On Wed, 2007-07-04 at 16:30 +0200, Patrick McHardy wrote: [...] > The kernel doesn't have any multicast listeners (yet).
Right. > I wonder if thats really a good idea to use multicast for device > configuration. Unicast transmissions from userspace to kernel > are reliable when you don't use MSG_DONTWAIT. For multicasts > doing the same would mean blocking on each receiver when the > receive queue is full. That's a good point actually. Are transmissions from userspace to userspace also reliable in that case? In fact, we haven't quite decided yet whether we want all configuration to be via netlink. I strongly prefer this, but other people say that userspace<->userspace communication is nothing that nl80211 should be involved in. What I initially wanted was to publish something like "Device wlan0 is managed by netlink pid 12345" (or 0 if the kernel is doing it) and then configuration would be "send to <number the kernel told you>". However, that got me into problems when trying to determine "is the process owning netlink pid 12345 still alive" at which point Herbert suggested the use of multicast groups (and doing the exclusion "only one manager per netdev" in userspace instead of the kernel). johannes
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