From nobody Mon Jun 8 20:41:41 2026 Received: from mail-dl1-f74.google.com (mail-dl1-f74.google.com [74.125.82.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7AAA9408018 for ; Tue, 26 May 2026 17:29:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779816574; cv=none; b=XYT5poNkAVsU5j0vZZtrIR7AjEk5riNIyOrSg0mFhqwDyxvflI0M0K7kXyC/aHZs3b9wOtd2kDKVE/DnhmxvKg7cu3OnQ5KBr3qP0vjd0oDhXCmz/GZgCtcKbFBLMXpUDXAWw7yU/XuHR/7Qt5LJbCqY2Mpk4lCL07OPOJIuZ7A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779816574; c=relaxed/simple; bh=TZMl/vbynpYCMuoy+zlBxwb8SZbk6c3T9r8Vgf0xHtU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=SYkhcG8eWuA5ro6T9b0JZefMg/Pk35cOiJL8WjI1YyerLwl3z6zBEyYw37yKAYFHvDkNe7RMUFACAVm9FFU/Ugumc4cUyAUa/hKyBz7Y/CsJ17wLGS///iI8KCrPxX4UL3VaF8d2m0jaTIBtS/uop0lLkh6JL+aTeO5wu5qXxPU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--xur.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=ETRoMpxF; arc=none smtp.client-ip=74.125.82.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--xur.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ETRoMpxF" Received: by mail-dl1-f74.google.com with SMTP id a92af1059eb24-135fe34cb98so9980559c88.0 for ; Tue, 26 May 2026 10:29:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1779816572; x=1780421372; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=eiEM96aKYd3kcaWuwa98b5ndrq8URQSfe6VJqlTBd7w=; b=ETRoMpxFOCDFyXX3/eiGpFyiYnXu9uqA1b89tSyySv+d0y3j+EJs5JwjR4DbWobrWw cI4/JYgAcCqJOxCA38rD9wYKMzfJs60kOvHgcft6ZHBLh9y4cSq9u/xBkw8MJaQOuyn+ HPbl2hUtYepUigerS7KLQ2UcNSNF25mTWPG41adZNMkpSAynQF5Lmy8kTRhdwHJckzTT bqLnWEqNJV3vpWO/UH4aw+bpsR+MTEY53RHzyPhluGwzv0/oKsvcHLM4745M2Uw5GsUC P4+2Zglk4PHvq95Ci0lxL6zomLr5ZRPGQbUL43KFl6GQOM5jXJ1/r7lsvD2fhtSHyOgS hH6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779816572; x=1780421372; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=eiEM96aKYd3kcaWuwa98b5ndrq8URQSfe6VJqlTBd7w=; b=ADZ/fJBWoA700eH/61KYZ4oyLx3sS/xHgCrGm8R5hUO8ji4SWL9TEH1CPbZ9cf1Zrq i1BGoFJL34xOnLaS0+5kxzmKkCte9neV4rvUaCaqRAKT1c8JJRW0/Xr4MYWRlQU+h3TP wAwB/rvF9rxV4QoruvKhnL3icr+aYVRxh8bipGwMi7gX6KMM8L0gnxy8q9nUXhMFsYNF JpP2Ucwm48Yn12myilSn0A6NE+24Mm1uKQV6YljQ2kLG78HfdYUwRSBhZGbtwqYYI/Gs qiCmvBE/fWDaOaW7AlxOynNl4lqxbJ0VK69UVdvxw7gW4mHe/TJg5TOfYEy1iEBMjebT 3GWg== X-Gm-Message-State: AOJu0YzuEKApY1ZW3fmZz1qXQuRN2xYJTQB9NUE7HXxfh3zjT2ve9TEz viFs0zQ3zFKVUqwQbWKRpJJZcd41XO0gXDa0jgci6GzaVNIxI1MUZUtX0mCDAhDAfd6O+A== X-Received: from dlzz41.prod.google.com ([2002:a05:7022:4a9:b0:135:e6d6:d140]) (user=xur job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:689d:b0:127:5cd6:fa45 with SMTP id a92af1059eb24-1365f818ee5mr8035316c88.14.1779816571294; Tue, 26 May 2026 10:29:31 -0700 (PDT) Date: Tue, 26 May 2026 10:29:24 -0700 In-Reply-To: <20260526172926.2717929-1-xur@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260526172926.2717929-1-xur@google.com> X-Mailer: git-send-email 2.54.0.746.g67dd491aae-goog Message-ID: <20260526172926.2717929-2-xur@google.com> Subject: [PATCH v10 1/3] kbuild: move vmlinux.a build rule to scripts/Makefile.vmlinux_a From: xur@google.com To: Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Yonghong Song , Bill Wendling , Justin Stitt , Miguel