HBM Retention Bake

Overview

The hbm_retention_bake is a specialized diagnostic that tests for thermal charge leakage within the physical memory cells. It verifies if the HBM capacitors can retain their electrical charge under extreme silicon temperatures.

Execution Mechanics

Unlike standard memory tests, the memory controllers are intentionally left idle during the stress phase:

1. Payload Injection: A highly distinct payload (0x12345678, 0x9ABCDEF0, etc.) is written to the entire VRAM allocation.
2. The Bake Phase: A pure ALU power virus is launched. This generates massive localized die heat without touching the memory interface.
3. Verification: After the bake duration finishes, the payload is read back to detect any bit flips or corrupted blocks caused by thermal leakage.

Target Subsystems

• Primary Target: Physical HBM Capacitors and memory cell integrity.

Failure Symptoms

Critical Failures

• Corrupted Blocks: The test will output [FAIL] Thermal Charge Leakage Detected if the heat caused the capacitors to lose their state before the hardware refresh cycle could recharge them.