> -----Original Message----- > > > Linux PCI subsytem has an option resource_alignment that can be > > applied to either a single device or all devices. Booting with > > pci=resource_aligment=4096 will align each device to a page. Do you > > think pciback should force resource_alignment=4096 for dom0? >
That sounds like a good idea. > Ideally Xen should keep track of the BARs position and size and refuse > to passthrough devices that have BARs sharing a page with other > devices BARs. > > > Are > > there other MMIO ranges to be concerned about adjacent to BARs? > > IIRC you can have two BARs of different devices in the same 4K page, > BARs are only aligned to it's size, so BARs smaller than 4K are not > required to be page aligned. If we had a notion of assignment groups for this, as well as devices sharing requester id, then Xen would not need to refuse pass-through, it would just require that all devices sharing the page were passed through as a unit. Paul
