lab 3

.bochsrc

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+###############################################################
+# bochsrc file for pragmalinux disk image.
+#
+# This file is provided both as .bochsrc and bochsrc so
+# that it works on win32 and unix.
+###############################################################
+
+# how much memory the emulated machine will have
+megs: 32
+
+# filename of ROM images
+romimage: file=$BXSHARE/BIOS-bochs-latest
+#, address=0xf0000
+vgaromimage: file=$BXSHARE/VGABIOS-lgpl-latest
+
+# Use the parallel port as an alternate console,
+# so that we can run Bochs without the GUI.
+parport1: enabled=1, file="/dev/stdout"
+#parport1: enabled=1, file="/dev/null"
+
+# uncommenting one of the following lines can be used to specify your
+# preferred display. (defaults to x11 for bochs-bin and to term for
+# bochs-term)
+
+#display_library: x
+
+# nogui can still be useful because you can see the output on the
+# parport1 from above
+#display_library: nogui
+
+# if using "term", you probably want to change the parport output to
+# go to a file or /dev/null
+#display_library: term
+
+# disk images
+ata0: enabled=1, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
+ata0-master: type=disk, mode=flat, path="./obj/kern/kernel.img", cylinders=25, heads=16, spt=25
+
+# choose the boot disk.
+boot: c
+
+# where do we send log messages?
+log: bochs.log
+#log: /dev/stdout
+
+# disable the mouse
+mouse: enabled=0
+
+#debug: action=ignore
+info: action=ignore
+error: action=report
+panic: action=ask
+
+# this changes how often the screen is refreshed.  Lowering it will
+# make your screen update more often, which will slow down emulation,
+# but will make the display respond faster.  It can also be useful if
+# you machine is panicing and the most recent screen changes are not
+# displayed before it panics.
+
+vga_update_interval: 100000
+
+# changing ips can lead to dramatically different performance.  It
+# also affects how quickly time passes in the emulated machine.
+# Setting it too low can cause clock interrupts to happen too rapidly.
+# Setting it too high will make the whole machine feel sluggish.
+# (Note: with using clock sync=realtime, the ips parameter is not
+# really used, although it is still used for vga updates)
+# ips: 2000000
+
+# This means that time in the emulated machine is the same as
+# realtime.  This can be scary because running the same simulation
+# twice in a row can lead to different results (because they started
+# at different times, for instance).  If you want to use non-real
+# time, then use sync=none.
+clock: sync=realtime, time0=local
+# clock: sync=none, time0=946681200 # jan 1, 2000
+
+keyboard_serial_delay: 10

.gitignore

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+bochs.log
+obj/*

CODING

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+JOS CODING STANDARDS
+
+It's easier on everyone if all authors working on a shared
+code base are consistent in the way they write their programs.
+We have the following conventions in our code:
+
+* No space after the name of a function in a call
+  For example, printf("hello") not printf ("hello").
+
+* One space after keywords "if", "for", "while", "switch".
+  For example, if (x) not if(x).
+
+* Space before braces.
+  For example, if (x) { not if (x){.
+
+* Function names are all lower-case separated by underscores.
+
+* Beginning-of-line indentation via tabs, not spaces.
+
+* Preprocessor macros are always UPPERCASE.
+  There are a few grandfathered exceptions: assert, panic,
+  static_assert, offsetof.
+
+* Pointer types have spaces: (uint16_t *) not (uint16_t*).
+
+* Multi-word names are lower_case_with_underscores.
+
+* Comments in imported code are usually C /* ... */ comments.
+  Comments in new code are C++ style //.
+
+* In a function definition, the function name starts a new line.
+  Then you can grep -n '^foo' */*.c to find the definition of foo.
+
+* Functions that take no arguments are declared f(void) not f().
+