Ojeda , Thomas Gleixner , Alice Ryhl , Sami Tolvanen , "Mike Rapoport (Microsoft)" , Rafael Aquini , Michael Ellerman , Stafford Horne , Christophe Leroy , Piotr Gorski , Rong Xu , Venkat Rao Bagalkote , Miguel Ojeda , Teresa Johnson Cc: linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Rong Xu From: Masahiro Yamada Move the build rule for vmlinux.a to a separate file in preparation for supporting distributed builds with Clang ThinLTO. Signed-off-by: Masahiro Yamada Tested-by: Rong Xu Tested-by: Piotr Gorski Tested-by: Nathan Chancellor Signed-off-by: Rong Xu --- Makefile | 16 +++++-------- scripts/Makefile.vmlinux_a | 46 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 52 insertions(+), 10 deletions(-) create mode 100644 scripts/Makefile.vmlinux_a diff --git a/Makefile b/Makefile index e27c91ea56fc..0fce9557a115 100644 --- a/Makefile +++ b/Makefile @@ -1291,7 +1291,7 @@ export ARCH_DRIVERS :=3D $(drivers-y) $(drivers-m) KBUILD_VMLINUX_OBJS :=3D built-in.a $(patsubst %/, %/lib.a, $(filter %/, $= (libs-y))) KBUILD_VMLINUX_LIBS :=3D $(filter-out %/, $(libs-y)) =20 -export KBUILD_VMLINUX_LIBS +export KBUILD_VMLINUX_OBJS KBUILD_VMLINUX_LIBS export KBUILD_LDS :=3D arch/$(SRCARCH)/kernel/vmlinux.lds =20 ifdef CONFIG_TRIM_UNUSED_KSYMS @@ -1300,16 +1300,12 @@ ifdef CONFIG_TRIM_UNUSED_KSYMS KBUILD_MODULES :=3D y endif =20 -# '$(AR) mPi' needs 'T' to workaround the bug of llvm-ar <=3D 14 -quiet_cmd_ar_vmlinux.a =3D AR $@ - cmd_ar_vmlinux.a =3D \ - rm -f $@; \ - $(AR) cDPrST $@ $(KBUILD_VMLINUX_OBJS); \ - $(AR) mPiT $$($(AR) t $@ | sed -n 1p) $@ $$($(AR) t $@ | grep -F -f $(src= tree)/scripts/head-object-list.txt) +PHONY +=3D vmlinux_a +vmlinux_a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt FORCE + $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vmlinux_a =20 -targets +=3D vmlinux.a -vmlinux.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt FORCE - $(call if_changed,ar_vmlinux.a) +vmlinux.a: vmlinux_a + @: =20 PHONY +=3D vmlinux_o vmlinux_o: vmlinux.a $(KBUILD_VMLINUX_LIBS) diff --git a/scripts/Makefile.vmlinux_a b/scripts/Makefile.vmlinux_a new file mode 100644 index 000000000000..9774f02b43b2 --- /dev/null +++ b/scripts/Makefile.vmlinux_a @@ -0,0 +1,46 @@ +# SPDX-License-Identifier: GPL-2.0-only + +PHONY :=3D __default +__default: vmlinux.a + +include include/config/auto.conf +include $(srctree)/scripts/Kbuild.include +include $(srctree)/scripts/Makefile.lib + +# Link of built-in-fixup.a +# ------------------------------------------------------------------------= --- + +# '$(AR) mPi' needs --thin to workaround the bug of llvm-ar <=3D 14 +quiet_cmd_ar_builtin_fixup =3D AR $@ + cmd_ar_builtin_fixup =3D \ + rm -f $@; \ + $(AR) cDPrS --thin $@ $(KBUILD_VMLINUX_OBJS); \ + $(AR) mPi --thin $$($(AR) t $@ | sed -n 1p) $@ $$($(AR) t $@ | grep -F -f= $(srctree)/scripts/head-object-list.txt) + +targets +=3D built-in-fixup.a +built-in-fixup.