allow a board to override link.ld

Author: jepler

ports/raspberrypi/Makefile

@@ -276,12 +276,13 @@ SRC_QSTR += $(SRC_C) $(SRC_SUPERVISOR) $(SRC_COMMON_HAL_EXPANDED) $(SRC_SHARED_M
 
 all: $(BUILD)/firmware.uf2
 
-$(BUILD)/firmware.elf: $(OBJ) link.ld
+LINK_LD := $(firstword $(wildcard boards/$(BOARD)/link.ld link.ld))
+$(BUILD)/firmware.elf: $(OBJ) $(LINK_LD)
 	$(STEPECHO) "LINK $@"
 	$(Q)echo $(OBJ) > $(BUILD)/firmware.objs
 	$(Q)echo $(PICO_LDFLAGS) > $(BUILD)/firmware.ldflags
-	$(Q)$(CC) -o $@ $(CFLAGS) @$(BUILD)/firmware.ldflags -Wl,-T,link.ld -Wl,-Map=$@.map -Wl,-cref -Wl,--gc-sections @$(BUILD)/firmware.objs
-	$(Q)$(SIZE) $@ | $(PYTHON) $(TOP)/tools/build_memory_info.py link.ld
+	$(Q)$(CC) -o $@ $(CFLAGS) @$(BUILD)/firmware.ldflags -Wl,-T,$(LINK_LD) -Wl,-Map=$@.map -Wl,-cref -Wl,--gc-sections @$(BUILD)/firmware.objs
+	$(Q)$(SIZE) $@ | $(PYTHON) $(TOP)/tools/build_memory_info.py $(LINK_LD)
 
 $(BUILD)/firmware.bin: $(BUILD)/firmware.elf
 	$(STEPECHO) "Create $@"