Index: kernel/generic/include/main/main.h
===================================================================
--- kernel/generic/include/main/main.h	(revision 6188fee70f91508871094638e99dcaf9d73efdc0)
+++ kernel/generic/include/main/main.h	(revision deed5101075d16614c9dfa62829d531701a50a20)
@@ -43,6 +43,4 @@
 extern uint8_t kdata_end[];
 
-extern uintptr_t stack_safe;
-
 extern void main_bsp(void);
 extern void main_ap(void);
Index: kernel/generic/src/main/main.c
===================================================================
--- kernel/generic/src/main/main.c	(revision 6188fee70f91508871094638e99dcaf9d73efdc0)
+++ kernel/generic/src/main/main.c	(revision deed5101075d16614c9dfa62829d531701a50a20)
@@ -132,14 +132,12 @@
 };
 
-context_t ctx;
-
-/** Lowest safe stack virtual address. */
-uintptr_t stack_safe = 0;
+static context_t ctx;
 
 // NOTE: All kernel stacks must be aligned to STACK_SIZE, see CURRENT.
-const size_t bootstrap_stack_size = STACK_SIZE;
-_Alignas(STACK_SIZE) uint8_t bootstrap_stack[STACK_SIZE];
+static const size_t bootstrap_stack_size = STACK_SIZE;
+static _Alignas(STACK_SIZE) uint8_t bootstrap_stack[STACK_SIZE];
+
 /* Just a convenient value for some assembly code. */
-const uint8_t *bootstrap_stack_top = bootstrap_stack + STACK_SIZE;
+uint8_t *const bootstrap_stack_top = bootstrap_stack + STACK_SIZE;
 
 /*