[PATCH v6 8/8] x86/setup: prepend embedded bootconfig cmdline before parse_early_param
From: Breno Leitao <leitao@debian.org>
Date: 2026-06-23 16:17:21
Also in:
bpf, linux-doc, linux-kbuild, lkml, llvm
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
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 <leitao@debian.org> --- 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 <linux/acpi.h> +#include <linux/bootconfig.h> #include <linux/console.h> #include <linux/cpu.h> #include <linux/crash_dump.h>
@@ -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; +} +#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