Initial commit

GRADING.md

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+# Grading
+
+1. Download student submissions:
+
+    ```bash
+    mkdir -p submissions
+    rsync -rtLP ${your_kerberos}@athena.dialup.mit.edu:/mit/6.828/web_scripts/$(date +"%Y")/uploads/lab-${lab_name}/ submissions/
+    ```
+
+2. Start the grading VM and SSH in:
+
+    ```bash
+    vagrant up
+    vagrant ssh
+    ```
+
+3. Grade submissions (in the VM):
+
+    ```bash
+    cd /xv6
+    ./batch-grade --config conf/lab-${lab_name}.json --output lab-${lab_name}.json submissions
+    ```
+
+4. Copy grades to Athena:
+
+    ```bash
+    rsync lab-${lab_name}.json ${your_kerberos}@athena.dialup.mit.edu:/mit/6.828/web_scripts/$(date +"%Y")/grades/
+    ```
+
+5. Import grades:
+
+    ```bash
+    ssh ${your_kerberos}@athena.dialup.mit.edu
+    cd /mit/6.828/web_scripts/$(date +"%Y")/
+    ./import-grades.py -l ${lab_name}
+    ```

LICENSE

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+The xv6 software is:
+
+Copyright (c) 2006-2019 Frans Kaashoek, Robert Morris, Russ Cox,
+                        Massachusetts Institute of Technology
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+

