<s>
Advanced	B-Operating_System
Synchronization	I-Operating_System
Facility	I-Operating_System
(	O
ASF	O
)	O
is	O
a	O
proposed	O
extension	O
to	O
the	O
x86-64	B-Device
instruction	B-General_Concept
set	I-General_Concept
architecture	I-General_Concept
that	O
adds	O
hardware	B-Operating_System
transactional	I-Operating_System
memory	I-Operating_System
support	O
.	O
</s>
<s>
No	O
released	O
microprocessors	B-Architecture
implement	O
the	O
extension	O
.	O
</s>
<s>
ASF	O
provides	O
the	O
capability	O
to	O
start	O
,	O
end	O
and	O
abort	O
transactional	O
execution	O
and	O
to	O
mark	O
CPU	B-Device
cache	B-General_Concept
lines	I-General_Concept
for	O
protected	O
memory	O
access	O
in	O
transactional	O
code	O
regions	O
.	O
</s>
<s>
Inside	O
transactional	O
code	O
regions	O
,	O
the	O
LOCK-prefixed	O
MOVx	O
reg/xmm	O
,	O
mem	O
,	O
PREFETCH	O
and	O
PREFETCHW	O
instructions	O
can	O
mark	O
up	O
to	O
four	O
cache	B-General_Concept
lines	I-General_Concept
for	O
protected	O
memory	O
access	O
.	O
</s>
<s>
Accesses	O
from	O
other	O
processor	O
cores	O
to	O
the	O
protected	O
cache	B-General_Concept
lines	I-General_Concept
result	O
in	O
exceptions	O
,	O
which	O
in	O
turn	O
cause	O
transaction	O
aborts	O
.	O
</s>
<s>
Stores	O
to	O
protected	O
cache	B-General_Concept
lines	I-General_Concept
must	O
be	O
performed	O
using	O
the	O
LOCK	O
MOVx	O
mem	O
,	O
reg/imm/xmm	O
instructions	O
.	O
</s>
<s>
Marked	O
cache	B-General_Concept
lines	I-General_Concept
can	O
be	O
released	O
from	O
protection	O
with	O
the	O
RELEASE	O
instruction	O
.	O
</s>
<s>
Transaction	O
aborts	O
generated	O
by	O
hardware	O
or	O
explicitly	O
requested	O
through	O
the	O
ABORT	O
instruction	O
rolls	O
back	O
modifications	O
to	O
the	O
protected	O
cache	B-General_Concept
lines	I-General_Concept
and	O
restarts	O
execution	O
from	O
the	O
instruction	O
following	O
the	O
top-level	O
SPECULATE	O
instruction	O
.	O
</s>
