11. ECLIC and PLIC Connection Diagram

The ECLIC and PLIC are independently configurable, so they can be co-existed or not, depends on configurations. The key points are as followings:

For the single-core real-time or micro-controller applications, it is recommended to just have ECLIC configured, as depicted in Interrupt Connection (for single-core with ECLIC configured only).
For the single-core Linux capable applications, it is recommended to configure PLIC. But in this case, the ECLIC can also be configured, hence, PLIC and ECLIC become coexisting.
- If the ECLIC is enabled by software, then the interrupts will be handled by ECLIC, and the PLIC will be bypassed, as depicted in Interrupt Connection (for single-core with PLIC/ECLIC configured and PLIC enabled).
  - In this mode, the hardware of UX class core can also worked as microcontroller, i.e., Nuclei UX class core is downward-compatible to Nuclei NX class core.
- If the ECLIC is disabled by software, then the interrupts will be handled by PLIC, and the ECLIC will be bypassed, as depicted in Interrupt Connection (for single-core with PLIC/ECLIC configured and ECLIC enabled).
For the symmetric multi-processor (SMP) Linux capable applications, it is recommended to just have PLIC configured only, as depicted in Interrupt Connection (for multi-core with PLIC configured only).

11.1. Single-core with ECLIC configured only

The following figure Interrupt Connection (for single-core with ECLIC configured only) is for single-core with ECLIC unit configured only.

The following figure Interrupt Connection (for single-core with PLIC/ECLIC configured and PLIC enabled) is for single-core with PLIC/ECLIC configured and PLIC enabled.

The following figure Interrupt Connection (for single-core with PLIC/ECLIC configured and ECLIC enabled) is for single-core with PLIC/ECLIC configured and ECLIC enabled.

The following figure Interrupt Connection (for multi-core with PLIC configured only) is for Multi-core with PLIC configured only.