On Tue, Nov 24, 2015 at 09:59:09PM +0000, Woodhouse, David wrote: > On Tue, 2015-11-24 at 13:53 -0800, Shaohua Li wrote: > > Currently if a device has rmrr or the device is a pci device, > > passthrough is disabled even with iommu=pt. The worry is moving such > > devices between domains don't work. But some users don't do the domain > > reassignment at all, disabling passthough punish everybody. And iommu=pt > > is a boot option, user knows the risk. So intead of failing the > > passthough, just print a warning and continue the passthough. > > We tend to suggest that iommu=pt gives you performance for the *decent* > devices, while dubious devices still get translated. So your crappy 32- > bit devices still get translated. And anything unfortunate enough to > have an RMRR can *still* get translated. > > I'm reluctant to change that. If it hurts you, kick your system vendor > until they stop doing stupid things with RMRRs.
Hmm, yes, it's a device with RMRR. Don't think we can ask vendor to stop it though. > I think we also need to revisit the whole 'iommu=pt' thing anyway and > define the semantics we expect across archiectures — given that SPARC > and POWER are doing passthrough for 'decent' devices by *default*. So > let's not tweak it right now. I'd really like an option to avoid the penality for RMRR devices. Would a new option like 'iommu=strictpt' work? _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
