read_checkpoint - 2023.1 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

Document ID
UG835
Release Date
2023-05-16
Version
2023.1 English

Read a design checkpoint

Syntax

read_checkpoint [‑cell <arg>] [‑incremental] [‑directive <arg>]
    [‑auto_incremental] [‑fix_objects <args>] [‑dcp_cell_list <args>]
    [‑force_incr] [‑quiet] [‑verbose] [<file>]

Usage

Name Description
[-cell] Replace this cell with the checkpoint. The cell must be a black box.
[-incremental] Input design checkpoint file to be used for re-using implementation.
[-directive] Mode of behavior (directive) for this command. Please refer to Arguments section of this help for values for this option. Default: RuntimeOptimized
[-auto_incremental] Enters automatic mode for incremental compile. This is less aggressive than the standard incremental mode and will readily switch from incremental algorithms to the default algorithms if results might not be maintained. Should not be used with -reuse_objects.
[-fix_objects] Fix only given list of cells, clock regions, SLRs or Design
[-dcp_cell_list] A list of cell/dcp pairs, e.g. {<cell1> <dcp1> <cell2> <dcp2>}. The option value should be in curly braces.
[-force_incr] Force switch to forcefully run incremental flow irrespective of rule/ML based criteria
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution
[<file>] Design checkpoint file

Categories

FileIO

Description

Reads a design checkpoint file (DCP) that contains the netlist, constraints, and may optionally have the placement and routing information of an implemented design. You can save design checkpoints at any stage in the design using the write_checkpoint command.

The read_checkpoint command simply reads the associated checkpoint file, without opening a design or project in-memory. To create a project from the imported checkpoint, use the open_checkpoint command instead of read_checkpoint, or use the link_design command after read_checkpoint to open the in-memory design from the checkpoint or checkpoint files currently read.

Note: When multiple design checkpoints are open in the Vivado® tool, you must use the current_project command to switch between the open designs. You can use current_design to check which checkpoint is the active design.
Important: The -incremental switch is not intended to merge two DCP files into a single design. It applies the placement and routing of the incremental checkpoint to the netlist objects in the current design.

After loading an incremental design checkpoint, you can use the report_incremental_reuse command to determine the percentage of physical data reused from the incremental checkpoint, in the current design. The place_design and route_design commands will run incremental place and route, preserving reused placement and routing information and incorporating it into the design solution.

Reading a design checkpoint with -incremental, loads the physical data into the current in-memory design. To clear out the incremental design data, you must either reload the current design, using open_run to open the synthesis run for instance, or read a new incremental checkpoint to overwrite the one previously loaded.

Arguments

-cell <arg> - (Optional) Specifies a black box cell in the current design to populate with the netlist data from the checkpoint file being read. This option cannot be used with -incremental, or any of its related options.

-auto_incremental - (Optional) Enables incremental algorithms only when the quality of the reference checkpoint is high. This allows a user to set this option and let the tool decide whether to run default or incremental algorithms.

-incremental - (Optional) Load a checkpoint file into an already open design to enable the incremental implementation design flow, where <file> specifies the path and filename of the incremental design checkpoint (DCP) file. In the incremental implementation flow, the placement and routing from the incremental DCP is applied to matching netlist objects in the current design to reuse existing placement and routing. Refer to the Vivado Design Suite User Guide: Implementation (UG904) for more information on incremental implementation.

-directive [ RuntimeOptimized | TimingClosure | Quick ] - (Optional) Specifies a directive, or mode of operation for the -incremental process.

  • RuntimeOptimized: The target WNS is the referenced from the incremental DCP. By default, more reuse from the reference checkpoint is encouraged.
  • TimingClosure: The target WNS is 0. This mode attempts to meet timing at the expense of runtime. Paths not meeting timing will be ripped up and the incremental algorithms will be applied to fix timing on the paths.
  • Quick: Specifies a low effort, non-timing-driven incremental implementation mode with the fastest runtime.

-fix_objects - (Optional) When -incremental is specified, mark the placement location of specifed cells as fixed (IS_LOC_FIXED) to prevent changes by the place_design command. This option will fix the placement of the specified list of cells, clock regions, SLRs or the current_design.

-dcp_cell_list <arg> - (Optional) Lets you specify a list of cell/dcp pairs. This lets you read in multiple DCP files for specified cells in a single run of the read_checkpoint command. The format is specified as a list of cell/DCP pairs enclosed in curly braces: {<cell1> <dcp1> <cell2> <dcp2>}.

-force_incr - (Optional) When -incremental is specified, forces the incremental flow irrespective of the incremental criteria checks. When -incremental is not specified the incremental flow may exit and continue in non-incremental flow.

Note: force_incr is only used along with the -incremental switch.
-quiet - (Optional) Execute the command quietly, returning no messages from the command. The command also returns TCL_OK regardless of any errors encountered during execution.
Note: Any errors encountered on the command-line, while launching the command, will be returned. Only errors occurring inside the command will be trapped.
-verbose - (Optional) Temporarily override any message limits and return all messages from this command.
Note: Message limits can be defined with the set_msg_config command.

<file> - (Required) The path and filename of the checkpoint file to read.

Note: If the path is not specified as part of the file name, the tool will search for the specified file in the current working directory and then in the directory from which the tool was launched.

Examples

The following example imports the specified checkpoint file into the tool, and then links the various design elements to create an in-memory design of the specified name:

read_checkpoint C:/Data/checkpoint.dcp
link_design -name Test1

This example reads a design checkpoint on top of the current design for incremental place and route of the design:

read_checkpoint -incremental C:/Data/routed.dcp

This example reads a design checkpoint. Incremental algorithms will be used only if the timing is nearly met and if there is a high reuse:

read_checkpoint -auto_incremental C:/Data/routed.dcp