[ipxe-devel] Xen netfront support
sha0.miller at gmail.com
Tue Jul 29 22:58:41 UTC 2014
On 7/29/2014 18:20, Michael Brown wrote:
> I'm please to announce that iPXE now natively supports Xen netfront
> virtual NICs. This may be of interest to anyone wanting to use iPXE
> running in a Xen PV-HVM domain.
> I have one issue which I'm not sure how to handle, and would appreciate
> feedback from anyone who frequently uses Xen:
> For each configured NIC, Xen exposes both an emulated PCI NIC (for OSes
> with no native Xen drivers) and a netfront virtual NIC (for OSes with
> native Xen drivers). Xen provides a mechanism for OSes to "unplug" the
> emulated PCI NICs. Operating systems with native Xen drivers will
> typically unplug the emulated PCI NICs to prevent confusion.
> iPXE could easily unplug the emulated PCI NICs. However, this operation
> is irreversible. If the loaded OS does not include native Xen drivers,
> then it will not be able to see any network devices. This is undesirable.
Personally, I don't think seeing both NICs is a huge deal, as a Xen user
should be aware of the dual-NIC thing.
But: are there any ordering guarantees about which NIC of the pair is
going to be first (net0) in iPXE?
Also: Would the unplugging happen before any NIC-detection, if it were
going to happen? If so, that wouldn't suggest a 'xen-unplug' command,
Maybe it could just sit as a build option and those who desire the
guaranteed unplugging can build such. That seems to be the special
scenario; better confused with the possibility of poorer performance
with the emulated NIC than NICless at OS time, perhaps.
- Shao Miller
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