VDTF - Virtual Device Test Framework

Note A Linux driver development and benchmarking platform built on QEMU raspi3b emulation.

What it does

• Emulates BME280 sensor (I2C + SPI) in QEMU
• Implements custom kernel drivers for both interfaces
• Benchmarks latency, throughput, and CPU usage

Quick Start

./scripts/setup.sh        # build kernel + rootfs
./scripts/setup_qemu.sh   # build QEMU with custom devices
./scripts/make_image.sh   # package image
./deploy/start_qemu.sh    # boot

In guest

# upstream kernel driver
/root/test/load_kernel.sh
/root/test/bench kernel

# custom driver
/root/test/load_simple.sh
/root/test/bench simple

Results

I2C vs SPI (upstream driver)

	I2C	SPI
avg	264 us	90 us
p99	832 us	334 us
throughput	3787 /sec	11111 /sec

SPI is ~3x faster due to no ACK overhead and full-duplex communication.

Custom vs Upstream driver

	I2C kernel	I2C simple	SPI kernel	SPI simple
avg	264 us	761 us	90 us	140 us
throughput	3787 /sec	1314 /sec	11111 /sec	7142 /sec

Upstream driver is faster due to regmap caching and IIO framework optimizations.

QEMU Limitations

Timing reflects software overhead only. On real hardware, SPI advantage would be more pronounced (100kHz vs 10MHz clock).