Genode OS Framework
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Martin Stein 2633ff8661 alarm: fix information loss due to int-cast
When we have two time values of an unsigned integer type and we create
the difference and want to know wether it is positive or negative within
the same value we loose at least one half of the value range for casting
to signed integers. This was the case in the alarm scheduler when
checking wether an alarm already triggered. Even worse, we casted from
'unsigned long' to 'signed int' which caused further loss on at least
x86_64. Thus, big timeouts like ~0UL falsely triggered directly.

Now, we use an extra boolean value to remember in which period of the
time counter we are and to which period of the time counter the deadline
of an alarm belongs. This boolean switches its value each time the time
counter wraps. This way, we can avoid any casting by checking wether the
current time is of the same period as the deadline of the alarm that we
inspect. If so, the alarm is pending if "current time >= alarm
deadline", otherwise it is pending if "current time < alarm deadline".

Ref #2490
2017-10-05 17:39:56 +02:00
depot depot: public key for chelmuth 2017-06-19 12:35:54 +02:00
doc News item for version 17.08 2017-08-30 12:41:43 +02:00
repos alarm: fix information loss due to int-cast 2017-10-05 17:39:56 +02:00
tool tool/run: Wake On Lan support 2017-09-07 11:47:15 +02:00
.gitignore Tool for assembling API/source/binary archives 2017-05-31 13:15:56 +02:00
LICENSE License update to AGPLv3 2017-02-28 12:59:28 +01:00
README Update README 2017-08-30 10:01:35 +02:00
VERSION version: 17.08 2017-08-30 12:42:42 +02:00

                      =================================
                      Genode Operating System Framework
                      =================================


This is the source tree of the reference implementation of the Genode OS
architecture. For a general overview about the architecture, please refer to
the project's official website:

:Official project website for the Genode OS Framework:

  [https://genode.org/documentation/general-overview]

The current implementation can be compiled for 8 different kernels: Linux,
L4ka::Pistachio, L4/Fiasco, OKL4, NOVA, Fiasco.OC, seL4, and a custom
kernel for running Genode directly on ARM-based hardware. Whereas the Linux
version serves us as development vehicle and enables us to rapidly develop the
generic parts of the system, the actual target platforms of the framework are
microkernels. There is no "perfect" microkernel - and neither should there be
one. If a microkernel pretended to be fit for all use cases, it wouldn't be
"micro". Hence, all microkernels differ in terms of their respective features,
complexity, and supported hardware architectures.

Genode allows the use of each of the kernels listed above with a rich set of
device drivers, protocol stacks, libraries, and applications in a uniform way.
For developers, the framework provides an easy way to target multiple different
kernels instead of tying the development to a particular kernel technology. For
kernel developers, Genode contributes advanced workloads, stress-testing their
kernel, and enabling a variety of application use cases that would not be
possible otherwise. For users and system integrators, it enables the choice of
the kernel that fits best with the requirements at hand for the particular
usage scenario.


Documentation
#############

The primary documentation is the book "Genode Foundations", which is available
on the front page of Genode website:

:Download the book "Genode Foundations":

  [https://genode.org]

The book describes Genode in a holistic and comprehensive way. It equips you
with a thorough understanding of the architecture, assists developers with the
explanation of the development environment and system configuration, and
provides a look under the hood of the framework. Furthermore, it contains the
specification of the framework's programming interface.

The project has a quarterly release cycle. Each version is accompanied with
detailed release documentation, which is available at the documentation
section of the project website:

:Release documentation:

  [https://genode.org/documentation/release-notes/]


Directory overview
##################

The source tree is composed of the following subdirectories:

:'doc':

  This directory contains general documentation. Please consider the following
  document for a quick guide to get started with the framework:

  ! doc/getting_started.txt

  If you are curious about the ready-to-use components that come with the
  framework, please review the components overview:

  ! doc/components.txt

:'repos':

  This directory contains the so-called source-code repositories of Genode.
  Please refer to the README file in the 'repos' directory to learn more
  about the roles of the individual repositories.

:'tool':

  Source-code management tools and scripts. Please refer to the README file
  contained in the directory.

:'depot' and 'public':

  Local depot and public archive of Genode packages. Please refer to

  ! doc/depot.txt

  for more details.


Additional community-maintained components
##########################################

The components found within the main source tree are complemented by a growing
library of additional software, which can be seamlessly integrated into Genode
system scenarios.

:Genode-world repository:

  [https://github.com/genodelabs/genode-world]


Contact
#######

The best way to get in touch with Genode developers and users is the project's
mailing list. Please feel welcome to join in!

:Genode Mailing Lists:

  [https://genode.org/community/mailing-lists]


Commercial support
##################

The driving force behind the Genode OS Framework is the German company Genode
Labs. The company offers commercial licensing, trainings, support, and
contracted development work:

:Genode Labs website:

  [https://www.genode-labs.com]