Visible to Intel only — GUID: ewa1405098489932
Ixiasoft
Visible to Intel only — GUID: ewa1405098489932
Ixiasoft
3.8. Addition of Timing Constraints
One noteworthy constraint in s5_net is the multicycle constraint for the kernel reset in the top_post.sdc file. Using global routing saves routing resources and provides more balanced skew. However, the delay across the global route might cause recovery timing issues that limit kernel clock speed. Although Intel® requires all logic to exit reset mode in the same clock cycle, it is not necessary for the exit to happen in the same clock cycle as reset deassertion. Therefore, Intel® adds a multicycle setup constraint of 2 and multicycle hold of 1 to the kernel reset. Without these additions, even with reset drivers located directly adjacent to global clock buffers, the highest kernel Fmax that Intel® achieves is around 320 MHz.