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  3. AR# 2893: M1.4 Map: DROP_SPEC property takes priority over other TIMESPECs regardless of where it is specified in the flow

AR# 2893

M1.4 Map: DROP_SPEC property takes priority over other TIMESPECs regardless of where it is specified in the flow

Description

Keywords: DROP_SEPC, TIMESPEC, MAP, M1.4, priority

Urgency: Standard

Reference #: 18676

General Description: M1.4:
The DROP_SPEC is a TIMESPEC-related constraint that allows
you to designate that timing analysis should not be performed
on a specific TIMESPEC property. DROP_SPEC can only be
specified within constraint files.

Map does not follow standard constraint priority ordering
when implementing the DROP_SPEC constraint. The standard
way of determining which set of constraints takes priority
depends on what point in the flow the set of constraints is
specified, as follows:

(Lowest to Highest:
Schematic -> .NCF file -> .UCF file -> .PCF file)

This means that constraints specified in a .NCF file
(including DROP_SPEC), may be overridden by other constraints
specified in constraint files read in by M1 at later stages
of the implementation flow.

Currently the DROP_SPEC constraint takes priority no matter
where it is specified within the flow.

Solution

Currently there is no work around.
AR# 2893
Date 03/27/2000
Status Archive
Type General Article