On Tuesday 07 October 2008 21:42:41 Avi Kivity wrote: > Sheng Yang wrote: > > Seems we needn't tell userspace if MSI can be enabled. It's determined > > mostly by the device, and pci_enable_msi() checked that. > > > > So I think QEmu can expose MSI capability if the device got it. If it's > > fail to be enabled, just fall back to IRQ and return error to QEmu is > > enough, of course, QEmu should set MSI enable bit after kernel space > > done. > > Do we need to add the additional condition, "and if the host kernel > supports it"?
Well, for VT-d, it's impossible because CONFIG_DMAR depends on CONFIG_PCI_MSI... And for non-VT-d(I don't know about PV or AMD IOMMU), from 2.6.18, MSI support have been added, before KVM merged. And we also got ifndef CONFIG_PCI_MSI, pci_enable_msi return -1. So we can still fall back to IRQ without error. How do you think? -- regards Yang, Sheng -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
