+++ /dev/null
-<!-- Copyright (C) 2003 Red Hat, Inc. -->
-<!-- This material may be distributed only subject to the terms -->
-<!-- and conditions set forth in the Open Publication License, v1.0 -->
-<!-- or later (the latest version is presently available at -->
-<!-- http://www.opencontent.org/openpub/). -->
-<!-- Distribution of the work or derivative of the work in any -->
-<!-- standard (paper) book form is prohibited unless prior -->
-<!-- permission is obtained from the copyright holder. -->
-<HTML
-><HEAD
-><TITLE
->µITRON and eCos</TITLE
-><meta name="MSSmartTagsPreventParsing" content="TRUE">
-<META
-NAME="GENERATOR"
-CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
-"><LINK
-REL="HOME"
-TITLE="eCos Reference Manual"
-HREF="ecos-ref.html"><LINK
-REL="UP"
-TITLE="µITRON API"
-HREF="compat-uitron-microitron-api.html"><LINK
-REL="PREVIOUS"
-TITLE="µITRON API"
-HREF="compat-uitron-microitron-api.html"><LINK
-REL="NEXT"
-TITLE="Task Management Functions"
-HREF="compat-uitron-task-management-functions.html"></HEAD
-><BODY
-CLASS="SECT1"
-BGCOLOR="#FFFFFF"
-TEXT="#000000"
-LINK="#0000FF"
-VLINK="#840084"
-ALINK="#0000FF"
-><DIV
-CLASS="NAVHEADER"
-><TABLE
-SUMMARY="Header navigation table"
-WIDTH="100%"
-BORDER="0"
-CELLPADDING="0"
-CELLSPACING="0"
-><TR
-><TH
-COLSPAN="3"
-ALIGN="center"
->eCos Reference Manual</TH
-></TR
-><TR
-><TD
-WIDTH="10%"
-ALIGN="left"
-VALIGN="bottom"
-><A
-HREF="compat-uitron-microitron-api.html"
-ACCESSKEY="P"
->Prev</A
-></TD
-><TD
-WIDTH="80%"
-ALIGN="center"
-VALIGN="bottom"
->Chapter 32. µITRON API</TD
-><TD
-WIDTH="10%"
-ALIGN="right"
-VALIGN="bottom"
-><A
-HREF="compat-uitron-task-management-functions.html"
-ACCESSKEY="N"
->Next</A
-></TD
-></TR
-></TABLE
-><HR
-ALIGN="LEFT"
-WIDTH="100%"></DIV
-><DIV
-CLASS="SECT1"
-><H1
-CLASS="SECT1"
-><A
-NAME="COMPAT-UITRON-OVER-ECOS">µITRON and <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->eCos</I
-></SPAN
-></H1
-><P
->The <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->eCos</I
-></SPAN
-> kernel implements the functionality
-used by the µITRON compatibility subsystem.
-The configuration of the kernel influences the behavior of µITRON
-programs.</P
-><P
->In particular, the default configuration has time slicing
-(also known as round-robin scheduling) switched on; this means that
-a task can be moved from <TT
-CLASS="VARNAME"
->RUN</TT
-> state
-to <TT
-CLASS="VARNAME"
->READY</TT
-> state at any time, in
-order that one of its peers may run. This is not strictly conformant
-to the µITRON specification, which
-states that timeslicing may be implemented by periodically issuing
-a <TT
-CLASS="LITERAL"
->rot_rdq(0)</TT
-> call from
-within a periodic task or cyclic handler; otherwise it is expected
-that a task runs until it is pre-empted in consequence of synchronization
-or communication calls it makes, or the effects of an interrupt
-or other external event on a higher priority task cause that task
-to become <TT
-CLASS="VARNAME"
->READY</TT
->. To disable timeslicing
-functionality in the kernel and µITRON
-compatibility environment, please disable the
-<TT
-CLASS="LITERAL"
->CYGSEM_KERNEL_SCHED_TIMESLICE</TT
->
-configuration option in the kernel package. A description of kernel
-scheduling is in <A
-HREF="kernel-overview.html"
->Kernel Overview</A
->. </P
-><P
->For another example, the semantics of task queueing when waiting
-on a synchronization object depend solely on the way the underlying
-kernel is configured. As discussed above, the multi-level queue
-scheduler is the only one which is µITRON
-compliant, and it queues waiting tasks in FIFO order. Future releases
-of that scheduler might be configurable to support priority ordering
-of task queues. Other schedulers might be different again: for example
-the bitmap scheduler can be used with the µITRON
-compatibility layer, even though it only allows one task at each
-priority and as such is not µITRON
-compliant, but it supports only priority ordering of task queues.
