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rumprun unikernel environment
This documents the specific steps needed to build a runnable rumprun unikernel using QEMU, an open source machine emulator and virtualizer. A more generic rumprun tutorial can be read here.
The rumprun repository provides the rumprun unikernel for various platforms. Rumprun uses the drivers offered by rump kernels, adds a libc and an application environment on top, and provides a toolchain with which to build existing POSIX-y applications as rumprun unikernels.
Platforms currently support by rumprun are hw/x86 and Xen/x86+x64, with more being worked on. Platform support is modular with the maximal amount of code shared between platforms, and generally speaking only bootstrap code and glue to I/O devices and the clock are required for supporting a new platform.
First step is to copy the repo
git clone https://github.com/rumpkernel/rumprun.git
and install QEMU
sudo apt-get install QEMU
cd into rumprun directory. Assuming you have gcc compiling for x64 by default, you must specify the -m32 flag like below as 32bit is the only supported hw for now. If a different target other than the host hardware is desired, you must specify CC=cross-compiler. See https://github.com/rumpkernel/wiki/wiki/Repo:-rumprun for info.
./build-rr.sh hw -- -F ACFLAGS=-m32
NOTE: This is how you recompile and build the components after making a kernel src change
To compile a program consisting of a single C module for the hw platform:
rumprun-bmk-cc -o test test.c -c
If writing an app that makes direct system-calls to the RK, then one must disable the rump_fermented check within the rumpbake shell code. This located on line 102. The end of rump-bmk-cc compiles in a symbol called rump-fermented, which is what rumpbake checks for. Because we end the compiler before all files are linked in due to the -c flag, rump-fermented is never changed- hence the necessary work around.
baking is done using the rumpbake tool. (found in app-tools) It takes the binary produced by the compiler and produces a runnable image. The parameters are the output image and target name.
rumpbake hw_generic test.bin test
use rumpbake list to see the available targets. Or, to use your own target, you can edit the rumpbake.conf to add a new configuration with specific rump libraries.
The rumprun tool helps hide the details of running a unikernel from platform to platform, to provide a uniform experience.
rumprun hw -i prog
To debug you need to both start qemu paused and connecting to an a port. GDB will then connect to this port, find the right debug symbols and start the app through the continue command.
Make sure when you first compile the app using rumprun-bmk-cc you set the -g flag.
Terminal 1:
From application directory
$<rumprun dir>/app-tools/rumprun qemu -ip -D 1234 <app>
Terminal 2: From application directory
$gdb
$target remote:1233
$file <app>
$y
Set desired break points...
$c