Calculate the optimal memory location for overlay plugins, and use plugin.lds for linking them. This gets rid of hand-adjusted archos.lds, making it easy to use overlay plugins on other lowmem targets. * Fix some duplicate and incorrect dependencies. * Change the way libs are filtered, so that a lib can be specified more than once. This allows to get rid of explicitly linking gcc-support.o, fixing empty plugins on some simulator platforms.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@20163 a1c6a512-1295-4272-9138-f99709370657

11 files changed, 102 insertions, 236 deletions

diff --git a/apps/plugins/chessbox/archos.lds b/apps/plugins/chessbox/archos.lds
deleted file mode 100644
index a419fce0bc..0000000000
--- a/apps/plugins/chessbox/archos.lds
+++ /dev/null
@@ -1,44 +0,0 @@
-#include "config.h"
-
-/* linker script for chessbox as an overlay,
- * only used/ necessary for SH-based archos targets */
-
-OUTPUT_FORMAT(elf32-sh)
-
-#define DRAMORIG 0x09000000
-#define PLUGIN_LENGTH PLUGIN_BUFFER_SIZE
-
-#define OVERLAY_LENGTH 0x30000
-#define OVERLAY_ORIGIN (DRAMORIG + (MEMORYSIZE * 0x100000) - PLUGIN_LENGTH - OVERLAY_LENGTH)
-
-MEMORY
-{
-   OVERLAY_RAM : ORIGIN = OVERLAY_ORIGIN, LENGTH = OVERLAY_LENGTH
-}
-
-SECTIONS
-{
-    .header : {
-        _plugin_start_addr = .;
-        KEEP(*(.header))
-    } > OVERLAY_RAM
-
-    .text : {
-        *(.text*)
-    } > OVERLAY_RAM
-
-    .rodata : {
-        *(.rodata*)
-    } > OVERLAY_RAM
-
-    .data : {
-        *(.data*)
-    } > OVERLAY_RAM
-
-    .bss : {
-        *(.bss*)
-        *(COMMON)
-        . = ALIGN(0x4);
-        _plugin_end_addr = .;
-    } > OVERLAY_RAM
-}
diff --git a/apps/plugins/chessbox/chessbox.make b/apps/plugins/chessbox/chessbox.make
index 220f0839e3..43df3ab264 100644
--- a/apps/plugins/chessbox/chessbox.make
+++ b/apps/plugins/chessbox/chessbox.make
@@ -17,20 +17,17 @@ OTHER_SRC += $(CHESSBOX_SRC)
 
 ifndef SIMVER
 ifneq (,$(strip $(foreach tgt,RECORDER ONDIO,$(findstring $(tgt),$(TARGET)))))
-    ## archos recorder targets
-    CHESSBOX_INLDS := $(CHESSBOX_SRCDIR)/archos.lds
+    ### lowmem targets
     ROCKS += $(CHESSBOX_OBJDIR)/chessbox.ovl
+    CHESSBOX_OUTLDS = $(CHESSBOX_OBJDIR)/chessbox.link
+    CHESSBOX_OVLFLAGS = -T$(CHESSBOX_OUTLDS) -Wl,--gc-sections -Wl,-Map,$(basename $@).map
 else
     ### all other targets
-    CHESSBOX_INLDS := $(APPSDIR)/plugins/plugin.lds
     ROCKS += $(CHESSBOX_OBJDIR)/chessbox.rock
 endif
-    CHESSBOX_OVLFLAGS = -T$(CHESSBOX_OUTLDS) -Wl,--gc-sections -Wl,-Map,$(basename $@).map
-    CHESSBOX_OUTLDS = $(CHESSBOX_OBJDIR)/chessbox.lds
 else
     ### simulator
     ROCKS += $(CHESSBOX_OBJDIR)/chessbox.rock
-    CHESSBOX_OVLFLAGS = $(SHARED_FLAG) # <-- from Makefile
 endif
 
 ifeq ($(CPU),sh)
@@ -40,15 +37,18 @@ else
 CHESSBOXFLAGS = $(filter-out -O%,$(PLUGINFLAGS)) -O2
 endif
 
