| .. _pmp: |
| |
| Physical Memory Protection (PMP) |
| ================================ |
| |
| The Physical Memory Protection (PMP) unit implements region-based memory access checking in-accordance with the RISC-V Privileged Specification, version 1.11. |
| The following configuration parameters are available to control PMP checking: |
| |
| +----------------+---------------+----------------------------------------------------------+ |
| | Parameter | Default value | Description | |
| +================+===============+==========================================================+ |
| | PMPEnable | 0 | PMP support enabled | |
| +----------------+---------------+----------------------------------------------------------+ |
| | PMPNumRegions | 4 | Number of implemented regions (1 - 16) | |
| +----------------+---------------+----------------------------------------------------------+ |
| | PMPGranularity | 0 | Minimum match granularity :math:`2^{G+2}` bytes (0 - 31) | |
| +----------------+---------------+----------------------------------------------------------+ |
| |
| When PMPEnable is zero, the PMP module is not instantiated and all PMP registers read as zero (regardless of the value of PMPNumRegions) |
| |
| PMP Integration |
| --------------- |
| |
| Addresses from the instruction fetch unit and load-store unit are passed to the PMP module for checking, and the output of the PMP check is used to gate the external request. |
| To maintain consistency with external errors, the instruction fetch unit and load-store unit progress with their request as if it was granted externally. |
| The PMP error is registered and consumed by the core when the data would have been consumed. |
| |
| PMP Granularity |
| --------------- |
| |
| The PMP granularity parameter is used to reduce the size of the address matching comparators by increasing the minimum region size. |
| When the granularity is greater than zero, NA4 mode is not available and will be treated as OFF mode. |
