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Margo
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Add exercises.
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‎kernel4x/.gdbinit

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init-if-undefined $target_set = 0
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if $target_set == 0
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set arch i386:x86-64
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target remote localhost:1234
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file obj/kernel.full
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add-symbol-file obj/bootsector.full 0x7c00
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add-symbol-file obj/p-alloc.full 0x100000
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add-symbol-file obj/p-recurse.full 0x100000
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add-symbol-file obj/p-fork.full 0x100000
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add-symbol-file obj/p-panic.full 0x100000
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source build/functions.gdb
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display/5i $pc
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set $target_set = 1
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end

‎kernel4x/.gitignore

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*~
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core*
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log.txt
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os[0-9]*.img
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obj
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weensyos1
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weensyos1.tar.gz

‎kernel4x/BRANCHES.md

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Here is the code we worked through in class for OS02. Each successive
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modification is checked in to a git branch. You should be able to
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examine a specific branch with `git checkout origin/BRANCHNAME`, and
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to see differences with `git diff master origin/v02` and similar
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commands. Remember to return to the master branch with
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`git checkout master` when you're done.
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* master: initial OS02.
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* v01: Evil: alloc attacks the kernel with a bad argument.
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* v02: Good: kernel checks its arguments more carefully.
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* v03: Evil: alloc attacks the kernel with another bad argument.
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* v04: Good: kernel checks its arguments even more carefully.
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* v05: Kernel adds automatic stack page allocation (for recurse).
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* v06: Evil: recurse tries to kill the kernel.
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* v07: Good: kernel checks stack page allocation.
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* v08: A version of fork.
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* v09: Good: Kernel starts checking argument to panic system call.
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* v10: Good: Kernel completes checking argument to panic system call.

‎kernel4x/COPYRIGHT

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The files in this directory are:
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/*
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* Copyright (C) 2006-2012 Eddie Kohler
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* Copyright (C) 2005 Regents of the University of California
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* Copyright (C) 1997 Massachusetts Institute of Technology
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*
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* This software is being provided by the copyright holders under the
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* following license. By obtaining, using and/or copying this software,
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* you agree that you have read, understood, and will comply with the
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* following terms and conditions:
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*
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* Permission to use, copy, modify, distribute, and sell this software
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* and its documentation for any purpose and without fee or royalty is
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* hereby granted, provided that the full text of this NOTICE appears on
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* ALL copies of the software and documentation or portions thereof,
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* including modifications, that you make.
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*
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* THIS SOFTWARE IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE NO
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* REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED. BY WAY OF EXAMPLE,
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* BUT NOT LIMITATION, COPYRIGHT HOLDERS MAKE NO REPRESENTATIONS OR
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* WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR
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* THAT THE USE OF THE SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY
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* THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS. COPYRIGHT
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* HOLDERS WILL BEAR NO LIABILITY FOR ANY USE OF THIS SOFTWARE OR
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* DOCUMENTATION.
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*
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* The name and trademarks of copyright holders may NOT be used in
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* advertising or publicity pertaining to the software without specific,
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* written prior permission. Title to copyright in this software and any
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* associated documentation will at all times remain with copyright
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* holders. See the file AUTHORS which should have accompanied this software
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* for a list of all copyright holders.
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*
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* This file may be derived from previously copyrighted software. This
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* copyright applies only to those changes made by the copyright
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* holders listed in the AUTHORS file. The rest of this file is covered by
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* the copyright notices, if any, listed below.
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*/

