nextpnr failed to route 6 RAMB36E1 design, gives ERROR: Failed to route arc 0 of net 'modules_2.mem_ext.Memory.0.8.genblk1.genblk1.CAS_B', from SITEWIRE/RAMB36_X3Y21/CASCADEOUTB to SITEWIRE/RAMB36_X2Y28/CASCADEINB

[mirekez]

ERROR_Failed_to_route_arc_0_of_net_modules_2_mem_ext_Memory_0_8_genblk1_genblk1_CAS_B.zip

Info: Device utilization:
Info: SLICE_LUTX: 15157/126800 11%
Info: SLICE_FFX: 332/126800 0%
Info: CARRY4: 1026/15850 6%
Info: PSEUDO_GND: 1/30932 0%
Info: PSEUDO_VCC: 1/30932 0%
Info: HARD0: 0/ 2376 0%
Info: RAMB18E1: 0/ 270 0%
Info: FIFO18E1: 0/ 135 0%
Info: RAMBFIFO36E1: 0/ 135 0%
Info: RAMB36E1: 6/ 135 4%
Info: DSP48E1: 5/ 240 2%

Vivado works (resource usage is different in Vivado, more BRAMS are used)

[mirekez]

adding very small design with same error, probably will
ERROR_Failed_to_route_arc_0_of_net_modules_3_mem_ext_Memory_0_0_genblk1_genblk1_CAS_A.zip
be easier to debug

Info: Device utilisation:
Info: SLICE_LUTX: 543/126800 0%
Info: SLICE_FFX: 108/126800 0%
Info: CARRY4: 44/15850 0%
Info: PSEUDO_GND: 1/30932 0%
Info: PSEUDO_VCC: 1/30932 0%
Info: HARD0: 0/ 2376 0%
Info: RAMB18E1: 0/ 270 0%
Info: FIFO18E1: 0/ 135 0%
Info: RAMBFIFO36E1: 0/ 135 0%
Info: RAMB36E1: 4/ 135 2%