[ae68ff0] | 1 | @c |
---|
[6449498] | 2 | @c COPYRIGHT (c) 1988-2002. |
---|
[ae68ff0] | 3 | @c On-Line Applications Research Corporation (OAR). |
---|
| 4 | @c All rights reserved. |
---|
| 5 | @c |
---|
[139b2e4a] | 6 | @c $Id$ |
---|
| 7 | @c |
---|
[ae68ff0] | 8 | |
---|
| 9 | @chapter Fatal Error Manager |
---|
[20515fc] | 10 | |
---|
[169502e] | 11 | @cindex fatal errors |
---|
| 12 | |
---|
[ae68ff0] | 13 | @section Introduction |
---|
| 14 | |
---|
| 15 | The fatal error manager processes all fatal or |
---|
| 16 | irrecoverable errors. The directive provided by the fatal error |
---|
| 17 | manager is: |
---|
| 18 | |
---|
| 19 | @itemize @bullet |
---|
[f331481c] | 20 | @item @code{@value{DIRPREFIX}fatal_error_occurred} - Invoke the fatal error handler |
---|
[ae68ff0] | 21 | @end itemize |
---|
| 22 | |
---|
| 23 | @section Background |
---|
| 24 | |
---|
[169502e] | 25 | @cindex fatal error detection |
---|
| 26 | @cindex fatal error processing |
---|
| 27 | @cindex fatal error user extension |
---|
| 28 | |
---|
[ae68ff0] | 29 | The fatal error manager is called upon detection of |
---|
| 30 | an irrecoverable error condition by either RTEMS or the |
---|
| 31 | application software. Fatal errors can be detected from three |
---|
| 32 | sources: |
---|
| 33 | |
---|
| 34 | @itemize @bullet |
---|
| 35 | @item the executive (RTEMS) |
---|
| 36 | @item user system code |
---|
| 37 | @item user application code |
---|
| 38 | @end itemize |
---|
| 39 | |
---|
| 40 | RTEMS automatically invokes the fatal error manager |
---|
| 41 | upon detection of an error it considers to be fatal. Similarly, |
---|
| 42 | the user should invoke the fatal error manager upon detection of |
---|
| 43 | a fatal error. |
---|
| 44 | |
---|
| 45 | Each status or dynamic user extension set may include |
---|
| 46 | a fatal error handler. The fatal error handler in the static |
---|
| 47 | extension set can be used to provide access to debuggers and |
---|
| 48 | monitors which may be present on the target hardware. If any |
---|
| 49 | user-supplied fatal error handlers are installed, the fatal |
---|
| 50 | error manager will invoke them. If no user handlers are |
---|
| 51 | configured or if all the user handler return control to the |
---|
| 52 | fatal error manager, then the RTEMS default fatal error handler |
---|
| 53 | is invoked. If the default fatal error handler is invoked, then |
---|
| 54 | the system state is marked as failed. |
---|
| 55 | |
---|
| 56 | Although the precise behavior of the default fatal |
---|
| 57 | error handler is processor specific, in general, it will disable |
---|
| 58 | all maskable interrupts, place the error code in a known |
---|
| 59 | processor dependent place (generally either on the stack or in a |
---|
| 60 | register), and halt the processor. The precise actions of the |
---|
| 61 | RTEMS fatal error are discussed in the Default Fatal Error |
---|
[17a3c69] | 62 | Processing chapter of the Applications Supplement document for |
---|
[ae68ff0] | 63 | a specific target processor. |
---|
| 64 | |
---|
| 65 | @section Operations |
---|
[20515fc] | 66 | |
---|
[ae68ff0] | 67 | @subsection Announcing a Fatal Error |
---|
| 68 | |
---|
[adee5979] | 69 | @findex _Internal_errors_What_happened |
---|
| 70 | |
---|
[75e22db] | 71 | The @code{@value{DIRPREFIX}fatal_error_occurred} directive is invoked when a |
---|
[ae68ff0] | 72 | fatal error is detected. Before invoking any user-supplied |
---|
| 73 | fatal error handlers or the RTEMS fatal error handler, the |
---|
[75e22db] | 74 | @code{@value{DIRPREFIX}fatal_error_occurred} |
---|
| 75 | directive stores useful information in the |
---|
[7e8a1fc] | 76 | variable @code{_Internal_errors_What_happened}. This @value{STRUCTURE} |
---|
[ae68ff0] | 77 | contains three pieces of information: |
---|
| 78 | |
---|
| 79 | @itemize @bullet |
---|
| 80 | @item the source of the error (API or executive core), |
---|
| 81 | |
---|
| 82 | @item whether the error was generated internally by the |
---|
| 83 | executive, and a |
---|
| 84 | |
---|
| 85 | @item a numeric code to indicate the error type. |
---|
