Added stage 2 of the assessment with stack management

Changed Stage 1 to use full registers and the si register instead of splitting them

stage2/Makefile

@@ -0,0 +1,102 @@
+# Try to infer the correct TOOLPREFIX if not set
+ifndef TOOLPREFIX
+TOOLPREFIX := $(shell if i386-jos-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
+	then echo 'i386-jos-elf-'; \
+	elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
+	then echo ''; \
+	else echo "***" 1>&2; \
+	echo "*** Error: Couldn't find an i386-*-elf version of GCC/binutils." 1>&2; \
+	echo "*** Is the directory with i386-jos-elf-gcc in your PATH?" 1>&2; \
+	echo "*** If your i386-*-elf toolchain is installed with a command" 1>&2; \
+	echo "*** prefix other than 'i386-jos-elf-', set your TOOLPREFIX" 1>&2; \
+	echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
+	echo "*** To turn off this error, run 'gmake TOOLPREFIX= ...'." 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# If the makefile can't find QEMU, specify its path here
+# QEMU = qemu-system-i386
+
+# Try to infer the correct QEMU
+ifndef QEMU
+QEMU = $(shell if which qemu > /dev/null; \
+	then echo qemu; exit; \
+	elif which qemu-system-i386 > /dev/null; \
+	then echo qemu-system-i386; exit; \
+	elif which qemu-system-x86_64 > /dev/null; \
+	then echo qemu-system-x86_64; exit; \
+	else \
+	qemu=/Applications/Q.app/Contents/MacOS/i386-softmmu.app/Contents/MacOS/i386-softmmu; \
+	if test -x $$qemu; then echo $$qemu; exit; fi; fi; \
+	echo "***" 1>&2; \
+	echo "*** Error: Couldn't find a working QEMU executable." 1>&2; \
+	echo "*** Is the directory containing the qemu binary in your PATH" 1>&2; \
+	echo "*** or have you tried setting the QEMU variable in Makefile?" 1>&2; \
+	echo "***" 1>&2; exit 1)
+endif
+
+CC = $(TOOLPREFIX)gcc
+AS = $(TOOLPREFIX)gas
+LD = $(TOOLPREFIX)ld
+OBJCOPY = $(TOOLPREFIX)objcopy
+OBJDUMP = $(TOOLPREFIX)objdump
+CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -O2 -Wall -MD -ggdb -m32 -Werror -fno-omit-frame-pointer
+CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
+ASFLAGS = -m32 -gdwarf-2 -Wa,-divide
+# FreeBSD ld wants ``elf_i386_fbsd''
+LDFLAGS += -m $(shell $(LD) -V | grep elf_i386 2>/dev/null | head -n 1)
+
+# Disable PIE when possible (for Ubuntu 16.10 toolchain)
+ifneq ($(shell $(CC) -dumpspecs 2>/dev/null | grep -e '[^f]no-pie'),)
+CFLAGS += -fno-pie -no-pie
+endif
+ifneq ($(shell $(CC) -dumpspecs 2>/dev/null | grep -e '[^f]nopie'),)
+CFLAGS += -fno-pie -nopie
+endif
+
+xv6.img: bootblock bootblock2
+	dd if=/dev/zero of=xv6.img count=10000
+	dd if=bootblock of=xv6.img conv=notrunc
+	dd if=bootblock2 of=xv6.img seek=1 conv=notrunc
+
+bootblock: bootasm.S 
+	$(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c bootasm.S
+	$(LD) $(LDFLAGS) -N -e start -Ttext 0x7C00 -o bootblock.o bootasm.o 
+	$(OBJCOPY) -S -O binary -j .text bootblock.o bootblock
+	./sign.pl bootblock
+
+bootblock2: bootasm2.S
+	$(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c bootasm2.S
+	$(LD) $(LDFLAGS) -N -e start -Ttext 0x9000 -o bootblock2.o bootasm2.o 
+	$(OBJCOPY) -S -O binary -j .text bootblock2.o bootblock2
+
+
+.PRECIOUS: %.o
+
+clean: 
+	rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \
+	*.o *.d *.asm *.sym vectors.S bootblock bootblock2 entryother \
+	initcode initcode.out kernel xv6.img fs.img kernelmemfs \
+	xv6memfs.img mkfs \
+	syscall.h syscalltable.h usys.S 
+
+# run in emulators
+
+# try to generate a unique GDB port
+GDBPORT = $(shell expr `id -u` % 5000 + 25000)
+# QEMU's gdb stub command line changed in 0.11
+QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
+	then echo "-gdb tcp::$(GDBPORT)"; \
+	else echo "-s -p $(GDBPORT)"; fi)
+ifndef CPUS
+CPUS := 1
+endif
+QEMUOPTS = -drive file=xv6.img,index=0,media=disk,format=raw -smp $(CPUS) -m 512 $(QEMUEXTRA)
+
+qemu: xv6.img
+	$(QEMU) -vga std -serial mon:stdio $(QEMUOPTS)
+
+qemu-gdb: xv6.img 
+	@echo "*** Now run 'gdb'." 1>&2
+	$(QEMU) -vga std -serial mon:stdio $(QEMUOPTS) -S -gdb tcp::1234
+