‎kernel4x/GNUmakefile

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IMAGE = os02.img
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all: $(IMAGE)
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# '$(V)' controls whether the lab makefiles print verbose commands (the
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# actual shell commands run by Make), as well as the "overview" commands
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# (such as '+ cc lib/readline.c').
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#
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# For overview commands only, run 'make all'.
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# For overview and verbose commands, run 'make V=1 all'.
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V = 0
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ifeq ($(V),1)
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compile = $(CC) $(CPPFLAGS) $(CFLAGS) $(DEPCFLAGS) $(1)
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link = $(LD) $(LDFLAGS) $(1)
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run = $(1) $(3)
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else
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compile = @/bin/echo " " $(2) $< && $(CC) $(CPPFLAGS) $(CFLAGS) $(DEPCFLAGS) $(1)
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link = @/bin/echo " " $(2) $(patsubst %.full,%,$@) && $(LD) $(LDFLAGS) $(1)
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run = @$(if $(2),/bin/echo " " $(2) $(3) &&,) $(1) $(3)
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endif
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-include build/rules.mk
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# Object sets
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BOOT_OBJS = $(OBJDIR)/bootstart.o $(OBJDIR)/boot.o
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KERNEL_OBJS = $(OBJDIR)/k-exception.o $(OBJDIR)/kernel.o \
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$(OBJDIR)/k-hardware.o $(OBJDIR)/k-loader.o $(OBJDIR)/lib.o \
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$(OBJDIR)/k-malloc.o \
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$(if $(wildcard k-secret.c),$(OBJDIR)/k-secret.o,)
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KERNEL_LINKER_FILES = link/kernel.ld link/shared.ld
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PROCESS_BINARIES = $(OBJDIR)/p-alloc $(OBJDIR)/p-recurse $(OBJDIR)/p-fork \
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$(OBJDIR)/p-panic
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PROCESS_BINARIES_FULL = $(patsubst %,%.full,$(PROCESS_BINARIES))
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PROCESS_LIB_OBJS = $(OBJDIR)/lib.o $(OBJDIR)/process.o
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PROCESS_OBJS = $(patsubst %,%.o,$(PROCESS_BINARIES)) $(PROCESS_LIB_OBJS)
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PROCESS_LINKER_FILES = link/process.ld link/shared.ld
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# Generic rules for making object files
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$(PROCESS_OBJS): $(OBJDIR)/%.o: %.c $(BUILDSTAMPS)
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$(call compile,-O1 -DWEENSYOS_PROCESS -c $< -o $@,COMPILE)
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$(OBJDIR)/%.o: %.c $(BUILDSTAMPS)
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$(call compile,-DWEENSYOS_KERNEL -c $< -o $@,COMPILE)
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$(OBJDIR)/boot.o: $(OBJDIR)/%.o: boot.c $(BUILDSTAMPS)
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$(call compile,-Os -fomit-frame-pointer -c $< -o $@,COMPILE)
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$(OBJDIR)/%.o: %.S $(BUILDSTAMPS)
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$(call compile,-c $< -o $@,ASSEMBLE)
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# Specific rules for WeensyOS
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$(OBJDIR)/kernel.full: $(KERNEL_OBJS) $(PROCESS_BINARIES) $(KERNEL_LINKER_FILES)
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$(call link,-T $(KERNEL_LINKER_FILES) -nostdlib -o $@ $(KERNEL_OBJS) -b binary $(PROCESS_BINARIES),LINK)
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$(PROCESS_BINARIES_FULL): \
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$(OBJDIR)/p-%.full: $(OBJDIR)/p-%.o $(PROCESS_LIB_OBJS) $(PROCESS_LINKER_FILES)
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$(call link,-T $(PROCESS_LINKER_FILES) -nostdlib -o $@ $< $(PROCESS_LIB_OBJS),LINK)
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$(OBJDIR)/%: $(OBJDIR)/%.full
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$(call run,$(OBJDUMP) -S $< >$@.asm)
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$(call run,$(NM) -n $< >$@.sym)
