ppc64le on x86_64: QEMU user-mode emulation

You can run ppc64le binaries on your x86_64 computer with QEMU user-mode emulation!

This is a quick way to run simple programs. It needs less resources than full-system emulation. On the other hand, it provides an environment that is less similar to an original system, of course, and relies on the local filesystem.

Either way, it can be handy to test and debug simple programs locally.

QEMU

Let’s build the QEMU target for user-mode emulation of the ppc64le architecture (ppc64le-linux-user).

Download (for example, a stable release):

$ wget https://download.qemu.org/qemu-2.11.0.tar.xz
$ tar xf qemu-2.11.0.tar.xz
$ cd qemu-2.11.0

Build:

$ ./configure --target-list=ppc64le-linux-user
...
host CPU          x86_64
host big endian   no
target list       ppc64le-linux-user
...

Or you can build both the user-mode and full-system emulation targets:

$ ./configure --target-list=ppc64le-linux-user,ppc64-softmmu
...
host CPU          x86_64
host big endian   no
target list       ppc64le-linux-user ppc64-softmmu
...

And:

$ make -j $(nproc)
...
  LINK    ppc64le-linux-user/qemu-ppc64le

Run:

$ cp ppc64le-linux-user/qemu-ppc64le ~/bin

$ qemu-ppc64le --version
qemu-ppc64le version 2.11.0
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers

Alpine Linux

Now, let’s test that with the busybox binary from Alpine Linux (used in the full-system emulation post).

Download:

$ wget http://dl-cdn.alpinelinux.org/alpine/v3.7/releases/ppc64le/alpine-vanilla-3.7.0-ppc64le.iso

Extract busybox and the dynamic loader (dependency):

$ mkdir mount-iso
$ sudo mount alpine-vanilla-3.7.0-ppc64le.iso mount-iso
$ gzip -dc mount-iso/boot/initramfs-vanilla | cpio -id bin/busybox lib/ld-musl-powerpc64le.so.1
$ sudo umount mount-iso

Notice that both files are ppc64le binaries:

$ file bin/busybox 
bin/busybox: ELF 64-bit LSB shared object, 64-bit PowerPC or cisco 7500, version 1 (SYSV), dynamically linked (uses shared libs), stripped

$ file lib/ld-musl-powerpc64le.so.1 
lib/ld-musl-powerpc64le.so.1: ELF 64-bit LSB shared object, 64-bit PowerPC or cisco 7500, version 1 (SYSV), dynamically linked, stripped

Let’s try busybox’s uname function:

$ qemu-ppc64le lib/ld-musl-powerpc64le.so.1 bin/busybox uname -sm
Linux ppc64le

Cool, it’s ppc64le!

In order not to include the dynamic loader and busybox in commands, you can:

• Set the QEMU_LD_PREFIX environment variable (ELF interpreter prefix)
  to where lib/ld-musl-powerpc64le.so.1 is ($PWD) or ./ in this example):
  $ export QEMU_LD_PREFIX=$PWD

• UPDATE (2018-03-17) [the method above is preferred over this one]:
  Copy the dynamic loader to /lib (does not affect other stuff):
  $ sudo cp lib/ld-musl-powerpc64le.so.1 /lib

• Create a symlink to busybox named after the function:
  $ ln -s bin/busybox uname

It looks better (say, more normal) now:

$ qemu-ppc64le ./uname -sm
Linux ppc64le

And that runs on a x86_64 computer!

$ uname -sm
Linux x86_64

Now let’s try busybox’s md5sum function – something more complex, processor-instruction wise:

$ ln -s bin/busybox md5sum

$ qemu-ppc64le ./md5sum alpine-vanilla-3.7.0-ppc64le.iso
ef574f1fe9b2b021a43c85ebd451b47a  alpine-vanilla-3.7.0-ppc64le.iso

It perfectly matches the native md5sum:

$ md5sum alpine-vanilla-3.7.0-ppc64le.iso
ef574f1fe9b2b021a43c85ebd451b47a  alpine-vanilla-3.7.0-ppc64le.iso

Hooray!

So, QEMU user-mode emulation can be of great help with simple programs, like the basics on ppc64le.