axdevice

axdevice is a reusable, OS-agnostic device abstraction layer designed for virtual machines. It allows dynamic device configuration and MMIO emulation in no_std environments, making it suitable for hypervisors or operating systems targeting RISC-V or AArch64.

✨ Highlights

• 📦 Componentized: Designed as a modular crate to be integrated into any OS or hypervisor.
• 🧩 Flexible device abstraction: Supports dynamic device registration and MMIO handling.
• 🛠️ No std required: Uses alloc and core only, suitable for bare-metal development.
• 🧵 Thread-safe: Devices are stored using Arc, ready for multicore use.
• 🧱 Easily extensible: Just plug in device types via axdevice_base::BaseDeviceOps.

📦 Structure

• config.rs: Defines AxVmDeviceConfig, a wrapper for device configuration input.
• device.rs: Defines AxVmDevices, manages and dispatches MMIO to registered devices.

📐 Dependency Graph

               +-------------------+
               |  axvmconfig       | <- defines EmulatedDeviceConfig
               +-------------------+
                         |
                         v
+------------------+     uses      +-----------------------+
|  axdevice        +-------------->+  axdevice_base::trait |
|  (this crate)    |               +-----------------------+
+------------------+                      ^
        |                                 |
        v                                 |
+------------------+                      |
|  axaddrspace     | -- GuestPhysAddr ----+
+------------------+

🔁 Usage Flow

[1] Load VM device config (Vec<EmulatedDeviceConfig>)
        ↓
[2] Create AxVmDeviceConfig
        ↓
[3] Pass into AxVmDevices::new()
        ↓
[4] MMIO access triggers handle_mmio_{read,write}
        ↓
[5] Device selected by GuestPhysAddr
        ↓
[6] Forwarded to BaseDeviceOps::handle_{read,write}()

🚀 Example

use axdevice::{AxVmDeviceConfig, AxVmDevices};

// Step 1: Load configuration (e.g. from .toml or hypervisor setup)
let config = AxVmDeviceConfig::new(vec![/* EmulatedDeviceConfig */]);

// Step 2: Initialize devices
let devices = AxVmDevices::new(config);

// Step 3: Emulate MMIO access
let _ = devices.handle_mmio_read(0x1000_0000, 4);
devices.handle_mmio_write(0x1000_0000, 4, 0xdead_beef);

📦 Dependencies

• axvmconfig
• axaddrspace
• axdevice_base
• log, alloc, cfg-if, axerrno