what is rockbox?what all can be done with it?is it safe to use that?do my device funcition properly on using that or is it harmful or cause any virus?do my device function normally if I use that?

n what’s the difference b/w sansa firmware n rockbox?Is  it llegal to use that

Please stop asking the same questions in multiple threads here. :angry:

Have you tried using Google in looking up Rockbox and going to their website?