Re: Generic PV Guests on XCP?

[Ian Campbell <Ian.Campbell@citrix.com>]

On Wed, 2010-03-24 at 18:14 +0000, Phil Winterfield (winterfi) wrote: 
> Has anyone attempted to run a generic (read non Linux/Windows)
> paravirtualized guest OS instance on XCP -0.1.1?  A good example would
> just be building mini-OS and running it as a guest instance on XCP.
> My company has PV OS prototype version of one of its products that has
> been running on non-XCP versions of Xen and I would like to evaluate
> whether XCP is a suitable platform.  In order to do this I need to get
> past some pretty basic questions and issues.  For example, if you were
> to run mini-OS in a VM, what template would you start with?  I started
> out with "Other install media" but it is unclear if that is
> appropriate.  I was able to create the guest instance shown below, but
> that leads to the other questions, i.e.

I don't think you want to start from a template here, since none of the
existing ones meet your needs/usecase. You can create a basic VM
instance with "xe vm-create" and then configure that however you need by
modifying the various fields on the VM object. You may choose to convert
it to a template for convenience of instantiating multiple copies (using
"xe vm-install").

> 1)     How do the old config file startup parameters for my OS
> instance map to the new ‘xe’ syntax, e.g. 

Given a VM UUID (call it $VM) returned by xe vm-create you can do "xe
vm-param-set uuid=$VM param1=val1 param2=val2" just like you have been
doing. I think the fields are all documented in the reference manual --
unfortunately I can't find the XCP version anywhere online. Does anyone
know where this is?

Until that document is found I think the core stuff you are interested
in the same as on XenServer stuff so that reference doc should be enough
to get you going:
http://docs.vmd.citrix.com/XenServer/5.5.0/1.0/en_gb/api/docs/html/browser.html

Once you have created the VM you probably want to set PV-bootloader,
PV-kernel, PV-ramdisk, PV-args as you are now.

If you aren't going to create a template then you can just use "xe
vm-disk-add" to add disks to your VM as required. If you are going to
convert to a template and install from there then it would be better to
set other-config:disks to a suitable snippet of XML to create the
appropriate disks at vm-install time -- see the existing templates for
an example of the syntax.

> memory = 2048

I think you have to use xe vm-memory-{static,dynamic}-range-set instead
of vm-param-set for these ones. Each one takes a min and a max. In the
first instance I'd just set them all the same, i.e. "2048MiB" but in the
future if you are interested in enabling ballooning you can set ranges
etc.

> vcpu=1

Set VCPUs-max and VCPUs-at-startup. Again I would set them to the same
value to start with until you want to be able to dynamically add more
VCPUs than you started with to your VM without rebooting.

> on_crash = 'coredump-destroy'

You can set "action-after-crash" to one of "Preserve", "Destroy",
"Restart". I don't know if there is a direct equivalent to
coredump-destroy in XCP.

> 2)     How do I connect to the serial console on the OS instance?  For
> instance, when I do:

The consoles are exported via XenAPI in VNC format. You need a XenAPI
client which is capable of attaching to these. Looks like
http://www.xvpsource.org/ is the place to look?

Personally I usually use /opt/xensource/debug/vncproxy (copied to my
workstation) to create a local socket on my workstation which is proxied
to the XCP host and then run vncviewer locally against that proxy.

Ian.