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt FORCE + $(call if_changed,ar_builtin_fixup) + +# vmlinux.a +# ------------------------------------------------------------------------= --- + +targets +=3D vmlinux.a +vmlinux.a: built-in-fixup.a FORCE + $(call if_changed,copy) + +# Add FORCE to the prerequisites of a target to force it to be always rebu= ilt. +# ------------------------------------------------------------------------= --- + +PHONY +=3D FORCE +FORCE: + +# Read all saved command lines and dependencies for the $(targets) we +# may be building above, using $(if_changed{,_dep}). As an +# optimization, we don't need to read them if the target does not +# exist, we will rebuild anyway in that case. + +existing-targets :=3D $(wildcard $(sort $(targets))) + +-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd) + +.PHONY: $(PHONY) --=20 2.54.0.746.g67dd491aae-goog From nobody Mon Jun 8 20:41:41 2026 Received: from mail-dl1-f74.google.com (mail-dl1-f74.google.com [74.125.82.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 31F0E40803A for ; Tue, 26 May 2026 17:29:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779816574; cv=none; b=O/6+HSWShgl3piTQz+KR0ZZ6CCNXHdpgXm+TbgmPEMcO3TamkP1AmouG4OgGz+CVDa8rAOv/LGaXXF/9csefu2WONqJof3pent+P39qPgJcrbgcl8zhc3garKWeLPAY8NS/Q+36vJ3iw0qhrnuAaJQhnAo7144uyjhzd+NCGnNg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779816574; c=relaxed/simple; bh=IrM04IvPDo1sb9vHOovgPk1Y41bQl7xbfqKK2Qsjgi4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=GXDy05tpKQsXZ/RN6XE7XnfYhAslxx0xaKCwBbop9jPi8XIOAyVmwhJbxuoveWn9YKCD0U/Af5vxHtDlGYt3ZiqRrDz7TWZIMlkxduCZ65xOSZb09JZc1DW2HqdcT0BLYZIgScHGt7FY9AZ3SaeJMNDwMgYBVpc7gE1FsXp2Kgo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--xur.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=cU7sfiML; arc=none smtp.client-ip=74.125.82.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--xur.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="cU7sfiML" Received: by mail-dl1-f74.google.com with SMTP id a92af1059eb24-1353a6f29deso8589749c88.1 for ; Tue, 26 May 2026 10:29:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1779816572; x=1780421372; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=GSth3bH8wQN7DeJyLy/4rKJnmvPjIvLAam/FmnUx4yQ=; b=cU7sfiMLDU6gVECR76rMbwW26neasLjc3Raru1vsacodn4jKQrloQeGGtZkwId3lUA oaR0Ipp8JIzsW+K2PEvscVPJBg43JeaLPUi5oJ0cIUxseRwJ6x4e6KvPBz9OMzs0bwBh AQmMUMO9my3O147EsXyuz7QgoPOBsPLa72fPdrsrblYWs364CIG+SEcveuALs6J0XGd7 O6Tc4wsqtaTD9th9asj3ApEjxwNb2ZE/UAw4YRrBhnwInl3GfM15X0iftuiJEPiJLz7T WszMYf4yZi1Fq7dGg9+TKVGKrP68K9ARcAoUrtj4fjwMgPcPYBqwduXzi0HKcMiWnV0F NRRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779816572; x=1780421372; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=GSth3bH8wQN7DeJyLy/4rKJnmvPjIvLAam/FmnUx4yQ=; b=ePDcCFvB9mDcIk2UZGDMHaKJ6kRpr1Ct90CbYsF3tmfn7kFE25hEl8MXgFSIgyfxh+ ftLWWJRG+If6TU5XRvH37A9GeMfVb81zsRKr1qi2vuXxx0eV6V/X7bFcXV1q+qSskrxk P9pvZ2l32RvUHKioN/4CqCiEWB9uxMkObTuy+zKJdXqSWMNdbPslxzRzri7ardem2c6g Iez3sO2qfsdWD65Bsj3qWjnvMaFLIBsCm/sH1MM7K/0q2BSiTpE28JqiyXNmkAyYV2CS qJA13N8uczHIp54i4DTrO+ukc5XyzixqVlbV1LSobzHkK+AB6vZZCAAj12N6cksHfGOk tlMw== X-Gm-Message-State: AOJu0YyW0CsP3DuvXdsrlAcq5CjgjDK8UcGOIIAiqVwn9c/gRnK+hRVL 6N0C1/8aEXuYjJ19l/Yz8KfGTgzeD4UHgzPGlU8uRYYTV7Eag/Ep6o0UTUzjnhelvuBNJg== X-Received: from dlbef14.prod.google.com ([2002:a05:7022:f4e:b0:135:cc8b:4336]) (user=xur job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:511:b0:12d:ceaf:ffcc