They will play four shows, including London's O2 Arena next June
The rocker made the comment about the U2 frontman during a Twitter Q&A
All-star line up in California also sees Jack White and Foster The People perform
The Canadian singer has unfinished business with his '60s band
Young says his high-resolution music service will "save the sound of music"
Nirvana frontman included a snippet from one of Young's lyrics in farewell letter
Neil Young and Crazy Horse release their second album of the year, 'Psychedelic Pill', in October
The singer quit alcohol and marijuana for a 'different perspective'
His second album this year with Crazy Horse is out on October 29