Generating the SLR Crossing Report - Generating the SLR Crossing Report - 2026.1 English - UG906

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)
Document ID
UG906
Release Date
2026-06-23
Version
2026.1 English

You can run the report_slr_crossing command in Tcl only. Run it after placement on designs that use devices with more than one SLR.

To generate a basic report with default settings and write it to the file slr_crossing.rpt.
report_slr_crossing -file slr_crossing.rpt
You can combine the -file option with any other option.

Limit the SLR Crossing by Fanout table with both -max_nets <n> and -fanout_greater_than <m> switches.

  • The-max_nets <n> switch limits the number of reported nets when the number of nets exceeding the minimum fanout specified is higher than max nets value. (Default: 20)
  • The -fanout_greater_than <m> switch limits the number of nets reported when the number of nets meeting the meeting the fanout threshold is lower than the value of max nets. (Default: 10)
For example, use the following to generate a report for nets with fanout greater than 100 and limit the output to 20 nets:
report_slr_crossing -fanout_greater_than 100 -max_nets 20

The -hierarchical_depth <integer> switch limits the report to the specified number of hierarchical levels below the top level. Use this option when the report becomes too big to manage due to a high number of hierarchies. Default = 0 which is unlimited.

The following example generates the report for two levels below the top level:
report_slr_crossing -hierarchical_depth 2 -file slr_crossing.rpt

The -cells <list_of_hierarchical_cell_names> switch limits the report to a given hierarchy list and the hierarchies below each cell specified. When you run in this mode:

  • For tables SLR Connectivity, SLR Connectivity Matrix, and SLR CLB Logic and Dedicated Block Utilization, the report generates one table per cell.
  • For tables SLR Crossings by Logic Levels, SLR Crossings by Fanout, and SLR Crossings by Hierarchy of Driver, information is combined for all specified cells.

The following example generates the report for cells cellA and cellB:

report_slr_crossing -cells [get_cells [list cellA cellB]]

Additional options include the following:

-append
Append to an existing file. By default, the command creates a new file and overwrites it if it exists.
-quiet
Suppress any errors generated during report generation.
-return_string
Return the report as a string that you can pass to a Tcl variable. By default, the report is written to the Tcl Console.