-$(CHESSBOX_OUTLDS): $(CHESSBOX_INLDS) $(CHESSBOX_OBJ)
-        $(call PRINTS,PP $(<F))$(call preprocess2file,$<,$@)
+$(CHESSBOX_OBJDIR)/chessbox.rock: $(CHESSBOX_OBJ)
+
+$(CHESSBOX_OBJDIR)/chessbox.refmap: $(CHESSBOX_OBJ)
 
-$(CHESSBOX_OBJDIR)/chessbox.rock: $(CHESSBOX_OBJ) $(CHESSBOX_OUTLDS) $(PLUGINBITMAPLIB)
+$(CHESSBOX_OUTLDS): $(PLUGIN_LDS) $(CHESSBOX_OBJDIR)/chessbox.refmap
+        $(call PRINTS,PP $(@F))$(call preprocess2file,$<,$@,-DOVERLAY_OFFSET=$(shell \
+                $(TOOLSDIR)/ovl_offset.pl $(CHESSBOX_OBJDIR)/chessbox.refmap))
 
-$(CHESSBOX_OBJDIR)/chessbox.ovl: $(CHESSBOX_OBJ) $(CHESSBOX_OUTLDS) $(PLUGINBITMAPLIB)
+$(CHESSBOX_OBJDIR)/chessbox.ovl: $(CHESSBOX_OBJ) $(CHESSBOX_OUTLDS)
         $(SILENT)$(CC) $(PLUGINFLAGS) -o $(basename $@).elf \
                 $(filter %.o, $^) \
-                $(filter %.a, $^) \
+                $(filter %.a, $+) \
                 -lgcc $(CHESSBOX_OVLFLAGS)
         $(call PRINTS,LD $(@F))$(OC) -O binary $(basename $@).elf $@
 
diff --git a/apps/plugins/goban/archos.lds b/apps/plugins/goban/archos.lds
deleted file mode 100644
index c17346ff0b..0000000000
--- a/apps/plugins/goban/archos.lds
+++ /dev/null
@@ -1,43 +0,0 @@
-#include "config.h"
-
-/* linker script for goban as an overlay */
-
-OUTPUT_FORMAT(elf32-sh)
-
-#define DRAMORIG 0x09000000
-#define PLUGIN_LENGTH PLUGIN_BUFFER_SIZE
-
-#define OVERLAY_LENGTH 0x10000
-#define OVERLAY_ORIGIN (DRAMORIG + (MEMORYSIZE * 0x100000) - PLUGIN_LENGTH - OVERLAY_LENGTH)
-
-MEMORY
-{
-   OVERLAY_RAM : ORIGIN = OVERLAY_ORIGIN, LENGTH = OVERLAY_LENGTH
-}
-
-SECTIONS
-{
-    .header : {
-        _plugin_start_addr = .;
-        KEEP(*(.header))
-    } > OVERLAY_RAM
-
-    .text : {
-        *(.text*)
-    } > OVERLAY_RAM
-
-    .rodata : {
-        *(.rodata*)
-    } > OVERLAY_RAM
-
-    .data : {
-        *(.data*)
-    } > OVERLAY_RAM
-
-    .bss : {
-        *(.bss*)
-        *(COMMON)
-        . = ALIGN(0x4);
-        _plugin_end_addr = .;
-    } > OVERLAY_RAM
-}
diff --git a/apps/plugins/goban/goban.make b/apps/plugins/goban/goban.make
index b8866fbc4f..03f2276659 100644
--- a/apps/plugins/goban/goban.make
+++ b/apps/plugins/goban/goban.make
@@ -7,7 +7,6 @@
 # $Id$
 #
 
-
 GOBAN_SRCDIR := $(APPSDIR)/plugins/goban
 GOBAN_BUILDDIR := $(BUILDDIR)/apps/plugins/goban
 
