[PATCH] bootconfig: Apply early options from embedded config

@@ -169,6 +169,10 @@ Boot Kernel With a Boot Config
 There are two options to boot the kernel with bootconfig: attaching the
 bootconfig to the initrd image or embedding it in the kernel itself.
 
+Early options (those registered with ``early_param()``) may only be
+specified in the embedded bootconfig, because the initrd is not yet
+available when early parameters are processed.
+
 Attaching a Boot Config to Initrd
 ---------------------------------
 

@@ -1534,6 +1534,12 @@ config BOOT_CONFIG_EMBED
 	  image. But if the system doesn't support initrd, this option will
 	  help you by embedding a bootconfig file while building the kernel.
 
+	  Unlike bootconfig attached to initrd, the embedded bootconfig also
+	  supports early options (those registered with early_param()). Any
+	  kernel.* key in the embedded bootconfig is applied before
+	  parse_early_param() runs. Early options in initrd bootconfig will
+	  not be applied.
+
 	  If unsure, say N.
 
 config BOOT_CONFIG_EMBED_FILE

@@ -416,9 +416,63 @@ static int __init warn_bootconfig(char *str)
 	return 0;
 }
 
+/*
+ * do_early_param() is defined later in this file but called from
+ * bootconfig_apply_early_params() below, so we need a forward declaration.
+ */
+static int __init do_early_param(char *param, char *val,
+				 const char *unused, void *arg);
+
+/*
+ * bootconfig_apply_early_params - dispatch kernel.* keys from the embedded
+ * bootconfig as early_param() calls.
+ *
+ * early_param() handlers must run before most of the kernel initialises
+ * (e.g. before the GIC driver reads irqchip.gicv3_pseudo_nmi).  A bootconfig
+ * attached to the initrd arrives too late for this because the initrd is not
+ * mapped yet when early params are processed.  The embedded bootconfig lives
+ * in the kernel image itself (.init.data), so it is always reachable.
+ *
+ * This function is called from setup_boot_config() which runs in
+ * start_kernel() before parse_early_param(), making the timing correct.
+ */
+static void __init bootconfig_apply_early_params(void)
+{
+	char val_buf[COMMAND_LINE_SIZE];
+	struct xbc_node *knode, *root;
+	const char *val;
+
+	root = xbc_find_node("kernel");
+	if (!root)
+		return;
+
+	/*
+	 * Keys that do not match any early_param() handler are silently
+	 * ignored — do_early_param() always returns 0.
+	 */
+	xbc_node_for_each_key_value(root, knode, val) {
+		if (xbc_node_compose_key_after(root, knode, xbc_namebuf, XBC_KEYLEN_MAX) < 0)
+			continue;
+
+		if (!val) {
+			do_early_param(xbc_namebuf, NULL, NULL, NULL);
+			continue;
+		}
+
+		/*
+		 * We need to copy const char *val to a char pointer,
+		 * which is what do_early_param() need, given it might
+		 * call strsep(), strtok() later.
+		 */
+		strscpy(val_buf, val, sizeof(val_buf));
+		do_early_param(xbc_namebuf, val_buf, NULL, NULL);
+	}
+}
+
 static void __init setup_boot_config(void)
 {
 	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
+	bool using_embedded = false;
 	const char *msg, *data;
 	int pos, ret;
 	size_t size;

@@ -427,8 +481,17 @@ static void __init setup_boot_config(void)
 	/* 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);
+		/*
+		 * Record that we are using the embedded config so that
+		 * bootconfig_apply_early_params() is called below.
+		 * When CONFIG_BOOT_CONFIG_EMBED is not set,
+		 * xbc_get_embedded_bootconfig() is a stub returning NULL, so
+		 * data is always NULL here and using_embedded stays false.
+		 */
+		using_embedded = data;
+	}
 
 	strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 	err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,

@@ -466,6 +529,8 @@ 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);
+		if (using_embedded)
+			bootconfig_apply_early_params();
 		/* keys starting with "kernel." are passed via cmdline */
 		extra_command_line = xbc_make_cmdline("kernel");
 		/* Also, "init." keys are init arguments */