[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Struggling with PCI-Passthrough
On 2014-03-24 19:18, Alexander Brychcy wrote: As ever there are only problems with domU #2. The first one, that i could not passthrough an USB controller resolved. No matter at which port you plug an USB device on the mainboard, it is always assigned to the XHCI controller. I found that on Intel ICH USB controllers the PCI USB device that the USB device is attached to changes dependant on what is connected. There is some odd routing going on. This is especially the case when a USB hub is connected to a port. If you just want to pass through, say, a keyboard, it is stable, but IIRC the device has to be connected to theport before you re-assign the PCI device that is the port to xen-pcistub. My motherboard also comes with a NEC USB 3.0 adapter on-board which doesn't suffer from this problem, so for VMs that require multiple USB devices I have a USB hub on that controller and I pass the whole controller to the VM. My workaround is to add another PCIe USB controller for the vm, so i'm still able to have usb connection in dom0 for backup or other purposes. Sounds similar to what I do. Note that you can also pass specific USB devices to the domU, rather than using PCI passthrough for the USB controllers. Unfortunately this comes with ~5% CPU idling overhead in domU due to USB polling. Tried to passthrough a NIC to verify if it is a bios related bug. This works without any problems and nothing freezes at all. I suspect you are just seeing the Intel ICH USB weirdness I described above. So last but not least the VGA Passthrough. Issue is still present. HVM boots and GPU is assigned and working. But after some time respectively an application tries to access some kind of function the whole system freezes. How much RAM are you passing to the VM? It is possible your motherboard suffers from the same problem as mine and IOMEM DMA is bypassing the root PCIe hub. Do the following:lspci -v | grep "Memory at" | sed -e 's/.*Memory at //' -e 's/ .*//' | sort Convert the first address that comes back from hex, and set the amount of memory you are passing to your VM to a few MB below that. Then see if the crash still happens after a while. If it doesn't, then there is a good chance that what is happening is that your VM's memory is trampling over the IOMEM region of the host because it isn't being translated by the IOMMU, probably because DMA is bypassing it. In my case this is caused by a bug/feature of NF200 PCIe switches, but it could also be caused by a buggy motherboard chipset or firmware. Nearly forgot the RAM problem. The maximum amount of RAM i can assign tothe HVM when i passthrough the GPU is 3GB. Haven't tried it yet but may this patch still be usable with 4.4.0? http://www.davidgis.fr/blog/index.php?2013/04/05/937-xen-43-unstable-vga-passthrough-hd-7970-windows-7-64-bits-with-more-than-3gb-for-ram I think this is for a different bug, but probably worth a try depending on what results you get with domU memory size reduced to ensure it cannot trample IOMEM regions. Gordan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |