It is said in TLDP doc for the kernel that map variable is used as a bitmask. If Nth block is free, correspondingly the Nth bit is set. How is this implemented using the map variable? what I cant comprehend is the significance of making map as: "unsigned long* map" Can someone help me in this regard!! -- With regards, Jagadeesh Bhaskar P -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/