Running xv6 on Apple Silicon Mac

So I was trying to run xv6 ( a popular lightweight os by MIT ) in my m1 macbook. Every tutorial on the internet was failing. So I thought…

First download the source code of xv6:

git clone https://github.com/mit-pdos/xv6-public.git

Now we will be using some cross compiler to compile the source code into arm instruction based executable, instead of regular x86 instruction based exectable. We are using i686-elf-gcc for this. Install the cross compiler toolchain of i686-elf-gcc using homebrew :

brew install i686-elf-gcc

Now we will use this cross compiler gcc instead of our native gcc to compiler our source code. To achieve this, we will change our Makefile into the following:

OBJS = \
 bio.o\
 console.o\
 exec.o\
 file.o\
 fs.o\
 ide.o\
 ioapic.o\
 kalloc.o\
 kbd.o\
 lapic.o\
 log.o\
 main.o\
 mp.o\
 picirq.o\
 pipe.o\
 proc.o\
 sleeplock.o\
 spinlock.o\
 string.o\
 swtch.o\
 syscall.o\
 sysfile.o\
 sysproc.o\
 trapasm.o\
 trap.o\
 uart.o\
 vectors.o\
 vm.o\

# Cross-compiling (e.g., on Mac OS X)
TOOLPREFIX = i686-elf-gcc

# Using native tools (e.g., on X86 Linux)
#TOOLPREFIX = 

# 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 -MD -ggdb -fno-omit-frame-pointer
CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
ASFLAGS = -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 kernel
 dd if=/dev/zero of=xv6.img count=10000
 dd if=bootblock of=xv6.img conv=notrunc
 dd if=kernel of=xv6.img seek=1 conv=notrunc

xv6memfs.img: bootblock kernelmemfs
 dd if=/dev/zero of=xv6memfs.img count=10000
 dd if=bootblock of=xv6memfs.img conv=notrunc
 dd if=kernelmemfs of=xv6memfs.img seek=1 conv=notrunc

bootblock: bootasm.S bootmain.c
 $(CC) $(CFLAGS) -fno-pic -O -nostdinc -I. -c bootmain.c
 $(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c bootasm.S
 $(LD) $(LDFLAGS) -N -e start -Ttext 0x7C00 -o bootblock.o bootasm.o bootmain.o
 $(OBJDUMP) -S bootblock.o > bootblock.asm
 $(OBJCOPY) -S -O binary -j .text bootblock.o bootblock
 ./sign.pl bootblock

entryother: entryother.S
 $(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c entryother.S
 $(LD) $(LDFLAGS) -N -e start -Ttext 0x7000 -o bootblockother.o entryother.o
 $(OBJCOPY) -S -O binary -j .text bootblockother.o entryother
 $(OBJDUMP) -S bootblockother.o > entryother.asm

initcode: initcode.S
 $(CC) $(CFLAGS) -nostdinc -I. -c initcode.S
 $(LD) $(LDFLAGS) -N -e start -Ttext 0 -o initcode.out initcode.o
 $(OBJCOPY) -S -O binary initcode.out initcode
 $(OBJDUMP) -S initcode.o > initcode.asm

kernel: $(OBJS) entry.o entryother initcode kernel.ld
 $(LD) $(LDFLAGS) -T kernel.ld -o kernel entry.o $(OBJS) -b binary initcode entryother
 $(OBJDUMP) -S kernel > kernel.asm
 $(OBJDUMP) -t kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernel.sym

# kernelmemfs is a copy of kernel that maintains the
# disk image in memory instead of writing to a disk.
# This is not so useful for testing persistent storage or
# exploring disk buffering implementations, but it is
# great for testing the kernel on real hardware without
# needing a scratch disk.
MEMFSOBJS = $(filter-out ide.o,$(OBJS)) memide.o
kernelmemfs: $(MEMFSOBJS) entry.o entryother initcode kernel.ld fs.img
 $(LD) $(LDFLAGS) -T kernel.ld -o kernelmemfs entry.o  $(MEMFSOBJS) -b binary initcode entryother fs.img
 $(OBJDUMP) -S kernelmemfs > kernelmemfs.asm
 $(OBJDUMP) -t kernelmemfs | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernelmemfs.sym

tags: $(OBJS) entryother.S _init
 etags *.S *.c

vectors.S: vectors.pl
 ./vectors.pl > vectors.S

ULIB = ulib.o usys.o printf.o 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

