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AR# 65696

Vivado 2015.x - ERROR: [Place 30-499] Multi-column shapes placement failed

Description

I have a design based on a module containing 8LUT+16FF.

I specify RLOC attributes in HDL to have the BELs packed into the same CLB. In the top level, the module is called 25 times.

I then draw a pblock ranging slice_x0y0:slice_x9y4, expecting the instances to 100% fit into this region.

However, the following error occurs in place_design:

ERROR: [Place 30-499] Multi-column shapes placement failed.
Failed to commit 5 or more multi-column (RPM) shapes.
Those shapes are listed below (for big shapes only first 20 instances are listed):

Is it a valid error and how can I work around this?

Solution

Multi-column macros in devices with irregular column spacing are difficult to support.

The placer cannot exhaustively check all potential column choices. Therefore an RLOC_ORIGIN is necessary to point the placer to a legal column placement.

It is best to avoid multi-column macros unless you want to also specify the placement location.


The work-around would be to add LOC or RLOC_ORIGIN to the instances instead of drawing the pblock.

Alternatively, modify the basic module to occupy a single slice, double the generate loop, and keep the pblock.

AR# 65696
Date Created 10/13/2015
Last Updated 02/19/2016
Status Active
Type General Article
Tools
  • Vivado Design Suite