HVM-PV & xenbus: how to load the proper xen-XXXfront modules?

HVM-PV & xenbus: how to load the proper xen-XXXfront modules?

[AL13N]

Hi,

in HVM installation: xenbus is compiled in kernel and xen-netfront and xen-
blkfront are compiled as module...

is there some kind of way that xenbus via udev loads the proper xen-netfront 
and xen-blkfront modules?

how does this system work?

should udev query the xenbus like it does the usb or pci bus? to load modules?

Re: HVM-PV & xenbus: how to load the proper xen-XXXfront modules?

[Andrew Cooper]

On 04/04/13 07:38, AL13N wrote:
> Hi,
>
> in HVM installation: xenbus is compiled in kernel and xen-netfront and xen-
> blkfront are compiled as module...
>
> is there some kind of way that xenbus via udev loads the proper xen-netfront 
> and xen-blkfront modules?
>
> how does this system work?
>
> should udev query the xenbus like it does the usb or pci bus? to load modules?

xenbus is built in because it is a pre-req for xenstore which is a
pre-req for all xen-{net,blk,etc}{front,back} drivers.  It used to be a
module, but was causing too many problems.

>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

Re: HVM-PV & xenbus: how to load the proper xen-XXXfront modules?

[AL13N]

> On 04/04/13 07:38, AL13N wrote:
>> Hi,
>>
>> in HVM installation: xenbus is compiled in kernel and xen-netfront and
>> xen-
>> blkfront are compiled as module...
>>
>> is there some kind of way that xenbus via udev loads the proper
>> xen-netfront
>> and xen-blkfront modules?
>>
>> how does this system work?
>>
>> should udev query the xenbus like it does the usb or pci bus? to load
>> modules?
>
> xenbus is built in because it is a pre-req for xenstore which is a
> pre-req for all xen-{net,blk,etc}{front,back} drivers.  It used to be a
> module, but was causing too many problems.

ok, i get this, but what is the correct way to load the xen-XXXfront
modules in a HVM-PV?

is it really just checking if it's a xen and just probe all the modules
and see which ones work? or is there a better way?

Re: HVM-PV & xenbus: how to load the proper xen-XXXfront modules?

[Ian Campbell]

On Thu, 2013-04-04 at 12:00 +0100, AL13N wrote:
> > On 04/04/13 07:38, AL13N wrote:
> >> Hi,
> >>
> >> in HVM installation: xenbus is compiled in kernel and xen-netfront and
> >> xen-
> >> blkfront are compiled as module...
> >>
> >> is there some kind of way that xenbus via udev loads the proper
> >> xen-netfront
> >> and xen-blkfront modules?
> >>
> >> how does this system work?
> >>
> >> should udev query the xenbus like it does the usb or pci bus? to load
> >> modules?
> >
> > xenbus is built in because it is a pre-req for xenstore which is a
> > pre-req for all xen-{net,blk,etc}{front,back} drivers.  It used to be a
> > module, but was causing too many problems.
> 
> ok, i get this, but what is the correct way to load the xen-XXXfront
> modules in a HVM-PV?

The xen-platform-pci device must be built in, it will detect xen and
enumerated the xen bus, which will generate hotplug events which will
cause udev to DTWT like it does for all hardware buses and their
drivers. This is no different for xenbus than any other bus (e.g. pci).

Ian.