@@ -18,31 +17,30 @@ OTHER_SRC += $(GOBAN_SRC)
 
 ifndef SIMVER
 ifneq (,$(strip $(foreach tgt,RECORDER ONDIO,$(findstring $(tgt),$(TARGET)))))
-    ### archos recorder targets
-    GOBAN_INLDS := $(GOBAN_SRCDIR)/archos.lds
+    ### lowmem targets
     ROCKS += $(GOBAN_BUILDDIR)/goban.ovl
+    GOBAN_OUTLDS = $(GOBAN_BUILDDIR)/goban.link
+    GOBAN_OVLFLAGS = -T$(GOBAN_OUTLDS) -Wl,--gc-sections -Wl,-Map,$(basename $@).map
 else
     ### all other targets
-    GOBAN_INLDS := $(APPSDIR)/plugins/plugin.lds
     ROCKS += $(GOBAN_BUILDDIR)/goban.rock
 endif
-    GOBAN_OVLFLAGS = -T$(GOBAN_OUTLDS) -Wl,--gc-sections -Wl,-Map,$(basename $@).map
-    GOBAN_OUTLDS = $(GOBAN_BUILDDIR)/goban.lds
 else
     ### simulator
     ROCKS += $(GOBAN_BUILDDIR)/goban.rock
-    GOBAN_OVLFLAGS = $(SHARED_FLAG) # <-- from Makefile
 endif
 
-$(GOBAN_OUTLDS): $(GOBAN_INLDS) $(GOBAN_OBJ)
-        $(call PRINTS,PP $(<F))$(call preprocess2file,$<,$@)
+$(GOBAN_BUILDDIR)/goban.rock: $(GOBAN_OBJ)
 
-$(GOBAN_BUILDDIR)/goban.rock: $(GOBAN_OBJ) $(GOBAN_OUTLDS)
+$(GOBAN_BUILDDIR)/goban.refmap: $(GOBAN_OBJ)
+
+$(GOBAN_OUTLDS): $(PLUGIN_LDS) $(GOBAN_BUILDDIR)/goban.refmap
+        $(call PRINTS,PP $(@F))$(call preprocess2file,$<,$@,-DOVERLAY_OFFSET=$(shell \
+                $(TOOLSDIR)/ovl_offset.pl $(GOBAN_BUILDDIR)/goban.refmap))
 
 $(GOBAN_BUILDDIR)/goban.ovl: $(GOBAN_OBJ) $(GOBAN_OUTLDS)
         $(SILENT)$(CC) $(PLUGINFLAGS) -o $(basename $@).elf \
                 $(filter %.o, $^) \
-                $(filter %.a, $^) \
+                $(filter %.a, $+) \
                 -lgcc $(GOBAN_OVLFLAGS)
         $(call PRINTS,LD $(@F))$(OC) -O binary $(basename $@).elf $@
-
diff --git a/apps/plugins/plugin.lds b/apps/plugins/plugin.lds
index ccf60100bf..e7ed9b1844 100644
--- a/apps/plugins/plugin.lds
+++ b/apps/plugins/plugin.lds
@@ -125,7 +125,10 @@ OUTPUT_FORMAT(elf32-littlemips)
 #ifdef CODEC
 #define THIS_LENGTH CODEC_SIZE
 #define THIS_ORIGIN CODEC_ORIGIN
-#else
+#elif defined OVERLAY_OFFSET
+#define THIS_LENGTH (DRAMSIZE - OVERLAY_OFFSET)
+#define THIS_ORIGIN (DRAMORIG + OVERLAY_OFFSET)
+#else /* plugin */
 #define THIS_LENGTH PLUGIN_LENGTH
 #define THIS_ORIGIN PLUGIN_ORIGIN
 #endif
diff --git a/apps/plugins/plugins.make b/apps/plugins/plugins.make
index 7314888eed..8be87b94c1 100644
--- a/apps/plugins/plugins.make
+++ b/apps/plugins/plugins.make
@@ -26,24 +26,25 @@ PLUGINLIB_OBJ := $(PLUGINLIB_SRC:.c=.o)
 PLUGINLIB_OBJ := $(PLUGINLIB_OBJ:.S=.o)
 PLUGINLIB_OBJ := $(subst $(ROOTDIR),$(BUILDDIR),$(PLUGINLIB_OBJ))
 
