Re: udev naming problems for eth*

[egallego@babel.ls.fi.upm.es (Emilio Jesús Gallego Arias)]

Hello!

martin f krafft <madduck@debian.org> writes:

> also sprach Emilio Jesús Gallego Arias <egallego@babel.ls.fi.upm.es> [2006.01.18.1254 +0100]:
>> As far as I can tell, network interface names are given by the
>> kernel and they've nothing to do with udev.
>> 
>> To get a stable naming you should use some package like ifrename.
>
> ifrename is a hack and needed for 2.4 kernels only these days. udev

As it has been pointed by Tomas Hood, udev is the same hack that
ifrename of a custom nameif script and it is not race free. Indeed,
some of the DEV_NET events are special-cased in half of udev due to
not having a device file associated.

A netif name is given in the kernel, udev only tries to rename it (as
the other tools do):

udev_add.c:287
	} else if (udev->type == DEV_NET) {
		/* look if we want to change the name of the netif */
		if (strcmp(udev->name, udev->kernel_name) != 0) {
			retval = rename_net_if(udev);
			if (retval != 0)
				goto exit;

			info("renamed netif to '%s'", udev->name);
			/* we've changed the name, now fake the devpath, cause the
			 * original kernel name sleeps with the fishes and we don't
			 * get an event from the kernel with the new name
			 */
			pos = strrchr(udev->devpath, '/');
			if (pos != NULL) {
				pos[1] = '\0';
				strlcat(udev->devpath, udev->name, sizeof(udev->devpath));
				strlcpy(udev->kernel_name, udev->name, sizeof(udev->kernel_name));
				setenv("DEVPATH", udev->devpath, 1);
				setenv("INTERFACE", udev->name, 1);
			}
		}

With the current situation, upstream (kernel) support is needed to do
the rename in a successfully way. You could retry the rename, but then
you'd get into liveliness issues (you want eth0->eth1 and eth1->eth0,
etc...).

So I think that using other tools for the job is equally appropriate.

I'll stop now as I really have no clue about udev and this has nothing
to do with the original post.

Regards, sorry for the noise and keep up the good work with Debian, 

Emilio