Makefile

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+K=kernel
+U=user
+LWIP=lwip
+
+OBJS = \
+  $K/entry.o \
+  $K/start.o \
+  $K/console.o \
+  $K/printf.o \
+  $K/uart.o \
+  $K/kalloc.o \
+  $K/spinlock.o \
+  $K/string.o \
+  $K/main.o \
+  $K/vm.o \
+  $K/proc.o \
+  $K/swtch.o \
+  $K/trampoline.o \
+  $K/trap.o \
+  $K/syscall.o \
+  $K/sysproc.o \
+  $K/bio.o \
+  $K/fs.o \
+  $K/log.o \
+  $K/sleeplock.o \
+  $K/file.o \
+  $K/pipe.o \
+  $K/exec.o \
+  $K/sysfile.o \
+  $K/kernelvec.o \
+  $K/plic.o \
+  $K/virtio_disk.o \
+  $K/buddy.o \
+  $K/list.o
+
+# uncomment for lab net
+#OBJS += \
+  $K/net.o \
+  $K/virtio_net.o \
+  $(LWIP)/core/init.o \
+  $(LWIP)/core/def.o \
+  $(LWIP)/core/dns.o \
+  $(LWIP)/core/inet_chksum.o \
+  $(LWIP)/core/ip.o \
+  $(LWIP)/core/mem.o \
+  $(LWIP)/core/memp.o \
+  $(LWIP)/core/netif.o \
+  $(LWIP)/core/pbuf.o \
+  $(LWIP)/core/raw.o \
+  $(LWIP)/core/stats.o \
+  $(LWIP)/core/sys.o \
+  $(LWIP)/core/tcp.o \
+  $(LWIP)/core/tcp_in.o \
+  $(LWIP)/core/tcp_out.o \
+  $(LWIP)/core/timeouts.o \
+  $(LWIP)/core/udp.o \
+  $(LWIP)/core/ipv4/autoip.o \
+  $(LWIP)/core/ipv4/dhcp.o \
+  $(LWIP)/core/ipv4/etharp.o \
+  $(LWIP)/core/ipv4/icmp.o \
+  $(LWIP)/core/ipv4/igmp.o \
+  $(LWIP)/core/ipv4/ip4_frag.o \
+  $(LWIP)/core/ipv4/ip4.o \
+  $(LWIP)/core/ipv4/ip4_addr.o \
+  $(LWIP)/api/err.o \
+  $(LWIP)/netif/ethernet.o \
+
+# riscv64-unknown-elf- or riscv64-linux-gnu-
+# perhaps in /opt/riscv/bin
+#TOOLPREFIX =
+
+# Try to infer the correct TOOLPREFIX if not set
+ifndef TOOLPREFIX
+TOOLPREFIX := $(shell if riscv64-unknown-elf-objdump -i 2>&1 | grep 'elf64-big' >/dev/null 2>&1; \
+	then echo 'riscv64-unknown-elf-'; \
+	elif riscv64-linux-gnu-objdump -i 2>&1 | grep 'elf64-big' >/dev/null 2>&1; \
+	then echo 'riscv64-linux-gnu-'; \
+	else echo "***" 1>&2; \
+	echo "*** Error: Couldn't find an riscv64 version of GCC/binutils." 1>&2; \
+	echo "*** To turn off this error, run 'gmake TOOLPREFIX= ...'." 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+QEMU = qemu-system-riscv64
+
+CC = $(TOOLPREFIX)gcc
+AS = $(TOOLPREFIX)gas
+LD = $(TOOLPREFIX)ld
+GDB = $(TOOLPREFIX)gdb
+OBJCOPY = $(TOOLPREFIX)objcopy
+OBJDUMP = $(TOOLPREFIX)objdump
+
+CFLAGS = -Wall -Werror -O -fno-omit-frame-pointer -ggdb
+CFLAGS += -MD
+CFLAGS += -mcmodel=medany
+CFLAGS += -ffreestanding -fno-common -nostdlib -mno-relax
+CFLAGS += -I.
+CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
+
+# Disable PIE when possible (for Ubuntu 16.10 toolchain)
+ifneq ($(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
+
+CFLAGS += -I $K/lwip -I $(LWIP)/include
+
+LDFLAGS = -z max-page-size=4096
+
+$K/kernel: $(OBJS) $K/kernel.ld $U/initcode
+	$(LD) $(LDFLAGS) -T $K/kernel.ld -o $K/kernel $(OBJS)
+	$(OBJDUMP) -S $K/kernel > $K/kernel.asm
+	$(OBJDUMP) -t $K/kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $K/kernel.sym
+
+$U/initcode: $U/initcode.S
+	$(CC) $(CFLAGS) -nostdinc -I. -Ikernel -c $U/initcode.S -o $U/initcode.o
+	$(LD) $(LDFLAGS) -N -e start -Ttext 0 -o $U/initcode.out $U/initcode.o
+	$(OBJCOPY) -S -O binary $U/initcode.out $U/initcode
+	$(OBJDUMP) -S $U/initcode.o > $U/initcode.asm
+
+tags: $(OBJS) _init
+	etags *.S *.c
+
+ULIB = $U/ulib.o $U/usys.o $U/printf.o $U/umalloc.o
+
+_%: %.o $(ULIB)
+	$(LD) $(LDFLAGS) -N -e main -Ttext 0 -o $@ $^
+	$(OBJDUMP) -S $@ > $*.asm
+	$(OBJDUMP) -t $@ | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $*.sym
+
+$U/usys.S : $U/usys.pl
+	perl $U/usys.pl > $U/usys.S
+
+$U/usys.o : $U/usys.S
+	$(CC) $(CFLAGS) -c -o $U/usys.o $U/usys.S
+
+$U/_forktest: $U/forktest.o $(ULIB)
+	# forktest has less library code linked in - needs to be small
+	# in order to be able to max out the proc table.
+	$(LD) $(LDFLAGS) -N -e main -Ttext 0 -o $U/_forktest $U/forktest.o $U/ulib.o $U/usys.o
+	$(OBJDUMP) -S $U/_forktest > $U/forktest.asm
