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Do not mask edge-triggered interrupts to avoid losing them while masked, see Intel 82093AA I/O Advanced Programmable Interrupt Controller (IOAPIC) specification, section 3.4.2, "Interrupt Mask": "When this bit is 1, the interrupt signal is masked. Edge-sensitive interrupts signaled on a masked interrupt pin are ignored (i.e., not delivered or held pending)" Or to quote Linus Torvalds on the subject: "Now, edge-triggered interrupts are a _lot_ harder to mask, because the Intel APIC is an unbelievable piece of sh*t, and has the edge-detect logic _before_ the mask logic, so if a edge happens _while_ the device is masked, you'll never ever see the edge ever again (unmasking will not cause a new edge, so you simply lost the interrupt)." So when you "mask" an edge-triggered IRQ, you can't really mask it at all, because if you did that, you'd lose it forever if the IRQ comes in while you masked it. Instead, we're supposed to leave it active, and set a flag, and IF the IRQ comes in, we just remember it, and mask it at that point instead, and then on unmasking, we have to replay it by sending a self-IPI." [1] [1] - http://yarchive.net/comp/linux/edge_triggered_interrupts.html Ref #1448
=================================
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:
[http://genode.org/documentation/general-overview]
The current implementation can be compiled for 8 different kernels: Linux,
L4ka::Pistachio, L4/Fiasco, OKL4, NOVA, Fiasco.OC, Codezero, 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.
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.
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:
[http://genode.org/community/mailing-lists]