with SMTP id a92af1059eb24-1365f812d65mr6760491c88.5.1779816572178; Tue, 26 May 2026 10:29:32 -0700 (PDT) Date: Tue, 26 May 2026 10:29:25 -0700 In-Reply-To: <20260526172926.2717929-1-xur@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260526172926.2717929-1-xur@google.com> X-Mailer: git-send-email 2.54.0.746.g67dd491aae-goog Message-ID: <20260526172926.2717929-3-xur@google.com> Subject: [PATCH v10 2/3] kbuild: change --thin back to 'T' in $(AR) From: xur@google.com To: Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Yonghong Song , Bill Wendling , Justin Stitt , Miguel Ojeda , Thomas Gleixner , Alice Ryhl , Sami Tolvanen , "Mike Rapoport (Microsoft)" , Rafael Aquini , Michael Ellerman , Stafford Horne , Christophe Leroy , Piotr Gorski , Rong Xu , Venkat Rao Bagalkote , Miguel Ojeda , Teresa Johnson Cc: linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Rong Xu The '-T' flag in $(AR) is no longer problematic since the minimum requirement for LLVM has been updated to version 15. As of LLVM 14 and onward, the '-T' flag functions identically to the '--thin' flag. Fixed the issue seen on IBM Power11 System: ar: unrecognized option '--thin' Reported-by: Venkat Rao Bagalkote Closes: https://lore.kernel.org/linux-next/476507c9-a371-4864-9e87-572c1eca= e82d@linux.ibm.com/ Signed-off-by: Rong Xu --- scripts/Makefile.vmlinux_a | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/scripts/Makefile.vmlinux_a b/scripts/Makefile.vmlinux_a index 9774f02b43b2..650d44330d1f 100644 --- a/scripts/Makefile.vmlinux_a +++ b/scripts/Makefile.vmlinux_a @@ -10,12 +10,12 @@ include $(srctree)/scripts/Makefile.lib # Link of built-in-fixup.a # ------------------------------------------------------------------------= --- =20 -# '$(AR) mPi' needs --thin to workaround the bug of llvm-ar <=3D 14 +# '$(AR) mPi' needs 'T' to workaround the bug of llvm-ar <=3D 14 quiet_cmd_ar_builtin_fixup =3D AR $@ cmd_ar_builtin_fixup =3D \ rm -f $@; \ - $(AR) cDPrS --thin $@ $(KBUILD_VMLINUX_OBJS); \ - $(AR) mPi --thin $$($(AR) t $@ | sed -n 1p) $@ $$($(AR) t $@ | grep -F -f= $(srctree)/scripts/head-object-list.txt) + $(AR) cDPrST $@ $(KBUILD_VMLINUX_OBJS); \ + $(AR) mPiT $$($(AR) t $@ | sed -n 1p) $@ $$($(AR) t $@ | grep -F -f $(src= tree)/scripts/head-object-list.txt) =20 targets +=3D built-in-fixup.a built-in-fixup.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt FORCE --=20 2.54.0.746.g67dd491aae-goog From nobody Mon Jun 8 20:41:41 2026 Received: from mail-dy1-f201.google.com (mail-dy1-f201.google.com [74.125.82.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4171140B6DB for ; Tue, 26 May 2026 17:29:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779816576; cv=none; b=ax61yoJ23VaXYS3c2sfK3hDWu8sQsiXAhBJK1nEVB0iyVFxn+1EWygPCnYRiLKQW7RlzebRl3zFK/VggVwSNEdQ0G5xzNv8qenHN7SpXUnZq4jXQeJsArvxxwYbkANDh6M3GECSEXkC4M/bGtGiba9moDFdsN0DnNz9HFpRUsP0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779816576; c=relaxed/simple; bh=RRuwmW6B6ZLVhlCNZ1zg4gsGaC+fc6wLxUw99Hw0WQU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=kfNBQUDMDDdqQkfNdRdywVYW2Y4y6AapBNzVn4tfjY9dO+yap//vu8glQQ909XEJ+NNxhKbENG9bIWQG5BRarokE7JmAJWlRPn9AS+8372U5K+u0FI/Z0MbyaBWPBpu9Ygo/fjkAk20w2LFI1zI7vQcl6EKLf7VEPeR8kKUOzjE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--xur.