Hardware Reference
In-Depth Information
The OSEK/VDX standard specifies two types of Interrupt Service Routines (ISR):
ISR1
:
simpler and faster, does not implement a call to the scheduler at the end
of the interrupt handler;
ISR2
:
this mechanism can call primitives that change the scheduling behavior.
The end of the ISR is a rescheduling point.
ISR1 always has higher
priority than ISR2.
An important feature of OSEK/VDX kernels is the possibility to fine-tune the footprint
by removing error checking code from the production versions, as well as define hooks
that will be called by the system when specific events occur. These features allow the
programmer to fine-tune the application footprint, which will be larger (and safer)
when debugging and smaller in production, when most bugs are found and removed
from the code.
To support a better debugging experience, the OSEK/VDX standard defines a textual
language, named ORTI, which describes where the various objects of the operating
system are allocated. The ORTI file is typically generated by the OIL compiler and
is used by debuggers to print detailed information about operating system objects de-
fined in the system (for example, the debugger could print the list of the task in an
application with their current status).
AUTOSAR OS
Starting from the OSEK/VDX specification, AUTOSAR
2
(AUTomotive Open System
ARchitecture) defines a standard for automotive software architecture, jointly devel-
oped by automobile manufacturers, suppliers and tool developers, to minimize the
current barriers among functional domains in future vehicle applications.
Within the AUTOSAR standard, AUTOSAR OS provides the specification at the op-
erating system level, extending the OSEK/VDX standard functionality in various di-
rections, including memory protection, operating system applications, deadline moni-
toring, execution time monitoring, multi-core support, and scheduling tables (for im-
plementing time triggered activities).
The AUTOSAR OS specification extends and defines those behaviors that were left
unspecified as "implementation dependent" in the OSEK/VDX specification, and pro-
poses a configuration system described using AUTOSAR XML files.
2
AUTOSAR: http://www.autosar.org
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