diff --git a/cmd/Kconfig b/cmd/Kconfig
index 9e8b692..f962bb7 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -332,6 +332,18 @@
 	help
 	  Do FDT related setup before booting into the Operating System.
 
+config SUPPORT_EXTENSION_SCAN
+	bool
+
+config CMD_EXTENSION
+	bool "Extension board management command"
+	select CMD_FDT
+	depends on SUPPORT_EXTENSION_SCAN
+	help
+	  Enables the "extension" command, which allows to detect
+	  extension boards connected to the system, and apply
+	  corresponding Device Tree overlays.
+
 config CMD_GO
 	bool "go"
 	default y
diff --git a/cmd/Makefile b/cmd/Makefile
index 4977fa1..9d10e07 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -54,6 +54,7 @@
 endif
 obj-$(CONFIG_CMD_ADTIMG) += adtimg.o
 obj-$(CONFIG_CMD_ABOOTIMG) += abootimg.o
+obj-$(CONFIG_CMD_EXTENSION) += extension_board.o
 obj-$(CONFIG_CMD_ECHO) += echo.o
 obj-$(CONFIG_ENV_IS_IN_EEPROM) += eeprom.o
 obj-$(CONFIG_CMD_EEPROM) += eeprom.o
diff --git a/cmd/extension_board.c b/cmd/extension_board.c
new file mode 100644
index 0000000..bbb4812
--- /dev/null
+++ b/cmd/extension_board.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2021
+ * Köry Maincent, Bootlin, <kory.maincent@bootlin.com>
+ */
+
+#include <common.h>
+#include <command.h>
+#include <malloc.h>
+#include <extension_board.h>
+#include <mapmem.h>
+#include <linux/libfdt.h>
+#include <fdt_support.h>
+
+static LIST_HEAD(extension_list);
+
+static int extension_apply(struct extension *extension)
+{
+	char *overlay_cmd;
+	ulong extrasize, overlay_addr;
+	struct fdt_header *blob;
+
+	if (!working_fdt) {
+		printf("No FDT memory address configured. Please configure\n"
+		       "the FDT address via \"fdt addr <address>\" command.\n");
+		return CMD_RET_FAILURE;
+	}
+
+	overlay_cmd = env_get("extension_overlay_cmd");
+	if (!overlay_cmd) {
+		printf("Environment extension_overlay_cmd is missing\n");
+		return CMD_RET_FAILURE;
+	}
+
+	overlay_addr = env_get_hex("extension_overlay_addr", 0);
+	if (!overlay_addr) {
+		printf("Environment extension_overlay_addr is missing\n");
+		return CMD_RET_FAILURE;
+	}
+
+	env_set("extension_overlay_name", extension->overlay);
+	if (run_command(overlay_cmd, 0) != 0)
+		return CMD_RET_FAILURE;
+
+	extrasize = env_get_hex("filesize", 0);
+	if (!extrasize)
+		return CMD_RET_FAILURE;
+
+	fdt_shrink_to_minimum(working_fdt, extrasize);
+
+	blob = map_sysmem(overlay_addr, 0);
+	if (!fdt_valid(&blob))
+		return CMD_RET_FAILURE;
+
+	/* apply method prints messages on error */
+	if (fdt_overlay_apply_verbose(working_fdt, blob))
+		return CMD_RET_FAILURE;
+
+	return CMD_RET_SUCCESS;
+}
+
+static int do_extension_list(struct cmd_tbl *cmdtp, int flag,
+			     int argc, char *const argv[])
+{
+	int i = 0;
+	struct extension *extension;
+
+	if (list_empty(&extension_list)) {
+		printf("No extension registered - Please run \"extension scan\"\n");
+		return CMD_RET_SUCCESS;
+	}
+
+	list_for_each_entry(extension, &extension_list, list) {
+		printf("Extension %d: %s\n", i++, extension->name);
+		printf("\tManufacturer: \t\t%s\n", extension->owner);
+		printf("\tVersion: \t\t%s\n", extension->version);
+		printf("\tDevicetree overlay: \t%s\n", extension->overlay);
+		printf("\tOther information: \t%s\n", extension->other);
+	}
+	return CMD_RET_SUCCESS;
+}
+
