New challenges ahead

[Norman Feske]

Hello,

with each new Genode release, we find ourself inspired to reach out for
a growing number of use cases of the framework. There is a dedicated
Wiki page for documenting those ideas:

  http://genode.org/community/wiki/Challenges

However, this Wiki page received not much love during the last year.
Now, after having released the version 11.02, we took the chance to
reiterate over the many ideas that popped up recently. We are actually
pretty excited about all the prospects that have become feasible now.

So if you are curious about what kinds of projects we have in mind in
the mid term, have fun browsing through the project proposals. If one of
these topics catches your interest, we'd be happy about you joining in
with the development. Also, if you have additional ideas, please do not
hesitate to tell us more.

Here are the challenges that we just added, sorted by category:


Applications
============

Chrome web browser
~~~~~~~~~~~~~~~~~~

The Chrome web browser promises to address the most pressing security
concerns of web application by isolation measures, in particular the
sandboxing of plugins and the confinement of individual web
applications. As we demonstrated with the Genode Live CD 10.11, Genode
facilitates a more natural way to pursue such techniques compared with
current commodity operating systems. Furthermore, the use of Genode as
base platform for Chrome would strengthen the web-browser security by
dwarfing its trusted computing base by two orders of magnitude
compared to the use of Linux as base platform. This would allow Chrome
to be considered as a secure interface to the web for use cases in the
high-assurance domain.


VNC server implementing Genode's framebuffer session interface
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

With 'Input' and 'Framebuffer', Genode provides two low-level inter-
faces used by interactive applications. For example, the Nitpicker
GUI server uses these interfaces as a client and, in turn, exports
multiple virtual 'Framebuffer' and 'Input' interfaces to its clients.
This enables a highly modular use of applications such as the nesting
of GUIs. By implementing the 'Framebuffer' and 'Input' interfaces with
a VNC server implementation, all graphical workloads of Genode would
become available over the network. One immediate application of this
implementation is the remote testing of graphical Genode applications
running on a headless server.


Tiled window manager
~~~~~~~~~~~~~~~~~~~~

At Genode Labs, we pursue the goal to shape Genode into an general-
purpose operating system suitable for productive work. The feature
set needed to achieve this goal largely depends on the tools and
applications daily used by the Genode engineers. As one particularly
important tool for being highly productive, we identified a tiled user
interface. Currently, all developers at Genode Labs embrace either the
Ion3 window manager or the tiled Terminator terminal emulator. Hence,
we desire to have a similar mode of user interaction on Genode as
well. The goal of this challenge is to identify the most important
usage patters and the implementation of a tiled GUI that multiplexes
the framebuffer into a set of tiled and tabbed virtual framebuffers.

Related to this work, the low-level 'Framebuffer' and 'Input'
interfaces should be subject to a revision, for example for enabling
the flexible change of framebuffer sizes as needed by a tiled user
interface.


Interactive sound switchbox based on the Audio_out session interface
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Since version 10.05, Genode features a highly flexible configuration
concept that allows the arbitrary routing of session requests
throughout the hierarchic process structure. Even though primarily
designed for expressing mandatory-access control rules, the concept
scales far beyond this use case. For example, it can be used to run
an arbitrary number of processes implementing the same interface and
connecting the different interface implementations. One special case
of this scenario is a chain of audio filters with each using the
'Audio_out' session interface for both roles client and server.
Combined with the Nitpicker GUI server and Genode's support for
real-time priorities, this base techniques enable the creation of
flexible audio mixer / switchboard applications, which require
dedicated frameworks (e.g., Jack audio) on traditional operating
systems. The goal of this project is to create a show case
implementation demonstrating the feasibility for creating high-
quality audio applications on Genode. Furthermore, we wish for
feedback regarding the current design of our bulk streaming interface
when used for low-latency applications.


