From 50270a820c85bbd548725af2329f97a3f8773fd5 Mon Sep 17 00:00:00 2001
From: Wolfvak <soherrera1@hotmail.com>
Date: Sat, 15 Mar 2025 10:25:23 -0300
Subject: [PATCH] Split up the ARM9 code and data sections (#883)

* Split up the ARM9 code (.text, .vectors) and data (.rodata, .data, .bss) sections into their own ELFs.

This allows us to use more ARM9 WRAM while leaving the 128k BootROM mirror intact.

* use the makefile definition

* Also dump section headers on .dis file
---
 .gitignore      |  1 +
 Makefile        | 14 +++++++++-----
 Makefile.build  |  3 ++-
 Makefile.common |  1 +
 arm9/Makefile   |  6 ++++++
 arm9/link.ld    | 20 +++++++++++++-------
 6 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/.gitignore b/.gitignore
index a9f5fc8..5ff6ec3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 *.obj
 *.elf
 *.map
+*.dis
 
 # Precompiled Headers
 *.gch
diff --git a/Makefile b/Makefile
index da57d2e..5cda78c 100644
--- a/Makefile
+++ b/Makefile
@@ -52,7 +52,7 @@ export CFLAGS  := -DDBUILTS="\"$(DBUILTS)\"" -DDBUILTL="\"$(DBUILTL)\"" -DVERSIO
                   -fomit-frame-pointer -ffast-math -std=gnu11 -MMD -MP \
                   -Wno-unused-function -Wno-format-truncation -Wno-format-nonliteral $(INCLUDE) -ffunction-sections -fdata-sections
 export LDFLAGS := -Tlink.ld -nostartfiles -Wl,--gc-sections,-z,max-page-size=4096
-ELF := arm9/arm9.elf arm11/arm11.elf
+ELF := arm9/arm9_code.elf arm9/arm9_data.elf arm11/arm11.elf
 
 .PHONY: all firm $(VRAM_TAR) elf release clean
 all: firm
@@ -104,9 +104,13 @@ $(TRF_FOLDER)/%.trf: $(JSON_FOLDER)/%.json
 
 %.elf: .FORCE
 	@echo "Building $@"
-	@$(MAKE) --no-print-directory -C $(@D)
+	@$(MAKE) --no-print-directory -C $(@D) $(@F)
 
-arm9/arm9.elf: $(VRAM_TAR) $(LANGUAGE_INL)
+# Indicate a few explicit dependencies:
+# The ARM9 data section depends on the VRAM drive
+arm9/arm9_data.elf: $(VRAM_TAR) $(LANGUAGE_INL)
+# And the code section depends on the data section being built already
+arm9/arm9_code.elf: arm9/arm9_data.elf
 
 firm: $(ELF) $(TRF_FILES)
 	@mkdir -p $(call dirname,"$(FIRM)") $(call dirname,"$(FIRMD)")
@@ -114,9 +118,9 @@ firm: $(ELF) $(TRF_FILES)
 	@echo "[VERSION] $(VERSION)"
 	@echo "[BUILD] $(DBUILTL)"
 	@echo "[FIRM] $(FIRM)"
-	@$(PY3) -m firmtool build $(FIRM) $(FTFLAGS) -g -D $(ELF) -C NDMA XDMA
+	@$(PY3) -m firmtool build $(FIRM) $(FTFLAGS) -g -D $(ELF) -C NDMA NDMA XDMA
 	@echo "[FIRM] $(FIRMD)"
-	@$(PY3) -m firmtool build $(FIRMD) $(FTDFLAGS) -g -D $(ELF) -C NDMA XDMA
+	@$(PY3) -m firmtool build $(FIRMD) $(FTDFLAGS) -g -D $(ELF) -C NDMA NDMA XDMA
 
 vram0: $(VRAM_TAR) .FORCE # legacy target name
 
diff --git a/Makefile.build b/Makefile.build
index 0a36f6f..6df0778 100755
--- a/Makefile.build
+++ b/Makefile.build
@@ -11,11 +11,12 @@ all: $(TARGET).elf
 
