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Re: [libvirt] [PATCH 1/2] Add VSCSI bus type and VSCSI controller type for pseries guest.



On Fri 04 May 2012 05:55:46 PM CST, Daniel P. Berrange wrote:
On Fri, May 04, 2012 at 05:49:54PM +0800, Li Zhang wrote:
On 05/04/2012 05:04 PM, Daniel P. Berrange wrote:
On Fri, May 04, 2012 at 10:05:13AM +0800, Li Zhang wrote:
Now, there is only SCSI bus and controller type in libvirt.
And when configuring VSCSI controller, it needs to configure
the spapr-vio bus address type externally. It's a little
inconvenient to configure the controller type.

This patch is to add VSCSI bus type and VSCSI controller type.
And handle with the problems when VSCSI and SCSI devices
working together, by assign the even number to index of
VSCSI controller and odd number to index of SCSI controller.

And when the VSCSI controller is always assigned as SPAPRVIO
bus address type and SCSI controller will be always assigned
as PCI bus address, which is implemented according to the
controllers' type.

So when one disk is based on VSCSI controller, then assign
the bus as 'vscsi', and one right VSCSI controller will be
selected.

I'm not at all convinced by this description that we need
a new controller type. At most we need a separate<address/>
type for the VSCSI controller under an existing SCSI controller
element.


The problem is that when using two kinds of SCSI controller,
vscsi and scsi, which are based on different address type and
model at the same time, it needs to specify the model and address
type externally. And it's hard to find the right controller for
disk to use, only by the 'sdx'.

Sure, but there's nothing special about s390 / vSCSI in that
respect.  If you have a guest with a SATA controller and a
SCSI controller you have the same problem. If you have multiple
disk controllers assigned to the guest, and are adding a disk,
then you are responsible for providing an<address>  element
for the disk to indicate which controller it should be added
to.

 OK. I see. I will try that way.

The automagic guessing of controllers is only ever intended
to work in the simple case where you have 1 kind of controller

Got it.  Thanks. :)

Daniel



--
Best Regards
Li

IBM LTC, China System&Technology Lab, Beijing


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