Add initial support for UART I/O

Resources:
- https://github.com/bztsrc/raspi3-tutorial/tree/master/03_uart1
- https://www.youtube.com/watch?v=r3Ye08ktcMo

1 files changed, 9 insertions, 7 deletions

diff --git a/Makefile b/Makefile
index 475c160..f531a02 100644
--- a/Makefile
+++ b/Makefile
@@ -3,17 +3,18 @@
 .PHONY: clean run
 
 # Compiler.
-AS      := arm-none-eabi-as
-CC      := arm-none-eabi-gcc
-OBJCOPY := arm-none-eabi-objcopy
+AS      := aarch64-elf-as
+CC      := aarch64-elf-gcc
+LD      := aarch64-elf-ld
+OBJCOPY := aarch64-elf-objcopy
 
 # Paths.
 SRC_DIR   := src
 BUILD_DIR := build
 
 # Output files.
-ELF := $(BUILD_DIR)/kernel7.elf
-IMG := $(BUILD_DIR)/kernel7.img
+ELF := $(BUILD_DIR)/kernel8.elf
+IMG := $(BUILD_DIR)/kernel8.img
 
 # Bootstrapping files.
 OBJ_START = $(BUILD_DIR)/start.o
@@ -22,6 +23,7 @@ SRC_LINK = $(SRC_DIR)/linker.ld
 
 CFLAGS := -Wall -ffreestanding -O2 -nostdlib -lgcc -mgeneral-regs-only
 AFLAGS :=
+LDFLAGS :=
 
 default: $(IMG)
 
@@ -35,7 +37,7 @@ $(IMG): $(BUILD_DIR) $(ELF)
         $(OBJCOPY) $(ELF) -O binary $(IMG)
 
 $(ELF): $(OBJ_START) $(OBJ_MAIN)
-        $(CC) $(CFLAGS) -T $(SRC_LINK) -o $(ELF) $(OBJ_START) $(OBJ_MAIN)
+        $(LD) $(LDFLAGS) -T $(SRC_LINK) -o $(ELF) $(OBJ_START) $(OBJ_MAIN)
 
 clean:
         rm -rf $(BUILD_DIR)
@@ -44,4 +46,4 @@ $(BUILD_DIR):
         mkdir -p $(BUILD_DIR)
 
 run: $(IMG)
-        qemu-system-aarch64 -M raspi3 -kernel $(IMG) -d in_asm -serial null -serial stdio
+        qemu-system-aarch64 -M raspi3 -kernel $(IMG) -serial null -serial stdio