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=dJHSnieH; arc=none smtp.client-ip=74.125.82.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--xur.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="dJHSnieH" Received: by mail-dy1-f201.google.com with SMTP id 5a478bee46e88-2fded513994so2829535eec.1 for ; Tue, 26 May 2026 10:29:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1779816573; x=1780421373; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=62qbdDbm+27B8JP8wMqUFd2P0lIFnwesmZHdDdyZ1gw=; b=dJHSnieHwIB3TSNyq7+RfAOWFUWagLsgNuUbJcxkpzMfskpJnGhNSRpKofbuAZa10g kIByHu8KzyYGgMTxbp3hJ1D/pIPEwfrop23zhseZOr0ghVJw+PzHYSn7PJVCWf0dy03A C/3g5eE4cpAD2drTS2jIMgeCISUW+Otso0AmOBV7Pck/u+8JukWSr9sS0HVXQ2ax/Si1 s2ESkEEa9eSj7GvlPzAXjWqScwC8MNoH8WFo4NqwDfzO29aMfoetl0YhGsWJIochQKkG p+3tRb8AUe5oJ/TgDQczMfWL0wI91qRgiBhIjC21+C0k+kmnWKKbsvt1UulSmxlAMwmN eqdQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779816573; x=1780421373; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=62qbdDbm+27B8JP8wMqUFd2P0lIFnwesmZHdDdyZ1gw=; b=oUFf4Mpdr3AMNbQyZYGN4KHRAdGGD6YgrQtioO8TFNQFXhoPEi7cOqbK7Qkl8FnN/B qcrofPicx3kTkUhHmXx7fC2D0Ttegdx5HzXY24NgKpjE9qHtCD/iOPDo/8HxziLL7a5c RJR9Lp4EbqdvFwNZOaCQUPjc/hvuxQUTwyEtQoot5SwcfYNVWPZSp+luFSNT4v0kzacU 1TZHjro49RerbSvAfoZiXFtkjYBFoij6mlh+JBkRZII9ViKWcaNDWG2W3xTlcGLo036S 8sLubR9DT9DK8dhqm7aE2f5+fg8CD2ydPRQt14Vp2WaoRgw30uW3FPKVSTkd9XzSdD9Q kWRg== X-Gm-Message-State: AOJu0YwzPf8fjPQW+oksMYgfzHZzyMQgLq8MnaPlqe767RhJAHYdTj6L 1o3rVXf7S6yJw6h+pm8vHMavsqZKdpdyeZVucOq8Ccsn6VAfO5S5nw7yYMd2XZGJwKkhIA== X-Received: from dyblc25.prod.google.com ([2002:a05:7301:1319:b0:304:9f4b:631]) (user=xur job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7301:10cc:b0:2f4:3a9c:818c with SMTP id 5a478bee46e88-3044919c752mr8136530eec.29.1779816573120; Tue, 26 May 2026 10:29:33 -0700 (PDT) Date: Tue, 26 May 2026 10:29:26 -0700 In-Reply-To: <20260526172926.2717929-1-xur@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260526172926.2717929-1-xur@google.com> X-Mailer: git-send-email 2.54.0.746.g67dd491aae-goog Message-ID: <20260526172926.2717929-4-xur@google.com> Subject: [PATCH v10 3/3] kbuild: distributed build support for Clang ThinLTO From: xur@google.com To: Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Yonghong Song , Bill Wendling , Justin Stitt , Miguel Ojeda , Thomas Gleixner , Alice Ryhl , Sami Tolvanen , "Mike Rapoport (Microsoft)" , Rafael Aquini , Michael Ellerman , Stafford Horne , Christophe Leroy , Piotr Gorski , Rong Xu , Venkat Rao Bagalkote , Miguel Ojeda , Teresa Johnson Cc: linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Rong Xu Add distributed ThinLTO build support for the Linux kernel. This new mode offers several advantages: (1) Increased flexibility in handling user-specified build options. (2) Improved user-friendliness for developers. (3) Greater convenience for integrating with objtool and livepatch. Note that "distributed" in this context refers to a term that differentiates in-process ThinLTO builds by invoking backend compilation through the linker, not necessarily building in distributed environments. Distributed ThinLTO is enabled via the `CONFIG_LTO_CLANG_THIN_DIST` Kconfig option. For example: > make LLVM=3D1 defconfig > scripts/config -e LTO_CLANG_THIN_DIST > make LLVM=3D1 oldconfig > make LLVM=3D1 vmlinux -j <..