Ortwin Glück: [Code] zeroconf, avahi, bonjour USE flag confusion in Gentoo

There is a bit of confusion about the Zero Configuration technology in Gentoo. I am trying to clear the clouds a bit here.

There are two separate implementations of the Zeroconf standard available on Linux today:

• Bonjour from Apple, also known as mDNSResponder or mDNSResponderPosix
• Avahi from freedesktop.org

That's why you need to choose which one to use (and you probably want Avahi). You can not install both at the same time. There are several USE flags that control that choice:

• zeroconf: if enabled you wish to use/enable the Zeroconf technology. If disabled no Zeroconf technology will be supported.
• bonjour: same as zeroconf but a local USE flag. So you should keep the two USE flags in sync. And Gentoo devs should care to clean the mess up. Contrary to its name it does not select the Bonjour implementation!
• avahi: Selects between Bonjour and Avahi. If enabled, Avahi will be installed, if  disabled Bonjour will be installed. As long as zeroconf and bonjour USE flags are disabled, this flag has no meaning.
• mdnsresponder-compat: if Avahi is used (avahi USE flag is enabled), this flag controls the installation of a Bonjour compatibility layer for. Necessary for packages like ntp that are only compatible with Bonjour, and not Avahi natively.