From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 362BA43C04C; Wed, 27 May 2026 16:42:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779900143; cv=none; b=uZ2oJoZF1UY8GKfFYjEp+OWmDRT8s2hkaEKe4P2cwUy7wdF7tcPIn4GKDHQ5Vn3VdbyBIe+5RCIL6HjZeDXHdf71l/Qtqkjew/EOJy8n5fc00bQgNgwPW7hKvphzYCZ2r6FB/TF9dFOA2TmxFcwqWOxSx8vBLvxhxHXjXurOXYw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779900143; c=relaxed/simple; bh=qjd3tguTj0WFwiPlEIeVbyzh3f1Zu6w1BXCkFvwK7q8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=EU/bn5+gyGCDtlaVxIObaLKerNa9t6/WyjPjEWCOERWtxc/I35d9KY4RcxJDDizO4aXxSsTOQzKCM6fxnBXkiiFXBGXNh6gT7JUQvK2Yhp77fJ4w/HQAX+Cph9t7tFBygXHfJEih2YJzlM/okmyE/xf7dWlXgG51g62dyAiXZVI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=K6UsFZbj; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="K6UsFZbj" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:Cc:To:In-Reply-To:References: Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description; bh=M13mLGQRBGUn1JxQb9Dlyz/7Efn1k3VV1WqpaU1q/a4=; b=K6UsFZbj+JXviEdG9m6WNbH9Tw 5QSlnUl9QvrvMWS4HDJGbv9Z7yAooG7PE8b7H90qq2NoRILPxivZQ6vI+F971jdfTgqlCxuIQZki0 HDJJ6UtSeXe1kOLz8hGZ5nHBdnDqwpLRmaxGQZ5elAob6WuW5MBWFpXyqlO0tW2EMU+q9aBUUOFQM ZxlFj/rOUwmp7IybXI4tFl70jln5pb7ydn5nBhKTb3q3u4oIOomoRq0ue6DKT33TsvsB1D+YgQ0w3 Mye8dMT560SfSDjfwuTeOw4IwjkylTNCtTSo2hAmy8Zk+PTlr3cuLqNcEp7EsGdRO1e/EyHFUwqSg dAetBJWw==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wSHKW-003JPh-2O; Wed, 27 May 2026 16:42:05 +0000 From: Breno Leitao Date: Wed, 27 May 2026 09:41:35 -0700 Subject: [PATCH 2/4] bootconfig: render embedded bootconfig as a kernel cmdline at build time Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260527-bootconfig_using_tools-v1-2-b6906a86e7d5@debian.org> References: <20260527-bootconfig_using_tools-v1-0-b6906a86e7d5@debian.org> In-Reply-To: <20260527-bootconfig_using_tools-v1-0-b6906a86e7d5@debian.org> To: Masami Hiramatsu , Andrew Morton , Nathan Chancellor , paulmck@kernel.org, Nicolas Schier Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, bpf@vger.kernel.org, Breno Leitao , kernel-team@meta.com X-Mailer: b4 0.16-dev-d5d98 X-Developer-Signature: v=1; a=openpgp-sha256; l=6974; i=leitao@debian.org; h=from:subject:message-id; bh=qjd3tguTj0WFwiPlEIeVbyzh3f1Zu6w1BXCkFvwK7q8=; b=owEBbQKS/ZANAwAIATWjk5/8eHdtAcsmYgBqFx7N/lN7BhCSbH5GyUOsWhONOBrZ7ohZPrPON R0xqw+moQ6JAjMEAAEIAB0WIQSshTmm6PRnAspKQ5s1o5Of/Hh3bQUCahcezQAKCRA1o5Of/Hh3 bZTtEACbVcAO3TU/zsDr8yMKV8XfYFC+IbG/J+PhYQAny8E4igdDdFIwTHWmCs0wwF6KiLFVX2e h3q9vjgOiqc2yXfSE/poRW7rEO+LVfv7kPQBGHtcQjJmt1lp4ivKrXzdSEfSwS6s7lE+UE4iWVc DC5u4FpjklxYBVddUleJKIVBjvxKi7fbJsH0vthVeWyhb8T7P0Hr6xop/2R+kKN0ZLWPTQh8F7w CreMF1OHwoa/Q+8QEuWTGUj0X7ZtVaDdll5lL1ZXFvl/WuO5l+Xc6hc5BCx8iyNYuhSTtqzbK3M lvf/LkYwG9DJ8A43xInUnpCU3np5/NEdGEAsL39HA1o+CcItVP4+7lyEyvg5EwdOL1mqBGYF8yy gXiZpSVSI6iFCr9H46QwItINk8coMXG8Bbx/KvCvQM8zBe2f+oGXr1kQ3fpdoKz2xD0u6g6HSct 6JxZvEVkidtqgo5RxKxgDSRowSoLh6EvLvT/4EZ+m8NQyEw6Vx1JexxzIWN6xKXMSQfBdzRhT7L TG1BW9mCyarX9HyCAdnadiXqa+LQ/AYY12PFG3Hxq4gvZld/5f5ccmQBpi56ixhbn9BuLIWJCRg w3kOaYI1ExzZqlEyOCOAX0gjy0ecyXr7nlOTS8Q14lkYOBm878LtyYn020z5IMapnBtXoS+L/x3 MnU2JqgBJlX9BuQ== X-Developer-Key: i=leitao@debian.org; a=openpgp; fpr=AC8539A6E8F46702CA4A439B35A3939FFC78776D X-Debian-User: leitao Add the