Relax Library Requirement on Configurations

Proposal Details

• Who Updates:Main.CliffordWalinsky
• Date Proposed:2013-11-06
• Date Last Updated:2013-11-06
• Bugzilla Reference: 295

Current Situation

The 1076-2008 LRM, section 3.4 "Configuration declarations", states the following:

"For a configuration of a given design entity, both the configuration declaration and the corresponding entity declaration shall reside in the same library."

See Bugzilla 295

Requirement

This proposal would remove the requirement that every configuration shall reside in the same library as the entity that it configures.

Implementation details

Allow configurations and their associated entities to reside within different libraries. This issue has been prototyped in a vendor's simulator and used in production environments without any issue.

Code Examples

Assuming entity top1 resides within (logical) library lib1, the following configuration declaration can be compiled to reside outside library lib1:

library lib1;
library lib2;
configuration conf1 of lib1.top1 is
    for arch_top1
        for label1 : comp_bottom1
            use entity lib2.bottom1
        end for;
    end for;
end conf1;

Arguments FOR

This proposal allows configurations to reside within libraries containing design units that achieve similar design goals. For example, if all design units of a library are high-level RTL, configurations specifying that components shall be instantiated with RTL designs will naturally reside in the same RTL library.

Arguments AGAINST

Supporters

CliffordWalinsky

-- Brent Hayhoe - 2013-12-06

-- JimLewis - 2014-12-04

-- PatrickLehmann - 2016-02-11

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