[ae68ff0] | 1 | @c |
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[6449498] | 2 | @c COPYRIGHT (c) 1988-2002. |
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[ae68ff0] | 3 | @c On-Line Applications Research Corporation (OAR). |
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| 4 | @c All rights reserved. |
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| 5 | |
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| 6 | @chapter Fatal Error Manager |
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[20515fc] | 7 | |
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[169502e] | 8 | @cindex fatal errors |
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| 9 | |
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[ae68ff0] | 10 | @section Introduction |
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| 11 | |
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| 12 | The fatal error manager processes all fatal or |
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| 13 | irrecoverable errors. The directive provided by the fatal error |
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| 14 | manager is: |
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| 15 | |
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| 16 | @itemize @bullet |
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[f331481c] | 17 | @item @code{@value{DIRPREFIX}fatal_error_occurred} - Invoke the fatal error handler |
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[e2e5b492] | 18 | @item @code{@value{DIRPREFIX}fatal} - Invoke the fatal error handler with error source |
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[ae68ff0] | 19 | @end itemize |
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| 20 | |
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| 21 | @section Background |
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| 22 | |
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[169502e] | 23 | @cindex fatal error detection |
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| 24 | @cindex fatal error processing |
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| 25 | @cindex fatal error user extension |
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| 26 | |
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[ae68ff0] | 27 | The fatal error manager is called upon detection of |
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| 28 | an irrecoverable error condition by either RTEMS or the |
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| 29 | application software. Fatal errors can be detected from three |
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| 30 | sources: |
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| 31 | |
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| 32 | @itemize @bullet |
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| 33 | @item the executive (RTEMS) |
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| 34 | @item user system code |
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| 35 | @item user application code |
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| 36 | @end itemize |
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| 37 | |
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| 38 | RTEMS automatically invokes the fatal error manager |
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| 39 | upon detection of an error it considers to be fatal. Similarly, |
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| 40 | the user should invoke the fatal error manager upon detection of |
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| 41 | a fatal error. |
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| 42 | |
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| 43 | Each status or dynamic user extension set may include |
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| 44 | a fatal error handler. The fatal error handler in the static |
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| 45 | extension set can be used to provide access to debuggers and |
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| 46 | monitors which may be present on the target hardware. If any |
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| 47 | user-supplied fatal error handlers are installed, the fatal |
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| 48 | error manager will invoke them. If no user handlers are |
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| 49 | configured or if all the user handler return control to the |
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| 50 | fatal error manager, then the RTEMS default fatal error handler |
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| 51 | is invoked. If the default fatal error handler is invoked, then |
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| 52 | the system state is marked as failed. |
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| 53 | |
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| 54 | Although the precise behavior of the default fatal |
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| 55 | error handler is processor specific, in general, it will disable |
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| 56 | all maskable interrupts, place the error code in a known |
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| 57 | processor dependent place (generally either on the stack or in a |
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| 58 | register), and halt the processor. The precise actions of the |
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| 59 | RTEMS fatal error are discussed in the Default Fatal Error |
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[17a3c69] | 60 | Processing chapter of the Applications Supplement document for |
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[ae68ff0] | 61 | a specific target processor. |
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| 62 | |
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| 63 | @section Operations |
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[20515fc] | 64 | |
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[ae68ff0] | 65 | @subsection Announcing a Fatal Error |
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| 66 | |
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[adee5979] | 67 | @findex _Internal_errors_What_happened |
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| 68 | |
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[75e22db] | 69 | The @code{@value{DIRPREFIX}fatal_error_occurred} directive is invoked when a |
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[ae68ff0] | 70 | fatal error is detected. Before invoking any user-supplied |
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| 71 | fatal error handlers or the RTEMS fatal error handler, the |
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[75e22db] | 72 | @code{@value{DIRPREFIX}fatal_error_occurred} |
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| 73 | directive stores useful information in the |
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[7e8a1fc] | 74 | variable @code{_Internal_errors_What_happened}. This @value{STRUCTURE} |
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[ae68ff0] | 75 | contains three pieces of information: |
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| 76 | |
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| 77 | @itemize @bullet |
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| 78 | @item the source of the error (API or executive core), |
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| 79 | |
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| 80 | @item whether the error was generated internally by the |
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| 81 | executive, and a |
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| 82 | |
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| 83 | @item a numeric code to indicate the error type. |
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| 84 | @end itemize |
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| 85 | |
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| 86 | The error type indicator is dependent on the source |
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| 87 | of the error and whether or not the error was internally |
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[75e22db] | 88 | generated by the executive. If the error was generated |
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| 89 | from an API, then the error code will be of that API's |
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| 90 | error or status codes. The status codes for the RTEMS |
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[9c8530f7] | 91 | API are in cpukit/rtems/include/rtems/rtems/status.h. Those |
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[75e22db] | 92 | for the POSIX API can be found in <errno.h>. |
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[ae68ff0] | 93 | |
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[75e22db] | 94 | The @code{@value{DIRPREFIX}fatal_error_occurred} directive is responsible |
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[ae68ff0] | 95 | for invoking an optional user-supplied fatal error handler |
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| 96 | and/or the RTEMS fatal error handler. All fatal error handlers |
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| 97 | are passed an error code to describe the error detected. |
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| 98 | |
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| 99 | Occasionally, an application requires more |
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| 100 | sophisticated fatal error processing such as passing control to |
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| 101 | a debugger. For these cases, a user-supplied fatal error |
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| 102 | handler can be specified in the RTEMS configuration table. The |
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| 103 | User Extension Table field fatal contains the address of the |
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[75e22db] | 104 | fatal error handler to be executed when the |
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| 105 | @code{@value{DIRPREFIX}fatal_error_occurred} |