PDF reader for E-Government use
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A facility for reading PDF and E-Book documents is one of the
indispensable features Genode has to provide to be considered for
general-purpose computing. The goal of this work is to identify a
suitable open-source PDF engine and port it as native application to
Genode. The challenging part is to keep the complexity of this
application as low as possible in order to enable the use of this
application as a trusted document reader. Further ideas envision the
use of PDF files as medium for sensitive documents combined with
measures for protecting the integrity of the displayed information.
For example, when processing contracts or similar sensitive documents
in E-Government scenarios, the consumer of such documents expects the
correct display of all the information as expressed by the creator of
the document. In the event of a compromised PDF engine or a man-in-the
middle attacker manipulating the PDF file, the consumer of the
document requires a way to identify such security breaches. In this
context, running the PDF engine in a sandboxed Genode subsystem has
two incentives. First, the attack surface for manipulating the PDF
engine gets dramatically reduced, and second, the integrity of the
result of the PDF engine can be measured by an independent trusted
component facilitating Genode secure GUI server (Nitpicker).


Graphical on-target IPC tracing tool using Qt4
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Analysing the interaction of components of a multi-server operating
system such as Genode is important to discover bottlenecks of the
system and for debugging highly complex usage scenarios involving many
processes. Currently, Genode handles this problem with two approaches.
First, Genode's recursive structure enables the integration of a
subsystem in a basic OS setup featuring only those drivers and
components used for the particular subsystem. After the successful
integration of such a subsystem, it can be embedded into a far more
complex application scenario without any changes. With this approach,
the subject to analyse can be kept at a reasonable level at
integration time. For debugging purposes, the current approach is
using the debugging facilities of the respective base platforms (e.g.,
using GDB on Linux, the Fiasco kernel debugger, the OKL4 kernel
debugger).

However, in many cases, bottlenecks do not occur when integrating
individual sub systems but after integrating multiple of such
subsystems into a large application scenario. For such scenarios,
existing debugging methodologies do not scale. A tool is desired that
is able to capture the relationships between processes of a
potentially large process hierarchy, to display communication and
control flows between those processes, and to visualize the
interaction of threads with the kernel's scheduler.

Since Qt4 is available natively on Genode, the creation of both
offline and on-target analysis tools has become feasible. The first
step of this project is creating an interactive on-target tool, that
displays the interaction of communicating threads as captured on the
running system. The tool should work on a selected kernel that
provides a facility for tracing IPC messages.


Application frameworks
======================

Running the Meego application stack on Genode using Qt4
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

With Genode 11.02, Qt4 4.7.1 has become available. The most prominent
feature of this version is the new QML language to design GUIs using
a declarative language. This technique is targeted specifically to
mobile applications and other touch-based devices. The goal of this
project is to run the Meego application stack natively on Genode.
First, the software components and Meego-specific Linux customizations
must be identified. For each such component, it must be decided
whether to port its code or to reimplement its interface. The
immediate goal of the first step is running one Meego example
application natively on Genode.


Python Qt4 bindings
~~~~~~~~~~~~~~~~~~~

With the Python interpreter and the port of the Qt4 framework, the
principle components for Python-based GUIs on Genode are available.
However, the glue between both components is missing. The incentive of
this work is supplementing our Python port with the modules needed for
real applications and porting the Qt4 bindings to Genode. This would
bring Genode one step closer to executing modern Python-based GUI
applications (in particular KDE4 applications).


Evaluation of porting GTK+ to Genode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

With Qt4, we have demonstrated the feasibility to run a highly-complex
application framework via Genode on a wide range of microkernels. That
leaves the question of looking into the other major toolkit in town,
namely GTK+ as used by Firefox and the Gnome desktop.


Cairographics
~~~~~~~~~~~~~

Cairo is a high-quality 2D vector graphics engine used by a large
number of open-source projects, in particular GTK+. Hence the port of
Cairo is a prerequisite for the GTK+ challenge. In addition, it would
enable the use of further libraries such as Poppler.


Device drivers
==============

SATA block driver
~~~~~~~~~~~~~~~~~

Genode already features a session interface for accessing block
devices. Currently, there exist two implementations of this interface,
which are the ATAPI block driver for accessing CDROMs and a loopback
block driver. The goal of this project is a working SATA driver that
enables the persistent storage of data on disk. It is a prerequisite
for enabling the use of real file systems with Genode. We regard our
ATAPI driver as a suitable starting point for such an undertaking.


Gallium3D
~~~~~~~~~

Genode 10.08 introduced Gallium3D including the GPU driver for Intel
GMA CPUs. With this initial version, we demonstrated that the powerful
software stack for running hardware-accelerated 3D applications can be
deployed on Genode. At the same time, it motivates us to reach out for
even more ambitious goals:

First, the current approach executes the GPU driver alongside the
complete Gallium3D software stack and the application code in one
address space. To enable the use of multiple hardware-accelerated
applications running at the same time, the GPU driver must run
separated from the Gallium3D code as done on Linux. The preliminary
interfaces for this decomposition are already in place but there are
several open questions. Most importantly, the page-fault handling of
buffer objects mapped in the application's address space.

