Created xbboot.

xbboot/target-echokernel/.gitignore

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+echo-kernel.bin
+echo-kernel.dump
+echo-kernel.lst
+echo-kernel.o
+echo-kernel.sym
+echo-kernel.map
+echo-kernel.elf
+head.lst
+head.o
+serial.lst
+serial.o

xbboot/target-echokernel/Makefile

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+#
+# Authors: Wolfgang Spraul <wolfgang@qi-hardware.com>
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version
+# 3 of the License, or (at your option) any later version.
+#
+
+ifeq ($(CROSS_COMPILE),)
+$(error CROSS_COMPILE variable not set, should point to .../mipsel-openwrt-linux-)
+endif
+
+CC	= $(CROSS_COMPILE)gcc
+AR	= $(CROSS_COMPILE)ar rcsv
+LD	= $(CROSS_COMPILE)ld
+OBJCOPY	= $(CROSS_COMPILE)objcopy
+NM	= $(CROSS_COMPILE)nm
+OBJDUMP	= $(CROSS_COMPILE)objdump
+
+DEBUG_CFLAGS = -g -Wa,-a=$(basename $@).lst
+# Wolfgang saw data corruptions in stage2 when dealing with ECC data on random writes
+# to NAND. Disabling the unit-at-a-time optimization reproducibly fixed the bug.
+# The compiler may be optimizing in a way that conflicts with how the hardware ECC
+# registers work. Since other register accesses might be affected too it seems the best
+# is to disable this optimization right now.
+CFLAGS	= -mips32 -O2 -fno-exceptions -fno-unit-at-a-time -fno-zero-initialized-in-bss \
+	-ffunction-sections -fomit-frame-pointer -msoft-float -G 0 $(DEBUG_CFLAGS)
+LDFLAGS	= -nostdlib -T target.ld $(CFLAGS)
+LIBS	= -lstdc++ -lc -lm -lgcc
+VPATH   = ../target-common
+
+OBJS	= echo-kernel.o serial.o
+
+all: echo-kernel.elf
+	$(OBJCOPY) -O binary echo-kernel.elf echo-kernel.bin
+	$(OBJDUMP) -D echo-kernel.elf > echo-kernel.dump
+	$(NM) echo-kernel.elf | sort > echo-kernel.sym
+	$(OBJDUMP) -h echo-kernel.elf > echo-kernel.map
+
+echo-kernel.elf: head.o $(OBJS)
+	$(CC) $(LDFLAGS) $^ -o $@
+
+.c.o:
+	$(CC) $(CFLAGS) -o $@ -c $<
+.cpp.o:
+	$(CC) $(CFLAGS) -fno-rtti -fvtable-gc -o $@ -c $<
+.S.o:
+	$(CC) $(CFLAGS) -o $@ -c $<
+
+clean:
+	rm -f $(addprefix echo-kernel., bin dump elf map sym)
+	rm -f head.o head.lst $(OBJS) $(OBJS:.o=.lst)

xbboot/target-echokernel/echo-kernel.c

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+//
+// Authors: Wolfgang Spraul <wolfgang@qi-hardware.com>
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version
+// 3 of the License, or (at your option) any later version.
+//
+
+#include <inttypes.h>
+#include "../target-common/jz4740.h"
+#include "../target-common/serial.h"
+
+void c_main();
+
+void pre_main(void)
+{
+	volatile unsigned int start_addr, got_start, got_end, addr, offset;
+
+	/* get absolute start address  */
+	__asm__ __volatile__(			
+		"move %0, $20\n\t"
+		: "=r"(start_addr)
+		: 
+		);			
+
+	/* get related GOT address  */
+	__asm__ __volatile__(			
+		"la $4, _GLOBAL_OFFSET_TABLE_\n\t"
+		"move %0, $4\n\t"
+		"la $5, _got_end\n\t"
+		"move %1, $5\n\t"
+		: "=r"(got_start),"=r"(got_end)
+		: 
+		);			
+
+	/* calculate offset and correct GOT*/
+	offset = start_addr - 0x80000000;	
+ 	got_start += offset;
+	got_end  += offset;
+
+	for ( addr = got_start + 8; addr < got_end; addr += 4 )
+		*((volatile unsigned int *)(addr)) += offset; // add offset to correct all GOT
+
+//	fw_args = (struct fw_args *)(start_addr + 0x8);       //get the fw args from memory
+	UART_BASE = 0xB0030000;
+	serial_puts("Start address is:");
+	serial_put_hex(start_addr);
+	serial_puts("Address offset is:");
+	serial_put_hex(start_addr - 0x80000000);
+	serial_puts("GOT corrected to:");
+	serial_put_hex(got_start);
+	c_main();
+}
+
+void c_main()
+{
+	// start infinite 'echo' kernel
+	while (1) {
+		if (serial_tstc()) {
+			int c = serial_getc();
+			serial_putc(c);
+			if (c == '\r')
+				serial_putc('\n');
+		}
+	}
+}

xbboot/target-echokernel/head.S

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+//
+// Authors: Wolfgang Spraul <wolfgang@qi-hardware.com>
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version
+// 3 of the License, or (at your option) any later version.
+//
+
+	.text
+	.extern pre_main
+		
+	.globl _start
+	.set noreorder
+_start:
+	b	real_start
+	nop
+	.word	0x0                  //	its address == start address + 8
+	.word	0x0
+	.word	0x0
+	.word	0x0
+	.word	0x0
+	.word	0x0
+	.word	0x0
+	.word	0x0
+
+real_start:	
+	/* setup stack, jump to C code */
+	add	$29, $20, 0x3ffff0 // sp locate at start address offset 0x2ffff0
+	add	$25, $20, 0x40     // t9 = pre_main()
+	j	$25
+	nop
+
+	.set reorder

xbboot/target-echokernel/target.ld

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+OUTPUT_ARCH(mips)
+ENTRY(_start)
+MEMORY
+{
+	ram	: ORIGIN = 0x80000000 , LENGTH = 3M
+}
+
+SECTIONS
+{
+	. = ALIGN(4);
+	.text : { *(.text*) } > ram
+
+	. = ALIGN(4);
+	.rodata : { *(.rodata*) } > ram
+
+	. = ALIGN(4);
+	.sdata : { *(.sdata*) } > ram
+
+	. = ALIGN(4);
+	.data : { *(.data*) *(.scommon*) *(.reginfo*) } > ram
+
+	_gp = ALIGN(16);
+
+	.got : { *(.got*) } > ram
+	_got_end = ABSOLUTE(.);	
+
+	. = ALIGN(4);
+	.sbss : { *(.sbss*) } > ram
+	.bss : { *(.bss*) } > ram
+	. = ALIGN (4);
+}