AHCI Storage Driver
Advanced Host Controller Interface for Serial ATA
Overview
AHCI is the modern standard for SATA (Serial ATA) storage. It replaces the legacy IDE/ATA interface with a more efficient DMA-based approach. AOS supports AHCI for faster disk I/O.
AHCI vs Legacy ATA
| Feature | Legacy ATA | AHCI |
|---|---|---|
| Data Transfer | PIO (slow) | DMA (fast) |
| Command Queue | One at a time | 32 parallel |
| Interface | I/O ports | Memory-mapped |
AHCI Command Submission
- Write command table to memory
- Set command list entry
- Write command issue register
- Controller executes command via DMA
- IRQ signals completion
- Read command completion status
Key Takeaways
- ✓ AHCI is modern SATA standard
- ✓ DMA-based for efficient transfers
- ✓ Supports command queueing
- ✓ Memory-mapped register access
- ✓ Interrupt-driven completion