build-time pipeline that renders the "kernel" subtree of CONFIG_BOOT_CONFIG_EMBED_FILE into a flat cmdline string and stashes it in .init.rodata as embedded_kernel_cmdline[]. A follow-up patch adds the runtime helper that prepends this string to boot_command_line during early architecture setup so parse_early_param() sees the values. The build wires up: tools/bootconfig -C kernel - userspace tool already shared with lib/bootconfig.c, used here in -C mode to render a bootconfig file to a cmdline lib/embedded-cmdline.S - .incbin's the rendered text plus a NUL lib/Makefile rule - runs tools/bootconfig at build time Makefile prepare dep - ensures tools/bootconfig is built first, same pattern as tools/objtool and tools/bpf/resolve_btfids Drop the test target from tools/bootconfig/Makefile's default 'all' recipe so that hooking the binary into the kernel build does not run test-bootconfig.sh on every prepare. The tests stay available as 'make -C tools/bootconfig test', matching the convention of tools/objtool and tools/bpf/resolve_btfids whose 'all' targets only build the binary. Require BOOT_CONFIG_EMBED_FILE to be non-empty before the new option can be enabled, otherwise tools/bootconfig -C runs against an empty file and prints a parse error on every kernel build. The feature gates on CONFIG_ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG, a silent symbol arches select once they've wired the prepend call into setup_arch(). No arch selects it in this patch, so the user-visible CONFIG_BOOT_CONFIG_EMBED_CMDLINE is not yet enableable; when an arch later opts in, the runtime behavior is added by the follow-up patches. Signed-off-by: Breno Leitao --- Makefile | 5 +++++ init/Kconfig | 33 +++++++++++++++++++++++++++++++++ lib/Makefile | 16 ++++++++++++++++ lib/embedded-cmdline.S | 16 ++++++++++++++++ tools/bootconfig/Makefile | 2 +- 5 files changed, 71 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index d59f703f9797..3ee259d00a9a 100644 --- a/Makefile +++ b/Makefile @@ -1543,6 +1543,11 @@ prepare: tools/bpf/resolve_btfids endif endif +# lib/Makefile invokes tools/bootconfig to render the embedded bconf to cmdline. +ifdef CONFIG_BOOT_CONFIG_EMBED_CMDLINE +prepare: tools/bootconfig +endif + # The tools build system is not a part of Kbuild and tends to introduce # its own unique issues. If you need to integrate a new tool into Kbuild, # please consider locating that tool outside the tools/ tree and using the diff --git a/init/Kconfig b/init/Kconfig index ca35184532dc..5f491a5ac4b8 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1569,6 +1569,39 @@ config BOOT_CONFIG_EMBED_FILE This bootconfig will be used if there is no initrd or no other bootconfig in the initrd. +config ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG + bool + help + Selected by architectures whose setup_arch() prepends the + build-time-rendered embedded bootconfig cmdline to + boot_command_line before parse_early_param() runs. + +config BOOT_CONFIG_EMBED_CMDLINE + bool "Render embedded bootconfig as kernel cmdline at build time" + depends on BOOT_CONFIG_EMBED + depends on BOOT_CONFIG_EMBED_FILE != "" + depends on ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG + default n + help + Render the "kernel" subtree