+
+$U/_uthread: $U/uthread.o $U/uthread_switch.o $(ULIB)
+	$(LD) $(LDFLAGS) -N -e main -Ttext 0 -o $U/_uthread $U/uthread.o $U/uthread_switch.o $(ULIB)
+	$(OBJDUMP) -S $U/_uthread > $U/uthread.asm
+
+mkfs/mkfs: mkfs/mkfs.c $K/fs.h
+	gcc -Werror -Wall -I. -o mkfs/mkfs mkfs/mkfs.c
+
+# Prevent deletion of intermediate files, e.g. cat.o, after first build, so
+# that disk image changes after first build are persistent until clean.  More
+# details:
+# http://www.gnu.org/software/make/manual/html_node/Chained-Rules.html
+.PRECIOUS: %.o
+
+UPROGS=\
+	$U/_lazytests\
+	$U/_cat\
+	$U/_echo\
+	$U/_forktest\
+	$U/_grep\
+	$U/_init\
+	$U/_kill\
+	$U/_ln\
+	$U/_ls\
+	$U/_mkdir\
+	$U/_rm\
+	$U/_sh\
+	$U/_stressfs\
+	$U/_usertests\
+	$U/_wc\
+	$U/_zombie\
+	$U/_cowtest\
+	$U/_uthread\
+	$U/_call\
+	$U/_testsh\
+	$U/_kalloctest\
+	$U/_bcachetest\
+	$U/_alloctest\
+	$U/_specialtest\
+	# $U/_symlinktest\
+
+fs.img: mkfs/mkfs README user/xargstest.sh $(UPROGS)
+	mkfs/mkfs fs.img README user/xargstest.sh $(UPROGS)
+
+-include kernel/*.d user/*.d
+-include lwip/api/*.d lwip/core/*.d lwip/core/ipv4/*.d lwip/netif/*.d
+
+clean:
+	rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \
+	*/*.o */*.d */*.asm */*.sym \
+	$(LWIP)/*/*.o $(LWIP)/*/*.d \
+	$(LWIP)/*/*/*.o $(LWIP)/*/*/*.d \
+	$U/initcode $U/initcode.out $K/kernel fs.img \
+	mkfs/mkfs .gdbinit \
+        $U/usys.S \
+	$(UPROGS)
+
+# try to generate a unique GDB port
+GDBPORT = $(shell expr `id -u` % 5000 + 25000)
+PORT80  = $(shell expr $(GDBPORT) + 1)
+# 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 := 3
+endif
+
+QEMUEXTRA = 
+QEMUOPTS = -machine virt -bios none -kernel $K/kernel -m 128M -smp $(CPUS) -nographic
+QEMUOPTS += -drive file=fs.img,if=none,format=raw,id=x0 -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
+QEMUOPTS += -no-user-config
+QEMUOPTS += -device virtio-net-device,netdev=en0 -object filter-dump,id=f0,netdev=en0,file=en0.pcap
+# to foward a host port $(PORT80) to port 80 inside QEMU,
+# use "-netdev type=user,id=en0,hostfwd=tcp::$(PORT80)-:80"
+QEMUOPTS += -netdev type=user,id=en0
+
+qemu: $K/kernel fs.img
+	$(QEMU) $(QEMUOPTS)
+
+qemu-trace: $K/kernel stacktrace fs.img
+	$(QEMU) $(QEMUOPTS) | ./stacktrace
+
+.gdbinit: .gdbinit.tmpl-riscv
+	sed "s/:1234/:$(GDBPORT)/" < $^ > $@
+
+qemu-gdb: $K/kernel .gdbinit fs.img
+	@echo "*** Now run 'make gdb' in another window." 1>&2
+	$(QEMU) $(QEMUOPTS) -S $(QEMUGDB)
+
+gdb: $K/kernel .gdbinit
+	$(GDB)
+
+##
+##  FOR submitting lab solutions
+##
+
+LAB := $(shell git symbolic-ref --short HEAD 2> /dev/null)
+ifeq ($(LAB),)
+LAB := $(shell cat conf/LAB)
+endif
+
+ifneq ($(V),@)
+GRADEFLAGS += -v
+endif
+
+print-gdbport:
+	@echo $(GDBPORT)
+
+grade:
+	@echo $(MAKE) clean
+	@$(MAKE) clean || \
+	  (echo "'make clean' failed.  HINT: Do you have another running instance of xv6?" && exit 1)
+	./grade-lab-$(LAB) $(GRADEFLAGS)
+
+handin-check:
+	@if ! test -d .git; then \
+		echo No .git directory, is this a git repository?; \
+		false; \
+	fi
+	@if test "$$(git symbolic-ref HEAD)" != refs/heads/$(LAB); then \
+		git branch; \
+		read -p "You are not on the $(LAB) branch.  Hand-in the current branch? [y/N] " r; \
+		test "$$r" = y; \
+	fi
+	@if ! git diff-files --quiet || ! git diff-index --quiet --cached HEAD; then \
+		git status -s; \
+		echo; \
+		echo "You have uncomitted changes.  Please commit or stash them."; \
+		false; \
+	fi
+	@if test -n "`git status -s`"; then \
+		git status -s; \
+		read -p "Untracked files will not be handed in.  Continue? [y/N] " r; \
+		test "$$r" = y; \
+	fi
+
+tarball: handin-check
+	echo $(LAB) > conf/LAB
+	git archive --format=tar -o lab-$(LAB)-handin.tar HEAD
+	tar rf lab-$(LAB)-handin.tar conf/LAB
+	gzip -f lab-$(LAB)-handin.tar
+
+.PHONY: qemu qemu-gdb gdb qemu-trace tarball tarball-pref clean grade handin-check

