diff --git a/arch/arm/mach-rockchip/board.c b/arch/arm/mach-rockchip/board.c
index 3fadf7e4122..75d6693e28a 100644
--- a/arch/arm/mach-rockchip/board.c
+++ b/arch/arm/mach-rockchip/board.c
@@ -472,9 +472,18 @@ __weak int misc_init_r(void)
 __weak int board_rng_seed(struct abuf *buf)
 {
 	struct udevice *dev;
-	size_t len = 0x8;
+	ulong len = env_get_ulong("rng_seed_size", 10, 64);
 	u64 *data;
 
+	if (len < 64) {
+		/*
+		 * rng_seed_size should be at least 32 bytes for Linux 5.19+,
+		 * or 64 for older Linux kernel versions
+		 */
+		log_warning("Value for rng_seed_size (%lu) too low, Linux kernel RNG may fail to initialize early\n",
+			    len);
+	}
+
 	data = malloc(len);
 	if (!data) {
 		printf("Out of memory\n");
diff --git a/common/Kconfig b/common/Kconfig
index 90cee19d413..14a6c44c804 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -928,6 +928,9 @@ config BOARD_RNG_SEED
 	  new seed for use on subsequent boots, and whether or not the
 	  kernel should account any entropy from the given seed.
 
+	  Default seed size (64 bytes) can be overridden by a decimal
+	  environment variable rng_seed_size.
+
 endmenu
 
 menu "Update support"
diff --git a/doc/usage/environment.rst b/doc/usage/environment.rst
index cc33d3ec0f2..7bd9ffce8d8 100644
--- a/doc/usage/environment.rst
+++ b/doc/usage/environment.rst
@@ -323,6 +323,11 @@ netretry
     Useful on scripts which control the retry operation
     themselves.
 
+rng_seed_size
+    Size of random value added to device-tree node /chosen/rng-seed.
+    This variable is given as a decimal number.
+    If unset, 64 bytes is used as the default.
+
 silent_linux
     If set then Linux will be told to boot silently, by
     adding 'console=' to its command line. If "yes" it will be
diff --git a/include/fdt_support.h b/include/fdt_support.h
index 741e2360c22..9447a64e060 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -202,7 +202,8 @@ int ft_board_setup(void *blob, struct bd_info *bd);
  *
  * This function is called if CONFIG_BOARD_RNG_SEED is set, and must
  * be provided by the board. It should return, via @buf, some suitable
- * seed value to pass to the kernel.
+ * seed value to pass to the kernel. Seed size could be set in a decimal
+ * environment variable rng_seed_size and it defaults to 64 bytes.
  *
  * @param buf         A struct abuf for returning the seed and its size.
  * @return            0 if ok, negative on error.