-# multifile plugins (subdirs):
-PLUGINSUBDIRS := $(call preprocess, $(APPSDIR)/plugins/SUBDIRS)
-
-# include <dir>.make from each subdir (yay!)
-$(foreach dir,$(PLUGINSUBDIRS),$(eval include $(dir)/$(notdir $(dir)).make))
-
 ### build data / rules
 ifndef SIMVER
 PLUGIN_LDS := $(APPSDIR)/plugins/plugin.lds
 PLUGINLINK_LDS := $(BUILDDIR)/apps/plugins/plugin.link
+OVERLAYREF_LDS := $(BUILDDIR)/apps/plugins/overlay_ref.link
 endif
 
+# multifile plugins (subdirs):
+PLUGINSUBDIRS := $(call preprocess, $(APPSDIR)/plugins/SUBDIRS)
+
+# include <dir>.make from each subdir (yay!)
+$(foreach dir,$(PLUGINSUBDIRS),$(eval include $(dir)/$(notdir $(dir)).make))
+
 OTHER_INC += -I$(APPSDIR)/plugins -I$(APPSDIR)/plugins/lib
 
 # special compile flags for plugins:
-PLUGINFLAGS = -I$(APPSDIR)/plugins -DPLUGIN $(CFLAGS) 
+PLUGINFLAGS = -I$(APPSDIR)/plugins -DPLUGIN $(CFLAGS)
 
-$(ROCKS): $(PLUGINLIB) $(APPSDIR)/plugin.h $(PLUGINLINK_LDS) $(PLUGINBITMAPLIB)
+$(ROCKS): $(APPSDIR)/plugin.h $(PLUGINLINK_LDS) $(PLUGINLIB) $(PLUGINBITMAPLIB)
 
 $(PLUGINLIB): $(PLUGINLIB_OBJ)
         $(SILENT)$(shell rm -f $@)
@@ -54,11 +55,16 @@ $(PLUGINLINK_LDS): $(PLUGIN_LDS)
         $(shell mkdir -p $(dir $@))
         $(call preprocess2file,$<,$@,-DLOADADDRESS=$(LOADADDRESS))
 
+$(OVERLAYREF_LDS): $(PLUGIN_LDS)
+        $(call PRINTS,PP $(@F))
+        $(shell mkdir -p $(dir $@))
+        $(call preprocess2file,$<,$@,-DOVERLAY_OFFSET=0)
+
 $(BUILDDIR)/credits.raw credits.raw: $(DOCSDIR)/CREDITS
         $(call PRINTS,Create credits.raw)perl $(APPSDIR)/plugins/credits.pl < $< > $(BUILDDIR)/$(@F)
 
 # special dependencies
-$(BUILDDIR)/apps/plugins/wav2wv.rock: $(BUILDDIR)/apps/codecs/libwavpack.a
+$(BUILDDIR)/apps/plugins/wav2wv.rock: $(BUILDDIR)/apps/codecs/libwavpack.a $(PLUGINLIB)
 
 # special pattern rule for compiling plugin lib (with -ffunction-sections)
 $(BUILDDIR)/apps/plugins/lib/%.o: $(ROOTDIR)/apps/plugins/lib/%.c
@@ -74,15 +80,22 @@ ifdef SIMVER
  PLUGINLDFLAGS = $(SHARED_FLAG) # <-- from Makefile
 else
  PLUGINLDFLAGS = -T$(PLUGINLINK_LDS) -Wl,--gc-sections -Wl,-Map,$*.map
+ OVERLAYLDFLAGS = -T$(OVERLAYREF_LDS) -Wl,--gc-sections -Wl,-Map,$*.refmap
 endif
 
