Step 4: Understanding the Report - 2023.2 English

Vivado Design Suite Tutorial: Design Analysis and Closure Techniques (UG938)

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2023.2 English

This step explains the different sections of the generated QoR Suggestions report. On the left of the report window, you can navigate to the different sections of the report; on the right, more information is provided.

  1. In the Suggestion Report, select GENERATED. This brings up the report section shown in the following figure.

    The GENERATED section provides a list of all the suggestions that have been generated at this stage of the current run. Each suggestion has a description that details the reason for the suggestion. For each suggestion, the following information is also provided.

    Table 1. RQS Summary Column Description
    Item Description Comment
    GENERATED_AT This shows what stage of the design the suggestion was generated at. Typical values are place_design or route_design. As you progress through the design stages, the decisions that the tool makes are based on the information available at the time. Information accuracy increases after placement and again after routing.
    APPLICABLE_FOR This stage must be rerun for the suggestion to take effect. Most suggestions are executed at either synth_design or place_design.
    AUTOMATIC Indicates if the suggestion is executed automatically or if manual intervention is required. Automatic suggestions either recommend a switch to the tool or a property to be added to a cell or net.
    INCREMENTAL FRIENDLY Indicates if the suggestion is optimized for the incremental flow. Non-incremental friendly suggestions must be already present in the reference checkpoint. If you want to add non-incremental friendly suggestions, an updated reference checkpoint must be used.
    SCOPE Indicates the target synthesis run level. GLOBALSCOPE is top level. Otherwise, a sub-module is targeted. Allows a single RQS file to be used on top-level and sub-module out of context (OOC) synthesis runs. Only applicable to synthesis suggestions.

    The other sections of the report usually provide details about the individual suggestions that have been generated.

  2. Click the RQS_XDC_1_1 hyperlink. This takes you to the detailed section for this suggestion.

    The suggestion description says that the timing constraint is too tight for the given path(s). The path has a large negative slack that stands out in a timing report. Timing paths use net delays that are optimal. This gives the tools the correct order to place and route them. Close analysis shows this is a 600 MHz path with high logic levels. This path needs to be fixed.

  3. Click the back arrow button ( ) to go back to the GENERATED view.
  4. In the GENERATED view, click the RQS_TIMING-33_2-1 row. You can see this is an AUTOMATIC suggestion that is applicable for synth_design (see the APPLICABLE_FOR column). This indicates that you must rerun the synth_design command to make use of this suggestion.

    When you select the row in the GENERATED view, the suggestion object is selected and the properties can be seen in the QoR Suggestion Properties window. If you examine the COMMAND property, you can confirm that it generates a retiming forward property for synth_design.

  5. In the GENERATED view, click the RQS_TIMING-33_2-1 ID to go to the details table for that suggestion. Careful examination of the Endpoint column confirms that this is the same path that was mentioned for RQS_XDC-1-1.
  6. In the GENERATED view, you can see the remaining suggestions. The RQS_CLOCK-9 suggestion is applicable for place_design. The RQS_TIMING-44 suggestion is similar to the existing one.
  7. Only select the four suggestions highlighted in the following image to written to the RQS suggestion object file:

  8. Click Write Suggestions. When the Write Suggestions to Project dialog box opens, ensure it is set to write to the rqs_report.rqs file in the utils_1 directory, as shown in the following figure. Select Copy sources to project.

  9. Examine the Sources window. The RQS file has been added to the utils_1 fileset. This ensures that the file is captured using the get_files command and recognized in the next step when you add the file to a run.