README

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+xv6 is a re-implementation of Dennis Ritchie's and Ken Thompson's Unix
+Version 6 (v6).  xv6 loosely follows the structure and style of v6,
+but is implemented for a modern RISC-V multiprocessor using ANSI C.
+
+ACKNOWLEDGMENTS
+
+xv6 is inspired by John Lions's Commentary on UNIX 6th Edition (Peer
+to Peer Communications; ISBN: 1-57398-013-7; 1st edition (June 14,
+2000)). See also https://pdos.csail.mit.edu/6.828/, which
+provides pointers to on-line resources for v6.
+
+The following people have made contributions: Russ Cox (context switching,
+locking), Cliff Frey (MP), Xiao Yu (MP), Nickolai Zeldovich, and Austin
+Clements.
+
+We are also grateful for the bug reports and patches contributed by
+Silas Boyd-Wickizer, Anton Burtsev, Dan Cross, Cody Cutler, Mike CAT,
+Tej Chajed, eyalz800, Nelson Elhage, Saar Ettinger, Alice Ferrazzi,
+Nathaniel Filardo, Peter Froehlich, Yakir Goaron,Shivam Handa, Bryan
+Henry, Jim Huang, Alexander Kapshuk, Anders Kaseorg, kehao95, Wolfgang
+Keller, Eddie Kohler, Austin Liew, Imbar Marinescu, Yandong Mao, Matan
+Shabtay, Hitoshi Mitake, Carmi Merimovich, Mark Morrissey, mtasm, Joel
+Nider, Greg Price, Ayan Shafqat, Eldar Sehayek, Yongming Shen, Cam
+Tenny, tyfkda, Rafael Ubal, Warren Toomey, Stephen Tu, Pablo Ventura,
+Xi Wang, Keiichi Watanabe, Nicolas Wolovick, wxdao, Grant Wu, Jindong
+Zhang, Icenowy Zheng, and Zou Chang Wei.
+
+The code in the files that constitute xv6 is
+Copyright 2006-2019 Frans Kaashoek, Robert Morris, and Russ Cox.
+
+ERROR REPORTS
+
+Please send errors and suggestions to Frans Kaashoek and Robert Morris
+(kaashoek,[email protected]). The main purpose of xv6 is as a teaching
+operating system for MIT's 6.828, so we are more interested in
+simplifications and clarifications than new features.
+
+BUILDING AND RUNNING XV6
+
+You will need a RISC-V "newlib" tool chain from
+https://github.com/riscv/riscv-gnu-toolchain, and qemu compiled for
+riscv64-softmmu. Once they are installed, and in your shell
+search path, you can run "make qemu".