Hi; I have a feature for the ARM M profile emulation which I think needs to be implemented by giving it a separate mmu index value. [The HFNMIENA control bit allows "privileged and execution priority is higher than 0" to run with the MPU effectively off even if normal privileged execution has enabled the MPU.]
I could implement this by just bumping ARM's NB_MMU_MODES to 8 and using the extra value for this. On the other hand, several of the current 7 index values are not needed for M profile CPUs, so in theory I could reuse one of those (so it would have different meanings if the CPU was M profile or not). But that feels like it would be pretty accident-prone, since so much of the code is shared. So, just how expensive is having an extra MMU mode which isn't actually used? Is it bad enough to be worth the reduced maintainability? thanks -- PMM
