<s>
A	O
machine	B-Device
state	I-Device
register	I-Device
(	O
MSR	O
)	O
is	O
one	O
of	O
three	O
process	O
control	O
registers	O
present	O
in	O
the	O
PowerPC	B-Architecture
processor	I-Architecture
architecture	O
.	O
</s>
<s>
The	O
implementation	O
details	O
of	O
the	O
machine	B-Device
state	I-Device
register	I-Device
will	O
vary	O
from	O
model	O
to	O
model	O
.	O
</s>
<s>
Below	O
are	O
two	O
representative	O
implementations	O
,	O
the	O
32-bit	O
Freescale	O
e200z3	B-Device
PowerPC	B-Architecture
core	O
and	O
the	O
64-bit	O
IBM	B-Architecture
PowerPC	I-Architecture
.	O
</s>
<s>
The	O
contents	O
of	O
the	O
register	O
may	O
be	O
read	O
using	O
the	O
move	O
from	O
machine	B-Device
state	I-Device
register	I-Device
(	O
mfmsr	O
)	O
instruction	O
and	O
may	O
be	O
modified	O
by	O
executing	O
the	O
return	O
from	O
interrupt	B-Application
(	O
rfi	O
,	O
rfci	O
,	O
rfdi	O
)	O
,	O
system	O
call	O
(	O
sc	O
)	O
and	O
move	O
to	O
machine	B-Device
state	I-Device
register	I-Device
(	O
mtmsr	O
)	O
instructions	O
.	O
</s>
<s>
The	O
machine	B-Device
state	I-Device
register	I-Device
can	O
be	O
read	O
using	O
the	O
mfmsr	O
instruction	O
and	O
modified	O
using	O
the	O
mtmsr[d],	O
rfid	O
and	O
hrfid	O
instructions	O
.	O
</s>
<s>
While	O
the	O
machine	B-Device
state	I-Device
register	I-Device
found	O
in	O
the	O
PowerPC	B-Architecture
architecture	O
and	O
the	O
model-specific	B-General_Concept
registers	I-General_Concept
found	O
in	O
IA-32	B-Device
and	O
x86-64	B-Device
architectures	O
fulfill	O
similar	O
functions	O
and	O
the	O
initialism	O
"	O
MSR	O
"	O
can	O
refer	O
to	O
either	O
,	O
there	O
are	O
important	O
differences	O
that	O
distinguish	O
them	O
.	O
</s>
<s>
The	O
machine	B-Device
state	I-Device
register	I-Device
,	O
a	O
single	O
register	O
,	O
provides	O
coarse-grained	O
control	O
over	O
a	O
small	O
number	O
of	O
machine	O
functions	O
.	O
</s>
<s>
In	O
contrast	O
,	O
dozens	O
to	O
hundreds	O
of	O
model-specific	B-General_Concept
registers	I-General_Concept
exist	O
on	O
recent	O
IA-32	B-Device
and	O
x86_64	O
architectures	O
and	O
provide	O
a	O
much	O
finer	O
granularity	O
of	O
both	O
reporting	O
and	O
control	O
of	O
machine	O
state	O
.	O
</s>
<s>
The	O
term	O
"	O
machine	B-Device
state	I-Device
register	I-Device
"	O
does	O
not	O
appear	O
in	O
Intel	O
and	O
AMD	O
documentation	O
;	O
likewise	O
"	O
model-specific	B-General_Concept
register	I-General_Concept
"	O
does	O
not	O
appear	O
in	O
IBM	O
and	O
Freescale	O
documentation	O
.	O
</s>
