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RENESAS TOOL NEWS on July 16, 2005: RSO-M3T-MR308-050716D
A Note on Using the Real-Time OSes
M3T-MR308 and M3T-MR30 |
Please take note of the following problem in using the real-time OSes
M3T-MR308 and M3T-MR30 (they are used for the M16C family of MCUs):
- On issuing the isus_tsk system call to a task that is entering the DORMANT state
- Products and Versions Concerned
- M3T-MR308 V.1.00 Release 1 through M3T-MR308 V.1.20 Release 1B
(for the M32C/90, M32C/80, and M16C/80 series of MCUs)
- M3T-MR30 V.1.00 Release 1 through M3T-MR30 V.3.30 Release 1
(for the M16C/60, M16C/30, M16C/Tiny, M16C/20, and M16C/10 series of MCUs)
- Description
If the isus_tsk system call is issued to a task that is entering
the DORMANT state by the ext_tsk system call, either of the
following symptoms may arise, prohibiting the system from operating
properly:
| (1) |
The isus_tsk system call does not return E_OBJ but E_OK. |
| (2) |
Even when a task is ready to be carried out with the same
priority as the task to which the ext_tsk system call has been
issued, the former task is taken off from the ready queue while
remaining ready to be performed, which incurs contradiction
in the management of the kernel. |
- 2.1 Condition
- This problem may occur if the following conditions are all satisfied:
| (1) |
The isus_tsk system call is issued from the interrupt handler, alarm handler, or cyclic handler. |
| (2) |
The task to which isus_tsk is issued is the one that can enter the DORMANT state. |
| (3) |
The handler that issues isus_tsk has been invoked by an interrupt requested while the ext_tsk system call is performed. |
| (4) |
The ext_tsk system call in (3) is issued from the task to which isus_tsk has been issued. |
-
Workaround
Handle the task to which isus_tsk is issued in an infinite loop so
that it cannot be entered to the DORMANT state by ext_tsk as shown
in the example below.
Example
------------------------------------------------------
void task1(INT stacd )
{
. . . . . . . . . . . . . . . . . . . . . . . .
while(1){
/* Task carried out */
. . . . . . . . . . . . . . . . . . . . . . . .
}
}
void inth(void)
{
. . . . . . . . . . . . . . . . . . . . . . . .
isus_tsk(ID_task1);
. . . . . . . . . . . . . . . . . . . . . . . .
}
------------------------------------------------------
- Schedule of Fixing the Problem
we plan to fix this problem in its next release.
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