0x40000000(1 GB). To lower the mapped base for a Linux process, the file
/proc/<pid>/mapped_basemust 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.
sqlpluswill later be executed:
$ echo $$
# echo 268435456 > /proc/<pid>/mapped_base
sqlplusin 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.