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ROCm, a New Era in Open GPU Computing

Platform for GPU-Enabled HPC and Ultrascale Computing

Hardware to Play ROCm

ROCm Platform Supports Two Graphics Core Next (GCN) GPU Generations

Supported CPU

ROCm Platform leverages modern CPUs supporting PCI Express 3.0 or greater, exploiting advanced capabilities including PCIe Atomics (Fetch and Add, Compare and Swap, Unconditional Swap, AtomicOp Completion). To find out more; PCIe Atomics and Large Bar Overview

To support ROCm programming model, the GPUs are installed in PCIe slots with PCI Express 3.0 or higher capabilities with transfer rates of 8.0 GT/s in either x16 or x8 lanes. The system configuration can have the PCIe slots directly on CPU’s root port or a PCIe switch port. The CPU root must indicate PCIe AtomicOp Completion capabilities and any intermediate switch must indicate PCIe AtomicOp Routing capabilities.

PCIe root port must report and support

All PCIe switches between GPU End Point and Root Point must report and support

Note that the physical PCIe slot size does not guarantee support for ROCm. We have reports of few consumer motherboards which support physical x16 PCIe slots, but the PCIe connector is electrically connected as x4 PCIe Express 2.0 from the Southbridge. Since the PCIe slot connector matters to the GPU, care must be taken to not place them in on motherboards configured this way.

ROCm Kernel driver logs if ROCm capable GPUs are installed on system that does not support PCIe atomics.

Example text from kernel log: kfd: skipped device 1002:7300, PCI rejects atomics

When you install your GPU’s Make sure you install them on real PCIexpress Gen3 (PCIe Gen3) x16 or x8 lanes directly on CPU’s Root I/O controller or a PCIe Switch directly attached to the CPU’s Root I/O controller. We have seen many issue with Consumer motherboard which support Physical x16 Connectors, but the connector is electrically connected as PCIe Gen2 x4, if you see this it is typically hanging off the Southbridge PCIe I/O controller. If your motherboard is configured this way please do not use this connector for your GPU.

Current CPU which support PCIe Gen3 + PCIe Atomics are:
Curently Not supported

AMD Carrizo based APU have limited support due to OEM & ODM’s Carrizo enabled Laptop, All In One System and Desktop system had inconsistency in supporting the correct System BIOS configurations for ROCm driver enablement. Before you buy a Carrizo system to run ROCm. You should check the SBIOS to see if has an option to enable IOMMUv2. If this is enabled, next we need test for the correct CRAT Table support to properly configure the driver.