让64位的WSL（windows 子 linux系统）支持运行32位程序

参考：https://github.com/Microsoft/WSL/issues/2468

---

Presuming a fresh Ubuntu WSL instance, you'll need to install the qemu-user-static package, add the i386 binfmt, enable the i386 architecture, update your package lists, and install some i386 packages:

Install qemu and binfmt

sudo apt update
sudo apt install qemu-user-static
sudo update-binfmts --install i386 /usr/bin/qemu-i386-static --magic '\x7fELF\x01\x01\x01\x03\x00\x00\x00\x00\x00\x00\x00\x00\x03\x00\x03\x00\x01\x00\x00\x00' --mask '\xff\xff\xff\xff\xff\xff\xff\xfc\xff\xff\xff\xff\xff\xff\xff\xff\xf8\xff\xff\xff\xff\xff\xff\xff'

[Edit: whoops, need to update package lists, added sudo apt update]

This will activate i386 support by causing them to be executed through qemu-i386-static, and drop a config file into /var/lib/binfmts/ for future reactivation.

You will need to reactivate this every time you restart WSL and want i386 support:

sudo service binfmt-support start

Enable i386 architecture and packages

sudo dpkg --add-architecture i386
sudo apt update
sudo apt install gcc:i386

Try it out

$ file /usr/bin/gcc-5
/usr/bin/gcc-5: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=2637bb7cb85f8f12b40f03cd015d404930c3c790, stripped

$ /usr/bin/gcc-5 --version
gcc-5 (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gcc helloworld.c -o helloworld

$ ./helloworld
Hello, world!

$ file helloworld
helloworld: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=3a0c7be5c6a8d45613e4ef2b7b3474df6224a5da, not stripped

Proof

And to prove it really was working, disable i386 support and try again:

$ sudo service binfmt-support stop
 * Disabling additional executable binary formats binfmt-support [ OK ]

$ ./helloworld
-bash: ./helloworld: cannot execute binary file: Exec format error

---