Add a configuration option for dynamic stack management

arch/Kconfig

@@ -199,11 +199,6 @@ config ARCH_HEAP_VBASE
 	---help---
 		The virtual address of the beginning of the heap region.
 
-config ARCH_STACK_VBASE
-	hex "Virtual stack base"
-	---help---
-		The virtual address of the beginning the stack region
-
 config ARCH_TEXT_NPAGES
 	int "Max .text pages"
 	default 1
@@ -228,6 +223,30 @@ config ARCH_HEAP_NPAGES
 		This, along with knowledge of the page size, determines the size of
 		the heap virtual address space. Default is 1.
 
+config ARCH_STACK_DYNAMIC
+	bool "Dynamic stack"
+	default n if !BUILD_KERNEL || !LIBC_EXECFUNCS
+	default y if BUILD_KERNEL && LIBC_EXECFUNCS
+	---help---
+		Select this option if the user process stack resides in its own
+		address space.  The naming of this selection implies that dynamic
+		stack allocation is supported.  Certainly this option must be set if
+		dynamic stack allocation is supported by a platform.  But the more
+		general meaning of this configuration environment is simply that the
+		stack has its own address space.
+
+		NOTE:  This options is also *required* if BUILD_KERNEL and
+		LIBC_EXECFUNCS are selected.  Why?  Because the caller's stack must
+		be preserved in its own address space when we instantiate the
+		environment of the new process in order to initialize it.
+
+if ARCH_STACK_DYNAMIC
+
+config ARCH_STACK_VBASE
+	hex "Virtual stack base"
+	---help---
+		The virtual address of the beginning the stack region
+
 config ARCH_STACK_NPAGES
 	int "Max. stack pages"
 	default 1
@@ -236,6 +255,8 @@ config ARCH_STACK_NPAGES
 		This, along with knowledge of the page size, determines the size of
 		the stack virtual address space. Default is 1.
 
+endif # ARCH_STACK_DYNAMIC
+
 config ARCH_PGPOOL_MAPPING
 	bool "Have page pool mapping"
 	default n