Beyond the Controller: IvyLink™ CXL Memory Fabric Architecture

Standard CXL controllers give you a compliant link. But memory pooling demands more — dynamic allocation, QoS guarantees, multi-host cache coherence, and RAS that doesn’t exist in the spec.

The Controller Gap

CXL 3.0 spec defines the wire protocol. But a standard controller gives you:

• Link initialization and training
• Transaction layer (PCIe + CXL.mem/cache)
• Basic register interface

What it doesn’t give you:

• Memory Pool Manager — dynamic allocation, tiering, QoS across hosts
• Fabric Manager — topology discovery, routing, congestion control
• Coherency Agent — multi-host cache coherence for CXL.cache
• Security/RAS Agent — SPDM, telemetry, predictive failure

Hyperscalers build these in-house. We productized them.

IvyLink™ CXL Memory Fabric Architecture

┌─────────────────────────────────────────────────────────────┐
│                    CXL Memory Fabric                          │
├─────────────────────────────────────────────────────────────┤
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────┐          │
│  │ CXL 3.0     │  │ CXL 3.0     │  │ CXL 3.0     │          │
│  │ Controller  │  │ Controller  │  │ Controller  │          │
│  └──────┬──────┘  └──────┬──────┘  └──────┬──────┘          │
│         │                │                │                  │
│         └────────────────┼────────────────┘                  │
│                          ▼                                   │
│              ┌─────────────────────────┐                     │
│              │    Memory Pool Manager  │  ← Our IP          │
│              │  (Allocation/Tiering/QoS)│                   │
│              └───────────┬─────────────┘                     │
│                          ▼                                   │
│              ┌─────────────────────────┐                     │
│              │    Fabric Manager       │  ← Our IP          │
│              │ (Topology/Routing/QoS)  │                     │
│              └───────────┬─────────────┘                     │
│                          ▼                                   │
│              ┌─────────────────────────┐                     │
│              │  Coherency Agent        │  ← Our IP          │
│              │  (Multi-host CXL.cache) │                     │
│              └───────────┬─────────────┘                     │
│                          ▼                                   │
│              ┌─────────────────────────┐                     │
│              │  Security/RAS Agent     │  ← Our IP          │
│              │  (SPDM/Telemetry)       │                     │
│              └─────────────────────────┘                     │
└─────────────────────────────────────────────────────────────┘

Key Differentiators

1. Memory Pool Manager

Dynamic allocation with QoS guarantees — not best-effort:

• Guaranteed bandwidth per tenant via weighted fair queuing
• Latency isolation — tail latency < 500ns even under contention
• Tiering policies — hot/cold data migration between HBM/DDR/CXL.mem

2. Fabric Manager

CXL 3.0 enables multi-level switching. Our fabric manager handles:

• Topology discovery (CXL 3.0 hierarchy)
• Adaptive routing with congestion avoidance
• QoS-aware routing — latency-sensitive traffic gets priority paths

3. Coherency Agent

CXL.cache enables multi-host coherence. Our agent implements:

• Directory-based coherence with distributed directories
• Snoop filter reducing broadcast traffic by 89%
• Conflict resolution for concurrent writes from multiple hosts

4. Security/RAS Agent

Production hardening beyond the spec:

• SPDM 1.2 for device authentication and measurement
• Telemetry streaming — latency histograms, error counters, predictive failure
• Predictive failure — ML-based wear-out detection for CXL memory modules

Silicon Validation (130nm CMOS5L)

Component	Area	Power @ 32 GT/s
CXL Controller	2.1 mm²	850 mW
Memory Pool Manager	0.4 mm²	45 mW
Fabric Manager	0.3 mm²	32 mW
Coherency Agent	0.5 mm²	58 mW
Security/RAS	0.2 mm²	18 mW
Total	3.5 mm²	~1.0 W

Business Model: Solution + Service

We don’t just sell RTL. We deliver:

1. Customized RTL — tailored to your topology (2/4/8-socket, switch topology)
2. Firmware stack — Linux kernel driver, SPDM stack, telemetry agent
3. Integration service — 3-month bring-up support
4. SLA-backed support — 24/7 for hyperscalers

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Learn more about IvyLink™ CXL Memory Fabric → Product Page | Contact Sales