| 86 | @end itemize |
---|
| 87 | |
---|
| 88 | The error type indicator is dependent on the source |
---|
| 89 | of the error and whether or not the error was internally |
---|
[75e22db] | 90 | generated by the executive. If the error was generated |
---|
| 91 | from an API, then the error code will be of that API's |
---|
| 92 | error or status codes. The status codes for the RTEMS |
---|
[9c8530f7] | 93 | API are in cpukit/rtems/include/rtems/rtems/status.h. Those |
---|
[75e22db] | 94 | for the POSIX API can be found in <errno.h>. |
---|
[ae68ff0] | 95 | |
---|
[75e22db] | 96 | The @code{@value{DIRPREFIX}fatal_error_occurred} directive is responsible |
---|
[ae68ff0] | 97 | for invoking an optional user-supplied fatal error handler |
---|
| 98 | and/or the RTEMS fatal error handler. All fatal error handlers |
---|
| 99 | are passed an error code to describe the error detected. |
---|
| 100 | |
---|
| 101 | Occasionally, an application requires more |
---|
| 102 | sophisticated fatal error processing such as passing control to |
---|
| 103 | a debugger. For these cases, a user-supplied fatal error |
---|
| 104 | handler can be specified in the RTEMS configuration table. The |
---|
| 105 | User Extension Table field fatal contains the address of the |
---|
[75e22db] | 106 | fatal error handler to be executed when the |
---|
| 107 | @code{@value{DIRPREFIX}fatal_error_occurred} |
---|
[ae68ff0] | 108 | directive is called. If the field is set to NULL or if the |
---|
| 109 | configured fatal error handler returns to the executive, then |
---|
| 110 | the default handler provided by RTEMS is executed. This default |
---|
| 111 | handler will halt execution on the processor where the error |
---|
| 112 | occurred. |
---|
| 113 | |
---|
| 114 | @section Directives |
---|
| 115 | |
---|
| 116 | This section details the fatal error manager's |
---|
| 117 | directives. A subsection is dedicated to each of this manager's |
---|
| 118 | directives and describes the calling sequence, related |
---|
| 119 | constants, usage, and status codes. |
---|
| 120 | |
---|
[169502e] | 121 | @c |
---|
| 122 | @c |
---|
| 123 | @c |
---|
[ae68ff0] | 124 | @page |
---|
| 125 | @subsection FATAL_ERROR_OCCURRED - Invoke the fatal error handler |
---|
| 126 | |
---|
[169502e] | 127 | @cindex announce fatal error |
---|
| 128 | @cindex fatal error, announce |
---|
| 129 | |
---|
[ae68ff0] | 130 | @subheading CALLING SEQUENCE: |
---|
| 131 | |
---|
[61389eac] | 132 | @ifset is-C |
---|
[169502e] | 133 | @findex rtems_fatal_error_occurred |
---|
[ae68ff0] | 134 | @example |
---|
| 135 | void volatile rtems_fatal_error_occurred( |
---|
| 136 | rtems_unsigned32 the_error |
---|
| 137 | ); |
---|
| 138 | @end example |
---|
[61389eac] | 139 | @end ifset |
---|
| 140 | |
---|
| 141 | @ifset is-Ada |
---|
| 142 | @example |
---|
| 143 | procedure Fatal_Error_Occurred ( |
---|
| 144 | The_Error : in RTEMS.Unsigned32 |
---|
| 145 | ); |
---|
| 146 | @end example |
---|
| 147 | @end ifset |
---|
[ae68ff0] | 148 | |
---|
| 149 | @subheading DIRECTIVE STATUS CODES |
---|
| 150 | |
---|
| 151 | NONE |
---|
| 152 | |
---|
| 153 | @subheading DESCRIPTION: |
---|
| 154 | |
---|
| 155 | This directive processes fatal errors. If the FATAL |
---|
| 156 | error extension is defined in the configuration table, then the |
---|
| 157 | user-defined error extension is called. If configured and the |
---|
| 158 | provided FATAL error extension returns, then the RTEMS default |
---|
| 159 | error handler is invoked. This directive can be invoked by |
---|
| 160 | RTEMS or by the user's application code including initialization |
---|
| 161 | tasks, other tasks, and ISRs. |
---|
| 162 | |
---|
| 163 | @subheading NOTES: |
---|
| 164 | |
---|
| 165 | This directive supports local operations only. |
---|
| 166 | |
---|
| 167 | Unless the user-defined error extension takes special |
---|
| 168 | actions such as restarting the calling task, this directive WILL |
---|
| 169 | NOT RETURN to the caller. |
---|
| 170 | |
---|
| 171 | The user-defined extension for this directive may |
---|
| 172 | wish to initiate a global shutdown. |
---|