Please take a look at the patches I've put together to the linker files for multi-core.
The fundamental issue that necessitates this change is that the ARMv6/v7 MPU is quite constrained in terms of configuration - the size has to be an exact power of 2, and the base address has to be aligned to the size. This means that we need to group data together in memory so that we can minimize the gaps that we have to introduce to meet the MPU* requirements. To that end, I've grouped all the privileged data together and grouped all the unprivileged data together, and introduced a new #define, S_DATA_UNPRIV_START, that (optionally, in multi-core only) allows the start address of the unprivileged secure data to be specified. This then enables configuring a single MPU region to cover all the unprivileged secure data. Note that only data sections are affected - code is left alone (mostly because the PSoC6 platform has so little Flash that we can't afford any padding at all).
https://review.trustedfirmware.org/c/trusted-firmware-m/+/1731 groups the privileged data separate from the unprivileged https://review.trustedfirmware.org/c/trusted-firmware-m/+/1732 adds support for S_DATA_UNPRIV_START
Thanks,
Chris
* In this email I've said "MPU". Technically it's the "SMPU (System Memory Protection Unit) on PSoC6, but that has the same limitations as the ARMv6 MPU.
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