Wahlberg spent five months preparing for his role as Chris Cole, working with a vocal coach, growing his hair, attending the metal scene and wandering around Los Angeles in-character. A concert scene was shot at the Los Angeles Memorial Sports Arena before 10,000 Metallica and Megadeth fans. While filming one Steel Dragon performance, the crew pranked Wahlberg by playing Marky Mark's ''Good Vibrations'' instead of a rock track, and footage of this is featured during the film's end credits. By 2001, Warner renamed the project from Metal God to Rock Star in order to attract a broader rock fandom instead of just metal fans.

did mark wahlberg do his own singing in the movie rockstar?
yes