Hi all ,
             This is Prasad,Can any one help me regarding the following command,

linux-3fuv:/opt/uml # ./linux ubd0=root_fs

my doubt is what kind of file is ubd0 file? is it device file?were does it reside?in host system or guest system?

my host system does Not have this file under /dev not uml directory.

please clear my doubt.....