2 Encoder Control

The fields required to control a Trace Encoder are defined in the RISC-V Trace Control Interface Specification, which is intended to apply to any and all RISC-V trace encoders, regardless of encoding protocol. This chapter details which of those fields apply to E-Trace. To avoid replication, descriptions are not provided here; additional E-Trace specific context or clarification is provided only where required.

How fields are organized and accessed (e.g packet based or memory mapped) is outside the scope of this document. If a memory mapped approach is adopted, the 'Trace Component Register Map' from the RISC-V Trace Control Interface Specification should be used.

Note: Upto and including the E-Trace v2.0.0 specification, which predated the creation of the RISC-V Trace Control Interface Specification, the full field definitions were included in this chapter. For versions later than this, the field definitions have simply moved from this specification to the RISC-V Trace Control Interface Specification, without any change to their meaning. However, in order to create a more widely applicable protocol agnostic specification it has been necessary to change the field names in the process.

The applicability of fields for E-trace is categorized as follows:

N: Not applicable
M: Mandatory
O: Optional
MD: Mandatory if data trace is supported
OD: Optional for data trace

2.1 Basic Control

The following fields control basic encoding behavior.

Table 1. Basic Control

Field	Applicability	E-Trace Specific Details
trTeActive	M
trTeEnable	M
trTeInstTracing	M
trTeDataTracing	MD
trTeInstTrigEnable	O
trTeDataTrigEnable	OD
trTeInstStallOrOverflow	O
trTeDataStallOrOverflow	OD
trTeInstStallEn	O
trTeDataStallEn	OD
trTeEmpty	O	Recommended if the trace datapath requires manual flushing when trace is disabled.
trTeDataDrop	OD
trTeDataDropEn	OD
trTeInhibitSrc	O
trTeInstSyncMode	M	If hardcoded, must be to a non-zero value.
trTeInstSyncMax	M	May be hardcoded.
trTeFormat	M	Must be set to 0 (denoting E-Trace format).
trTeVerMajor	M
trTeVerMinor	M
trTeCompType	M
trTeProtocolMajor	M	Must be 0 to indicate this version (2.0.x) of the E-Trace protocol.
trTeProtocolMinor	M	Must be 0.
trTeSrcID	O
trTeSrcBits	O

2.2 Optional Modes

See Section 3.2 for details of the modes covered in this section.

Table 2. Optional and run-time configurable modes.

Field	Applicability	E-Trace Specific Details
trTeInstNoAddrDiff	O
trTeInstNoTrapAddr	O
trTeInstEnSequentialJump	O
trTeInstEnImplicitReturn	O
trTeInstEnBranchPrediction	O
trTeInstJumpTargetCache	O
trTeDataNoValue	OD
trTeDataNoAddr	OD
trTeDataAddrCompress	OD
trTeContext	N	Hardcode to 0.
trTeInstMode	N	Hardcode to 7.
trTeInstImplicitReturnMode	N	Hardcode to 0.
trTeInstEnRepeatedHistory	N	Hardcode to 0.
trTeInstEnAllJumps	N	Hardcode to 0.
trTeInstExtendAddrMSB	N	Hardcode to 0.

2.3 Filtering

See Section 5 for details of the filtering capabilities covered in this section.

Table 3. Trace filtering selection

2.1 Basic Control​

2.2 Optional Modes​

2.3 Filtering​

2.1 Basic Control

2.2 Optional Modes

2.3 Filtering