Mirage kFreeBSD Backend
This tiny project is about putting Mirage to the FreeBSD kernel space for evaluation. Contents of this repository currently is as follows.
Please do note that this is a work-in-progress effort, which will work
only on the
amd64 architecture with a recent FreeBSD -CURRENT. In
addition, some of the original features may not be yet implemented fully
In order to be able to build the sources, one has to install the OCaml compiler from the Ports Collection. (It has been tested with version 3.12.1 so far.)
# cd /usr/ports/lang/ocaml # make install clean
It is also required to install the findlib utility.
# cd /usr/ports/devel/ocaml-findlib # make install clean
Installing the Customized Standard Library
There is a customized standard library (which sources were ripped of the 3.12.1 OCaml distribution) to be built before one could work with the sources. It is in the following directory.
It contains a standalone version of the modified sources that could be
compiled using BSD make. It is possible to specify the place of the
used OCaml toolchain by the
PREFIX variable. By default, that is
# make install clean
This command will install the
mirage-stdlib package that all the
others rely on.
Installing the Rest of the Packages
The other OCaml packages available are as follows.
packages/cstruct packages/lwt packages/mirage-platform
All of them will be needed to build Mirage's OS module, which is then
required to build a FreeBSD kernel module. Packages
are stripped and adapted versions of the corresponding packages, while
mirage-platform implements the internals of the
Each of them can be installed from its directory with a single command (as root):
# make install clean
Creating and Loading An Application as Kernel Module
There is also a sample test application added in the following directory.
It does not require to be installed, it is enough to build it (as root).
This should generate a kernel module under the name
then could be loaded into the running kernel.
Warning: It is not guaranteed that the module will behave as expected. Loading the module may result in a crash and, as a side effect, in data loss. Do not try this on a production machine ever. You have been warned!
Note that since the kernel module is not installed to the default module path, one must specify it by the name of the file.
# kldload ./mirage.ko
Upon the successful loading, some sysctl(3) variables should be created
under the MIB
Set parameters for the run-time system. It is a string value that may take
exactly the same options as the
OCAMLRUNPARAM environment variable in the
Start the code inside the kernel module. Writing any value to this variable will trigger the initialization routine and launches the execution of the embedded OCaml program. Note that a program may be restarted many times, however this is not recommended -- reload the module first instead.
# sysctl kern.mirage.run=1
Tracing with DTrace
There are some Statically Defined Tracing (SDT) probes added to the sources for tracing, profiling and debugging purposes. The currently active probes can be listed by the following command.
# dtrace -l -P mirage
Some D scripts can be found under the
dtrace directory in the
Note: In order to make this work, upgrading to a recent FreeBSD -CURRENT is
strongly recommended. The probes are added to a kernel module, which may
only work with base system revisions after r233552. It is also required to
dtraceall kernel module and have the
for the system. (Note that this is already enabled in the aforementioned
Contact & Contribute
If there are patches, comments, problem reports or any other feedback, feel free to post them to the Mirage mailing list.