What is the meaning of "sga_max_size= # internally adjusted" I used following command to get backup of my spfile. 

CREATE PFILE='c:/test_init.ora' FROM MEMORY;


it has following lines related to memory. 

memory_max_target=12G
memory_target=8G
__java_pool_size=16M
log_buffer=4743168 # log buffer update
__pga_aggregate_target=6G
_pga_max_size=1258280K
processes=400
sga_max_size=2G # internally adjusted
__sga_target=2G
__shared_io_pool_size=0
__shared_pool_size=704M
_smm_max_size=629140
_smm_min_size=1024
_smm_px_max_size=3145728


I wonder about "# internally adjusted" comment. What does it mean?
It means it was adjusted by Oracle, because it was not specified explicitly.
When using Automatic Memory Management, you need to set only the memory_target parameter, the sga/pga parameters are handled internally by the database automatically.