Public | Automated Build

Last pushed: 2 years ago
Short Description
Rump kernel unikernels for userspace
Full Description


Frankenlibc is a build tool to build applications with userspace rump kernels
based unikernels, as well as for some bare metal platforms.

Buildbot for various platforms at

build with "make", or with "./" for additional options.

Frankenlibc provides a small libc that is enough to let the fiber-based librumpuser
library run natively on your platform without any system libraries. It
combines this library, the rump kernel, and NetBSD's libc into a single
libc that you can just use to link against applications to make them run
against a rump kernel rather than the host.

Currently there are three userspace implementations included, NetBSD, Linux and FreeBSD,
and one very basic baremetal implementation, qemu-arm, plus a work in progress spike target
for the riscv simulator. The currently supported and tested architecture/OS
combinations are: Linux x86_64, i386, arm, powerpc64, mips, NetBSD x86_64, i386, arm, FreeBSD
x86_64, i386. There is work in progress support for powerpc, aarch64 and riscv64. Both arm
and mips work with hard and soft float. Powerpc64 supports the v1 ELF ABI only at present, arm is
EABI only, and mips is o32 ABI only. Additional implementations and architectures
will be added soon.

There is also an option to build a deterministic version with no random numbers and a fake
clock, so runs are completely repeatable.

There is a wrapper called rexec ("rump exec") that can pass in files, block devices
and tap devices as network devices, and will also run the program in a seccomp
sandbox on Linux or under Capsicum on FreeBSD. These are pretty aggressive, eg
open cannot be called, but you may want to add further sandboxing in addition. The
wrapper will also drop any root privileges and capabilities.

A compiler wrapper is generated in rump/bin to compile your own programs, which works out
the best method to wrap the compiler. Essentially you just need to use the include files,
libc and other libraries and crt files in the rump/ output directory. For gcc a spec file
is used, while many clang installations can use a sysroot, although eg NetBSD's linker
does not support sysroot. For most systems a line like the following will work if you
do not use the wrapper:

gcc -nostdinc -Irump/include -Lrump/lib -Brump/lib -o rumpobj/tests/hello -static tests/hello.c

A number of NetBSD system tools are built as part of the build, named with the rump. prefix eg,
rump.ifconfig, rump.newfs, rump.tar to allow simple tests and file system manipulation.

A docker repository with the tools built for linux is available at
Docker hub or with

docker pull justincormack/frankenlibc
docker run -e RUMP_VERBOSE=1 justincormack/frankenlibc rexec rump.helloworld

Some more experimental docker repositories with application builds are also available at the
same location, with builds of Nginx, Nginx with Lua.

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Source Repository