From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B45B8399004; Wed, 24 Jun 2026 08:47:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782290842; cv=none; b=D83yb23PqoJAtt7BnOJxJTpuOmld3OM5Qrl6HP5MiTvOZtbmbd4wX1/pm0fk6ODLnYBO3RxkNHqA3XhAbEnBc3UoSPxeS+wH1QAQqTP2v0DcxynAQewUIpQeeyEbZjdCS0X1fiP/OlIYenwfrlrd5thzK2/KQE9VEICJtS4lL3o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782290842; c=relaxed/simple; bh=jE3gcUhZN5QjpxvUi4aBQycrshUHzLYz8Pu/BFvb4mc=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=UMirwwO0VMcqaG2h30vz7/geFR6KrK+bdf6wnaBUsIa7BfqexiJykgPyHHACi/+OXnfUxkKyTHgx61Xp7CYxnRWzMIvnK6XnxSRIdszhqpw5I0fnSd2lCOJtW6HJ0ObhO4HpGfg5zNmT/EyVNdPjnsxF91DeUTB4pNHi0vOcN/I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D02WJZsE; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D02WJZsE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B22711F00A3A; Wed, 24 Jun 2026 08:47:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782290841; bh=06XkZ5y3O4hhqWJxqfZyjIWWTZjCTfUMB2iMcf/ToR8=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=D02WJZsEa+kSPjocd0o/QLIlV9uqWdqi7pYolOxa+PleLrxk3CM9+TRfO33s00L/9 fp/QGrlGY4kwceOZ33LlBpz8QvkGYDdeHBtRIHMC0UXvRHSgnv6OIeTOiE+NqePXfC 4bKTWrzRm9Bbv0YkvKsfc7yr06aUTcHEEzg5385LDMd6QRzjVvc65ZwZB+hE+eIoJV rHgmIlNv6VZw7ZeYYs0EJp0Cvs2fwJApX2eqbQzfk/OPkAd7NRQ9vICKGYsy13fqd4 3Jk1XwnjwC87j9gSxbzFBDpeqdNJn5rUVieBN+Jr1wCRqaR7g+Y7SDjozY8iIGjmyk kTZGNmYlkSMEg== Date: Wed, 24 Jun 2026 17:47:17 +0900 From: Masami Hiramatsu (Google) To: Breno Leitao Cc: Andrew Morton , Nathan Chancellor , paulmck@kernel.org, Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Jonathan Corbet , Shuah Khan , 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, llvm@lists.linux.dev, linux-doc@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v6 8/8] x86/setup: prepend embedded bootconfig cmdline before parse_early_param Message-Id: <20260624174717.7230a3e18e2f8f7d3698055a@kernel.org> In-Reply-To: <20260623-bootconfig_using_tools-v6-8-640c2f587a3c@debian.org> References: <20260623-bootconfig_using_tools-v6-0-640c2f587a3c@debian.org> <20260623-bootconfig_using_tools-v6-8-640c2f587a3c@debian.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 23 Jun 2026 09:15:35 -0700 Breno Leitao wrote: > Call xbc_prepend_embedded_cmdline() in setup_arch() right after the > CONFIG_CMDLINE merge and before strscpy(command_line, ...) so the > build-time-rendered embedded bootconfig "kernel" subtree is part of > boot_command_line by the time parse_early_param() runs. early_param() > handlers (mem=, earlycon=, loglevel=, ...) now see values supplied via > CONFIG_BOOT_CONFIG_EMBED_FILE without parsing bootconfig at runtime. > > Gate the prepend on the same opt-in the runtime parser uses: prepend > when "bootconfig" is present on the command line, or when > CONFIG_BOOT_CONFIG_FORCE is set. Detect it with parse_args(), exactly > as setup_boot_config() does, so both agree on what counts as opt-in: > any "bootconfig" key regardless of value (bare, =0, =1, ...), and only > before the "--" that separates init arguments. Sharing the parser keeps > the early and late paths from diverging -- e.g. "bootconfig=0" or a > "-- bootconfig" meant for init must not apply the embedded keys early > while the runtime parser skips them. > > The prepend necessarily runs before setup_boot_config() detects an > initrd bootconfig, so an initrd cannot override the embedded "kernel" > keys for early_param(). This is intentional: the embedded cmdline acts > like a build-time CONFIG_CMDLINE. An initrd bootconfig's "kernel" keys > never reached early_param() anyway (they apply late via > extra_command_line), so nothing is lost -- the initrd keys still apply > late, with last-wins keeping the embedded values in effect. > > Signed-off-by: Breno Leitao > --- > arch/x86/Kconfig | 1 + > arch/x86/kernel/setup.c | 43 +++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 44 insertions(+) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 0de23e6471973..8ab11199c16d5 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -127,6 +127,7 @@ config X86 > select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 > select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 > select ARCH_SUPPORTS_CFI if X86_64 > + select ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG > select ARCH_USES_CFI_TRAPS if X86_64 && CFI > select ARCH_SUPPORTS_LTO_CLANG > select ARCH_SUPPORTS_LTO_CLANG_THIN > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 46882ce79c3a4..c973a2cebcd04 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -6,6 +6,7 @@ > * parts of early kernel initialization. > */ > #include > +#include > #include > #include > #include > @@ -881,6 +882,37 @@ static void __init x86_report_nx(void) > * Note: On x86_64, fixmaps are ready for use even before this is called. > */ > > +#ifdef CONFIG_CMDLINE_FROM_BOOTCONFIG > +static int __init bootconfig_optin(char *param, char *val, > + const char *unused, void *arg) > +{ > + if (!strcmp(param, "bootconfig")) > + *(bool *)arg = true; > + return 0; > +} > + > +/* > + * Did the user opt in to bootconfig on the kernel command line? Use > + * parse_args() so this matches setup_boot_config() exactly, including > + * stopping at the "--" that separates init arguments. > + */ > +static bool __init bootconfig_cmdline_requested(void) > +{ > + static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata; > + bool found = false; > + > + if (IS_ENABLED(CONFIG_BOOT_CONFIG_FORCE)) > + return true; > + > + strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE); > + if (IS_ERR(parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, > + &found, bootconfig_optin))) > + return false; > + > + return found; > +} It seems that this should be placed in a common place because it will be used from other architectures (and init/main.c too). Maybe we can introduce something like this? bool __init bootconfig_cmdline_requested(const char *boot_cmdline, int *end_offset); Thanks, > +#endif > + > void __init setup_arch(char **cmdline_p) > { > #ifdef CONFIG_X86_32 > @@ -924,6 +956,17 @@ void __init setup_arch(char **cmdline_p) > builtin_cmdline_added = true; > #endif > > +#ifdef CONFIG_CMDLINE_FROM_BOOTCONFIG > + /* > + * Prepend the build-time-rendered embedded "kernel" keys here so > + * parse_early_param() below sees them, gating on the same opt-in > + * as the runtime parser (see bootconfig_cmdline_requested()). > + */ > + if (bootconfig_cmdline_requested()) > + xbc_prepend_embedded_cmdline(boot_command_line, > + COMMAND_LINE_SIZE); > +#endif > + > strscpy(command_line, boot_command_line, COMMAND_LINE_SIZE); > *cmdline_p = command_line; > > > -- > 2.53.0-Meta > -- Masami Hiramatsu (Google)