On Thursday 24 December 2009 14:51:23 Simon Horman wrote: > On Thu, Dec 24, 2009 at 01:45:34AM +0100, Alexander Graf wrote: > > Am 23.12.2009 um 23:40 schrieb Chris Wright <chrisw@xxxxxxxxxxxx>: > > >[ resend, fixing email header, sorry for duplicate ] > > > > > >The default mode for device assignment is to rely on an IOMMU for > > >proper translations and a functioning device in the guest. The > > >current > > >logic makes this requirement advisory, and simply disables the request > > >for IOMMU if one is not found on the host. This makes for a confused > > >user when the device assignment appears to work, but the device in the > > >guest is not functioning (I've seen about a half-dozen reports with > > >this failure mode). > > > > > >Change the logic such that the default requires the IOMMU. Period. > > >If the host does not have an IOMMU, device assignment will fail. > > > > > >This is a user visible change, however I think the current > > >situation is > > >simply broken. > > > > > >And, of course, disabling the IOMMU requirement using the old: > > > > > > -pcidevice host=[addr],dma=none > > > > > >or the newer: > > > > > > -device pci-assign,host=[addr],iommu=0 > > > > > >will do what it always did (not require an IOMMU, and fail to work > > >properly). > > > > Yay! > > Sounds good to me. Though I am curious to know the reasoning > behind the current logic. > Sounds pretty good. :) I think maybe it due to we are interested in implementing PV DMA? -- regards Yang, Sheng -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
