I just compiled the uml-2.5.33 with the attached config files, and
start with "./linux mem=128M ubd0=./root_fs root=/dev/ubd/0", its works
fine and uml startup succesfully, but when I put the debug options in
the command line as "./linux mem=128M debug ubd0=./root_fs
root=/dev/ubd/0", uml fails to startup with msgs say
"VFS: Cannot open root device "ubd/0" or 00:00
Please append a correct "root=" boot option" just as the last 4 lines
in the attached message file.
I do not know why?