Add INIT_FNs to make sure that librm gets reallocated when needed.

src/arch/i386/transitions/librm_mgmt.c

@@ -12,6 +12,8 @@
 #include "stdint.h"
 #include "stddef.h"
 #include "string.h"
+#include "init.h"
+#include "basemem.h"
 #include "librm.h"
 
 /*
@@ -21,37 +23,14 @@
 
 /* Current location of librm in base memory */
 char *installed_librm = librm;
+static uint32_t installed_librm_phys;
 
-/*
- * Install librm to base memory
- *
+/* Whether or not we have base memory currently allocated for librm.
+ * Note that we *can* have a working librm present in unallocated base
+ * memory; this is the situation at startup for all real-mode
+ * prefixes.
  */
-void install_librm ( void *addr ) {
-	memcpy ( addr, librm, librm_size );
-	installed_librm = addr;
-}
-
-/*
- * Increment lock count of librm
- *
- */
-void lock_librm ( void ) {
-	inst_librm_ref_count++;
-}
-
-/*
- * Decrement lock count of librm
- *
- */
-void unlock_librm ( void ) {
-#ifdef DEBUG_LIBRM
-	if ( inst_librm_ref_count == 0 ) {
-		printf ( "librm: ref count gone negative\n" );
-		lockup();
-	}
-#endif
-	inst_librm_ref_count--;
-}
+static int allocated_librm = 0;
 
 /*
  * Allocate space on the real-mode stack and copy data there.
@@ -84,4 +63,105 @@ void remove_from_rm_stack ( void *data, size_t size ) {
 	inst_rm_stack.offset += size;
 };
 
+/*
+ * Install librm to base memory
+ *
+ */
+static inline void install_librm ( char *addr ) {
+	memcpy ( addr, librm, librm_size );
+	installed_librm = addr;
+}
+
+/*
+ * Uninstall librm from base memory.  This copies librm back to the
+ * "master" copy, so that it can be reinstalled to a new location,
+ * preserving the values for rm_ss and rm_sp from the old installed
+ * copy.
+ *
+ */
+static inline void uninstall_librm ( void ) {
+	memcpy ( librm, installed_librm, librm_size );
+}
+
+/*
+ * On entry, record the physical location of librm.  Do this so that
+ * we can update installed_librm after relocation.
+ *
+ * Doing this is probably more efficient than making installed_librm
+ * be a physical address, because of the number of times that
+ * installed_librm gets referenced in the remainder of the code.
+ *
+ */
+static void librm_init ( void ) {
+	installed_librm_phys = virt_to_phys ( installed_librm );
+}
+
+/*
+ * On exit, we want to leave a copy of librm in *unallocated* base
+ * memory.  It must be there so that we can exit via a 16-bit exit
+ * path, but it must not be allocated because nothing will ever
+ * deallocate it once we exit.
+ *
+ */
+static void librm_exit ( void ) {
+	/* Free but do not zero the base memory */
+	if ( allocated_librm ) {
+		free_base_memory ( installed_librm, librm_size );
+		allocated_librm = 0;
+	}
+}
+
+/*
+ * On reset, we want to free up our old installed copy of librm, if
+ * any, then allocate a new base memory block and install there.
+ *
+ */
+
+static void librm_reset ( void ) {
+	char *new_librm;
+
+	/* Point installed_librm back at last known physical location */
+	installed_librm = phys_to_virt ( installed_librm_phys );
+
+	/* Uninstall old librm */
+	uninstall_librm();
+
+	/* Free allocated base memory, if applicable */
+	librm_exit();
+
+	/* Allocate space for new librm */
+	new_librm = alloc_base_memory ( librm_size );
+	allocated_librm = 1;
+
+	/* Install new librm */
+	install_librm ( new_librm );
+}
+
+INIT_FN ( INIT_LIBRM, librm_init, librm_reset, librm_exit );
+
+
+
+
+/*
+ * Increment lock count of librm
+ *
+ */
+void lock_librm ( void ) {
+	inst_librm_ref_count++;
+}
+
+/*
+ * Decrement lock count of librm
+ *
+ */
+void unlock_librm ( void ) {
+#ifdef DEBUG_LIBRM
+	if ( inst_librm_ref_count == 0 ) {
+		printf ( "librm: ref count gone negative\n" );
+		lockup();
+	}
+#endif
+	inst_librm_ref_count--;
+}
+
 #endif /* KEEP_IT_REAL */