_forktest: 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 _forktest forktest.o ulib.o usys.o
 $(OBJDUMP) -S _forktest > forktest.asm

mkfs: mkfs.c fs.h
 gcc -o 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=\
 _cat\
 _echo\
 _forktest\
 _grep\
 _init\
 _kill\
 _ln\
 _ls\
 _mkdir\
 _rm\
 _sh\
 _stressfs\
 _usertests\
 _wc\
 _zombie\
 _ps\
 _dpro\
 _nice\

fs.img: mkfs README $(UPROGS)
 ./mkfs fs.img README $(UPROGS)

-include *.d

clean: 
 rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \
 *.o *.d *.asm *.sym vectors.S bootblock entryother \
 initcode initcode.out kernel xv6.img fs.img kernelmemfs \
 xv6memfs.img mkfs .gdbinit \
 $(UPROGS)

# make a printout
FILES = $(shell grep -v '^\#' runoff.list)
PRINT = runoff.list runoff.spec README toc.hdr toc.ftr $(FILES)

xv6.pdf: $(PRINT)
 ./runoff
 ls -l xv6.pdf

print: xv6.pdf

# run in emulators

bochs : fs.img xv6.img
 if [ ! -e .bochsrc ]; then ln -s dot-bochsrc .bochsrc; fi
 bochs -q

# 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 := 2
endif
QEMUOPTS = -drive file=fs.img,index=1,media=disk,format=raw -drive file=xv6.img,index=0,media=disk,format=raw -smp $(CPUS) -m 512 $(QEMUEXTRA)

qemu: fs.img xv6.img
 $(QEMU) -serial mon:stdio $(QEMUOPTS)

qemu-memfs: xv6memfs.img
 $(QEMU) -drive file=xv6memfs.img,index=0,media=disk,format=raw -smp $(CPUS) -m 256

qemu-nox: fs.img xv6.img
 $(QEMU) -nographic $(QEMUOPTS)

.gdbinit: .gdbinit.tmpl
 sed "s/localhost:1234/localhost:$(GDBPORT)/" < $^ > $@

qemu-gdb: fs.img xv6.img .gdbinit
 @echo "*** Now run 'gdb'." 1>&2
 $(QEMU) -serial mon:stdio $(QEMUOPTS) -S $(QEMUGDB)

qemu-nox-gdb: fs.img xv6.img .gdbinit
 @echo "*** Now run 'gdb'." 1>&2
 $(QEMU) -nographic $(QEMUOPTS) -S $(QEMUGDB)

# CUT HERE
# prepare dist for students
# after running make dist, probably want to
# rename it to rev0 or rev1 or so on and then
# check in that version.

EXTRA=\
 mkfs.c ulib.c user.h cat.c echo.c forktest.c grep.c kill.c\
 ln.c ls.c mkdir.c rm.c stressfs.c usertests.c wc.c zombie.c\
 printf.c umalloc.c nice.c, dpro.c ps.c\
 README dot-bochsrc *.pl toc.* runoff runoff1 runoff.list\
 .gdbinit.tmpl gdbutil\

dist:
 rm -rf dist
 mkdir dist
 for i in $(FILES); \
 do \
  grep -v PAGEBREAK $$i >dist/$$i; \
 done
 sed '/CUT HERE/,$$d' Makefile >dist/Makefile
 echo >dist/runoff.spec
 cp $(EXTRA) dist

dist-test:
 rm -rf dist
 make dist
 rm -rf dist-test
 mkdir dist-test
 cp dist/* dist-test
 cd dist-test; $(MAKE) print
 cd dist-test; $(MAKE) bochs || true
 cd dist-test; $(MAKE) qemu

# update this rule (change rev#) when it is time to
# make a new revision.
tar:
 rm -rf /tmp/xv6
 mkdir -p /tmp/xv6
 cp dist/* dist/.gdbinit.tmpl /tmp/xv6
 (cd /tmp; tar cf - xv6) | gzip >xv6-rev10.tar.gz  # the next one will be 10 (9/17)

.PHONY: dist-test dist

now just run:

make

and our execuable will be ready. you can run this execuable by running

make qemu

make sure you already have qemu installed for mac befor running this.