<s>
The	O
2	O
GB	O
limit	O
refers	O
to	O
a	O
physical	O
memory	O
barrier	O
for	O
a	O
process	O
running	O
on	O
a	O
32-bit	O
operating	B-General_Concept
system	I-General_Concept
,	O
which	O
can	O
only	O
use	O
a	O
maximum	O
of	O
2GB	O
of	O
memory	O
.	O
</s>
<s>
The	O
problem	O
mainly	O
affects	O
32-bit	O
versions	O
of	O
operating	B-General_Concept
systems	I-General_Concept
like	O
Microsoft	B-Application
Windows	I-Application
and	O
Linux	B-Application
,	O
although	O
some	O
variants	O
of	O
the	O
latter	O
can	O
overcome	O
this	O
barrier	O
.	O
</s>
<s>
It	O
is	O
also	O
found	O
in	O
servers	O
like	O
FTP	B-Protocol
servers	I-Protocol
or	O
embedded	O
systems	O
like	O
Xbox	B-Application
.	O
</s>
<s>
The	O
use	O
of	O
Physical	B-General_Concept
Address	I-General_Concept
Extension	I-General_Concept
(	O
PAE	B-General_Concept
)	O
can	O
help	O
overcome	O
this	O
barrier	O
by	O
making	O
longer	O
the	O
addresses	O
used	O
to	O
represent	O
mappings	O
between	O
virtual	B-Architecture
and	O
physical	O
memory	O
.	O
</s>
<s>
In	O
a	O
computer	O
with	O
a	O
32-bit	O
architecture	B-General_Concept
,	O
the	O
memory	B-General_Concept
address	I-General_Concept
stored	O
in	O
one	O
of	O
the	O
CPU	B-General_Concept
registers	I-General_Concept
will	O
be	O
limited	O
to	O
this	O
number	O
,	O
thus	O
the	O
number	O
of	O
possible	O
memory	B-General_Concept
locations	I-General_Concept
that	O
can	O
be	O
addressed	O
is	O
limited	O
to	O
exactly	O
2	O
gibibytes	O
,	O
or	O
roughly	O
2GB	O
.	O
</s>
<s>
While	O
Linux	B-Application
,	O
FreeBSD	B-Operating_System
,	O
and	O
most	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
support	O
PAE	B-General_Concept
so	O
long	O
as	O
the	O
hardware	O
does	O
,	O
Windows	O
needs	O
this	O
boot	O
option	O
enabled	O
manually	O
.	O
</s>
