Hi all, Sorry that I haven’t worked with FreeRTOS for a while. Recently when I re-picked up the latest FreeRTOS, I found out that the MPU wrappers of pvPortMalloc()/vPortFree() are removed from MPU_wrappers.h, even though MPU_pvPortMalloc()/MPU_vPortFree() still exist in mpu_wrappers.c I didn’t fo…

I am also confused that if the unprivileged task can not access the memory dedicated for allocation how the unprivileged task allocate a memory. And also, similar APIs such as MPU_vQueueDelete, can be called by a unprivileged task. I see no difference between pvPortMalloc and other APIs in the mpu_…

Remember that an unprivileged task can only directly access memory from a limited number of segments, and has full access to memory in any of those segments. If an unprivileged task could call pvPortMalloc, then for it to be able to use that memory, the entire heap would need to be in unprivileged …

So what about MPU_pvPortMalloc()? Can unprivileged task call it or not, according to current FreeRTOS design?

Yes, an unprivileged task can call it.

Hi Richard, So two heaps should be prepared. One should be configured as privileged access only by the MPU and is for the privileged tasks. The other should be configured as unprivileged access and privileged access by the MPU and is for the unprivileged tasks. So that the tasks can access their de…

@richard-damon Could you comment on the reply I posted above? Thanks!

First, a small disclaimer, I don’t use the MPU/Protected task feature much, so I am not real familiar with it. The basic thing to remember is that FreeRTOS starts as a simple RTOS, designed for a single simple processor, and then uses add-on code to support things like memory protection. As such, t…

[image] Sherryzhang2: If so, the MPU_pvPortMalloc should not exist. Because it raises to privileged to access the heap. An unprivileged task can still access the privileged tasks’ heap by calling MPU_pvPortMalloc. Yes, you are right and we will remove these. Thanks.

May I know why remove pvPortMalloc()/pvPortFree() from MPU_wrappers.h?

Kernel

hs2 (Hartmut Schaefer) July 15, 2020, 12:21pm 12

BTW there is a related maybe also interesting topic in the forum.

Topic		Replies	Views
No entry for pvPortMalloc/vPortFree in mpu_wrappers.h Kernel	1	462	January 31, 2017
Access to heap from unpriveleged task Kernel	3	3123	April 5, 2023
MPU Port in Cortex-M33 hits a halt when the stack is allocated from heap (10.3.1) Kernel	13	1576	October 8, 2020
Mpu_wrappers.h not using priviledged functions for kernel as default? Kernel	3	1330	January 29, 2021
Cortex-M4 MPU support Kernel	11	619	November 22, 2013

May I know why remove pvPortMalloc()/pvPortFree() from MPU_wrappers.h?

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