UEFI target groundwork: runtime: split baremetal memory setup (#5360)

* runtime: split baremetal memory setup
* add missing unsafe import

src/runtime/baremetal.go

@@ -7,36 +7,6 @@ import (
 	"unsafe"
 )
 
-//go:extern _heap_start
-var heapStartSymbol [0]byte
-
-//go:extern _heap_end
-var heapEndSymbol [0]byte
-
-//go:extern _globals_start
-var globalsStartSymbol [0]byte
-
-//go:extern _globals_end
-var globalsEndSymbol [0]byte
-
-//go:extern _stack_top
-var stackTopSymbol [0]byte
-
-var (
-	heapStart    = uintptr(unsafe.Pointer(&heapStartSymbol))
-	heapEnd      = uintptr(unsafe.Pointer(&heapEndSymbol))
-	globalsStart = uintptr(unsafe.Pointer(&globalsStartSymbol))
-	globalsEnd   = uintptr(unsafe.Pointer(&globalsEndSymbol))
-	stackTop     = uintptr(unsafe.Pointer(&stackTopSymbol))
-)
-
-// growHeap tries to grow the heap size. It returns true if it succeeds, false
-// otherwise.
-func growHeap() bool {
-	// On baremetal, there is no way the heap can be grown.
-	return false
-}
-
 //export malloc
 func libc_malloc(size uintptr) unsafe.Pointer {
 	// Note: this zeroes the returned buffer which is not necessary.

src/runtime/baremetal_memory.go

@@ -0,0 +1,35 @@
+//go:build baremetal
+
+package runtime
+
+import "unsafe"
+
+//go:extern _heap_start
+var heapStartSymbol [0]byte
+
+//go:extern _heap_end
+var heapEndSymbol [0]byte
+
+//go:extern _globals_start
+var globalsStartSymbol [0]byte
+
+//go:extern _globals_end
+var globalsEndSymbol [0]byte
+
+//go:extern _stack_top
+var stackTopSymbol [0]byte
+
+var (
+	heapStart    = uintptr(unsafe.Pointer(&heapStartSymbol))
+	heapEnd      = uintptr(unsafe.Pointer(&heapEndSymbol))
+	globalsStart = uintptr(unsafe.Pointer(&globalsStartSymbol))
+	globalsEnd   = uintptr(unsafe.Pointer(&globalsEndSymbol))
+	stackTop     = uintptr(unsafe.Pointer(&stackTopSymbol))
+)
+
+// growHeap tries to grow the heap size. It returns true if it succeeds, false
+// otherwise.
+func growHeap() bool {
+	// On baremetal, there is no way the heap can be grown.
+	return false
+}