Jan Kiszka wrote:
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
Addressed by the series I sent out today.
Does this mean I have a chance now that PCI passthrough of my WinTV
PVR-500 might work now?
What version is this and where can I get this for opensuse?
I still have the setup I used for testing with the host OS still
installed but not running so it would be really easy to try out new
releases of KVM (it is not a serious production server after all but
mainly used to run some websites and mailing lists).
o supporting cases where memory is not aligned on a 4K boundary
Hmm, I'm seeing warnings here when passing through one of my EHCIs, but
no fatal errors.
In my case, the domain just didn't start.
Btw. I was using 0.12.5 on opensuse 11.3 but could only find the sources
for 0.12.3 on download.opensuse.org (perhaps I looked wrong) and I
patched those for th 4K issue. PCI passthrough also did not work with my
wintv pci card with KVM 0.12.5.
* 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).
Note that this will not solve any real-time issue (if that is part of
your problem). E.g.: While my EHCIs work nicely in PCI-passthrough
scenarios, I'm unable to use certain webcams that sooner or later run
out of sync.
Jan
Is your point in this case that USB in a VM based on PCI passthrough
will always have problems when it comes to more real-time issues or does
this only apply to USB passthrough? I can imagine that PCI passthrough
is better since it uses hardware support. By the way, I have seen issues
in the past whereby the tv card stopped working because of high load on
the server running natively so real-time issues also exist apart from
virtualization.
Apart from this, I am definitely interested in getting updates for KVM
on opensuse. Is there a channel for that?
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