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Specifying names for tap interfaces



Hello,

New Xen versions will ship with upstream Qemu, which means we have to get ready to support new Qemu features not present in the previous versions of Qemu used by Xen. This also means that Xen developers are not allowing to post Qemu-xen specific changes, so all changes should be first committed and approved to regular Qemu and then backported to the Qemu Xen repository.

So far we are doing quite good, and new Qemu upstream seems to be working fine with Xen under NetBSD. The only remaining issue is with tap interfaces, so we can at least have a working basic HVM guest. New Qemu does not longer support the deprecated "bridge" parameter that NetBSD was using to attach the created tap interface to a given bridge.

Linux does this by passing the name of the tap interface Qemu has to create, so when the interface is created its name is known and can be used outside of Qemu.

From what I see, NetBSD has the option to fetch the name of the interface created, using the TAPGIFNAME ioctl, but this is not really helpful because we create the interface from Qemu, but the scripts that attach the network interface are launched from the toolstack (xl).

Will it be possible to provide a TAPSIFNAME ioctl to set the name of the created interface? I will start looking into this, but I would also like some feedback.

Thanks, Roger.


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