doc: update document of external memory

components/esp32/component.mk

@@ -8,11 +8,15 @@ ifndef CONFIG_NO_BLOBS
 LIBS += core rtc net80211 pp wpa smartconfig coexist wps wpa2 espnow phy mesh
 endif
 
+ifdef CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY  
+   # This linker script must come before esp32.common.ld
+   LINKER_SCRIPTS += esp32.extram.bss.ld
+endif
+
 #Linker scripts used to link the final application.
 #Warning: These linker scripts are only used when the normal app is compiled; the bootloader
 #specifies its own scripts.
-
-LINKER_SCRIPTS += esp32.rom.ld esp32.peripherals.ld
+LINKER_SCRIPTS += esp32.common.ld esp32.rom.ld esp32.peripherals.ld
 
 #Force pure functions from libgcc.a to be linked from ROM
 LINKER_SCRIPTS += esp32.rom.libgcc.ld
@@ -39,7 +43,6 @@ COMPONENT_ADD_LDFLAGS += $(COMPONENT_PATH)/libhal.a \
                          $(addprefix -l,$(LIBS)) \
                          -L $(COMPONENT_PATH)/ld \
                          -T esp32_out.ld \
-                         -T esp32.common_out.ld \
                          -u ld_include_panic_highint_hdl \
                          $(addprefix -T ,$(LINKER_SCRIPTS))
 
@@ -55,17 +58,12 @@ COMPONENT_ADD_LINKER_DEPS := $(ALL_LIB_FILES) $(addprefix ld/,$(LINKER_SCRIPTS))
 #
 # The library doesn't really depend on esp32_out.ld, but it
 # saves us from having to add the target to a Makefile.projbuild
-$(COMPONENT_LIBRARY): esp32_out.ld esp32.common_out.ld
+$(COMPONENT_LIBRARY): esp32_out.ld
 
 esp32_out.ld: $(COMPONENT_PATH)/ld/esp32.ld ../include/sdkconfig.h
 	$(CC) -I ../include -C -P -x c -E $< -o $@
 
-# Preprocess esp32.common.ld linker script to include configuration, becomes esp32.common_out.ld
-esp32.common_out.ld: $(COMPONENT_PATH)/ld/esp32.common.ld ../include/sdkconfig.h
-	$(CC) -I ../include -C -P -x c -E $< -o $@
-
-COMPONENT_EXTRA_CLEAN := esp32_out.ld 
-COMPONENT_EXTRA_CLEAN += esp32.common_out.ld
+COMPONENT_EXTRA_CLEAN := esp32_out.ld
 
 # disable stack protection in files which are involved in initialization of that feature
 stack_check.o: CFLAGS := $(filter-out -fstack-protector%, $(CFLAGS))