Build qemu as a library

unicorn_but_worse.sh

#!/bin/sh

set -e

[ -z "$1" ] && echo "Usage: $0 <target>" && exit 1

case "$(uname)" in
  Linux)
    ncpu="$(nproc)"
    ;;
  Darwin)
    ncpu="$(sysctl -n hw.physicalcpu)"
    ;;
esac

flags="$(./configure --help | perl -ne 'print if s/^  ([a-z][\w-]*) .*/\1/' | tail -n +2 | awk '{print "--disable-"$1}' ORS=' ')"

${2:-.}/configure --extra-cflags=-fPIC --target-list=$1 --disable-slirp $flags

make clean >/dev/null

file=$(mktemp)

make -n 2>/dev/null >$file

cmdline="$(cat $file | perl -ne "print if s/.*LINK.*$1.*&&  //" | perl -ne 's/ -o qemu-system-[a-z]+/ -shared -o libqemu.so/; print')"
vl="$(cat $file | perl -ne 'print if s/.*CC.*vl.o.*&& //' | head -n 1)"

# Build everything as usual
make "-j$ncpu" >/dev/null

# Build vl.c but better
$vl -D"main=__definetly_not_main_lmao__"

# Build a shared library, without vl.o and otherwise *exactly* the same
# flags.
cd $1

$cmdline

echo "$(echo "$vl" | grep -E -o '(-I|-f|-W|-m|-p)[^ ]+' | tr '\n' ' ')" \
  "$(echo "$cmdline" | grep -E -o '(-Wl|-l|-L)[a-z0-9-]+ ' | sed '/-labels/d' | sed '/-limits/d' | tr '\n' ' ')"

Usage.md

Place file into qemu root directory Do cd path/to/qemu && ./name_of_file name_of_target (i.e. x86_64-softmmu) Library is at /path/to/qemu/x86_64-softmmu/libqemu.so You might need to compile vl.c and link with it in your final binary, just do something like this:

#define main __definetly_not_main
#include "/path/to/qemu/vl.c"
#undef main

int main() {
  // Whatver you want to do with qemu
}

Please note that the cmdline on Line 26 of the script is outdated and incompatible with recent versions of the QEMU source. It currently defines to an empty string.