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code_coverage_Error_The_design_unit _somename_has_multiple_top-level_instances_in_the_design_enabled_for_coverage

MaheshKumar

Hi All,

I am doing code coverage, receiving following error;

ncelab: 14.10-s014: (c) Copyright 1995-2014 Cadence Design Systems, Inc.
TOOL: ncelab 14.10-s014: Started on Jan 09, 2018 at 12:09:19 IST
ncelab
-f ncelab.args
+incdir+../../rtl
+incdir+.
-MESSAGES
-WORK worklib
musbmhdrc_lpm_hostrst
musbmhdrc_lpictl
musbmhdrc_fsp
musbmhdrc_i2c
musbmhdrc_lpi
utm_lpi
ulpidec
i2c_model
-SNAPSHOT worklib.musbmhdrc_lpm_hostrst:v
-coverage all
-covfile mentor.ccf
-status
-covdut musbmhdrc

Elaborating the design hierarchy:
ncelab: *W,ICFUC: Unknown Command on line 2 of file mentor.ccf.
ncelab: *W,ICFUC: Unknown Command on line 3 of file mentor.ccf.
ncelab: *W,ICFUC: Unknown Command on line 4 of file mentor.ccf.
ncelab: *W,COVEOP: mentor.ccf:7 "-all" with set_expr_scoring is an expensive option as it selects all the expressions in the design. It has been deprecated and will not be supported in subsequent releases.
ncelab: *W,ICFUC: Unknown Command on line 11 of file mentor.ccf.
Caching library 'worklib' ....... Done
ncelab: *E,COVMDU: The design unit 'musbmhdrc' has multiple top-level instances in the design enabled for coverage.
ncelab: Memory Usage - 36.2M program + 20.7M data = 56.9M total (Peak 56.9M)
ncelab: CPU Usage - 0.0s system + 0.0s user = 0.0s total (0.1s, 92.2% cpu)
TOOL: ncelab 14.10-s014: Exiting on Jan 09, 2018 at 12:09:19 IST (total: 00:00:00)

This is the .ccf file;

select_coverage -block -expr -toggle -file ./../../rtl/
select_coverage -block -module musbmhdrc
set_assign_scoring
set_expr_scoring -all
set_expr_coverable_operators -all
set_branch_scoring
set_statement_scoring
set_implicit_block_scoring -off
set_explicit_block_scoring -off

where musbmhdrc is the top design name and musbmhdrc_lpm_hostrst is the respective testcase. Can anyone help to proceed further ?

  • StephenH

    Hi Mahesh.

    This would appear to be a limitation of the coverage system, the extended help message explains a bit more detail as well as two possible solutions:

    linux> nchelp ncelab COVMDU
    nchelp: 14.10-s014: (c) Copyright 1995-2014 Cadence Design Systems, Inc.
    ncelab/COVMDU =
    The coverage model requires that the design unit enabled for coverage
    has a single top-level instance in the design. If there are multiple
    top-level instances of the design unit enabled for coverage, you can
    define a top design unit, which instantiates all instances of the
    target design unit; and then enable the top design unit for coverage.
    Example:
    TOP
    / \
    A1 B1
    |
    A2
    In the given design hierarchy, an error is reported if only design unit
    'A' (having instances A1 and A2) is enabled for coverage. To resolve
    this issue:
    * Enable design unit 'TOP' for coverage, or
    * In addition to design unit A, enable design unit 'B' (having instance
    B1) for coverage.

    The reference to "top-level instances" is confusing, but if you ignore that precise wording, what it's saying is that none of the parent modules for musbmhdrc have coverage enabled. The simplest solution would probably be to add coverage for the hierarchy level(s) above musbmhdrc. You could also try turning on instance-based coverage, as that would have the same effect.

  • MaheshKumar
    in reply to StephenH

    That was useful. 

    Replaced the line;

    -coverage  all  -covfile some_name.ccf  -status  -covdut top_module_name;

    with this line;

    -coverage  all  -covfile  some_name.ccf - status; 

    Error resolved. 

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