The basic idea is following: you will configure two descriptors covering the same region. You will also enable the PID in both descriptors, so these descriptors are not considered as overlapping because also PID will be used to check if there's a hit or not. So, you can configure access rights for each process ID separately.
There's Process ID register in the core which is used to check if there's a hit or not. Your SW just writes this register as needed.
Now let's say we have descriptor X and descriptor Y covering the same area.
Descriptor X is configured for PID 3 and descriptor Y for PID 4.
Default value of PID (for main task) is 0.
How to use it with tasks:
void task1(void) /* covered by descriptor(s) X */
{
// Set Process ID 3
__MTSPR(SPR_PID,3);
/* run your code */
// Set Process ID back to 0
__MTSPR(SPR_PID,0);
}
void task2(void) /* covered by descriptor(s) Y */
{
// Set Process ID 4
__MTSPR(SPR_PID,4);
/* run your code */
// Set Process ID back to 0
__MTSPR(SPR_PID,0);
}
I'm not really sure if this can be implemented to MBDT, please ask here:
https://community.nxp.com/t5/Model-Based-Design-Toolbox-MBDT/bd-p/mbdt
Regards,
Lukas
The basic idea is following: you will configure two descriptors covering the same region. You will also enable the PID in both descriptors, so these descriptors are not considered as overlapping because also PID will be used to check if there's a hit or not. So, you can configure access rights for each process ID separately.
There's Process ID register in the core which is used to check if there's a hit or not. Your SW just writes this register as needed.
Now let's say we have descriptor X and descriptor Y covering the same area.
Descriptor X is configured for PID 3 and descriptor Y for PID 4.
Default value of PID (for main task) is 0.
How to use it with tasks:
void task1(void) /* covered by descriptor(s) X */
{
// Set Process ID 3
__MTSPR(SPR_PID,3);
/* run your code */
// Set Process ID back to 0
__MTSPR(SPR_PID,0);
}
void task2(void) /* covered by descriptor(s) Y */
{
// Set Process ID 4
__MTSPR(SPR_PID,4);
/* run your code */
// Set Process ID back to 0
__MTSPR(SPR_PID,0);
}
I'm not really sure if this can be implemented to MBDT, please ask here:
https://community.nxp.com/t5/Model-Based-Design-Toolbox-MBDT/bd-p/mbdt
Regards,
Lukas
That's what I wrote last time:
Those are writes to the core register PID. This value is then compared with PID defined in MPU descriptor.
Regards,
Lukas
Hello @lukaszadrapa
Thanks for your effort
I have one more question. I cannot find this register in the MPC5744P document, so could you tell me more about it, explain it in details, and tell me where I can find it since when I put it into my code it encounters an error?
Thanks in advance
