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| 1 | +# Report on a design prior to setting up a configuration |
| 2 | + |
| 3 | +This configuration allows running synthesis and floorplan |
| 4 | +to extract some basic information useful when setting |
| 5 | +up a config.mk file from scratch. |
| 6 | + |
| 7 | +Below, instructions are given to run synthesis, floorplan, placement and |
| 8 | +global route, then examine the results in the GUI to see what a |
| 9 | +realistic floorplan and settings might be for your Verilog files. |
| 10 | + |
| 11 | +The example below uses the designs/src/aes/*.v Verilog files, but |
| 12 | +the Verilog files do not have to be located in the OpenROAD-flow-scripts |
| 13 | +git repository, adjust the VERILOG_FILES argument to point to your Verilog |
| 14 | +files: |
| 15 | + |
| 16 | +``` |
| 17 | +make DESIGN_CONFIG=designs/asap7/minimal/config.mk DESIGN_NAME=aes_cipher_top VERILOG_FILES="$(ls designs/src/aes/*.v | xargs)" clean_synth synth gui_synth |
| 18 | +``` |
| 19 | + |
| 20 | +Where, the exploratory config.mk file to be replaced |
| 21 | +by a design specific config.mk file is: |
| 22 | + |
| 23 | +``` |
| 24 | +DESIGN_CONFIG=designs/asap7/minimal/config.mk |
| 25 | +``` |
| 26 | + |
| 27 | +Verilog files that to be investigated are specified by: |
| 28 | + |
| 29 | +``` |
| 30 | +VERILOG_FILES="$(ls designs/src/aes/*.v | xargs)" |
| 31 | +``` |
| 32 | + |
| 33 | +The Verilog top module name is specified by: |
| 34 | + |
| 35 | +``` |
| 36 | +DESIGN_NAME=aes_cipher_top |
| 37 | +``` |
| 38 | + |
| 39 | +Synthesis cleaned and re-run by: |
| 40 | + |
| 41 | +``` |
| 42 | +clean_synth synth |
| 43 | +``` |
| 44 | + |
| 45 | +The GUI is opened by the makefile target: |
| 46 | + |
| 47 | +``` |
| 48 | +gui_synth |
| 49 | +``` |
| 50 | + |
| 51 | +## `make gui_synth` OpenROAD GUI information |
| 52 | + |
| 53 | + |
| 54 | + |
| 55 | +The module hierarchy can here be examined to give a sense of |
| 56 | +area required for the default placement density. |
| 57 | + |
| 58 | +## `make gui_floorplan` OpenROAD GUI information |
| 59 | + |
| 60 | +Next to iterate on floorplan settings: |
| 61 | + |
| 62 | +``` |
| 63 | +make DESIGN_CONFIG=designs/asap7/minimal/config.mk DESIGN_NAME=aes_cipher_top VERILOG_FILES="$(ls designs/src/aes/*.v | xargs)" clean_floorplan floorplan gui_floorplan |
| 64 | +``` |
| 65 | + |
| 66 | +A few more things can be learned from looking at this minimal floorplan: |
| 67 | + |
| 68 | +- The pins are placed randomly on the edges and at least there |
| 69 | + is enough space on the edges to fit the top level pins |
| 70 | +- Check that the floorplan size is not completely unreasonable and |
| 71 | + at least there is a chance that this design could go through |
| 72 | + placement with this density. |
| 73 | + |
| 74 | + |
| 75 | + |
| 76 | +## `make gui_place` OpenROAD GUI information |
| 77 | + |
| 78 | +Next to iterate on placement settings: |
| 79 | + |
| 80 | +``` |
| 81 | +make DESIGN_CONFIG=designs/asap7/minimal/config.mk DESIGN_NAME=aes_cipher_top VERILOG_FILES="$(ls designs/src/aes/*.v | xargs)" clean_place place gui_place |
| 82 | +``` |
| 83 | + |
| 84 | + |
| 85 | + |
| 86 | + |
| 87 | + |
| 88 | +From placement more information about how to set up the config.mk |
| 89 | +file can be learned: |
| 90 | + |
| 91 | +- Examine estimated routing congestion to get a sense if there |
| 92 | + is a chance that the design can be routed. |
| 93 | +- Get a sense of size and location of modules |
| 94 | + |
| 95 | +## CTS(Clock tree Synthesis) |
| 96 | + |
| 97 | +After placement, CTS (clock tree synthesis is run). However the minimal design does |
| 98 | +not have a clock, so CTS runs quickly, but does nothing. |
| 99 | + |
| 100 | +## `make gui_grt` OpenROAD GUI information |
| 101 | + |
| 102 | +For non-trivial designs, some more work will need to be done in floorplan and |
| 103 | +placement before there is a chance that global routing will complete: |
| 104 | + |
| 105 | +``` |
| 106 | +make DESIGN_CONFIG=designs/asap7/minimal/config.mk DESIGN_NAME=aes_cipher_top VERILOG_FILES="$(ls designs/src/aes/*.v | xargs)" clean_place place gui_place |
| 107 | +``` |
| 108 | + |
| 109 | + |
| 110 | + |
| 111 | +Global routing congestion heatmap can be examined in the GUI. |
| 112 | + |
| 113 | +## Next steps |
| 114 | + |
| 115 | +Start creating a config.mk file for your design, write an .sdc file to |
| 116 | +examine timing and find reasonable values for the CORE_UTILIZATION |
| 117 | +and PLACE_DENSITY for your design considering routing congestion. |
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