> The build flow proceeds in four stages: 1. Perform FE compilation, mirroring the in-process ThinLTO mode. 2. Thin-link the generated IR files and object files. 3. Find all IR files and perform BE compilation, using the flags stored in the .*.o.cmd files. 4. Link the BE results to generate the final vmlinux.o. NOTE: This patch currently implements the build for the main kernel image (vmlinux) only. Kernel module support is planned for a subsequent patch. Tested on the following arch: x86, arm64, loongarch, and riscv. The earlier implementation details can be found here: https://discourse.llvm.org/t/rfc-distributed-thinlto-build-for-kernel/85934 Signed-off-by: Rong Xu Co-developed-by: Masahiro Yamada Signed-off-by: Masahiro Yamada Tested-by: Piotr Gorski Tested-by: Nathan Chancellor --- .gitignore | 2 ++ Makefile | 14 +++++++++---- arch/Kconfig | 19 ++++++++++++++++++ scripts/Makefile.lib | 7 +++++++ scripts/Makefile.thinlto | 40 ++++++++++++++++++++++++++++++++++++++ scripts/Makefile.vmlinux_a | 37 +++++++++++++++++++++++++++++++++++ scripts/mod/modpost.c | 15 +++++++++++--- 7 files changed, 127 insertions(+), 7 deletions(-) create mode 100644 scripts/Makefile.thinlto diff --git a/.gitignore b/.gitignore index 3044b9590f05..1cc34c9a5523 100644 --- a/.gitignore +++ b/.gitignore @@ -57,6 +57,7 @@ *.zst Module.symvers dtbs-list +builtin.order modules.order =20 # @@ -68,6 +69,7 @@ modules.order /vmlinux.32 /vmlinux.map /vmlinux.symvers +/vmlinux.thinlto-index /vmlinux.unstripped /vmlinux-gdb.py /vmlinuz diff --git a/Makefile b/Makefile index 0fce9557a115..857f08dcc952 100644 --- a/Makefile +++ b/Makefile @@ -1071,11 +1071,16 @@ export CC_FLAGS_SCS endif =20 ifdef CONFIG_LTO_CLANG -ifdef CONFIG_LTO_CLANG_THIN +ifdef CONFIG_LTO_CLANG_FULL +CC_FLAGS_LTO :=3D -flto +else CC_FLAGS_LTO :=3D -flto=3Dthin -fsplit-lto-unit + +# These LLVM options were initially added with only in-process ThinLTO +# support, so avoid distributed ThinLTO support for now. +ifdef CONFIG_LTO_CLANG_THIN KBUILD_LDFLAGS +=3D $(call ld-option,--lto-whole-program-visibility -mllvm= -always-rename-promoted-locals=3Dfalse) -else -CC_FLAGS_LTO :=3D -flto +endif endif CC_FLAGS_LTO +=3D -fvisibility=3Dhidden =20 @@ -1684,6 +1689,7 @@ endif # CONFIG_MODULES CLEAN_FILES +=3D vmlinux.symvers modules-only.symvers \ modules.builtin modules.builtin.modinfo modules.nsdeps \ modules.builtin.ranges vmlinux.o.map vmlinux.unstripped \ + vmlinux.thinlto-index builtin.order \ compile_commands.json rust/test \ rust-project.json .vmlinux.objs .vmlinux.export.c \ .builtin-dtbs-list .builtin-dtbs.S @@ -2145,7 +2151,7 @@ clean: $(clean-dirs) $(call cmd,rmfiles) @find . $(RCS_FIND_IGNORE) \ \( -name '*.[aios]' -o -name '*.rsi' -o -name '*.ko' -o -name '.*.cmd' \ - -o -name '*.ko.*' \ + -o -name '*.ko.*' -o -name '*.o.thinlto.bc' \ -o -name '*.dtb' -o -name '*.dtbo' \ -o -name '*.dtb.S' -o -name '*.dtbo.S' \ -o -name '*.dt.yaml' -o -name 'dtbs-list' \ diff --git a/arch/Kconfig b/arch/Kconfig index e86880045158..082483a3bbf8 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -861,6 +861,25 @@ config LTO_CLANG_THIN https://clang.llvm.org/docs/ThinLTO.html =20 If unsure, say Y. + +config LTO_CLANG_THIN_DIST + bool "Clang ThinLTO in distributed mode (EXPERIMENTAL)" + depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN + select LTO_CLANG + help + This option enables Clang's ThinLTO in distributed build mode. + In this mode, the linker performs the thin-link, generating + ThinLTO index files. Subsequently, the build system explicitly + invokes ThinLTO backend compilation using these index files + and pre-linked IR objects. The resulting native object files + are with the .thinlto-native.o suffix. + + This build mode offers improved visibility into the ThinLTO + process through explicit subcommand exposure. It also makes + final native object files directly available, benefiting + tools like objtool and kpatch. Additionally, it provides + crucial granular control over back-end options, enabling + module-specific compiler options, and simplifies debugging. endchoice =20 config ARCH_SUPPORTS_AUTOFDO_CLANG diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 0718e39cedda..b36c7c6817bd 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -249,6 +249,12 @@ ifdef CONFIG_LTO_CLANG cmd_ld_single =3D $(if $(objtool-enabled)$(is-single-obj-m), ; $(LD) $(ld_= flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@) endif =20 +ifdef CONFIG_LTO_CLANG_THIN_DIST +# Save the _c_flags, sliently. +quiet_cmd_save_c_flags =3D + cmd_save_c_flags =3D printf '\n%s\n' 'saved_c_flags_$@ :=3D $(call e= scsq,$(_c_flags))' >> $(dot-target).cmd +endif + quiet_cmd_cc_o_c =3D CC $(quiet_modtag) $@ cmd_cc_o_c =3D $(CC) $(c_flags) -c -o $@ $< \ $(cmd_ld_single) \ @@ -256,6 +262,7 @@ quiet_cmd_cc_o_c =3D CC $(quiet_modtag) $@ =20 define rule_cc_o_c $(call cmd_and_fixdep,cc_o_c) + $(call cmd,save_c_flags) $(call cmd,checksrc) $(call cmd,checkdoc) $(call cmd,gen_objtooldep) diff --git a/scripts/Makefile.thinlto b/scripts/Makefile.thinlto new file mode 100644 index 000000000000..03349ac69de5 --- /dev/null +++ b/scripts/Makefile.thinlto @@ -0,0 +1,40 @@ +PHONY :=3D __default +__default: + +include include/config/auto.conf +include $(srctree)/scripts/Kbuild.include +include $(srctree)/scripts/Makefile.lib + +native-objs :=3D $(patsubst %.o,%.thinlto-native.o,$(call read-file, vmlin= ux.thinlto-index)) + +__default: $(native-objs) + +# Generate .thinlto-native.o (obj) from .o (bitcode) and .thinlto.bc (summ= ary) files +# ------------------------------------------------------------------------= --- +quiet_cmd_cc_o_bc =3D CC $(quiet_modtag) $@ + be_flags =3D $(shell sed -n '/saved_c_flags_/s/.*:=3D //p' \ + $(dir $(<)).