-So which queueing scheme is supported is not really a property of
-the µITRON compatibility layer; it
-depends on the kernel. </P
-><P
->In this version of the µITRON
-compatibility layer, the calls to disable and enable scheduling
-and interrupts (<TT
-CLASS="FUNCTION"
->dis_dsp()</TT
->,
-<TT
-CLASS="FUNCTION"
->ena_dsp()</TT
->, <TT
-CLASS="FUNCTION"
->loc_cpu()</TT
->
-and <TT
-CLASS="FUNCTION"
->unl_cpu()</TT
->)
-call underlying kernel functions; in particular, the <TT
-CLASS="FUNCTION"
->xxx_dsp()</TT
-> functions
-lock the scheduler entirely, which prevents dispatching of DSRs; functions
-implemented by DSRs include clock counters and alarm timers. Thus time “stops” while
-dispatching is disabled with <TT
-CLASS="FUNCTION"
->dis_dsp()</TT
->. </P
-><P
->Like all parts of the <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->eCos</I
-></SPAN
-> system, the
-detailed semantics of the µITRON layer
-are dependent on its configuration and the configuration of other components
-that it uses. The µITRON configuration
-options are all defined in the file <TT
-CLASS="FILENAME"
->pkgconf/uitron.h</TT
->,
-and can be set using the configuration tool or editing the
-<TT
-CLASS="FILENAME"
->.ecc</TT
->
-file in your build directory by hand. </P
-><P
->An important configuration option for the µITRON
-compatibility layer is “Option: Return Error Codes for Bad Params”
-(
-<TT
-CLASS="LITERAL"
->CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</TT
->
-), which allows a lot of the error
-checking code in the µITRON compatibility layer to
-be removed. Of course this leaves a program open to undetected errors,
-so it should only be used once an application is fully debugged and
-tested. Its benefits include reduced code size and faster execution.
-However, it affects the API significantly, in that with this option
-enabled, bad calls do not return errors, but cause an assert
-failure (if that is itself enabled) or malfunction internally. There
-is discussion in more detail about this in each section below.</P
-><P
->We now give a brief description of the µITRON
-functions which are implemented in this release. Note that all C
-and C++ source files should have the following <TT
-CLASS="LITERAL"
->#include</TT
-> statement: </P
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
->#include <cyg/compat/uitron/uit_func.h></PRE
-></TD
-></TR
-></TABLE
-></DIV
-><DIV
-CLASS="NAVFOOTER"
-><HR
-ALIGN="LEFT"
-WIDTH="100%"><TABLE
-SUMMARY="Footer navigation table"
-WIDTH="100%"
-BORDER="0"
-CELLPADDING="0"
-CELLSPACING="0"
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
-><A
-HREF="compat-uitron-microitron-api.html"
-ACCESSKEY="P"
->Prev</A
-></TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-><A
-HREF="ecos-ref.html"
-ACCESSKEY="H"
->Home</A
-></TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
-><A
-HREF="compat-uitron-task-management-functions.html"
-ACCESSKEY="N"
->Next</A
-></TD
-></TR
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
->µITRON API</TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-><A
-HREF="compat-uitron-microitron-api.html"
-ACCESSKEY="U"
->Up</A
-></TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
->Task Management Functions</TD
-></TR
-></TABLE
-></DIV
-></BODY
-></HTML
->
\ No newline at end of file
projects / karo-tx-redboot.git / blobdiff