She looked one more time at the output of lspci . The device was still just a line of hexadecimal. But now, she had looked inside. And it made sense.
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. driver for pci device
pci_write_config_byte(pdev, 0x82, 0x01); pci_write_config_byte(pdev, 0x8F, 0x10); She looked one more time at the output of lspci
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. And it made sense
The file unfolded. Forty-thousand lines of C, a cathedral of bit twiddling and DMA descriptors. Elara began her liturgy.
The system exhaled a stream of hex and status flags. There it was: "Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411." But Elara didn't trust the name. Names were for users. She was after the soul of the thing.