On Wed, Dec 03, 2008 at 04:50:14PM -0500, Arnaud Lacombe wrote: > Hi, > > On Sat, Nov 29, 2008 at 4:41 PM, Quentin Garnier <cube%cubidou.net@localhost> > wrote: > >> Beside that, this do not solve the problem of the behavior of the > >> stat(2) syscall on a cloner device. > > > > Right. I was pointing out that the premise for the work was incorrect, > > which doesn't mean the work itself isn't useful. One thing to note, > > though, is that it is a bad idea to derive the name of the interface > > from the unit number, because we might want to make it possible to > > change interface names in the future, > The name isn't derived from the unit number, but the interface index > is derived from the device's minor. The current code already use this > "hack" to get the interface softc when accessed through /dev/tapN. The > major/minor -> name association belong to userland. No, it actually belongs to the kernel, along with a devfs implementation. The driver is in control of the minor namespace, not userland. But I see your point; currently the information is defined in two places independently, and it only works as long as the two agree. > > which means the network interface name and the device name might differ. > > > device name yes, major/minor no, cf above. But what matters is the network interface (i.e., struct ifnet) name. > > Which is why TAPGIFNAME takes an > > ifreq, which is something you can actually feed to a socket ioctl > > afterwards. > > > this is just YAITDI :-) but I'm not sure why a program using tap(4) > would use a socket. In general case, it opens the cloner device and > read/write through it. Because the only thing it needs the name for is to configure the network interface, which you do through socket ioctls with ifreqs. I really don't see any other possible use for the name of the interface. If your idea is that a process can open /dev/tap and then expect another process to open /dev/tapN to perform concurrent work, it's definitely the wrong way to do that. -- Quentin Garnier - cube%cubidou.net@localhost - cube%NetBSD.org@localhost "See the look on my face from staying too long in one place [...] every time the morning breaks I know I'm closer to falling" KT Tunstall, Saving My Face, Drastic Fantastic, 2007.
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