I needed to give write permission to file representing GPIO pins,out of curiosity i taught changing permissions of all files/folders,by mistake instead of doing chmod 755 * in the root
I did chmod 750 * and the system crashed(doesn't boot) ,although I solved the problem by overwriting the permission using a live cd.I didn't understand what went wrong with chmod 750 *,boot loader is not bothered about any of it ,boot loader simply copies the 1st sector of hard disk and hands over the control to OS.
Is it that the entry code is treated as others,or some process may be init needs those permissions to be set??