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$(call run,$(OBJCOPY) -j .text -j .rodata -j .data -j .bss $<,STRIP,$@)
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$(OBJDIR)/bootsector: $(BOOT_OBJS) link/boot.ld link/shared.ld
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$(call link,-T link/boot.ld link/shared.ld -nostdlib -o $@.full $(BOOT_OBJS),LINK)
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$(call run,$(OBJDUMP) -S $@.full >$@.asm)
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$(call run,$(NM) -n $@.full >$@.sym)
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$(call run,$(OBJCOPY) -S -O binary -j .text $@.full $@)
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$(OBJDIR)/mkbootdisk: build/mkbootdisk.c $(BUILDSTAMPS)
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$(call run,$(HOSTCC) -I. -o $(OBJDIR)/mkbootdisk,HOSTCOMPILE,build/mkbootdisk.c)
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$(OBJDIR)/k-binaries.c: GNUmakefile build/mkkbinaries.sh
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$(call run,$(SHELL) build/mkkbinaries.sh -c $(PROCESS_BINARIES) >,CREATE,$@)
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$(OBJDIR)/k-binaries.h: GNUmakefile build/mkkbinaries.sh
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$(call run,$(SHELL) build/mkkbinaries.sh -h $(PROCESS_BINARIES) >,CREATE,$@)
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$(OBJDIR)/k-loader.o: $(OBJDIR)/k-binaries.c
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$(OBJDIR)/k-malloc.o: $(OBJDIR)/k-binaries.c
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$(OBJDIR)/kernel.o $(OBJDIR)/k-hardware.o: $(OBJDIR)/k-binaries.h
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os02.img: $(OBJDIR)/mkbootdisk $(OBJDIR)/bootsector $(OBJDIR)/kernel
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$(call run,$(OBJDIR)/mkbootdisk $(OBJDIR)/bootsector $(OBJDIR)/kernel > $@,CREATE $@)
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run-%: run-qemu-%
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@:
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run-qemu-%: run-$(QEMUDISPLAY)-%
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@:
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run-graphic-%: %.img check-qemu
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$(call run,$(QEMU_PRELOAD) $(QEMU) $(QEMUOPT) $(QEMUIMG),QEMU $<)
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run-console-%: %.img check-qemu
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$(call run,$(QEMU_PRELOAD) $(QEMU) $(QEMUOPT) -curses $(QEMUIMG),QEMU $<)
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run-monitor-%: %.img check-qemu
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$(call run,$(QEMU_PRELOAD) $(QEMU) $(QEMUOPT) -monitor stdio $(QEMUIMG),QEMU $<)
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run-gdb-%: run-gdb-$(QEMUDISPLAY)-%
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@:
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run-gdb-graphic-%: %.img check-qemu
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$(call run,$(QEMU_PRELOAD) $(QEMU) $(QEMUOPT) -S -gdb tcp::1234 $(QEMUIMG) &,QEMU $<)
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$(call run,gdb -x .gdbinit,GDB)
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run-gdb-console-%: %.img check-qemu
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$(call run,$(QEMU_PRELOAD) $(QEMU) $(QEMUOPT) -curses -S -gdb tcp::1234 $(QEMUIMG),QEMU $<)
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run: run-qemu-$(basename $(IMAGE))
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run-qemu: run-qemu-$(basename $(IMAGE))
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run-graphic: run-graphic-$(basename $(IMAGE))
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run-console: run-console-$(basename $(IMAGE))
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run-monitor: run-monitor-$(basename $(IMAGE))
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run-quit: run-quit-$(basename $(IMAGE))
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run-gdb: run-gdb-$(basename $(IMAGE))
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run-gdb-graphic: run-gdb-graphic-$(basename $(IMAGE))
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run-gdb-console: run-gdb-console-$(basename $(IMAGE))
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run-graphic-gdb: run-gdb-graphic-$(basename $(IMAGE))
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run-console-gdb: run-gdb-console-$(basename $(IMAGE))
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# Kill all my qemus
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kill:
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-killall -u $$(whoami) $(QEMU)
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@sleep 0.2; if ps -U $$(whoami) | grep $(QEMU) >/dev/null; then killall -9 -u $$(whoami) $(QEMU); fi