Second, we'd like to complement our current Intel GMA GPU driver with
interrupt-based synchronization, namely vblank handling. This requires
an understanding of the Intel GMA interrupt code and the enhancement
of our driver environment.

Third, we desire the use of further Gallium3D drivers, in particular
the Nouveau and r300 drivers. The basic approach to bring these
drivers to Genode is the same as for Intel GMA but the respective
driver environments are yet to be developed.

If you are interested in low-level graphics hacking, GPUs, and
high-performance graphics, this project is ideal to get you on track.


Split USB core from USB device drivers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Genode's current USB support is based on the Linux USB stack running
as a single process on Genode. This process includes the USB core
logic, USB host controller driver as well as the USB device drivers
such as HID or USB storage. This monolithic USB process is rather
inflexible. Hence, we desire a decomposition of this solution such
that the USB host driver and each USB device driver runs in a separate
process.


IOMMU support on the NOVA Hypervisor
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The NOVA hypervisor is the first open-source microkernel with thorough
support for IOMMUs, which principally enables the use of untrusted
device drivers alongside sensitive software on one machine. Without an
IOMMU, each device driver for a device that operates with DMA, is able
to indirectly access the whole physical memory through programming the
device. With IOMMU, the physical memory addressable by DMA operations
can be restrained per device. The goal of this challenge is to enhance
Genode with I/O protection when running on the NOVA kernel. This would
clear the way towards reusing complex untrusted device drivers running
in dedicated device-driver OS instances.


I/O Kit
~~~~~~~

I/O Kit is the device-driver framework as used by the Darwin operating
system, which forms the basis for Mac OS X. The port of I/O Kit would
enable the easy re-use of the library of I/O-Kit-based device drivers
on Genode. As foundation of this project, we recommend to use the DDE
Kit API featured by Genode.


Support for multi-touch input devices
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The efforts towards enabling mobile application stacks such as Meego
and Android on Genode must be accompanied by a revision of Genode's
'Input' session interface to accommodate multi-touch input devices.
First, existing APIs such as multi-touch support in X11, Qt4, and
Android should be analysed. Based on these findings, we expect a
proposal for changing Genode's input interface. The interface
extension should be validated by a example driver implementing the
interface as well as an example applications.


System services
===============

Copy-on-write memory manager
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Genode's managed dataspaces provide a generalized page-table concept,
enabling servers to provide on-demand paged memory objects
(dataspaces) to clients. This concept is showcased by the ISO9660
driver, which provides on-demand paged ROM dataspaces to its clients.
Depending on the access pattern of the client, the ISO9660 server
loads the used parts of the ROM file from CDROM. Managed dataspaces
principally allow for a wide variety of interesting applications such
as the transparent migration of non-local and local memory in a NUMA
system, sparse dataspaces, swapping, and copy-on-write dataspaces. The
goal of this project is a dataspace manager that implements copy-on-
write semantics combined with a merging technique optimizing the
memory footprint at runtime. Pages of two managed dataspaces that
share the same content should be provided via read-only page sharing.
If one client attempts to change the content of a shared page, a new
physical copy of the page get created. Vice versa, if the content of
different pages converge, the sharing should be re-established. This
work is a follow-up of the diploma thesis "Cloning L4Linux" of
Sebastian Sumpf

  http://os.inf.tu-dresden.de/papers_ps/sumpf-diplom.pdf

On the course of this project, the managed dataspace concept of Genode
will be refined, in particular regarding the creation of read-only
dataspaces from read-write dataspaces.


HalVM
~~~~~

[http://halvm.org - HalVM] is an operating-system runtime that allows
for implementing low-level OS components in Haskell. Currently, HalVM
uses Xen as underlying kernel. The goal of this project is running
HalVM directly on Genode, which would enable the adoption of this
approach by the L4 community.