-$(BUILDDIR)/%.rock: $(GCCSUPPORT_OBJ) $(BUILDDIR)/%.o $(PLUGINLINK_LDS)
+$(BUILDDIR)/%.rock: $(BUILDDIR)/%.o
         $(call PRINTS,LD $(@F))$(CC) $(PLUGINFLAGS) -o $(BUILDDIR)/$*.elf \
                 $(filter %.o, $^) \
-                $(filter %.a, $^) \
+                $(filter %.a, $+) \
                 -lgcc $(PLUGINLDFLAGS)
 ifdef SIMVER
         $(SILENT)cp $(BUILDDIR)/$*.elf $@
 else
         $(SILENT)$(OC) -O binary $(BUILDDIR)/$*.elf $@
-endif
\ No newline at end of file
+endif
+
+$(BUILDDIR)/%.refmap: $(BUILDDIR)/%.o $(OVERLAYREF_LDS) $(PLUGINLIB) $(PLUGINBITMAPLIB)
+        $(call PRINTS,LD $(@F))$(CC) $(PLUGINFLAGS) -o /dev/null \
+                $(filter %.o, $^) \
+                $(filter %.a, $^) \
+                -lgcc $(OVERLAYLDFLAGS)
diff --git a/apps/plugins/rockboy/archos.lds b/apps/plugins/rockboy/archos.lds
deleted file mode 100644
index fcc3e6f922..0000000000
--- a/apps/plugins/rockboy/archos.lds
+++ /dev/null
@@ -1,44 +0,0 @@
-#include "config.h"
-
-/* linker script for rockboy as an overlay,
- * only used/ necessary for SH-based archos targets */
-
-OUTPUT_FORMAT(elf32-sh)
-
-#define DRAMORIG 0x09000000
-#define PLUGIN_LENGTH PLUGIN_BUFFER_SIZE
-
-#define OVERLAY_LENGTH 0x68000
-#define OVERLAY_ORIGIN (DRAMORIG + (MEMORYSIZE * 0x100000) - PLUGIN_LENGTH - OVERLAY_LENGTH)
-
-MEMORY
-{
-   OVERLAY_RAM : ORIGIN = OVERLAY_ORIGIN, LENGTH = OVERLAY_LENGTH
-}
-
-SECTIONS
-{
-    .header : {
-        _plugin_start_addr = .;
-        KEEP(*(.header))
-    } > OVERLAY_RAM
-
-    .text : {
-        *(.text*)
-    } > OVERLAY_RAM
-
-    .rodata : {
-        *(.rodata*)
-    } > OVERLAY_RAM
-
-    .data : {
-        *(.data*)
-    } > OVERLAY_RAM
-
-    .bss : {
-        *(.bss*)
-        *(COMMON)
-        . = ALIGN(0x4);
-        _plugin_end_addr = .;
-    } > OVERLAY_RAM
-}
diff --git a/apps/plugins/rockboy/rockboy.make b/apps/plugins/rockboy/rockboy.make
index bce549c43c..ca0ed17a0a 100644
--- a/apps/plugins/rockboy/rockboy.make
+++ b/apps/plugins/rockboy/rockboy.make
@@ -18,30 +18,30 @@ OTHER_SRC += $(ROCKBOY_SRC)
 
 ifndef SIMVER
 ifneq (,$(findstring RECORDER,$(TARGET)))
-    ## archos recorder targets
-    ROCKBOY_INLDS := $(ROCKBOY_SRCDIR)/archos.lds
+    ## lowmem targets
     ROCKS += $(ROCKBOY_OBJDIR)/rockboy.ovl
+    ROCKBOY_OUTLDS = $(ROCKBOY_OBJDIR)/rockboy.link
+    ROCKBOY_OVLFLAGS = -T$(ROCKBOY_OUTLDS) -Wl,--gc-sections -Wl,-Map,$(basename $@).map
 else
     ### all other targets
-    ROCKBOY_INLDS := $(APPSDIR)/plugins/plugin.lds
     ROCKS += $(ROCKBOY_OBJDIR)/rockboy.rock
 endif
-    ROCKBOY_OVLFLAGS = -T$(ROCKBOY_OUTLDS) -Wl,--gc-sections -Wl,-Map,$(basename $@).map
-    ROCKBOY_OUTLDS = $(ROCKBOY_OBJDIR)/rockboy.lds
 else
     ### simulator
     ROCKS += $(ROCKBOY_OBJDIR)/rockboy.rock
-    ROCKBOY_OVLFLAGS = $(SHARED_FLAG) # <-- from Makefile
 endif
 