‎kernel4x/README.md

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OS02
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=======
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Type `make run` to run our OS using the QEMU emulator. We expect this
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to work only on CS50 Appliance and other Linux hosts. If you have
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problems, check out Troubleshooting below.
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Running the OS
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--------------
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There are several ways to run the OS.
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* `make run`
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Build the OS and pop up a QEMU window to run it. Close the QEMU
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window to exit the OS.
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* `make run-console`
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Build the OS and run QEMU in the current terminal window. Press
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Control-C in the terminal to exit the OS.
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* `make run-gdb`
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Build the OS and run it in a QEMU window under GDB. A QEMU window
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pops up, but the virtual machine immediately stops for debugging.
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Gdb runs in the terminal. You can set breakpoints on OS,
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bootloader, or process functions (for instance, try `b kernel` to
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break at the kernel's entry point) and then type `c` to run the
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virtual machine until a breakpoint hits. Use `si`, `x`, `info
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reg`, etc. to view machine state. We compile the kernel with
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debugging symbols; this means even commands like `next` will work,
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and you can see the source lines corresponding to individual
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instructions. Close the QEMU window to exit the OS, and enter `q`
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in gdb to exit it.
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* `make run-gdb-console`
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Same as `make run-gdb`, but runs QEMU in the current terminal
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window. You must run gdb yourself in a *different* terminal
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window. Run `gdb -x .gdbinit` from this directory.
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In all of these run modes, QEMU also creates a file named `log.txt`.
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The code we hand out doesn't actually log anything yet, but you may
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find it useful to add your own calls to `log_printf` from the kernel.
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Finally, run `make clean` to clean up your directory.
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Source
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------
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Real operating systems are big. We have tried to boil down this OS to
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a minimum, comment it to help you, and separate x86 specifics from
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more fundamental issues. Here is an overview of the code.
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=== Important code ===
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* `kernel.c`: The kernel. Uses functions declared and described in
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`kernel.h` and `lib.h`.
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* `p-*.c`: The applications.
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Use functions declared and described in `process.h` and `lib.h`.
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=== Support code ===
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You can read this if you're interested, but the important stuff is
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declared and described in the files listed above.
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* `bootstart.S`, `boot.c`: The bootloader.
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* `k-hardware.c`: Functions that set up x86 hardware state using
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programmed I/O and memory-mapped I/O instructions.
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* `k-exception.S`: Kernel assembly code for handling exceptions
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(interrupts, traps, and faults).
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* `k-loader.c`: Kernel program loader, which loads processes from
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"image files" into memory.
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* `process.c`: Support code for applications.
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* `lib.c`, `lib.h`: Support code useful in both the kernel and
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applications.
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* `x86.h`: x86 hardware definitions, including functions that
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correspond to important x86 instructions.
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* `elf.h`: ELF support information. (ELF is a format used for
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executables.)
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Build Files
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-----------
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The main output of the build process is a disk image, `os01.img`. QEMU
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"boots" off this disk image, but it could also boot on real hardware!
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The build process also produces other files that you can look at and
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puts them in the `obj/` directory.
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* `obj/kernel.asm`
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This file is the output of `objdump -S` on the kernel. Use it to see
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the kernel's assembly code.
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* `obj/kernel.sym`
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This smaller file just lists all the kernel's symbols (i.e.,
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variable names).
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* `obj/p-hello.asm`, `obj/p-welcome.sym`
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Similar files are generated for process code.
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Troubleshooting
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---------------
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The OS runs using the QEMU full-system emulator. On CS50 Appliance,
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our makefiles will install QEMU for you. On your own Linux machine,
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you will need to install QEMU yourself. On Ubuntu-based hosts, run
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`sudo apt-get install qemu`. On Fedora-based hosts, run `sudo yum
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install qemu-system-x86`.
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If Control-C doesn't work on your QEMU, make sure you are using an
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actual Control key. On some machines QEMU ignores key remappings (such
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as swapping Control and Caps Lock).
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If Control-C still doesn't work on your QEMU -- for instance, because
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your OS kernel crashed with an assertion failure -- close it by
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running `make kill`.

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