Dbus emulation
~~~~~~~~~~~~~~

Dbus is a popular inter-process communication mechanism on Linux,
which enables user applications to respond to global system events and
announce state changes to other applications. It is extensively used
by modern desktop environments. To enable such applications to
integrate well with Genode, a Dbus emulation solution has to be
developed.


Wayland
~~~~~~~

With the availability of Gallium3D on Genode, the prospect for
incorporating further projects of the Linux graphics ecosystem into
Genode arises. [http://wayland.freedesktop.org/ - Wayland] is a window
server especially designed to be used with Gallium3D. Its design has
many similarities with Genode's Nitpicker GUI server, in particular
the decision to move window handling policies to the client and
thereby minimize the complexity of the GUI server. Whereas Nitpicker
was designed for high security, Wayland is targeted to creating GUIs
with fluid and tearless animations using hardware-accelerated
graphics. We believe that because of the many conceptual parallels
with Nitpicker, Wayland would fit very well into the Genode system.
However, as a prerequisite for this project, Genode's Gallium3D
support must be decomposed first. See the challenges regarding our
Gallium3D support for further information.


Runtime environments
====================

Terminal emulation for Noux
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Noux is an emulation environment for executing command-line-based GNU
applications on Genode. It was introduced with Genode 11.02. With the
current state, Noux is able to run several GNU coreutils without
modification, but it supports non-interactive applications only. The
goal of this work is the creation of a Nitpicker GUI client or
framebuffer client implementing a terminal emulator to be connected
with the stdio channels of Noux. This would enable us to go forward
with porting interactive GNU applications, in particular a shell, to
Genode.


Android's Dalvik VM natively on Genode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Dalvik is a Java virtual machine that is used for executing
applications on Android. By running Dalvik directly on Genode, the
Linux kernel could be removed from the trusted computing base of
Android, facilitating the use of this mobile OS in high-assurance
settings.


Vancouver VMM for Genode on the NOVA hypervisor
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Vancouver is the user-level virtual-machine monitor accompanying the
NOVA hypervisor. It combines a VT-based CPU virtualization with a rich
set of device models to run unmodified guest operating systems at
near-native performance. Since NOVA is a supported base platform of
Genode, running Vancouver in the dynamic Genode environment has become
feasible. By running Vancouver on Genode instead of NOVA's original
static userland would open up new use cases where the combination of
faithful virtualization with dynamic applications is desired.


Runtime for the D programming language
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The D systems programming language was designed to overcome many
gripes that exists with C++. In particular, it introduces a sane
syntax for meta programming, supports unit tests, and contract-based
programming. These features make D a compelling language to explore
when implementing OS components. Even though D is a compiled language,
it comes with a runtime providing support for exception handling and
garbage collection. The goal of the project is to explore the use of D
for Genode programs, porting the runtime to Genode, adapting the
Genode build system to accommodate D programs, and interfacing D
programs with other Genode components written in C++.


Platforms
=========

Multi-processor support on different base platforms
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Several of Genode's supported base platforms come with multi-processor
support, i.e., Linux, NOVA, L4ka::Pistachio, Codezero, and Fiasco.OC.
Each of these kernels follows a different approach for utilizing
multiple CPUs. For example, Linux and Codezero manage the association
of threads with CPUs largely transparent for user-level programs. In
contrast, NOVA makes the use of multiple CPUs explicit and constraints
the modes of IPC interaction of threads running on different CPUs.
Furthermore, kernels differ with regard to thread migration and
scheduling. The goal of this project is to identify ways to support
the SMP features of the respective kernels at Genode's API level such
that SMP can be easily utilized by Genode programs in a largely kernel
agnostic way.


