<s>
A	O
memory	B-General_Concept
protection	I-General_Concept
unit	I-General_Concept
(	O
MPU	O
)	O
,	O
is	O
a	O
computer	O
hardware	O
unit	O
that	O
provides	O
memory	B-General_Concept
protection	I-General_Concept
.	O
</s>
<s>
It	O
is	O
usually	O
implemented	O
as	O
part	O
of	O
the	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
(	O
CPU	O
)	O
.	O
</s>
<s>
MPU	O
is	O
a	O
trimmed	O
down	O
version	O
of	O
memory	B-General_Concept
management	I-General_Concept
unit	I-General_Concept
(	O
MMU	O
)	O
providing	O
only	O
memory	B-General_Concept
protection	I-General_Concept
support	O
.	O
</s>
<s>
It	O
is	O
usually	O
implemented	O
in	O
low	O
power	O
processors	O
that	O
require	O
only	O
memory	B-General_Concept
protection	I-General_Concept
and	O
do	O
not	O
need	O
the	O
full	O
fledged	O
feature	O
of	O
a	O
memory	B-General_Concept
management	I-General_Concept
unit	I-General_Concept
like	O
virtual	B-Architecture
memory	I-Architecture
management	O
.	O
</s>
<s>
The	O
MPU	O
allows	O
the	O
privileged	B-Operating_System
software	I-Operating_System
to	O
define	O
memory	O
regions	O
and	O
assign	O
memory	O
access	O
permission	O
and	O
memory	O
attributes	O
to	O
each	O
of	O
them	O
.	O
</s>
<s>
Depending	O
on	O
the	O
implementation	O
of	O
the	O
processor	B-General_Concept
,	O
the	O
number	O
of	O
supported	O
memory	O
regions	O
will	O
vary	O
.	O
</s>
<s>
The	O
memory	O
attributes	O
define	O
the	O
ordering	O
and	O
merging	O
behaviors	O
of	O
these	O
regions	O
,	O
as	O
well	O
as	O
caching	B-General_Concept
and	O
buffering	O
attributes	O
.	O
</s>
<s>
Cache	B-General_Concept
attributes	O
can	O
be	O
used	O
by	O
internal	O
caches	B-General_Concept
,	O
if	O
available	O
,	O
and	O
can	O
be	O
exported	O
for	O
use	O
by	O
system	O
caches	B-General_Concept
.	O
</s>
<s>
MPU	O
monitors	O
transactions	O
,	O
including	O
instruction	O
fetches	O
and	O
data	O
accesses	O
from	O
the	O
processor	B-General_Concept
,	O
which	O
can	O
trigger	O
a	O
fault	B-Error_Name
exception	I-Error_Name
when	O
an	O
access	B-Error_Name
violation	I-Error_Name
is	O
detected	O
.	O
</s>
<s>
The	O
main	O
purpose	O
of	O
memory	B-General_Concept
protection	I-General_Concept
is	O
to	O
prevent	O
a	O
process	B-Operating_System
from	O
accessing	O
memory	O
that	O
has	O
not	O
been	O
allocated	O
to	O
it	O
.	O
</s>
<s>
This	O
prevents	O
a	O
bug	B-Error_Name
or	O
malware	O
within	O
a	O
process	B-Operating_System
from	O
affecting	O
other	O
processes	O
,	O
or	O
the	O
operating	B-General_Concept
system	I-General_Concept
itself	O
.	O
</s>
