Re: [Qemu-devel] Why devfn will be -1

[Jan Kiszka <jan.kiszka@web.de>]

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Hi Le,

On 2014-07-01 04:34, Le Tan wrote:
> 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.

Hmm, I have no idea about the reason and would suggest to set a
conditional breakpoint on this function, then print the backtrace to see
where this comes from and analyze the device structure from where that
-1 was most probably taken.

Jan



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