Comment 0 for bug 1239160

When enabling Mir for Ubuntu Touch on the HTC Desire Z ("vision", community port maintained by me), the screen stays black and strange-looking vertical lines slowly appear within a few minutes after booting. Instead I'd expect it to show the unity 8 shell.

Unity 8 log shows an unhandled mir exception:
> terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::runtime_error> >'
> what(): ver requests info we dont provide. key:

The message is obviously truncated, further debugging revealed that it's actually "driver requests info we dont provide. key: 3". Key 3 is NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS.

After reading the comment explaining that key, I'm still not sure what it means, so I simply patched Mir to return 1 for that request in all three places (see related branch) and Mir now works on my device. *However*, there's a lot of flickering etc., so either that value of 1 is wrong, or there's some other problem.

This is using Touch cdimage 20131010 containing Mir 0.0.14+13.10.20131010-0ubuntu1.