Makefile

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+#
+# This makefile system follows the structuring conventions
+# recommended by Peter Miller in his excellent paper:
+#
+#	Recursive Make Considered Harmful
+#	http://aegis.sourceforge.net/auug97.pdf
+#
+OBJDIR := obj
+
+ifdef LAB
+SETTINGLAB := true
+else
+-include conf/lab.mk
+endif
+
+-include conf/env.mk
+
+ifndef SOL
+SOL := 0
+endif
+ifndef LABADJUST
+LABADJUST := 0
+endif
+
+ifndef LABSETUP
+LABSETUP := ./
+endif
+
+
+TOP = .
+
+# Cross-compiler jos toolchain
+#
+# This Makefile will automatically use the cross-compiler toolchain
+# installed as 'i386-jos-elf-*', if one exists.  If the host tools ('gcc',
+# 'objdump', and so forth) compile for a 32-bit x86 ELF target, that will
+# be detected as well.  If you have the right compiler toolchain installed
+# using a different name, set GCCPREFIX explicitly in conf/env.mk
+
+# try to infer the correct GCCPREFIX
+ifndef GCCPREFIX
+GCCPREFIX := $(shell if i386-jos-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
+	then echo 'i386-jos-elf-'; \
+	elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
+	then echo ''; \
+	else echo "***" 1>&2; \
+	echo "*** Error: Couldn't find an i386-*-elf version of GCC/binutils." 1>&2; \
+	echo "*** Is the directory with i386-jos-elf-gcc in your PATH?" 1>&2; \
+	echo "*** If your i386-*-elf toolchain is installed with a command" 1>&2; \
+	echo "*** prefix other than 'i386-jos-elf-', set your GCCPREFIX" 1>&2; \
+	echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
+	echo "*** To turn off this error, run 'gmake GCCPREFIX= ...'." 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# try to infer the correct QEMU
+ifndef QEMU
+QEMU := $(shell if which qemu > /dev/null; \
+	then echo qemu; exit; \
+	else \
+	qemu=/Applications/Q.app/Contents/MacOS/i386-softmmu.app/Contents/MacOS/i386-softmmu; \
+	if test -x $$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 conf/env.mk?" 1>&2; \
+	echo "***" 1>&2; exit 1)
+endif
+
+# try to generate a unique GDB port
+GDBPORT	:= $(shell expr `id -u` % 5000 + 25000)
+
+CC	:= $(GCCPREFIX)gcc -pipe
+AS	:= $(GCCPREFIX)as
+AR	:= $(GCCPREFIX)ar
+LD	:= $(GCCPREFIX)ld
+OBJCOPY	:= $(GCCPREFIX)objcopy
+OBJDUMP	:= $(GCCPREFIX)objdump
+NM	:= $(GCCPREFIX)nm
+
+# Native commands
+NCC	:= gcc $(CC_VER) -pipe
+TAR	:= gtar
+PERL	:= perl
+
+# Compiler flags
+# -fno-builtin is required to avoid refs to undefined functions in the kernel.
+CFLAGS := $(CFLAGS) $(DEFS) $(LABDEFS) -fno-builtin -I$(TOP) -MD
+CFLAGS += -Wall -Wno-format -Wno-unused -Werror -gstabs -m32
+
+# Add -fno-stack-protector if the option exists.
+CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
+
+# Common linker flags
+LDFLAGS := -m elf_i386
+
+# Linker flags for JOS user programs
+ULDFLAGS := -T user/user.ld
+
+GCC_LIB := $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
+
+# Lists that the */Makefrag makefile fragments will add to
+OBJDIRS :=
+
+# Make sure that 'all' is the first target
+all:
+
+# Eliminate default suffix rules
+.SUFFIXES:
+
+# Delete target files if there is an error (or make is interrupted)
+.DELETE_ON_ERROR:
+
+# make it so that no intermediate .o files are ever deleted
+.PRECIOUS: %.o $(OBJDIR)/boot/%.o $(OBJDIR)/kern/%.o \
+	$(OBJDIR)/lib/%.o $(OBJDIR)/fs/%.o $(OBJDIR)/user/%.o
+
+KERN_CFLAGS := $(CFLAGS) -DJOS_KERNEL -gstabs
+USER_CFLAGS := $(CFLAGS) -DJOS_USER -gstabs
+
+
+
+
+# Include Makefrags for subdirectories
+include boot/Makefrag
+include kern/Makefrag
+include lib/Makefrag
+include user/Makefrag
+
+
+IMAGES = $(OBJDIR)/kern/kernel.img
+QEMUOPTS = -hda $(OBJDIR)/kern/kernel.img -serial mon:stdio
+
+.gdbinit: .gdbinit.tmpl
+	sed "s/localhost:1234/localhost:$(GDBPORT)/" < $^ > $@
+
+qemu: $(IMAGES)
+	$(QEMU) $(QEMUOPTS)
+
+qemu-nox: $(IMAGES)
+	echo "*** Use Ctrl-a x to exit"
+	$(QEMU) -nographic $(QEMUOPTS)
+
+qemu-gdb: $(IMAGES) .gdbinit
+	@echo "*** Now run 'gdb'." 1>&2
+	$(QEMU) $(QEMUOPTS) -s -S -p $(GDBPORT)
+
+qemu-gdb-nox: $(IMAGES) .gdbinit
+	@echo "*** Now run 'gdb'." 1>&2
+	$(QEMU) -nographic $(QEMUOPTS) -s -S -p $(GDBPORT)
+
+which-qemu:
+	@echo $(QEMU)
+
+# For deleting the build
+clean:
+	rm -rf $(OBJDIR)
+
+realclean: clean
+	rm -rf lab$(LAB).tar.gz jos.out
+
+distclean: realclean
+	rm -rf conf/gcc.mk
+
+grade: $(LABSETUP)grade-lab$(LAB).sh
+	$(V)$(MAKE) clean >/dev/null 2>/dev/null
+	$(MAKE) all
+	sh $(LABSETUP)grade-lab$(LAB).sh
+
+handin: tarball
+	@echo Please visit http://pdos.csail.mit.edu/cgi-bin/828handin
+	@echo and upload lab$(LAB)-handin.tar.gz.  Thanks!
+
+tarball: realclean
+	tar cf - `find . -type f | grep -v '^\.*$$' | grep -v '/CVS/' | grep -v '/\.svn/' | grep -v '/\.git/' | grep -v 'lab[0-9].*\.tar\.gz'` | gzip > lab$(LAB)-handin.tar.gz
+
+# For test runs
+run-%:
+	$(V)rm -f $(OBJDIR)/kern/init.o $(IMAGES)
+	$(V)$(MAKE) "DEFS=-DTEST=_binary_obj_user_$*_start -DTESTSIZE=_binary_obj_user_$*_size" $(IMAGES)
+	echo "*** Use Ctrl-a x to exit"
+	$(QEMU) -nographic $(QEMUOPTS)
+
+xrun-%:
+	$(V)rm -f $(OBJDIR)/kern/init.o $(IMAGES)
+	$(V)$(MAKE) "DEFS=-DTEST=_binary_obj_user_$*_start -DTESTSIZE=_binary_obj_user_$*_size" $(IMAGES)
+	$(QEMU) $(QEMUOPTS)
+
+# This magic automatically generates makefile dependencies
+# for header files included from C source files we compile,
+# and keeps those dependencies up-to-date every time we recompile.
+# See 'mergedep.pl' for more information.
+$(OBJDIR)/.deps: $(foreach dir, $(OBJDIRS), $(wildcard $(OBJDIR)/$(dir)/*.d))
+	@mkdir -p $(@D)
+	@$(PERL) mergedep.pl $@ $^
+
+-include $(OBJDIR)/.deps
+
+always:
+	@:
+
+.PHONY: all always \
+	handin tarball clean realclean clean-labsetup distclean grade labsetup

