(12) United States Patent ao) Patent No.: Us 7,197,671 B2
Swaine et al. (45) Date of Patent: Mar. 27,2007
(54) GENERATION OF TRACE ELEMENTS
WITHIN A DATA PROCESSING APPARATUS
(75) Inventors: Andrew B Swaine, Welwyn Garden City (GB); David J Williamson,
Austin, TX (US)
(73) Assignee: Arm Limited, Cambridge (GB)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 536 days.
(21) Appl. No.: 10/452,904
(22) Filed: Jun. 3, 2003
(65) Prior Publication Data
US 2004/0030962 Al Feb. 12, 2004
Related U.S. Application Data
(63) Continuation-in-part of application No. 10/206,829, filed on Jul. 29, 2002, now Pat. No. 7,003,699.
A trace module traces changes in a subset of architectural state of a data processing apparatus. A trace generation unit receives input signals from components of the data processing apparatus indicative of a change in the subset of architectural state and generates a number of trace elements indicative of the change to enable a recipient of the trace elements to subsequently reconstruct the subset of architectural state. A table maintained by the trace generation unit identifies an architectural state derivable from previously generated trace elements. The trace generation unit references the table to determine which trace elements to generate. The table reduces the number of trace elements that need to be generated by providing a record of the architectural state which has already been provided to the recipient. Only those trace elements relating to changes in architectural state which are not derivable by the recipient need be generated.
70 Claims, 8 Drawing Sheets