MemoryPool: using hard defined mem pool size

[0xc0170]

Description

MemoryPool object contains this currently: char _pool_mem[((sizeof(T) + 3) & ~3) * pool_sz];

As we recently found out (reported by @embeddedteam103, see ARM-software/CMSIS_5#479) this calculation is not portable.

rtx_os.h defines osRtxMemoryPoolMemSize that we can use instead. Add the calculation to our mbed_os_storage_rtos header file.

cc @kjbracey-arm @c1728p9

Issue request type

[ ] Question
[ ] Enhancement
[X] Bug

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOCUSTRIA-324

[embeddedteam103]

The commit introducing this calculation says the size must be a multiple of 4 bytes.
Question: Is this part of the public API of cmsis-os, or implementation specific to RTX?

[0xc0170]

@mprse Can you review?

@embeddedteam103 What about the proposal above? Will it address the issue you have?

[embeddedteam103]

Not exactly, as this is part of the RTX api and not cmsis.
What I proposed in ARM-software/CMSIS_5#479 is wrap this RTX macro in a macro in a public API of cmsis and use it in mbed.

[0xc0170]

Not exactly, as this is part of the RTX api and not cmsis.

True. I see this as 2 step.

• First, we fix the hardcoded value here, as you need to redefine storage types anyway, so keep the C++ rtos objects not using RTX details. (this should be quick to fix and easy to replace later by CMSIS definition). Our rtos storage header file contains anyway RTX definitions.
• Second step, to discuss in CMSIS repo how CMSIS can provide abstraction for memory pool size and hopefully getting implemented

[0xc0170]

Looking at the issue we had with storage types,

https://github.com/ARM-software/CMSIS_5/blob/401391fc370397eb7eef4cd9d8f49e0f1d80e8b3/CMSIS/RTOS2/RTX/Include/rtx_os.h#L356

This was added to RTX but not yet to CMSIS. See ARM-software/CMSIS_5#167

[0xc0170]

@embeddedteam103 The issue 167 still needs to be addressed. Can you add your comments there as you use different implementation. This will revive the discussion, We can come up with a solution, and close 167.