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RENESAS TOOL NEWS [August 1, 2003: RSO-M3T-MR32R-030801D]
A Note on Using Real-Time OSes
M3T-MR32R
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Please take note of the following problem in using the M3T-MR32R real-time OSes for the M32R family MCUs:
- On using the chg_pri and ichg_pri system calls for changing the priority of a task
- Versions Concerned
M3T-MR32R V.3.40 Release 1 and V.3.50 Release 1
- Description
Using the chg_pri or ichg_pri system call may cause a write to an indefinite address to occur. As a result arises such a symptom that a task in a waiting state joins a READY queue, and the program may not run properly.
- Conditions
This problem may occur if the chg_pri or ichg_pri system call is issued to change the priority of a task in any of the following waiting states (including WAIT-SUSPEND states).
Note, however, that when a task issues the above system call to change its own priority, the problem will not arise.
- The waiting state produced by dly_tsk, tslp_tsk, or slp_tsk
- The state of waiting for an event flag
- The state of waiting for a message
- The state of waiting for a semaphore
- The state of waiting for the reception to a message buffer
- The state of waiting for the transmission from a message buffer
- The state of waiting for the reception of a Rendezvous
- The state of waiting for the call of a Rendezvous
- The state of waiting for the end of a Rendezvous
- The state of waiting for the acquisition of a variable-length memory pool
- The state of waiting for the acquisition of a fixed-length memory pool
- Workaround
Change the priority of a task in the READY or RUN state only.
- Schedule of Fixing the Problem
We plan to fix this problem in our next release of the product.
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