The default mapped base address for shared libraries in Red Hat Enterprise Linux 2.1 is 0x40000000 (1 GB). To lower the mapped base for a Linux process, the file /proc/<pid>/mapped_base must be changed where <pid> stands for the process ID. This means that his is not a system wide parameter. In order to change the mapped base for Oracle processes, the address mapping of the parent shell terminal session that spawns Oracle processes (instance) must be changed for the child processes to inherit the new mapping.

Login as oracle and run the following command to obtain the process ID of the shell where sqlplus will later be executed:

$ echo $$

Login as root in another shell terminal session and change the mapped_base for this process ID to 0x10000000 (decimal 268435456):

# echo 268435456 > /proc/<pid>/mapped_base

Now when Oracle processes are started with sqlplus in this shell, they will inherit the new mapping. But before Oracle can be started, the SGA Attach Address for shared memory must be lowered as well.