Copy .data section to RAM on boot, Makefile dependency generation

.gitignore

@@ -1,4 +1,5 @@
 *.o
+*.d
 main
 attach_gdb_to_this
 main

Makefile

@@ -6,11 +6,15 @@ OBJCOPY=m68k-elf-objcopy
 QEMU=/opt/m68k/bin/qemu-system-m68k
 
 CFLAGS=-nostdlib -nostartfiles -nodefaultlibs
+CFLAGS+=-Wall -Werror
 CFLAGS+=-m68000
 CFLAGS+=-Os
 
-main: assembly.o iv.o screen.o main.o exception.o linker.x kmem.o string.o
-	${LD} main.o assembly.o iv.o screen.o exception.o kmem.o string.o -o main -T linker.x -Map main.map
+SOURCES=assembly.c screen.c main.c exception.c kmem.c string.c
+OBJECTS=$(subst .c,.o,$(SOURCES))
+
+main: ${OBJECTS} iv.o linker.x
+	${LD} ${OBJECTS} iv.o -o main -T linker.x -Map main.map
 	cp main attach_gdb_to_this
 	${OBJCOPY} -O srec main
 
@@ -22,20 +26,15 @@ disassemble: main
 iv.o: iv.asm
 	${AS} -o iv.o iv.asm
 
-main.o: main.c
-	${CC} ${CFLAGS} -c main.c -o main.o
-
-assembly.o: assembly.h assembly.c
-	${CC} ${CFLAGS} -o assembly.o -c assembly.c
-
-screen.o: screen.h screen.c assembly.h
-	${CC} ${CFLAGS} -o screen.o -c screen.c
-
-exception.o: exception.c
-	${CC} ${CFLAGS} -o exception.o -c exception.c
+%.o: %.c
+	${CC} ${CFLAGS} -o $@ -c $<
+%.d: %.c
+	$(CC) -M $(CPPFLAGS) $< > $@.$$$$; \
+	sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \
+	rm -f $@.$$$$
 
-kmem.o: kmem.h kmem.c
-	${CC} -o kmem.o -c kmem.c
+DEPENDS=$(subst .c,.d,$(SOURCES))
+-include ${DEPENDS}
 
 run: main
 	${QEMU} -M cecs -nographic -kernel main -gdb tcp::1234
@@ -44,5 +43,5 @@ debug: main
 	${QEMU} -M cecs -nographic -kernel main -S -gdb tcp::1234
 
 clean:
-	rm assembly.o screen.o iv.o attach_gdb_to_this main main.o kmem.o main.map string.o
+	rm iv.o attach_gdb_to_this main main.map ${DEPENDS} ${OBJECTS}
 

iv.asm

@@ -1,9 +1,6 @@
-.data
-	.org	0x0
-	dc.l	__asm_stack__,main
 	.equ	__asm_stack__,0x4400
 	.section .text
-	dc.l	__asm_stack__,main
+	dc.l	__asm_stack__,entry
 	dc.l	excep_undef
 	dc.l	excep_undef
 	/* 4 */

kmem.c

@@ -8,7 +8,7 @@ char *blocks;
 
 void kfree(void *ptr) {
 	ptr = ptr - 4;
-	int size = *((int *)ptr);
+	int __attribute__ ((unused)) size = *((int *)ptr);
 	int index = (((int) ptr) - MEM_START)/MEM_BLOCK_SIZE;
 	CLRBIT(index);
 	*((int *)ptr) = 0;
@@ -53,7 +53,7 @@ void *kmalloc(int size) {
 void kmeminit() {
 	int needed_blocks = (MEM_BITSET_BYTES+MEM_BLOCK_SIZE-1)/MEM_BLOCK_SIZE;
 	int i;
-	blocks = (int *)MEM_START;
+	blocks = (char *)MEM_START;
 	for (i = 0; i < needed_blocks; i++)
 		SETBIT(i);
 	for (; i < MEM_BITSET_BITS; i++)

linker.x

@@ -9,12 +9,16 @@ SECTIONS {
 	.text : {
 		* (.text*);
 		* (.rodata*);
-		etext = .; /*End of test section*/
 	} >ROM
 	/* The C code needs to reference all initialized data at its RAM address,
 	   but we want it to be writable.  This causes the .data section to
 	   be physically located after the .text section in ROM, but referenced
 	   at its RAM address.  Code must copy this data section to RAM at boot.
 	 */
-	.data : AT (etext) { * (.data); } >RAM
+	.data :  {
+		data_load = LOADADDR(.data);
+		data_start = .;
+		* (.data);
+		data_end = .;
+	} >RAM AT>ROM
 }

main.c

@@ -1,6 +1,30 @@
 #include "assembly.h"
 #include "screen.h"
 #include "kmem.h"
+#include "string.h"
+
+extern unsigned char data_load;
+extern unsigned char data_start;
+extern unsigned char data_end;
+
+int foo = 0xdeadbeef;
+
+/* Copy the .data section from ROM to RAM */
+static void copy_data(void)
+{
+	unsigned char *rom_data = &data_load;
+	unsigned char *ram_data = &data_start;
+
+	if (foo == 0xdeadbeef)
+		putstr("Warning: .data appears initialized before copying\n");
+
+	/* Could be replaced with a call to memcpy */
+	while (ram_data < &data_end) {
+		*(ram_data++) = *(rom_data++);
+	}
+	if (foo != 0xdeadbeef)
+		putstr("Warning: .data not initialized as expected\n");
+}
 
 void *test_malloc(int bytes) {
 	void *ptr = kmalloc(bytes);
@@ -19,15 +43,16 @@ void test_free(void *ptr) {
 
 void memtest() {
 	void *p1 = test_malloc(124);
-	void *p2 = test_malloc(124);
+	void __attribute__ ((unused)) *p2 = test_malloc(124);
 	test_free(p1);
-	void *p3 = test_malloc(124);
+	void __attribute__ ((unused)) *p3 = test_malloc(124);
 
 }
 
 void shell() {
 	char ptr[64];
 
+	copy_data();
 	putstr("Welcome to the (unstable) C Kernel\n");
 
 	while(1)
@@ -57,7 +82,7 @@ void shell() {
 	}
 }
 
-void main() {
+void entry() {
 	__asm_initialize__();
 	kmeminit();