This document discusses transaction level debugging using the Virtual Methodology Model (VMM) and Verdi. It describes how VMM callbacks can be used to capture transaction information like start time, end time, and payload without needing changes to the existing bus functional model. This higher level of debugging looks at transactions spanning multiple clock cycles rather than clock-by-clock information. Verdi's $fsdbLog feature can also be used to log transaction information for browsing in the simulator.

1. Transaction Level Debug Demo with VMM & Verdi www.cvcblr.com/blog Rejuvenating VLSI Design-Verification!

2. Case Study: Transaction Level Debug with VMM Transactions – higher level of abstraction May span across several tens/hundreds of clock cycles Detailed clock-by-clock info available via HDL Debug waveforms Higher level debug – across transactions Abstract information about various transactions Tools not mature yet (NOVAS has some interesting features) VMM Callback provides a means of doing this Idea is still maturing from CVC Prototype available on request CVC Copyright Protected Material, www.cvcblr.com 2 www.cvcblr.com/blog

3. Transaction debug – what’s interesting? Not bit-by-bit, clock-by-clock info Just payload, Transaction IDENTIFIERS Start time, End time etc. February 22, 2007 (3) www.cvcblr.com/blog class s2p_xactn extends vmm_data; rand logic [31:0] pkt_pld; rand logic err_pkt; rand bit [7:0] pkt_length; ... class s2p_dbg_xactn extends s2p_xactn; time start_t, end_t; // Conceptually: data_id, stream_id, scenario_id; pkt_pld, err_pkt, ipg; ...

4. CVC Copyright Protected Material, www.cvcblr.com 4 www.cvcblr.com/blog Transaction debug through callback in VMM class s2p_cov_cbk extends extendsvmm_xactor_callbacks; virtual task before_sending ( s2p_cmd_xactor xactor, s2p_xactn x0); endtask : before_sending virtual task after_sending ( s2p_cmd_xactor xactor, s2p_xactn x0); endtask : after_sendingendclass : s2p_cov_cbk Update DBG_IF Update DBG_IF

5. www.cvcblr.com/blog Transaction debug February 22, 2007 (5)

6. Transaction Debug - summary Powerful application of callbacks Minimal (or no) changes to the existing BFM (if VMM compliant) HUGE productivity benefit – moves debug abstraction level higher up More automation possible via scripts and new VMM macros (CVC’s roadmap) February 22, 2007 (6) www.cvcblr.com/blog

7. Verdi’s $fsdbLog feature SpringSoft (erstwhile Novas) recently added transaction debug capability to Verdi™ Use $fsdbLog wherever a transaction can be seen/captured February 22, 2007 (7) www.cvcblr.com/blog msg= $psprintf("# %0d %0d %0d pld: %0d, kind : %s start_time: %0t end_time: %0t“, stream_id, scenario_id, data_id, pkt_pld,s_err_pkt, start_t, end_t); $fsdbLogInit(); $fsdbLog("XN_at_BFM","xaction_capture",0,$psprintf("%m"),msg);

8. February 22, 2007 (8) www.cvcblr.com/blog Detailed clock-by-clock info

9. February 22, 2007 (9) www.cvcblr.com/blog Textual transaction browser – all from single $fsdLog call!