<s>
The	O
Vx32	B-Application
virtual	O
extension	O
environment	O
is	O
an	O
application-level	B-Architecture
virtual	I-Architecture
machine	I-Architecture
implemented	O
as	O
an	O
ordinary	O
user-mode	O
library	O
and	O
designed	O
to	O
run	O
native	O
x86	B-Operating_System
code	O
.	O
</s>
<s>
Applications	O
can	O
link	O
with	O
and	O
use	O
Vx32	B-Application
in	O
order	O
to	O
create	O
safe	B-Language
,	O
OS-independent	O
execution	O
environments	O
,	O
in	O
which	O
to	O
run	O
untrusted	O
plug-ins	B-Application
or	O
other	O
extensions	O
written	O
in	O
any	O
language	O
that	O
compiles	O
to	O
x86	B-Operating_System
code	O
.	O
</s>
<s>
From	O
the	O
host	O
processor	O
's	O
viewpoint	O
,	O
plug-ins	B-Application
running	O
under	O
the	O
Vx32	B-Application
virtual	B-Operating_System
machine	I-Operating_System
monitor	I-Operating_System
run	O
in	O
the	O
context	O
of	O
the	O
application	O
process	O
itself	O
,	O
but	O
the	O
Vx32	B-Application
library	O
uses	O
dynamic	O
recompilation	O
to	O
prevent	O
the	O
"	O
guest	O
"	O
plug-in	B-Application
code	O
from	O
accessing	O
memory	O
or	O
jumping	O
to	O
instructions	O
outside	O
its	O
designated	O
sandbox	O
.	O
</s>
<s>
The	O
Vx32	B-Application
library	O
redirects	O
any	O
system	B-Operating_System
calls	I-Operating_System
the	O
plug-in	B-Application
makes	O
to	O
the	O
application	O
itself	O
rather	O
than	O
to	O
the	O
host	O
operating	B-General_Concept
system	I-General_Concept
,	O
thereby	O
giving	O
the	O
application	O
exclusive	O
control	O
over	O
the	O
API	B-Application
and	O
security	O
environment	O
in	O
which	O
the	O
plug-in	B-Application
code	O
executes	O
.	O
</s>
<s>
Vx32	B-Application
thus	O
provides	O
an	O
application	O
extension	O
facility	O
comparable	O
in	O
function	O
to	O
the	O
Java	B-Language
virtual	I-Language
machine	I-Language
(	O
JVM	B-Language
)	O
or	O
the	O
Common	O
Language	O
Runtime	O
(	O
CLR	O
)	O
,	O
but	O
with	O
less	O
overhead	O
and	O
with	O
the	O
ability	O
to	O
run	O
code	O
written	O
in	O
any	O
language	O
,	O
safe	B-Language
or	O
unsafe	O
.	O
</s>
<s>
Vx32	B-Application
's	O
primary	O
disadvantage	O
is	O
that	O
it	O
is	O
more	O
difficult	O
to	O
make	O
it	O
run	O
on	O
non-x86	O
host	O
processors	O
.	O
</s>
<s>
There	O
are	O
some	O
disadvantages	O
that	O
have	O
been	O
proposed	O
by	O
critics	O
of	O
Vx32	B-Application
.	O
</s>
<s>
Some	O
have	O
argued	O
that	O
Vx32	B-Application
is	O
closely	O
tied	O
to	O
the	O
IA-32	B-Device
instruction	I-Device
set	I-Device
,	O
which	O
makes	O
it	O
difficult	O
to	O
use	O
on	O
non-x86	O
architectures	O
.	O
</s>
<s>
Also	O
,	O
the	O
IA-32e	O
(	O
AMD64	O
)	O
mode	O
cannot	O
be	O
used	O
by	O
guests	O
(	O
the	O
host	O
can	O
still	O
run	O
in	O
64-bit	O
mode	O
)	O
,	O
because	O
of	O
the	O
use	O
of	O
segmentation	B-General_Concept
which	O
is	O
inherent	O
to	O
Vx32	B-Application
's	O
design	O
.	O
</s>