+static int do_extension_scan(struct cmd_tbl *cmdtp, int flag,
+			     int argc, char *const argv[])
+{
+	struct extension *extension, *next;
+	int extension_num;
+
+	list_for_each_entry_safe(extension, next, &extension_list, list) {
+		list_del(&extension->list);
+		free(extension);
+	}
+	extension_num = extension_board_scan(&extension_list);
+
+	if (extension_num < 0)
+		return CMD_RET_FAILURE;
+
+	printf("Found %d extension board(s).\n", extension_num);
+
+	return CMD_RET_SUCCESS;
+}
+
+static int do_extension_apply(struct cmd_tbl *cmdtp, int flag,
+			      int argc, char *const argv[])
+{
+	struct extension *extension = NULL;
+	struct list_head *entry;
+	int i = 0, extension_id, ret;
+
+	if (argc < 2)
+		return CMD_RET_USAGE;
+
+	if (strcmp(argv[1], "all") == 0) {
+		list_for_each_entry(extension, &extension_list, list) {
+			ret = extension_apply(extension);
+			if (ret != CMD_RET_SUCCESS)
+				break;
+		}
+	} else {
+		extension_id = simple_strtol(argv[1], NULL, 10);
+		list_for_each(entry, &extension_list) {
+			if (i == extension_id) {
+				extension = list_entry(entry, struct extension,  list);
+				break;
+			}
+			i++;
+		}
+
+		if (!extension) {
+			printf("Wrong extension number\n");
+			return CMD_RET_FAILURE;
+		}
+
+		ret = extension_apply(extension);
+	}
+
+	return ret;
+}
+
+static struct cmd_tbl cmd_extension[] = {
+	U_BOOT_CMD_MKENT(scan, 1, 1, do_extension_scan, "", ""),
+	U_BOOT_CMD_MKENT(list, 1, 0, do_extension_list, "", ""),
+	U_BOOT_CMD_MKENT(apply, 2, 0, do_extension_apply, "", ""),
+};
+
+static int do_extensionops(struct cmd_tbl *cmdtp, int flag, int argc,
+			   char *const argv[])
+{
+	struct cmd_tbl *cp;
+
+	/* Drop the extension command */
+	argc--;
+	argv++;
+
+	cp = find_cmd_tbl(argv[0], cmd_extension, ARRAY_SIZE(cmd_extension));
+	if (cp)
+		return cp->cmd(cmdtp, flag, argc, argv);
+
+	return CMD_RET_USAGE;
+}
+
+U_BOOT_CMD(extension, 3, 1, do_extensionops,
+	"Extension board management sub system",
+	"scan - scan plugged extension(s) board(s)\n"
+	"extension list - lists available extension(s) board(s)\n"
+	"extension apply <extension number|all> - applies DT overlays corresponding to extension boards\n"
+);
diff --git a/configs/tools-only_defconfig b/configs/tools-only_defconfig
index e16f702..c6f287e 100644
--- a/configs/tools-only_defconfig
+++ b/configs/tools-only_defconfig
@@ -8,6 +8,7 @@
 # CONFIG_CMD_BOOTD is not set
 # CONFIG_CMD_BOOTM is not set
 # CONFIG_CMD_ELF is not set
+# CONFIG_CMD_EXTENSION is not set
 CONFIG_BOOTP_DNS2=y
 # CONFIG_CMD_DATE is not set
 CONFIG_OF_CONTROL=y
diff --git a/doc/usage/extension.rst b/doc/usage/extension.rst
new file mode 100644
index 0000000..2b88398
--- /dev/null
+++ b/doc/usage/extension.rst
@@ -0,0 +1,111 @@
+.. SPDX-License-Identifier: GPL-2.0+
+.. Copyright 2021, Kory Maincent <kory.maincent@bootlin.com>
+
+U-Boot extension board usage (CONFIG_EXTENSION)
+===============================================
+
+Synopsis
+--------
+
+::
+
+    extension scan
+    extension list
+    extension apply <extension number|all>
+
+Description
+-----------
+
+The "extension" command proposes a generic U-Boot mechanism to detect
+extension boards connected to the HW platform, and apply the appropriate
+Device Tree overlays depending on the detected extension boards.
