When the first Radeon HD 7900 "Southern Islands" graphics cards were shipping, AMD ended up releasing a special driver release in order to support the new GCN hardware under Linux. The support wasn't found in that month's usual Catalyst Linux driver release. This goes contrary to what AMD has been striving for since the Radeon HD 4800 "RV770" days when they first shipped same-day support after a troubling past of taking a year or more for hardware enablement several generations ago on their old driver architecture.
It wasn't just a slow-start for the HD 7900 series on Linux, but it seems the HD 7700 is starting out in the same shaky steps. Released on Wednesday by AMD was a special Linux driver, which is the AMD 8.932.5.2 driver, and provides support for the recently-launched Radeon HD 7700 series.
By recently-launched, the Radeon HD 7700 hardware was shipping two weeks ago and at that time there was a supported Windows Catalyst driver available...
Meanwhile, contrary to earlier statements by their marketing representatives, AMD still hasn't sent out any Radeon HD 7000 series samples to Phoronix. Therefore I'm unable to verify the state of the Catalyst Linux driver as it stands today for this latest hardware to see how well it performs or what other caveats there may be within its driver stack. For users of previous hardware generations there already tends to be plenty of problems with AMD's binary blob, so hopefully this latest generation doesn't present any new problems.