfl= ags) -o $@ $< + cmd_plugin_cxx_so_c =3D $(HOSTCXX) $(plugin_cxxflags) $(plugin_ldfl= ags) -o $@ $<; touch include/generated/global-rebuild.h Link: https://lore.kernel.org/linux-kbuild/CAK7LNATDbxc+3HQ6zoSk9t-Lkf4MSNm= EUN6S5EqoVWnBQw_K6g@mail.gmail.com/T/#me069145443a17f0b464c13814424dbba0d97= 0863 [1] Cc: Kees Cook Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier Tested-by: Nicolas Schier --- Makefile | 9 ++++++++- arch/um/Makefile | 3 ++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 5aa9ee52a765..64811eebd549 100644 --- a/Makefile +++ b/Makefile @@ -558,7 +558,8 @@ USERINCLUDE :=3D \ -I$(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 =20 # Use LINUXINCLUDE when you must reference the include/ directory. # Needed to be compatible with the O=3D option @@ -1257,6 +1258,11 @@ endif include/config/kernel.release: FORCE $(call filechk,kernel.release) =20 +filechk_empty =3D 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 +=3D prepare archprepare =20 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 =3D $(patsubst $(KERNEL_DEFINES),,$(patsubst = -I%,,$(KBUILD_CFLAGS))) \ -D_FILE_OFFSET_BITS=3D64 -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 =20 #This will adjust *FLAGS accordingly to the platform. include $(srctree)/$(ARCH_DIR)/Makefile-os-Linux --=20 2.43.0