© 2013 IBM Corporation Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Erez Bilgory Alex Goryachev Ronny Morad Tali Rabetti IBM Research – Haifa June 2013

2 Background: System-level simulation Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation  Pre-silicon, system- level RTL simulation: –Many cores (possibly multithreaded) –Many I/O devices, bridges, HW accelerators, message- passing components –All components run in parallel –Only RTL, no real SW in the simulated system Processor Core#1 Processor Core#N HW accelerator unit I/O BFM#2 I/O BFM#1 Memory Message passing unit System bus I/O bus Processor Core#2 … IO bridge Memory controller

3 Background: Test generator Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Concrete test cases (including instruction stream for each processor core) Abstract test case (High level test description) System-level test generator

4 Background: Test generator Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation System-level test generator Memory Read IO rd Memory write Send message to core 2 IO Wr Memory write Send message to core 1 IO Rd Memory read Core 1 Core 2 Mix 10 instructions of types: 50%: 25%: Memory access IO Rd/Wr Send message Abstract test case Concrete test cases

5 Background: Message passing component Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Message Passing Unit FIFO 0 FIFO 1 FIFO 4 FIFO 2 FIFO 3 FIFO 0 FIFO 1 FIFO 4 FIFO 2 FIFO 3 connection Table E0 E1 E2 (1) Write data (2) Initiate message transmission (3) Read data Processor Core#1 Processor Core#2 Processor Core#3 Input Output Processor Core#4

6 Background: Message passing component Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Message Passing Unit FIFO 0 FIFO 1 FIFO 4 FIFO 2 FIFO 3 FIFO 0 FIFO 1 FIFO 4 FIFO 2 FIFO 3 connection Table E0 E1 E2 (1) Write data (2) Initiate message transmission Reconfigure entry (3) Read data Processor Core#1 Processor Core#2 Processor Core#3 Input Output Processor Core#4

7 Mix 10 instructions of types: 34%: 33%: Random Use entry Reconfigure entry The reconfiguration challenge: Shared connection table entry reconfiguration Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Random Reconfigure E1 Random Reconfigure E2 Use E1 Random Use E2 Reconfigure E1 Random Core 1Core 2 Random Runtime Actual runtime of each operation is unknown before simulation, and can change from simulation to simulation Random Reconfigure E1 Random Reconfigure E2 Use E1 Random Use E2 Reconfigure E1 Core 1Core 2

8 The reconfiguration challenge Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Core 1 Core 2 Random Reconfigure E1 Random Reconfigure E2 Use E1 Random Use E2 Reconfigure E1 Random The arrowed operations need to be synced

9 The reconfiguration challenge Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Core 1 Core 2 Random Reconfigure E1 Random Reconfigure E2 Use E1 Random Use E2 Reconfigure E1 Random Signal Poll Signal Poll Poll: Wait until a known value is written to a semaphore address before operation Signal: Write a known value to a semaphore address after operation

10 The reconfiguration challenge Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation  Is this scenario correct?  Does it have the needed synchronization operations?  Does it have deadlocks?  Lose the test generator’s power!  Only one test scenario Core 1 Core 2 Use entry 1 Signal semaphore 1 Random instructions Poll semaphore 1 Use entry 1 Poll semaphore 2 Use entry 2 Poll semaphore 3 Reconfigure entry 3 Signal semaphore 3 Use entry 2 Random instructions Poll semaphore 1 Reconfigure entry 1 Signal semaphore 1 Reconfigure entry 2 Signal semaphore 2 Use entry 3 Signal semaphore 3 Random instructions Poll semaphore 3 Use entry 3 Directed test, complete with needed synchronization operation

11 Our solution: Automatic synchronization Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Test generator tracker Transactions: thread, entry, use/Reconfigure Semaphore address and value to poll, if needed Addition The output of the tracker is a set of synchronization operations needed to preserve the intended ordering of specific transactions with respect to each other Other transactions remain unordered Template Test cases random Reconfigure E1 random Reconfigure E2 Use E1 random Use E2 Reconfigure E1 random Core 1Core 2

12 Our solution: Results Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Template before Core 1Core 2 Use entry 1 Signal semaphore 1 Random instructions Poll semaphore 1 Use entry 1 Poll semaphore 2 Use entry 2 Poll semaphore 3 Reconfigure entry 3 Signal semaphore 3 Use entry 2 Random instructions Poll semaphore 1 Reconfigure entry 1 Signal semaphore 1 Reconfigure entry 2 Signal semaphore 2 Use entry 3 Signal semaphore 3 Random instructions Poll semaphore 3 Use entry 3 BEFORE: Directed test, with synchronization operation AFTER: Totally random test, now possible Mix 10 instructions of types: 34%: 33%: Random Use entry Reconfigure entry

13 Summary Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation  Existing state-of-the-art constraint random test generator for system-level testing  New hardware requires entry reconfiguration as part of the verification  We implemented automatic barrier insertion that eliminates the need for complex directed tests  The new mechanism allows random generation of tests that use and reconfigure shared entries, with minimal intrusiveness  In the future, the same solution may be applicable for other reconfiguration challenges

© 2013 IBM Corporation For more information, contact: Erez Bilgory Alex Goryachev Ronny Morad Tali Rabetti IBM Research – Haifa Enabling easy creation of HW reconfiguration scenarios for system level pre-silicon simulation Thank You!