Re: [Xen-users] [Xen-devel] Cannot Start Linux Paravirtualized (PV) Guests with Xen 4.2-unstable

["Teo En Ming (Zhang Enming)" <singapore.mr.teo.en.ming@xxxxxxxxx>]

On 30/03/2012 05:09, Sergey Zhukov wrote:
> > 3) When I was installing Ubuntu 12.04 Beta 1 Precise Pangolin amd64 as
> > a HVM domU in either Xen 4.1.3-rc1-pre or Xen 4.2-unstable, it hanged
> > at COPYING FILES during installation. Hence I have to abort the HVM
> > domU installation. Disk I/O performance is very poor.
> > 4) Disk I/O performance is very poor with Debian 6.0 Squeeze PV domU
> > in Xen 4.2-unstable and with Fedora 16 x86-64 PV domU in Xen
> > 4.1.3-rc1-pre. The mouse cursor movement in both Fedora 16 and Debian
> > 6.0 Squeeze PV domU is very sluggish and unresponsive. It also takes a
> > long time to format filesystems and install packages in PV domU during
> > OS installation. What causes the performance penalty in disk I/O?
> > 5) Disk I/O performance is also very poor with Ubuntu 12.04 Beta 1 HVM
> > domU installation. Formatting filesystems and copying files during
> > installation take a long time. Mouse cursor movement is also very
> > unresponsive.
> I installed Ubuntu 12.04 beta server (AMD 64) and xen hypervisor from
> ubuntu xen packages (v4.1).
> Then I installed Ubuntu 10.04 server as PV DomU and Ubuntu 10.04 desktop
> as HVM DomU.
> I could not enable IO virtualization, because iommu=1 and iommu=verbose
> parameters seem to be not working.
Dear Sergey Zhukou,

Thank you very much for your reply.

I did not have to specify IOMMU=1 and IOMMU=verbose in my multiboot 
xen.gz command line in GRUB2. IOMMU is enabled by default in Xen 
4.2-unstable.
sudo xl dmesg | grep 'I/O Virtualisation'

(XEN) I/O Virtualisation Enabled

> When I run tests for my specific software I found, that in Ubuntu 10.04
> HVM DomU there are too many interrupts when dealing with network.
> Processor took about 50%si. I did not test disk IO, but think the
> picture should be the same.
When I am installing Ubuntu 12.04 Beta 1 HVM domU, the network 
connection gets disconnected and re-connected many times. Did your 
installation hanged at copying files while installing Ubuntu 10.04 HVM domU?
> But I found solution, which works perfect for me. I installed Ubuntu
> 12.04 desktop beta (i386) as PVHVM DomU. It installed without hangs and
> it works very fast with network and disk.
I do not know what is PVHVM, I only know PV domU and HVM domU separately.

> Only one thing looks ugly: I can't change maximal resolution of the
> desktop more than 1024x768 (despite of settings stdvga=1 and
> videoram=16)
>
> Also, I would like to know, how to enable verbose logs for iommu,
> because xm dmesg does not show me any information about VT-d. I have the
> line
> (XEN) Command line: placeholder iommu=verbose
> in the dmesg logs, but still not got verbose logs...
I do not know how to enable verbose logs for IOMMU.

Have you tried "sudo xl dmesg | grep VT-d"?

> Sergey Zhukov

--
Yours sincerely,

Mr. Teo En Ming (Zhang Enming)
Singapore


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