Erik Brakkee wrote:
Hi,
I am using a tv card in a VM and get jerky video.As I understand it,
the VM is using USB 1.1. However, when I set the USB controller in the
BIOS of my server to Fullspeed (12 Mbit/s) which is the USB 1.1 speed
I am able to get perfect results on the host but still on the guest
the video is jerky.
Are there some tuning parameters I can use or perhaps even kernel
configuration paramters on the host to solve this?
Cheers
Erik
Host: Motherboard Supermicro X8DTi-F, Intel Xeon L5630, 12MB
OS: Opensuse 11.3 64 bit
Guest: OS: Opensuse 11.3 64 bit
I can say now that I am giving up on getting this to work. One
alternative was to use PCI passthrough the USB hardware, but that
didn't work for the USB that was on the motherboard. So I bought a USB
PCI card and tried to use PCI passthrough for that. Unfortunately other
problems occured there.
For one, the problem with 4K alignment. But I could fix that by using
the pci=resource_alignment=... kernel parameter. In my grub/menu.lst it
says:
kernel /vmlinuz-2.6.34.7-0.5-default root=/dev/hsystem/root quiet
showopts intel_iommu=on
pci=resource_alignment=01:04.0;01:04.1;01:04.2 noirqdebug vga=0x31a
The noirqdebug flas was needed to avoid the host from disabling the IRQ
(it was a shared IRQ).
Using this, I could configure PCI passthrough and start the VM. Also the
USB device showed up there. Only it did not work at all.
Here is a summary of my journey up until know:
The original approach I wanted to use was to pass my old PCI card (WinTV
PVR-500) to a VM. This card is a well supported card and has been doing
fine for me. Because of the PCI passthrough problems with the wintv
card, I decided to try a USB card instead. This gave me a 'ctrl buffer
too small' issue that I could solve by taking the source RPM for kvm and
applying a known patch from red hat (increasing buffer size from 2048 to
8192). But then I got jerky video, probably due to USB 1.1 issues. To
bypass these I could use PCI passthrough for USB. But with the PCI
passthrough of this card I am again running into issues probably related
to Shared IRQs. So, after all this I am back to square one.
I have now modified my approach so instead of running a separate minimal
host with my old server as a guest, I am now running the old server
(same install) on the new hardware, using it as a host. I would
definitely be interested in trying this out further in the future. I
even tried Xen for a brief moment, only to realize that my host and
guest felt slower (slower startup and execution) and much more difficult
to handle.
From the experience of the last two days fulltime trying to get things
working I can only conclude that the following two features would be
really important to have:
* Extended PCI passthrough support
o shared IRQ support
o supporting cases where memory is not aligned on a 4K boundary
* USB passthrough
o support USB 2.0
o support USB 3.0 (but taking one step at a time, 2.0 would
also be great).
From the above, PCI passthrough improvements are most important as they
will also allow (cheap) workarounds for USB passthrough issues.
I am definitely interested in hearing about new releases from KVM. Is
there a mailing list I should subscribe to get information about the
latest releases without intermediate discussions? I would also be
interested in using latest stable versions of KVM for opensuse. Is there
any repository I can configure to get those?
Cheers
Erik
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