$(notdir $(<)).cmd) + cmd_cc_o_bc =3D \ + $(CC) $(be_flags) -x ir -fno-lto -Wno-unused-command-line-argument \ + -fthinlto-index=3D$(word 2, $^) -c -o $@ $< + +targets +=3D $(native-objs) +$(native-objs): %.thinlto-native.o: %.o %.o.thinlto.bc FORCE + $(call if_changed,cc_o_bc) + +# Add FORCE to the prerequisites of a target to force it to be always rebu= ilt. +# ------------------------------------------------------------------------= --- + +PHONY +=3D FORCE +FORCE: + +# Read all saved command lines and dependencies for the $(targets) we +# may be building above, using $(if_changed{,_dep}). As an +# optimization, we don't need to read them if the target does not +# exist, we will rebuild anyway in that case. + +existing-targets :=3D $(wildcard $(sort $(targets))) + +-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd) + +.PHONY: $(PHONY) diff --git a/scripts/Makefile.vmlinux_a b/scripts/Makefile.vmlinux_a index 650d44330d1f..15d92ee82dee 100644 --- a/scripts/Makefile.vmlinux_a +++ b/scripts/Makefile.vmlinux_a @@ -21,6 +21,41 @@ targets +=3D built-in-fixup.a built-in-fixup.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt FORCE $(call if_changed,ar_builtin_fixup) =20 +ifdef CONFIG_LTO_CLANG_THIN_DIST + +quiet_cmd_builtin.order =3D GEN $@ + cmd_builtin.order =3D $(AR) t $< > $@ + +targets +=3D builtin.order +builtin.order: built-in-fixup.a FORCE + $(call if_changed,builtin.order) + +quiet_cmd_ld_thinlto_index =3D LD $@ + cmd_ld_thinlto_index =3D \ + $(LD) $(KBUILD_LDFLAGS) -r --thinlto-index-only=3D$@ @$< + +targets +=3D vmlinux.thinlto-index +vmlinux.thinlto-index: builtin.order FORCE + $(call if_changed,ld_thinlto_index) + +quiet_cmd_ar_vmlinux.a =3D GEN $@ + cmd_ar_vmlinux.a =3D \ + rm -f $@; \ + while read -r obj; do \ + if grep -q $${obj} $(word 2, $^); then \ + echo $${obj%.o}.thinlto-native.o; \ + else \ + echo $${obj}; \ + fi; \ + done < $< | xargs $(AR) cDPrS --thin $@ + +targets +=3D vmlinux.a +vmlinux.a: builtin.order vmlinux.thinlto-index FORCE + $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.thinlto + $(call if_changed,ar_vmlinux.a) + +else + # vmlinux.a # ------------------------------------------------------------------------= --- =20 @@ -28,6 +63,8 @@ targets +=3D vmlinux.a vmlinux.a: built-in-fixup.a FORCE $(call if_changed,copy) =20 +endif + # Add FORCE to the prerequisites of a target to force it to be always rebu= ilt. # ------------------------------------------------------------------------= --- =20 diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index abbcd3fc1394..171886ac1726 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1487,13 +1487,22 @@ static void extract_crcs_for_object(const char *obj= ect, struct module *mod) char cmd_file[PATH_MAX]; char *buf, *p; const char *base; - int dirlen, ret; + int dirlen, baselen_without_suffix, ret; =20 base =3D get_basename(object); dirlen =3D base - object; =20 - ret =3D snprintf(cmd_file, sizeof(cmd_file), "%.*s.%s.cmd", - dirlen, object, base); + baselen_without_suffix =3D strlen(object) - dirlen - strlen(".o"); + + /* + * When CONFIG_LTO_CLANG_THIN_DIST=3Dy, the ELF is *.thinlto-native.o + * but the symbol CRCs are recorded in *.o.cmd file. + */ + if (strends(object, ".thinlto-native.o")) + baselen_without_suffix -=3D strlen(".thinlto-native"); + + ret =3D snprintf(cmd_file, sizeof(cmd_file), "%.*s.%.*s.o.cmd", + dirlen, object, baselen_without_suffix, base); if (ret >=3D sizeof(cmd_file)) { error("%s: too long path was truncated\n", cmd_file); return; --=20 2.54.0.746.g67dd491aae-goog