On Tue, 23 Jun 2026 09:15:35 -0700 Breno Leitao <[email protected]> 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 <[email protected]> > --- > 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; > +} 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) <[email protected]>
