[Qemu-devel] hello world pci device

[Yohann Martineau]

hello,

I'm learning uefi and qemu.

If I understand correctly, in uefi, device drivers contain at least three functions: supported, start and stop. When PCI devices are discovered, all drivers "supported" function is invoked and if this function returns true, its "start" function is invoked later to manage the device properly.

The "supported" function seems to be looking for pci vendor id and device id to know whether it supports this device or not.

I've tested hello world applications and drivers provided by intel on their tianocore site (with edk2). They suggest launching the uefi shell and either launching the application manually or loading the driver manually from the uefi shell. It works, I tested with OVMF and qemu. But now I want this driver invoked automatically when a PCI device is discovered.

To do this, I want to add a new fake device in qemu that will just trigger pci detection by uefi bios so that I can trigger my uefi driver code with dummy pci vendor and device ids.

I'm sorry, this is really a beginner's question and it has probably been asked many times, but is there a hello world device code for qemu somewhere? I've been looking for it but cannot find a clue.

I think I'll take an emulated pci device in qemu's source code and take it as an example, if you have any suggestion or typical mistakes to avoids...

Thank you,

yohann