diff options
Diffstat (limited to 'doc/bsp_howto/init.t')
| -rw-r--r-- | doc/bsp_howto/init.t | 42 |
1 files changed, 19 insertions, 23 deletions
diff --git a/doc/bsp_howto/init.t b/doc/bsp_howto/init.t index f91d15f934..d1486cca5f 100644 --- a/doc/bsp_howto/init.t +++ b/doc/bsp_howto/init.t @@ -41,7 +41,6 @@ for this functionality. @example ../../sparc/shared/start.S -../../sparc/shared/bspclean.c @end example @b{NOTE:} In most BSPs, the directory named @code{start340} in the @@ -93,10 +92,9 @@ to the shared @code{bootcard.c} framework then through the C Library, RTEMS, device driver initialization phases, and the context switch to the first application task. After this, the application executes until it calls @code{exit}, @code{rtems_shutdown_executive}, or some -other normal termination initiating routine and control is returned -to @code{bootcard.c} which allows the BSP to perform some cleanup in C -(@code{bsp_cleanup}) and then @code{boot_card} returns to the assembly -language which initially invoked it. +other normal termination initiating routine and a fatal system state is +reached. The optional @code{bsp_fatal_extension} initial extension can perform +BSP specific system termination. The routines invoked during this will be discussed and their location in the RTEMS source tree pointed out as we discuss each. @@ -197,28 +195,26 @@ this point in the initialization sequence. This is the last opportunity for the BSP to insert BSP specific code into the initialization sequence. @item It invokes the RTEMS directive -@code{rtems_initialize_start_multitasking()} which starts multitasking and context switches to the first task. @code{boot_card()} will not return until the application is shutdown. As part of this sequence the following actions occur: - -@itemize @bullet - -@item RTEMS will context switch to the first application task. As a -side-effect of this context switch, processor interrupts will be enabled. -This is often the source of a fatal error during BSP development because -the BSP did not clear and/or disable all interrupt sources and a spurious -interrupt will occur . - -@item When in the context of the first task but before its body has been +@code{rtems_initialize_start_multitasking()} +which initiates multitasking and performs a context switch to the +first user application task and may enable interrupts as a side-effect of +that context switch. The context switch saves the executing context. The +application runs now. The directive rtems_shutdown_executive() will return +to the saved context. The exit() function will use this directive. + +After a return to the saved context a fatal system state is reached. The +fatal source is RTEMS_FATAL_SOURCE_EXIT with a fatal code set to the value +passed to rtems_shutdown_executive(). + +The enabling of interrupts during the first context switch is often the source +for fatal errors during BSP development because the BSP did not clear and/or +disable all interrupt sources and a spurious interrupt will occur. + +When in the context of the first task but before its body has been entered, any C++ Global Constructors will be invoked. @end itemize -@item Finally after the application shutsdown RTEMS and control is -return to @code{boot_card()} from RTEMS, it invokes the BSP specific -routine @code{bsp_cleanup()} to perform any necessary board specific -shutdown actions. - -@end itemize - That's it. We just went through the entire sequence. @subsection bsp_start() - BSP Specific Initialization |