Shared Parameters and Ports

Every OVL checker takes the parameters and ports on this page, in addition to its own (see Checker Reference). Defaults come from std_ovl/std_ovl_defines.h and can be changed globally by defining the matching OVL_*_DEFAULT macro before compiling.

Shared parameters

Name	Default	Meaning
severity_level	OVL_ERROR (1)	How a violation is reported: OVL_FATAL (0), OVL_ERROR (1), OVL_WARNING (2), OVL_INFO (3).
property_type	OVL_ASSERT (0)	OVL_ASSERT (0) and OVL_ASSUME (1) report rule and X/Z violations. OVL_ASSERT_2STATE (3) and OVL_ASSUME_2STATE (4) report rule violations only, not X/Z. OVL_IGNORE (2) reports nothing and never drives fire.
msg	"VIOLATION"	Text added to every message from this instance. Use it to tell instances apart.
coverage_level	OVL_COVER_BASIC (2)	Bit mask of coverage to collect: OVL_COVER_SANITY (1), OVL_COVER_BASIC (2), OVL_COVER_CORNER (4), OVL_COVER_STATISTIC (8); OVL_COVER_ALL (15), OVL_COVER_NONE (0).
clock_edge	OVL_POSEDGE (1)	Clock edge the checker samples on: OVL_POSEDGE (1) or OVL_NEGEDGE (2). Not present on ovl_memory_async and ovl_memory_sync, which use wen_edge/ren_edge instead.
reset_polarity	OVL_ACTIVE_LOW (0)	Active level of reset: OVL_ACTIVE_LOW (0) or OVL_ACTIVE_HIGH (1).
gating_type	OVL_GATE_CLOCK (1)	What enable gates: OVL_GATE_CLOCK (1) gates the clock, OVL_GATE_RESET (2) holds the checker in reset, OVL_GATE_NONE (0) ignores enable. Define OVL_GATING_OFF to turn gating off for all checkers.

Shared ports

Name	Direction	Meaning
clock	input	Sampling clock. Not present on the unclocked checkers (ovl_proposition, ovl_never_unknown_async) or on ovl_memory_async/ovl_memory_sync.
reset	input	Checker reset; polarity set by reset_polarity.
enable	input	Checker enable; effect set by gating_type.
fire	output [2:0]	Violation flags, one cycle per violation (see below).

The fire output

Bit	Name	Set when
fire[0] (OVL_FIRE_2STATE)	fire_2state	The checker’s rule is violated.
fire[1] (OVL_FIRE_XCHECK)	fire_xcheck	A checked input has X or Z (OVL_ASSERT and OVL_ASSUME only).
fire[2] (OVL_FIRE_COVER)	fire_cover	A coverage point is hit. Not implemented in the AsFigo sv2012/ logic: always 0.

fire is driven only with -DOVL_VERILOG. With -DOVL_SVA the upstream wrappers tie it to 0 and report through SVA action blocks only.

Compile-time macros

Macro	Effect
OVL_VERILOG / OVL_SVA	Select plain-Verilog or SVA checker logic.
OVL_ASSERT_ON	Turn on the assertion checks. Without it the checkers do nothing.
OVL_COVER_ON	Turn on coverage collection.
OVL_XCHECK_OFF	Turn off all X/Z checks.
OVL_IMPLICIT_XCHECK_OFF	Turn off the implicit X/Z checks that each checker adds on its inputs.
OVL_MAX_REPORT_ERROR	Stop reporting after this many errors per instance.
OVL_FINISH_OFF	Report OVL_FATAL with $error instead of ending the simulation.
OVL_UVM	Report through uvm_fatal/uvm_error/uvm_warning/uvm_info instead of $fatal/$error/$warning/$info.
OVL_LEGACY_TASK	Use the original upstream reporting task (std_ovl_task_legacy.h).

Message format

Without OVL_UVM, a violation prints:

OVL_ERROR   : <assert_name> : <msg> : <error message>

where <assert_name> is the checker name in capitals (for example OVL_BITS) and <msg> is the instance’s msg parameter. The simulator adds the file, line, time and scope.