cd /usr/src/linux/drivers/net/ethernet/realtek/
She ran her analyzer: ./pcap_check --drop-test --interface eth0 --duration 60 .
Her fingers danced again. cat /sys/bus/pci/devices/0000:04:00.0/uevent . The kernel spat back the raw truth: DRIVER=r8169 . The generic driver. The workhorse.
The link came up. The drone's test pattern started: 10,000 packets per second, each with a sequence number.
The first ten seconds: perfect. Twenty seconds: perfect. Sixty seconds: zero drops.
Then she found it. The interrupt handler: rtl8169_interrupt . On a packet receive, the chip raises a line on the PCI bus. The kernel calls this routine. The routine reads a status register via MMIO. Then it does the dance: acknowledge the interrupt, schedule an NAPI poll, clear the bit.
Elara leaned back. The vineyard would be saved. The Pinot Noir would flow.