README.md

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+# os

boot/Makefrag

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+#
+# Makefile fragment for the JOS kernel.
+# This is NOT a complete makefile;
+# you must run GNU make in the top-level directory
+# where the GNUmakefile is located.
+#
+
+OBJDIRS += boot
+
+BOOT_OBJS := $(OBJDIR)/boot/boot.o $(OBJDIR)/boot/main.o
+
+$(OBJDIR)/boot/%.o: boot/%.c
+	@echo + cc -Os $<
+	@mkdir -p $(@D)
+	$(V)$(CC) -nostdinc $(KERN_CFLAGS) -Os -c -o $@ $<
+
+$(OBJDIR)/boot/%.o: boot/%.S
+	@echo + as $<
+	@mkdir -p $(@D)
+	$(V)$(CC) -nostdinc $(KERN_CFLAGS) -c -o $@ $<
+
+$(OBJDIR)/boot/main.o: boot/main.c
+	@echo + cc -Os $<
+	$(V)$(CC) -nostdinc $(KERN_CFLAGS) -Os -c -o $(OBJDIR)/boot/main.o boot/main.c
+
+$(OBJDIR)/boot/boot: $(BOOT_OBJS)
+	@echo + ld boot/boot
+	$(V)$(LD) $(LDFLAGS) -N -e start -Ttext 0x7C00 -o [email protected] $^
+	$(V)$(OBJDUMP) -S [email protected] >[email protected]
+	$(V)$(OBJCOPY) -S -O binary -j .text [email protected] $@
+	$(V)perl boot/sign.pl $(OBJDIR)/boot/boot