-$(ROCKBOY_OUTLDS): $(ROCKBOY_INLDS) $(ROCKBOY_OBJ)
-        $(call PRINTS,PP $(<F))$(call preprocess2file,$<,$@)
+$(ROCKBOY_OBJDIR)/rockboy.rock: $(ROCKBOY_OBJ)
+
+$(ROCKBOY_OBJDIR)/rockboy.refmap: $(ROCKBOY_OBJ)
 
-$(ROCKBOY_OBJDIR)/rockboy.rock: $(ROCKBOY_OBJ) $(ROCKBOY_OUTLDS) $(PLUGINBITMAPLIB)
+$(ROCKBOY_OUTLDS): $(PLUGIN_LDS) $(ROCKBOY_OBJDIR)/rockboy.refmap
+        $(call PRINTS,PP $(@F))$(call preprocess2file,$<,$@,-DOVERLAY_OFFSET=$(shell \
+                $(TOOLSDIR)/ovl_offset.pl $(ROCKBOY_OBJDIR)/rockboy.refmap))
 
-$(ROCKBOY_OBJDIR)/rockboy.ovl: $(ROCKBOY_OBJ) $(ROCKBOY_OUTLDS) $(PLUGINBITMAPLIB)
+$(ROCKBOY_OBJDIR)/rockboy.ovl: $(ROCKBOY_OBJ) $(ROCKBOY_OUTLDS)
         $(SILENT)$(CC) $(PLUGINFLAGS) -o $(basename $@).elf \
                 $(filter %.o, $^) \
-                $(filter %.a, $^) \
+                $(filter %.a, $+) \
                 -lgcc $(ROCKBOY_OVLFLAGS)
         $(call PRINTS,LD $(@F))$(OC) -O binary $(basename $@).elf $@
diff --git a/apps/plugins/zxbox/archos.lds b/apps/plugins/zxbox/archos.lds
deleted file mode 100644
index 5b4db7dc3e..0000000000
--- a/apps/plugins/zxbox/archos.lds
+++ /dev/null
@@ -1,44 +0,0 @@
-#include "config.h"
-
-/* linker script for zxbox as an overlay,
- * only used/ necessary for SH-based archos targets */
-
-OUTPUT_FORMAT(elf32-sh)
-
-#define DRAMORIG 0x09000000
-#define PLUGIN_LENGTH PLUGIN_BUFFER_SIZE
-
-#define OVERLAY_LENGTH 0x48000
-#define OVERLAY_ORIGIN (DRAMORIG + (MEMORYSIZE * 0x100000) - PLUGIN_LENGTH - OVERLAY_LENGTH)
-
-MEMORY
-{
-   OVERLAY_RAM : ORIGIN = OVERLAY_ORIGIN, LENGTH = OVERLAY_LENGTH
-}
-
-SECTIONS
-{
-    .header : {
-        _plugin_start_addr = .;
-        KEEP(*(.header))
-    } > OVERLAY_RAM
-
-    .text : {
-        *(.text*)
-    } > OVERLAY_RAM
-
-    .rodata : {
-        *(.rodata*)
-    } > OVERLAY_RAM
-
-    .data : {
-        *(.data*)
-    } > OVERLAY_RAM
-
-    .bss : {
-        *(.bss*)
-        *(COMMON)
-        . = ALIGN(0x4);
-        _plugin_end_addr = .;
-    } > OVERLAY_RAM
-}
diff --git a/apps/plugins/zxbox/zxbox.make b/apps/plugins/zxbox/zxbox.make
index 6f6d1ab693..24f8e91f20 100644
--- a/apps/plugins/zxbox/zxbox.make
+++ b/apps/plugins/zxbox/zxbox.make
@@ -17,12 +17,12 @@ OTHER_SRC += $(ZXBOX_SRC)
 
 ifndef SIMVER
 ifneq (,$(strip $(foreach tgt,RECORDER ONDIO,$(findstring $(tgt),$(TARGET)))))
-    ## archos recorder targets
-    ZXBOX_INLDS := $(ZXBOX_SRCDIR)/archos.lds
+    ## lowmem targets
     ROCKS += $(ZXBOX_OBJDIR)/zxbox.ovl
+    ZXBOX_OUTLDS = $(ZXBOX_OBJDIR)/zxbox.link
+    ZXBOX_LDFLAGS = -T$(ZXBOX_OUTLDS) -Wl,--gc-sections -Wl,-Map,$(basename $@).map
 else
     ### all other targets
-    ZXBOX_INLDS := $(APPSDIR)/plugins/plugin.lds
     ROCKS += $(ZXBOX_OBJDIR)/zxbox.rock
 endif
 else
@@ -32,22 +32,18 @@ endif
 
