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AR# 20909

6.3i XST - XST does not set the LEGACY_MODE attribute when a multiplier is used in the XtremeDSP slice (DSP48)

Description

Keywords: XST, DSP, Xtreme, DSP48, slice

Urgency: Standard

General Description:
When a multiply function gets inferred into the XstremeDSP slice (DSP48), XST sets the LEGACY_MODE attribute to NONE. When the multiplier is used, the XtremeDSP operates 50 MHz slower than if no multiplier is used. This can lead to timing errors if the design is constrained to go faster than the XtremeDSP can handle.

Solution

This problem has been fixed in the latest 7.1i Service Pack available at:
http://support.xilinx.com/xlnx/xil_sw_updates_home.jsp
The first service pack containing the fix is 7.1i Service Pack 1.
AR# 20909
Date Created 03/04/2005
Last Updated 07/18/2007
Status Archive
Type General Article