[Qemu-devel] Why devfn will be -1

[Le Tan]

Hi Jan,
I use pci_setup_iommu() to setup a PCIIOMMUFunc for the q35 pci bus.
In the iommu_fn, I print out the devfn parameter and find out that it
sometimes will be -1. So what does it mean?
The detail code is here:

In mch_init() function, I write like this:
PCIBus *pci_bus = PCI_BUS(qdev_get_parent_bus(DEVICE(mch)));
pci_setup_iommu(pci_bus, q35_host_dma_iommu, mch->iommu);

And in q35_host_dma_iommu(PCIBus *bus, void *opaque, int devfn), I
print out the devfn parameter, sometimes it will be -1.

Thanks very much!

Regards,
Le