 ZXBOXFLAGS = $(filter-out -O%,$(PLUGINFLAGS)) -O3 -funroll-loops
 
-ifdef SIMVER
- ZXBOX_LDFLAGS = $(SHARED_FLAG) # <-- from Makefile
-else
- ZXBOX_OUTLDS = $(ZXBOX_OBJDIR)/zxbox.lds
- ZXBOX_LDFLAGS = -T$(ZXBOX_OUTLDS) -Wl,--gc-sections -Wl,-Map,$(basename $@).map
-endif
+$(ZXBOX_OBJDIR)/zxbox.rock: $(ZXBOX_OBJ)
 
-$(ZXBOX_OUTLDS): $(ZXBOX_INLDS) $(ZXBOX_OBJ)
-        $(call PRINTS,PP $(<F))$(call preprocess2file,$<,$@)
+$(ZXBOX_OBJDIR)/zxbox.refmap: $(ZXBOX_OBJ)
 
-$(ZXBOX_OBJDIR)/zxbox.rock: $(ZXBOX_OBJ) $(ZXBOX_OUTLDS) $(PLUGINBITMAPLIB)
+$(ZXBOX_OUTLDS): $(PLUGIN_LDS) $(ZXBOX_OBJDIR)/zxbox.refmap
+        $(call PRINTS,PP $(@F))$(call preprocess2file,$<,$@,-DOVERLAY_OFFSET=$(shell \
+                $(TOOLSDIR)/ovl_offset.pl $(ZXBOX_OBJDIR)/zxbox.refmap))
 
-$(ZXBOX_OBJDIR)/zxbox.ovl: $(ZXBOX_OBJ) $(ZXBOX_OUTLDS) $(PLUGINBITMAPLIB) $(PLUGINLIB)
+$(ZXBOX_OBJDIR)/zxbox.ovl: $(ZXBOX_OBJ) $(ZXBOX_OUTLDS)
         $(SILENT)$(CC) $(PLUGINFLAGS) -o $(basename $@).elf \
                 $(filter %.o, $^) \
-                $(filter %.a, $^) \
+                $(filter %.a, $+) \
                 -lgcc $(ZXBOX_LDFLAGS)
         $(call PRINTS,LD $(@F))$(OC) -O binary $(basename $@).elf $@
 
diff --git a/tools/ovl_offset.pl b/tools/ovl_offset.pl
new file mode 100644
index 0000000000..89c3468556
--- /dev/null
+++ b/tools/ovl_offset.pl
@@ -0,0 +1,31 @@
+#!/usr/bin/perl
+
+# Calculate the highest possible location for an overlay based
+# on a reference map file (.refmap)
+
+sub map_scan {
+    my ($map) = @_;
+    my $ramstart = -1, $ramsize = -1, $startaddr = -1, $endaddr = -1;
+    open (MAP, "<$map");
+    while (<MAP>) {
+        if ($_ =~ /^PLUGIN_RAM +0x([0-9a-f]+) +0x([0-9a-f]+)$/) {
+            $ramstart = hex($1);
+            $ramsize = hex($2);
+        }
+        elsif ($_ =~ / +0x([0-9a-f]+) +_?plugin_start_addr = ./) {
+            $startaddr = hex($1);
+        }
+        elsif ($_ =~ / +0x([0-9a-f]+) +_?plugin_end_addr = ./) {
+            $endaddr = hex($1);
+        }
+    }
+    close (MAP);
+    if ($ramstart < 0 || $ramsize < 0 || $startaddr < 0 || $endaddr < 0
+        || $ramstart != $startaddr) {
+        printf "Could not analyze map file.\n";
+        exit 1;
+    }
+    return $ramstart + $ramsize - $endaddr;
+}
+
+printf map_scan($ARGV[0]) & ~0xf;