 .PHONY: clean
 clean:
-	@rm -rf $(BUILD) $(TARGET).elf $(TARGET).map
+	@rm -rf $(BUILD) $(TARGET).elf $(TARGET).dis $(TARGET).map
 
 $(TARGET).elf: $(OBJECTS) $(OBJECTS_COMMON)
 	@mkdir -p "$(@D)"
 	@$(CC) $(LDFLAGS) $^ -o $@
+	@$(OBJDUMP) -S -h $@ > $@.dis
 
 $(BUILD)/%.cmn.o: $(COMMON_DIR)/%.c
 	@mkdir -p "$(@D)"
diff --git a/Makefile.common b/Makefile.common
index d8c8258..24036db 100644
--- a/Makefile.common
+++ b/Makefile.common
@@ -1,3 +1,4 @@
+export OBJDUMP	:=	arm-none-eabi-objdump
 
 dirname   = $(shell dirname $(1))
 
diff --git a/arm9/Makefile b/arm9/Makefile
index 0c5b852..b31133b 100644
--- a/arm9/Makefile
+++ b/arm9/Makefile
@@ -15,3 +15,9 @@ LDFLAGS += $(SUBARCH) -Wl,--use-blx,-Map,$(TARGET).map -flto
 
 include ../Makefile.common
 include ../Makefile.build
+
+arm9_data.elf: arm9.elf
+	$(OBJCOPY) -O elf32-littlearm -j .rodata* -j .data* -j .bss* $< $@
+
+arm9_code.elf: arm9.elf
+	$(OBJCOPY) -O elf32-littlearm -j .text* -j .vectors* $< $@
diff --git a/arm9/link.ld b/arm9/link.ld
index 5ff9a63..b8beedf 100644
--- a/arm9/link.ld
+++ b/arm9/link.ld
@@ -5,7 +5,9 @@ ENTRY(_start)
 MEMORY
 {
     VECTORS (RX) : ORIGIN = 0x08000000, LENGTH = 64
-    AHBWRAM (RWX) : ORIGIN = 0x08000040, LENGTH = 512K - 64
+    CODEMEM (RX) : ORIGIN = 0x08000040, LENGTH = 512K - 64
+    BOOTROM (R)  : ORIGIN = 0x08080000, LENGTH = 128K /* BootROM mirrors, don't touch! */
+    DATAMEM (RW) : ORIGIN = 0x080A0000, LENGTH = 384K
 }
 
 SECTIONS
@@ -16,7 +18,7 @@ SECTIONS
         KEEP(*(.vectors));
         . = ALIGN(4);
         __vectors_len = ABSOLUTE(.) - __vectors_vma;
-    } >VECTORS AT>AHBWRAM
+    } >VECTORS AT>CODEMEM
 
     .text : ALIGN(4) {
         __text_s = ABSOLUTE(.);
@@ -24,24 +26,28 @@ SECTIONS
         *(.text*);
         . = ALIGN(4);
         __text_e = ABSOLUTE(.);
-    } >AHBWRAM
+    } >CODEMEM
 
     .rodata : ALIGN(4) {
         *(.rodata*);
         . = ALIGN(4);
-    } >AHBWRAM
+        __exidx_start = .;
+        *(.ARM.exidx* .gnu.linkonce.armexidx.*)
+        __exidx_end = .;
+        . = ALIGN(4);
+    } >DATAMEM
 
     .data : ALIGN(4) {
         *(.data*);
         . = ALIGN(4);
-    } >AHBWRAM
+    } >DATAMEM
 
-    .bss : ALIGN(4) {
+    .bss (NOLOAD) : ALIGN(4) {
         __bss_start = .;
         *(.bss*);
         . = ALIGN(4);
         __bss_end = .;
-    } >AHBWRAM
+    } >DATAMEM
 
     __end__ = ABSOLUTE(.);
 }