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[ae68ff0] | 106 | directive is called. If the field is set to NULL or if the |
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| 107 | configured fatal error handler returns to the executive, then |
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| 108 | the default handler provided by RTEMS is executed. This default |
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| 109 | handler will halt execution on the processor where the error |
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| 110 | occurred. |
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| 111 | |
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| 112 | @section Directives |
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| 113 | |
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| 114 | This section details the fatal error manager's |
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| 115 | directives. A subsection is dedicated to each of this manager's |
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| 116 | directives and describes the calling sequence, related |
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| 117 | constants, usage, and status codes. |
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| 118 | |
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[169502e] | 119 | @c |
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| 120 | @c |
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| 121 | @c |
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[ae68ff0] | 122 | @page |
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| 123 | @subsection FATAL_ERROR_OCCURRED - Invoke the fatal error handler |
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| 124 | |
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[169502e] | 125 | @cindex announce fatal error |
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| 126 | @cindex fatal error, announce |
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| 127 | |
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[ae68ff0] | 128 | @subheading CALLING SEQUENCE: |
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| 129 | |
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[61389eac] | 130 | @ifset is-C |
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[169502e] | 131 | @findex rtems_fatal_error_occurred |
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[ae68ff0] | 132 | @example |
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[dc6e830] | 133 | void rtems_fatal_error_occurred( |
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[ae10dbd] | 134 | uint32_t the_error |
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[ae68ff0] | 135 | ); |
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| 136 | @end example |
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[61389eac] | 137 | @end ifset |
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| 138 | |
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| 139 | @ifset is-Ada |
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| 140 | @example |
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| 141 | procedure Fatal_Error_Occurred ( |
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| 142 | The_Error : in RTEMS.Unsigned32 |
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| 143 | ); |
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| 144 | @end example |
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| 145 | @end ifset |
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[ae68ff0] | 146 | |
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| 147 | @subheading DIRECTIVE STATUS CODES |
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| 148 | |
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| 149 | NONE |
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| 150 | |
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| 151 | @subheading DESCRIPTION: |
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| 152 | |
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| 153 | This directive processes fatal errors. If the FATAL |
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| 154 | error extension is defined in the configuration table, then the |
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| 155 | user-defined error extension is called. If configured and the |
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| 156 | provided FATAL error extension returns, then the RTEMS default |
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| 157 | error handler is invoked. This directive can be invoked by |
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| 158 | RTEMS or by the user's application code including initialization |
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| 159 | tasks, other tasks, and ISRs. |
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| 160 | |
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| 161 | @subheading NOTES: |
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| 162 | |
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| 163 | This directive supports local operations only. |
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| 164 | |
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| 165 | Unless the user-defined error extension takes special |
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| 166 | actions such as restarting the calling task, this directive WILL |
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| 167 | NOT RETURN to the caller. |
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| 168 | |
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| 169 | The user-defined extension for this directive may |
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| 170 | wish to initiate a global shutdown. |
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[dc6e830] | 171 | |
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[e2e5b492] | 172 | @c |
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| 173 | @c |
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| 174 | @c |
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| 175 | @page |
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| 176 | @subsection FATAL - Invoke the fatal error handler with error source |
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| 177 | |
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| 178 | @cindex announce fatal error |
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| 179 | @cindex fatal error, announce |
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| 180 | |
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| 181 | @subheading CALLING SEQUENCE: |
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| 182 | |
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| 183 | @ifset is-C |
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| 184 | @findex rtems_fatal |
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| 185 | @example |
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| 186 | void rtems_fatal( |
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| 187 | rtems_fatal_source source, |
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| 188 | rtems_fatal_code error |
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| 189 | ); |
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| 190 | @end example |
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| 191 | @end ifset |
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| 192 | |
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| 193 | @subheading DIRECTIVE STATUS CODES |
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| 194 | |
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| 195 | NONE |
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| 196 | |
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| 197 | @subheading DESCRIPTION: |
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| 198 | |
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| 199 | This directive invokes the internal error handler with is internal set to |
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| 200 | false. See also @code{@value{DIRPREFIX}fatal_error_occurred}. |
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| 201 | |
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[dc6e830] | 202 | @c |
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| 203 | @c |
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| 204 | @c |
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| 205 | @page |
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| 206 | @subsection INTERNAL_ERROR_DESCRIPTION - Returns a description for an internal error code |
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| 207 | |
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| 208 | @cindex fatal error |
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| 209 | |
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| 210 | @subheading CALLING SEQUENCE: |
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| 211 | |
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| 212 | @ifset is-C |
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| 213 | @findex rtems_internal_error_description |
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| 214 | @example |
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| 215 | const char *rtems_internal_error_description( |
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| 216 | rtems_fatal_code error |
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| 217 | ); |
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| 218 | @end example |
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| 219 | @end ifset |
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| 220 | |
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| 221 | @subheading DIRECTIVE STATUS CODES |
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| 222 | |
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| 223 | The error code description or "?" in case the passed error code is invalid. |
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| 224 | |
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| 225 | @subheading DESCRIPTION: |
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| 226 | |
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| 227 | Returns a description for an internal error code. |
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