[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] dom0 linux: Reassign memory resources to device for pci passthrough.
On Thu, 9 Oct 2008 11:21:22 +0800 "Zhao, Yu" <yu.zhao@xxxxxxxxx> wrote: > On Thursday, October 09, 2008 7:44 AM, Yuji Shimada wrote: > >There is a similar function enabled by pci-mem-align boot > >parameter. Currently it is kept. But if many people agree with me, I'd > >like to remove it from dom0 linux, because there are two problems. > > > > - pci-mem-align reassigns all devices' memory resources if they are > > not page-aligned. This is not safe, because some devices are > > used by firmware. > > - pci-mem-align can't expand resource window of PCI-PCI bridge. > > Why the resource windows can't be expended? I think the > pci_bus_size_bridges takes care of this. So it shouldn't be a > problem and your pci_update_bridge appears unnecessary. Current pci_bus_size_bridges calculates the size and minimal alignment of resource window based on actual resource size. The values of them will be not changed if pci-mem-align is enabled. But if we make memory resource page-aligned, we need more space. My patch rounds up resource size to page size, on calculating the size of resource windows. > Regarding the first problem you mentioned, it could be easily fixed > by merging your "rassigndev=" parameter to quirk_align_mem_resources > so the function can selective twist the devices. If my "rassigndev=" parameter is merged to quirk_align_mem_resources, problem will occurs. Current quirk_align_mem_resources shifts resources simply. Resources will conflict easily. If confliction occurs, kernel reassigns conflicting resources. As a result, the resources of device which are not specified are reassigned. Additionally, the reassigned resource is not page-aligned. Thanks, -- Yuji Shimada _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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