On Mon, Jun 08, 2026 at 07:19:28PM +0900, Masami Hiramatsu wrote:
On Fri, 05 Jun 2026 05:03:37 -0700
Breno Leitao [off-list ref] wrote:
quoted
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 bootconfig opt-in: only fold in the embedded
kernel.* keys when "bootconfig" is present on the command line, or
CONFIG_BOOT_CONFIG_FORCE is set. Applying the embedded cmdline
unconditionally would (a) diverge from how embedded init.* keys are
treated and (b) break fail-safe recovery: a malformed embedded
console=/mem= could panic the boot with no way for the admin to disable
it by dropping "bootconfig" from the bootloader cmdline.
cmdline_find_option_bool() runs before parse_early_param(), so the gate
is cheap and correctly ordered.
Select ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG so the user-visible
CONFIG_BOOT_CONFIG_EMBED_CMDLINE option becomes selectable on x86.
This seems like a dummy config. what code does depend on this flag?
No C code reads ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG directly — it's
a silent gating symbol, the same ARCH_SUPPORTS_* idiom as
ARCH_SUPPORTS_CFI, ARCH_SUPPORTS_LTO_CLANG, etc.
Its only role is the depends on line of BOOT_CONFIG_EMBED_CMDLINE: an
arch selects it once its setup_arch() calls
xbc_prepend_embedded_cmdline(), and that makes the user-visible
BOOT_CONFIG_EMBED_CMDLINE selectable.
Right now, only x86 supports embedded bootconfig, thus, only x86 does
the following (last patch):
config X86
+ select ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG
So, no other platform can see CONFIG_BOOT_CONFIG_EMBED_CMDLINE.
quoted
--- a/init/main.c
+++ b/init/main.c
@@ -378,12 +378,15 @@ static void __init setup_boot_config(void)
int pos, ret;
size_t size;
char *err;
+ bool from_embedded = false;
/* Cut out the bootconfig data even if we have no bootconfig option */
data = get_boot_config_from_initrd(&size);
/* If there is no bootconfig in initrd, try embedded one. */
- if (!data)
+ if (!data) {
data = xbc_get_embedded_bootconfig(&size);
+ from_embedded = true;
Even from embedded bootconfig, if the arch set
ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG=n, this must be applied to
the cmdline as we are doing.
Right — that path is preserved. When the arch doesn't select
ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG, BOOT_CONFIG_EMBED_CMDLINE is
unselectable, so xbc_embedded_cmdline_applied() is the no-op stub
returning false.
quoted
strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,@@ -421,8 +424,17 @@ static void __init setup_boot_config(void)
} else {
xbc_get_info(&ret, NULL);
pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)size, ret);
- /* keys starting with "kernel." are passed via cmdline */
- extra_command_line = xbc_make_cmdline("kernel");
+ /*
+ * keys starting with "kernel." are passed via cmdline. When
+ * this bootconfig came from the embedded source and
+ * setup_arch() already prepended the rendered "kernel" subtree
+ * to boot_command_line, rendering again here would duplicate
+ * the keys in saved_command_line and make accumulating handlers
+ * (console=, earlycon=, ...) re-register the same value. Skip
+ * only when the prepend really happened.
Also, this should mention ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG=n case.
Ack, I will update
Thanks for the review,
--breno