Managing Aggressive Behavior in Reading Rooms: Practical Insights
Collection security expert Dr. Wolfgang-Valentin Ikas discusses strategies for dealing with readers who do not follow rules in manuscript reading rooms, including potential dangers and staff support methods. Addressing physical aggressiveness, training staff in de-escalation, considering security services or emergency buttons, and handling activist or terrorist threats are also explored.
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Bit-Exact ECC Recovery (BEER): Determining DRAM On-Die ECC Functions by Exploiting DRAM Data Retention Characteristics Minesh Patel, Jeremie S. Kim Taha Shahroodi, Hasan Hassan, Onur Mutlu MICRO 2020 (Session 2C Memory)
Minimum viable operating timings? Temperature dependence? Aggregate failure rates? What are the DRAM chip s reliability characteristics? Weak cell locations? Statistical error distributions? Inter-chip variation? System Designer Test/Validation Engineer Research Scientist Third-party DRAM consumer 2
DRAM Testing and Error Characterization On-die ECC Study observed bit flips Unknown & Proprietary Study observed bit flips Bit flips obfuscated by on-die ECC No feedback to CPU upon error correction 3
DRAM Testing and Error Characterization On-die ECC On-die ECC complicates third-party DRAM testing Study observed bit flips Bit flips obfuscated by on-die ECC Unknown & Proprietary No feedback to CPU 4
Overcoming Challenges of On-Die ECC Our goal: Determine exactlyhow on-die ECC obfuscates errors (i.e., its parity-check matrix) DRAM Chip ECC Logic I/O Data 5
BEER Methodology Induce uncorrectable errors 1 Aggregate unique error patterns 2 Solve for the parity-check matrix 3 BEER requires no special hardware or knowledge https://github.com/CMU-SAFARI/BEER 6
Experimental demonstration 80 LPDDR4 DRAM chips (3 major manufacturers) Two-Part Evaluation Simulated correctness and practicality Over 100,000 representative ECC codes of varying word lengths (4 247 bits) 7
1. Different manufacturers appear to use different parity-check matrices Experimental demonstration 80 LPDDR4 DRAM chips (3 major manufacturers) 2. Chips of the same model appear to use identical parity-check matrices Two-Part Evaluation 1. BEER works for all simulated test cases Simulated correctness and practicality Over 100,000 representative ECC codes of varying word lengths (4 247 bits) runtime and memory usage 2. BEER is practical in both 8
Crafting worst-case test patterns Studying raw bit error properties Profiling for error-prone physical cells Root-cause failure analysis BEER Use Cases Designing Systems Improving on-die ECC System-level error-mitigation mechanisms 9
Bit-Exact ECC Recovery (BEER): Determining DRAM On-Die ECC Functions by Exploiting DRAM Data Retention Characteristics Minesh Patel, Jeremie S. Kim Taha Shahroodi, Hasan Hassan, Onur Mutlu MICRO 2020 (Session 2C Memory)
