Embedded Peripherals IP User Guide

ID 683130
Date 10/24/2025
Public
Document Table of Contents
1. Introduction 2. Avalon® -ST Serial Peripheral Interface Core 3. SPI Core 4. SPI Agent/JTAG to Avalon® Host Bridge Cores 5. Intel eSPI Agent Core 6. eSPI to LPC Bridge Core 7. Ethernet MDIO Core 8. Intel FPGA 16550 Compatible UART Core 9. UART Core 10. Lightweight UART Core 11. JTAG UART Core 12. Intel FPGA Avalon® Mailbox Core 13. Intel FPGA Avalon® Mutex Core 14. Intel FPGA Avalon® I2C (Host) Core 15. Intel FPGA I2C Agent to Avalon® -MM Host Bridge Core 16. EPCS/EPCQA Serial Flash Controller Core 17. Intel FPGA Serial Flash Controller Core 18. Intel FPGA Serial Flash Controller II Core 19. Intel FPGA Generic QUAD SPI Controller Core 20. Intel FPGA Generic QUAD SPI Controller II Core 21. Interval Timer Core 22. Intel FPGA Avalon FIFO Memory Core 23. On-Chip Memory (RAM and ROM) Intel FPGA IP 24. On-Chip Memory II (RAM or ROM) Intel FPGA IP 25. PIO Core 26. PLL Cores 27. DMA Controller Core 28. Modular Scatter-Gather DMA Core 29. Scatter-Gather DMA Controller Core 30. Video Sync Generator and Pixel Converter Cores 31. Intel FPGA Interrupt Latency Counter Core 32. Performance Counter Unit Core 33. Vectored Interrupt Controller Core 34. System ID Peripheral Core 35. Intel FPGA GMII to RGMII Converter Core 36. HPS GMII to RGMII Adapter IP 37. Intel FPGA MII to RMII Converter Core 38. HPS GMII to TSE 1000BASE-X/SGMII PCS Bridge Core IP 39. Intel FPGA HPS EMAC to Multi-rate PHY GMII Adapter Core 40. Intel FPGA MSI to GIC Generator Core 41. Cache Coherency Translator IP 42. Altera ACE5-Lite Cache Coherency Translator

33.5.6.3. altera_vic_driver.enable_preemption_rs_<n>

Identifier: ALTERA_VIC_DRIVER_ENABLE_PREEMPTION_RS_<n>
Type: Boolean
Default value: 0
Destination file: system.h
Description: Enables interrupt preemption (nesting) if a higher priority interrupt is asserted while a lower priority ISR is executing, for all interrupts that target the specified register set number.

When this setting is enabled (set to 1), the vector table for each VIC utilizes a special interrupt funnel that manages preemption. All interrupts on all VIC instances assigned to that register set then use this funnel.

When a higher priority interrupt preempts a lower priority interrupt running in the same register set, the interrupt funnel detects this condition and saves the processor registers to the stack before calling the higher priority ISR. The funnel code restores registers and allows the lower priority ISR to continue running once the higher priority ISR completes.

Because this funnel contains additional overhead, enabling this setting increases interrupt response time substantially for all interrupts that target a register set where this type of preemption is enabled.

Use this setting if you must guarantee that a higher priority interrupt preempts a lower priority interrupt, and you assigned multiple interrupts at different priorities to the same Nios® II shadow register set.

Occurs: Per register set; <n> refers to the register set number.