Director Walter Salles and cast member Kristen Stewart pose during red carpet arrivals for the film "On The Road", in competition at the 65th Cannes Film Festival, May 23, 2012. (REUTERS/Jean-Paul Pelissier)

Acclaimed Brazilian filmmaker Walter Salles agonizes each time he makes a film, because every project takes years to gestate and birth. His Beat Generation drama On the Road -- which stars Kristen Stewart  -- is no exception.

Salles first proposed On the Road, which opens in limited release Friday, to Stewart in 2007, when he saw the then-unknown teenage actress in an early cut of Sean Penn's Into the Wild. Stewart was luminous in a support role.

But, when Salles finally got the go-ahead to do On the Road and start filming in Montreal -- the original home of Kerouac's parents and part of the legend -- Stewart had become a Hollywood star.

"What matters is that her passion for the role remained intact. She knew the character really well and she also knew she (Mary Lou) was several decades ahead of her time. It's interesting because On the Road is seen as a book about the friendship of men, basically, but they can't function without the women in their lives. And maybe the character who is more daring in there is Mary Lou, because she has this very unique capacity to define her past and her future."