From cf84236724ed6ae20667d55f119d0b6829234932 Mon Sep 17 00:00:00 2001
From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Tue, 12 Apr 2022 14:19:22 +0100
Subject: [PATCH] make hello_world relocatable with BOOT_INIT_BASE define

---
 hello_world/Makefile      | 20 ++++++++++++++++----
 hello_world/powerpc.lds.S | 16 ++++++++++++++++
 2 files changed, 32 insertions(+), 4 deletions(-)
 create mode 100644 hello_world/powerpc.lds.S

diff --git a/hello_world/Makefile b/hello_world/Makefile
index 230b265..180f7b9 100644
--- a/hello_world/Makefile
+++ b/hello_world/Makefile
@@ -5,21 +5,33 @@ ifneq ("$(ARCH)", "ppc64le")
 endif
 endif
 
+BOOT_INIT_BASE ?= 0xf0000000 # at QSPI address
+# BOOT_INIT_BASE ?= 0xff000000   # at ROM hi address (with coldboot firmware)
+# BOOT_INIT_BASE ?= 0x0        # start at zero (usual)
+
 CC = $(CROSS_COMPILE)gcc
 LD = $(CROSS_COMPILE)ld
 OBJCOPY = $(CROSS_COMPILE)objcopy
 
-CFLAGS = -Os -g -Wall -std=c99 -mabi=elfv2 -msoft-float -mno-string -mno-multiple -mno-vsx -mno-altivec -mlittle-endian -fno-stack-protector -mstrict-align -ffreestanding -fdata-sections -ffunction-sections -I../include
+CFLAGS = -Os -g -Wall -std=c99 -mabi=elfv2 -msoft-float -mno-string \
+                -mno-multiple -mno-vsx -mno-altivec -mlittle-endian \
+                -fno-stack-protector -mstrict-align -ffreestanding \
+                -fdata-sections -ffunction-sections -I../include \
+            -DBOOT_INIT_BASE=$(BOOT_INIT_BASE) 
+
 ASFLAGS = $(CFLAGS)
-LDFLAGS = -T powerpc.lds
+LDFLAGS = -static -nostdlib -T powerpc.lds --gc-sections
 
 all: hello_world.hex
 
+powerpc.lds: powerpc.lds.S
+	$(CC) $(CFLAGS) -P -E powerpc.lds.S -o powerpc.lds
+
 console.o: ../lib/console.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) -c $< -o $@
 
-hello_world.elf: hello_world.o head.o console.o
-	$(LD) $(LDFLAGS) -o $@ $^
+hello_world.elf: hello_world.o head.o console.o powerpc.lds
+	$(LD) $(LDFLAGS) -o $@ hello_world.o head.o console.o 
 
 hello_world.bin: hello_world.elf
 	$(OBJCOPY) -O binary $^ $@
diff --git a/hello_world/powerpc.lds.S b/hello_world/powerpc.lds.S
new file mode 100644
index 0000000..06cae4c
--- /dev/null
+++ b/hello_world/powerpc.lds.S
@@ -0,0 +1,16 @@
+SECTIONS
+{
+	. = BOOT_INIT_BASE;
+	_start = .;
+	start = _start;
+	. = BOOT_INIT_BASE;
+	.head : {
+		KEEP(*(.head))
+ 	}
+	. = BOOT_INIT_BASE + 0x1000;
+	.text : { *(.text) }
+	. = BOOT_INIT_BASE + 0x1800;
+	.data : { *(.data) }
+	.bss : { *(.bss) }
+}
+
-- 
2.30.2