diff --git a/doc/reference/drivers/index.rst b/doc/reference/drivers/index.rst
index 5905e8dbd34..e0f2ebe4e13 100644
--- a/doc/reference/drivers/index.rst
+++ b/doc/reference/drivers/index.rst
@@ -361,6 +361,9 @@ leading zeroes or sign (e.g. 32), or an equivalent symbolic name (e.g.
 ``\#define MY_INIT_PRIO 32``); symbolic expressions are *not* permitted (e.g.
 ``CONFIG_KERNEL_INIT_PRIORITY_DEFAULT + 5``).
 
+Drivers and other system utilities can determine whether startup is
+still in pre-kernel states by using the :cpp:func:`k_is_pre_kernel()`
+function.
 
 System Drivers
 **************
diff --git a/include/init.h b/include/init.h
index f484afb6022..9899c853037 100644
--- a/include/init.h
+++ b/include/init.h
@@ -25,22 +25,6 @@ extern "C" {
 #define _SYS_INIT_LEVEL_POST_KERNEL	2
 #define _SYS_INIT_LEVEL_APPLICATION	3
 
-extern s8_t z_sys_device_level;
-
-/**
- * @brief Test whether startup is in the before-main-task phase.
- *
- * This impacts which services are available for use, and the context
- * in which functions are run.
- *
- * @return true if and only if start up is still running pre-kernel
- * initialization.
- */
-static inline bool k_is_pre_kernel(void)
-{
-	return (z_sys_device_level < _SYS_INIT_LEVEL_POST_KERNEL);
-}
-
 /* A counter is used to avoid issues when two or more system devices
  * are declared in the same C file with the same init function.
  */
diff --git a/include/kernel.h b/include/kernel.h
index 95ee1131113..1ec67129cdf 100644
--- a/include/kernel.h
+++ b/include/kernel.h
@@ -1295,6 +1295,24 @@ extern bool k_is_in_isr(void);
  */
 __syscall int k_is_preempt_thread(void);
 
+/**
+ * @brief Test whether startup is in the before-main-task phase.
+ *
+ * This routine allows the caller to customize its actions, depending on
+ * whether it being invoked before the kernel is fully active.
+ *
+ * @note Can be called by ISRs.
+ *
+ * @return true if invoked before post-kernel initialization
+ * @return false if invoked during/after post-kernel initialization
+ */
+static inline bool k_is_pre_kernel(void)
+{
+	extern bool z_sys_post_kernel; /* in init.c */
+
+	return !z_sys_post_kernel;
+}
+
 /**
  * @}
  */
diff --git a/kernel/device.c b/kernel/device.c
index aff82511fec..a7fa6aa1681 100644
--- a/kernel/device.c
+++ b/kernel/device.c
@@ -23,8 +23,6 @@ extern u32_t __device_busy_end[];
 #define DEVICE_BUSY_SIZE (__device_busy_end - __device_busy_start)
 #endif
 
-s8_t z_sys_device_level;
-
 /**
  * @brief Execute all the device initialization functions at a given level
  *
@@ -48,7 +46,6 @@ void z_sys_device_do_config_level(s32_t level)
 		__device_init_end,
 	};
 
-	z_sys_device_level = level;
 	for (info = config_levels[level]; info < config_levels[level+1];
 								info++) {
 		int retval;
diff --git a/kernel/init.c b/kernel/init.c
index 955a56cbe46..9b79b51bb74 100644
--- a/kernel/init.c
+++ b/kernel/init.c
@@ -212,6 +212,8 @@ void z_data_copy(void)
 
 /* LCOV_EXCL_STOP */
 
+bool z_sys_post_kernel;
+
 /**
  *
  * @brief Mainline for kernel's background thread
@@ -233,6 +235,8 @@ static void bg_thread_main(void *unused1, void *unused2, void *unused3)
 	static const unsigned int boot_delay;
 #endif
 
+	z_sys_post_kernel = true;
+
 	z_sys_device_do_config_level(_SYS_INIT_LEVEL_POST_KERNEL);
 #if CONFIG_STACK_POINTER_RANDOM
 	z_stack_adjust_initialized = 1;