8 Byte stack align in interrups (vs. 4 byte)

See here to understand why it is needed:

https://community.arm.com/developer/ip-products/processors/f/cortex-m-forum/6344/what-is-the-meaning-of-a-64-bit-aligned-stack-pointer-address

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How it works:

Assume that interrupt strikes just after the program pushed a word on the stack, so the stack is not 8 bytes aligned.

To align the stack for the handler, hardware automatically pushes one more word as part of "stacking" procedure, and sets bit 9 of the saved PSR to remember this.

On exit from the handler the stack is automatically restored.

The fine manual to read is PM0253. Enjoy ))

--pa

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Hi.

I read this couple of times trying to understand this. But that raised even more questions :)

How can i see this is needed?

How can i see this work?

Probably this will be hard to obserwe. But when stack isn't 8byte aligned and in interrupt some 64-bit variable will be allocated on stack, then will be a problem. but chance for this is low and effect is unpredicted.

forcing this without any efects isn't an observation.

So Pavel i took yours clever advice, I've looked there one more time andto my surprise nothing more appeared. No more example explaining how it works. What is benefit of this 8 byte align. How can i use it.