Re: IPv4 configuration for Solaris guest domains

* Erik.Nordmark@xxxxxxx [2007-01-23 20:30:29]
> David Edmondson wrote:
>> I'd like to enhance Solaris network configuration slightly to allow
>> guest domain IPv4 details to be passed from the domain building
>> control tools through to the relevant components in Solaris
>> (svc:/network/physical and uts/common/fs/nfs/nfs_dlinet.c).
>>
>> Attached is a proposal, roughly in the form of a fasttrack.
>
> I'm confused by your statement that the DHCP configuration support
> is only for diskless systems (and tied to OBP).  The DHCP support in
> network/physical works for diskless systems - x86 and sparc.

Sorry, I missed the fact that support for setting bootp-response based
on grub provided data had been added.  I'll update the proposal.

> Are you talking about diskless Xen domains using DHCP and NFS?

Right now that is not supported, as neither the kernel nor the domain
building code are able to perform the DHCP discovery necessary to find
a local IP address to use to mount the root filesystem.

As you suggest below we could add that support to do the discovery in
the domain building tools and pass the data on.  That was not part of
this proposal.

> Is the proposal a short-term approach or something we should live
> with forever?

The mechanism for specifying parameters in the guest domain
configuration file is expected to be long lived.

The details of how those parameters are passed through to Solaris can
be changed, with the ease of change increasing further along the
pipeline (i.e. changing the Xen tools requires external interaction,
changing the kernel implementation is relatively easy, changing the
service scripts is easier still).

> I personally think it makes sense to be able to convey the IP
> configuration to a domU using the standard DHCP protocol;

I agree.  However, using the static configuration mechanism is very
common in the existing Xen community.

The domU can run a DHCP client itself - this works today if
/etc/dhcp.xnf0, etc. are present inside the domain.

The proposal would also allow the dom0 administrator to indicate that
the domU should run a DHCP client in the absence of any other
configuration data within the domain.

Without implementing the bootp-response pass through, DHCP with NFS
root would not work (only static or RARP).  Linux avoids this by
providing a simple DHCP client within the kernel.

> for static configuration from the perspective of dom0 this means
> that the DHCP server runs in dom0 and serves up that static
> information to the domU.

This is possible but not covered by the proposal.

dme.
-- 
David Edmondson, Sun Microsystems, http://www.dme.org