RTEMS PowerPC Applications Supplement
The PowerPC architecture does not provide for a dedicated interrupt stack. Thus by default, exception handlers would execute on the stack of the RTEMS task which they interrupted. This artificially inflates the stack requirements for each task since EVERY task stack would have to include enough space to account for the worst case interrupt stack requirements in addition to it's own worst case usage. RTEMS addresses this problem on the PowerPC by providing a dedicated interrupt stack managed by software.
During system initialization, RTEMS allocates the interrupt stack from the Workspace Area. The amount of memory allocated for the interrupt stack is determined by the interrupt_stack_size field in the CPU Configuration Table. As part of processing a non-nested interrupt, RTEMS will switch to the interrupt stack before invoking the installed handler.
RTEMS PowerPC Applications Supplement
Copyright © 1988-2004 OAR Corporation