Microkernelizing Linux
~~~~~~~~~~~~~~~~~~~~~~

Thanks to Genode's generic interfaces for I/O access as provided by
core, all Genode device drivers including drivers ported from Linux
and gPXE can be executed as user-level components on all supported
microkernels. However, so far, we have not enabled the use of these
device drivers on Linux as base platform. The goal of this project is
the systematic replacement of in-kernel Linux device drivers by Genode
processes running in user space, effectively reducing the Linux kernel
to a runtime for Genode's core process. But moving drivers to Genode
processes is just the beginning. By employing further Genode
functionality such as its native GUI, lwIP, and Noux, many protocol
stacks can effectively be removed from the Linux kernel.

The goal of this project is to evaluate how small the Linux kernel can
get when used as a microkernel.


Support for the Genode FPGA Graphics SoC platform
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

With Genode 11.02, we introduced the first version of native support
for the MicroBlaze softcore CPU. With this foundation laid, we can
proceed with bringing GUI-based interactive Genode applications to
FPGA-based SoC platforms. As target SoC design, we aspire to use the
open-source IP cores provided by the Genode FPGA Graphics Project:

  http://genode-labs.com/products/fpga-graphics


Support for the HelenOS/Spark kernel
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[http://www.helenos.org - HelenOS] is a microkernel-based multi-server
OS developed at the university of Prague. It is based on the Spark
microkernel, which runs on a wide variety of CPU architectures
including Sparc, MIPS, and PowerPC. This broad platform support makes
Spark an interesting kernel to look at alone. But a further motivation
is the fact that Spark does not follow the classical L4 road,
providing a kernel API that comes with an own terminology and
different kernel primitives. This makes the mapping of Spark's kernel
API to Genode a challenging endeavour and would provide us with
feedback regarding the universality of Genode's internal interfaces.
Finally, this project has the potential to ignite a further
collaboration between the HelenOS and Genode communities.


Support for the seL4 kernel
~~~~~~~~~~~~~~~~~~~~~~~~~~~

The seL4 kernel developed by NICTA and OK-Labs is the first formally
verified microkernel. It runs on the x86 and ARM architectures and
supports the execution of a paravirtualized version of Linux on top.
Even though seL4 is proprietary technology, a free binary release and
the specification of the kernel API has been published early 2011.
Being a capability-based kernel, seL4 is in the line of the current-
generation L4 kernels alongside NOVA and Fiasco.OC. Genode already
supports the latter two kernel, which hints at the feasibility to
support seL4 as well. Currently, the seL4 kernel comes with a rather
static user land, which is far from utilizing the full potential of
the kernel with regard to dynamic resource management. By adapting
Genode to seL4, a rich dynamic application workload would become
available to this kernel, which could potentially spawn interest in
extending the formal verification efforts at NICTA to the Genode
system executing dynamic real-world applications.


Support for the Barrelfish kernel
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[http://www.barrelfish.org - Barrelfish] is a so-called multi-kernel
OS designed for heterogeneous multi-processor systems. At its heart,
it is a microkernel-based multi-server OS. Its kernel provides
different mechanisms than L4-based kernels. Instead of managing
threads in the kernel, there is a mechanism for implementing
preemptive multi-threading at user level. Consequently, inter-process
communication does not address threads but protection domains. This
makes the Barrelfish kernel a very interesting and challenging target
for running Genode.


Support for the XNU kernel (Darwin)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

XNU is the kernel used by Darwin and Mac OS X. It is derived from the
MACH microkernel and extended with a UNIX-like syscall API. Because
the kernel is used for Mac OS X, it could represent an industry-
strength base platform for Genode supporting all CPU features as used
by Mac OS X.


Automated testing on the Codezero kernel
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The Genode release 11.02 introduced an automated testing framework for
all base platforms except for Codezero. Codezero was omitted because
its build and configuration system requires user interaction. The goal
of this project is to improve the Codezero configuration and build
system to interface easier with Genode and to automate the build-and-
integration procedure. This way, Codezero would become a base platform
subject to many regular tests as performed with the other platforms.


Optimizations
=============

Low-latency audio streaming
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Genode comes with an audio streaming interface called 'Audio_out'
session. It is based on a shared-memory packet stream accompanied with
asynchronous data-flow signals. For real-time audio processing
involving chains of Genode components, streams of audio data must be
carried at low latency, imposing constraints to buffer sizes and the
modes of operation of the audio mixer and audio drivers. The goal of
this project is to create a holistic design of the whole chain of
audio processing, taking thread-scheduling into account. A particular
challenge is the mixed output of real-time (small buffer, low latency)
and non-real-time (larger buffer to compensate jitter, higher latency)
audio sources.


-- 
Dr.-Ing. Norman Feske
Genode Labs

http://www.genode-labs.com · http://genode.org

Genode Labs GmbH · Amtsgericht Dresden · HRB 28424 · Sitz Dresden
Geschäftsführer: Dr.-Ing. Norman Feske, Christian Helmuth