+
+The "extension" command comes with three sub-commands:
+
+ - "extension scan" makes the generic code call the board-specific
+   extension_board_scan() function to retrieve the list of detected
+   extension boards.
+
+ - "extension list" allows to list the detected extension boards.
+
+ - "extension apply <number>|all" allows to apply the Device Tree
+   overlay(s) corresponding to one, or all, extension boards
+
+The latter requires two environment variables to exist:
+
+ - extension_overlay_addr: the RAM address where to load the Device
+   Tree overlays
+
+ - extension_overlay_cmd: the U-Boot command to load one overlay.
+   Indeed, the location and mechanism to load DT overlays is very setup
+   specific.
+
+In order to enable this mechanism, board-specific code must implement
+the extension_board_scan() function that fills in a linked list of
+"struct extension", each describing one extension board. In addition,
+the board-specific code must select the SUPPORT_EXTENSION_SCAN Kconfig
+boolean.
+
+Usage example
+-------------
+
+1. Make sure your devicetree is loaded and set as the working fdt tree.
+
+::
+
+    => run loadfdt
+    => fdt addr $fdtaddr
+
+2. Prepare the environment variables
+
+::
+
+    => setenv extension_overlay_addr 0x88080000
+    => setenv extension_overlay_cmd 'load mmc 0:1 ${extension_overlay_addr} /boot/${extension_overlay_name}'
+
+3. Detect the plugged extension board
+
+::
+
+    => extension scan
+
+4. List the plugged extension board information and the devicetree
+   overlay name
+
+::
+
+    => extension list
+
+5. Apply the appropriate devicetree overlay
+
+For apply the selected overlay:
+
+::
+
+    => extension apply 0
+
+For apply all the overlays:
+
+::
+
+    => extension apply all
+
+Simple extension_board_scan function example
+--------------------------------------------
+
+.. code-block:: c
+
+    int extension_board_scan(struct list_head *extension_list)
+    {
+        struct extension *extension;
+
+        extension = calloc(1, sizeof(struct extension));
+        snprintf(extension->overlay, sizeof(extension->overlay), "overlay.dtbo");
+        snprintf(extension->name, sizeof(extension->name), "extension board");
+        snprintf(extension->owner, sizeof(extension->owner), "sandbox");
+        snprintf(extension->version, sizeof(extension->version), "1.1");
+        snprintf(extension->other, sizeof(extension->other), "Extension board information");
+        list_add_tail(&extension->list, extension_list);
+
+        return 1;
+    }
diff --git a/include/extension_board.h b/include/extension_board.h
new file mode 100644
index 0000000..c530a0a
--- /dev/null
+++ b/include/extension_board.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2021
+ * Köry Maincent, Bootlin, <kory.maincent@bootlin.com>
+ */
+
+#ifndef __EXTENSION_SUPPORT_H
+#define __EXTENSION_SUPPORT_H
+
+struct extension {
+	struct list_head list;
+	char name[32];
+	char owner[32];
+	char version[32];
+	char overlay[32];
+	char other[32];
+};
+
+/**
+ * extension_board_scan - Add system-specific function to scan extension board.
+ * @param extension_list	List of extension board information to update.
+ * @return the number of extension.
+ *
+ * This function is called if CONFIG_CMD_EXTENSION is defined.
+ * Needs to fill the list extension_list with elements.
+ * Each element need to be allocated to an extension structure.
+ *
+ */
+int extension_board_scan(struct list_head *extension_list);
+
+#endif /* __EXTENSION_SUPPORT_H */