Flash Cache Configuration on XMC4500 Relax Kit Lite

[MartinMichelis]

Hi everyone,

I am currently working with the XMC4500 Relax Kit Lite using Zephyr Version 4.0.99.
I want to analyze the cache behavior of my code.

While investigating, I noticed that the flash region is mapped to the non-cached flash region at 0x0C000000, as described in the XMC4500 Reference Manual. I attempted to enable caching using the CONFIG_DCACHE and CONFIG_ICACHE options but had no success.

To work around this, I created an overlay for my board that maps the flash to the cached memory region at 0x08000000. After rebuilding, I observed the expected caching behavior in my code.

I have a few questions regarding this:

1. Am I doing something obviously wrong?
2. Is there a specific reason why the default configuration for this board maps flash to the non-cached region?
3. Is there an existing option or configuration to map flash to the cached region without requiring an overlay?

I’d appreciate any insights.
Thanks in advance!

Martin

[ldomaigne]

Hi Martin,

1. No, you are not doing anything obviously wrong.
2. The default configuration for this boards maps the flash to the non-cached region, because the original board DTS has defined it that way. The "flash node" definition is coming from this XMC dsti file.
3. Looking at the driver code, it does not look like there is any specific driver config option for this.

Your approach of using the devicetree overlay looks good to me.

[MartinMichelis]

Thank you for the clarification

[ldomaigne]

You're welcome!

[talih0]

@MartinMichelis, there is pull request to make this a default option:
#77722