of the embedded bootconfig file into a + flat cmdline string at kernel build time and prepend it to + boot_command_line during early architecture setup. This makes + early_param() handlers (e.g. mem=, earlycon=, loglevel=) see the + values supplied via the embedded bootconfig. + + The runtime bootconfig parser is unaffected, so tree-structured + consumers such as ftrace boot-time tracing keep working. + + Note: when an initrd also carries a bootconfig, its "kernel" + subtree is still parsed at runtime, but the embedded "kernel" + keys remain in boot_command_line for parse_early_param() and + end up later than the initrd keys in saved_command_line, so + parse_args() last-wins favors the embedded values. If you need + initrd to override embedded kernel.* keys, leave this option + off. + + If unsure, say N. + config CMDLINE_LOG_WRAP_IDEAL_LEN int "Length to try to wrap the cmdline when logged at boot" default 1021 diff --git a/lib/Makefile b/lib/Makefile index 6e72d2c1cce7..9de0ac7732a2 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -273,6 +273,22 @@ filechk_defbconf = cat $(or $(real-prereqs), /dev/null) $(obj)/default.bconf: $(CONFIG_BOOT_CONFIG_EMBED_FILE) FORCE $(call filechk,defbconf) +obj-$(CONFIG_BOOT_CONFIG_EMBED_CMDLINE) += embedded-cmdline.o +$(obj)/embedded-cmdline.o: $(obj)/embedded_cmdline.bin + +# Render the bootconfig "kernel" subtree to a flat cmdline string using +# the userspace tools/bootconfig parser (-C mode). The runtime prepend +# helper enforces COMMAND_LINE_SIZE at boot, so no build-time size +# check is performed here (COMMAND_LINE_SIZE is an arch header +# constant, not a Kconfig value). +quiet_cmd_render_cmdline = BCONF2C $@ + cmd_render_cmdline = \ + $(objtree)/tools/bootconfig/bootconfig -C $< > $@ + +targets += embedded_cmdline.bin +$(obj)/embedded_cmdline.bin: $(obj)/default.bconf $(objtree)/tools/bootconfig/bootconfig FORCE + $(call if_changed,render_cmdline) + obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o diff --git a/lib/embedded-cmdline.S b/lib/embedded-cmdline.S new file mode 100644 index 000000000000..7e2e1d81af96 --- /dev/null +++ b/lib/embedded-cmdline.S @@ -0,0 +1,16 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Embed the build-time-rendered bootconfig "kernel" subtree as a flat + * cmdline string. setup_arch() prepends this to boot_command_line on + * architectures that select ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG. + * + * Copyright (c) 2026 Meta Platforms, Inc. and affiliates + * Copyright (c) 2026 Breno Leitao + */ + .section .init.rodata, "aw" + .global embedded_kernel_cmdline +embedded_kernel_cmdline: + .incbin "lib/embedded_cmdline.bin" + .byte 0 + .global embedded_kernel_cmdline_end +embedded_kernel_cmdline_end: diff --git a/tools/bootconfig/Makefile b/tools/bootconfig/Makefile index 90eb47c9d8de..4e82fd9553cd 100644 --- a/tools/bootconfig/Makefile +++ b/tools/bootconfig/Makefile @@ -15,7 +15,7 @@ override CFLAGS += -Wall -g -I$(CURDIR)/include ALL_TARGETS := bootconfig ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS)) -all: $(ALL_PROGRAMS) test +all: $(ALL_PROGRAMS) $(OUTPUT)bootconfig: main.c include/linux/bootconfig.h $(LIBSRC) $(CC) $(filter %.c,$^) $(CFLAGS) $(LDFLAGS) -o $@ -- 2.54.0