<s>
The	O
hw.sensors	O
framework	O
is	O
a	O
kernel-level	O
hardware	O
sensors	O
framework	O
originating	O
from	O
OpenBSD	B-Operating_System
,	O
which	O
uses	O
the	O
sysctl	B-Application
kernel	B-Operating_System
interface	O
as	O
the	O
transport	O
layer	O
between	O
the	O
kernel	B-Operating_System
and	O
the	O
userland	B-Operating_System
.	O
</s>
<s>
,	O
the	O
framework	O
is	O
used	O
by	O
over	O
a	O
hundred	O
device	B-Application
drivers	I-Application
in	O
OpenBSD	B-Operating_System
to	O
export	O
various	O
environmental	O
sensors	O
,	O
with	O
temperature	O
sensors	O
being	O
the	O
most	O
common	O
type	O
.	O
</s>
<s>
Consumption	O
and	O
monitoring	O
of	O
sensors	O
is	O
done	O
in	O
the	O
userland	B-Operating_System
with	O
the	O
help	O
of	O
sysctl	B-Application
,	O
systat	B-Language
,	O
sensorsd	B-Application
,	O
ntpd	B-Application
,	O
snmpd	O
,	O
ports/sysutils/symon	O
and	O
GKrellM	B-Language
.	O
</s>
<s>
In	O
OpenBSD	B-Operating_System
,	O
the	O
framework	O
is	O
integrated	O
with	O
Dell	O
's	O
ESM	O
,	O
IPMI	O
and	O
I2C	O
,	O
in	O
addition	O
to	O
a	O
number	O
of	O
popular	O
Super	B-Device
I/O	I-Device
chips	O
through	O
.	O
</s>
<s>
A	O
major	O
difference	O
compared	O
to	O
other	O
solutions	O
like	O
lm_sensors	O
is	O
simplicity	O
and	O
a	O
works-by-default	O
approach	O
in	O
the	O
drivers	O
,	O
which	O
do	O
n't	O
require	O
nor	O
support	O
any	O
configurability	O
;	O
no	O
installation	O
or	O
configuration	O
actions	O
are	O
required	O
by	O
the	O
system	B-Application
administrator	I-Application
in	O
order	O
to	O
get	O
the	O
sensors	O
going	O
.	O
</s>
<s>
Support	O
for	O
automatic	O
monitoring	O
of	O
RAID	B-Architecture
drives	O
is	O
also	O
provided	O
through	O
the	O
sensors	O
framework	O
,	O
this	O
concept	O
of	O
sensors	O
of	O
drive	O
type	O
has	O
been	O
backported	O
by	O
NetBSD	B-Device
back	O
into	O
envsys	B-Device
in	O
2007	O
.	O
</s>
<s>
OpenNTPD	B-Application
uses	O
sensors	O
of	O
type	O
timedelta	O
in	O
order	O
to	O
synchronise	O
time	O
.	O
</s>
<s>
The	O
framework	O
was	O
originally	O
devised	O
in	O
2003	O
by	O
Alexander	O
Yurchenko	O
,	O
when	O
he	O
was	O
porting	O
several	O
envsys-based	O
drivers	O
from	O
NetBSD	B-Device
.	O
</s>
<s>
Instead	O
of	O
porting	O
NetBSD	B-Device
's	O
envsys	B-Device
,	O
a	O
simpler	O
sysctl-based	O
mechanism	O
was	O
developed	O
.	O
</s>
<s>
The	O
framework	O
received	O
a	O
major	O
uptick	O
in	O
usage	O
by	O
the	O
device	B-Application
drivers	I-Application
with	O
the	O
release	O
of	O
OpenBSD	B-Operating_System
3.9	O
,	O
where	O
in	O
a	O
period	O
of	O
merely	O
6	O
months	O
,	O
the	O
number	O
of	O
individual	O
drivers	O
using	O
the	O
framework	O
went	O
from	O
9	O
in	O
OpenBSD	B-Operating_System
3.8	O
(	O
released	O
)	O
to	O
33	O
in	O
OpenBSD	B-Operating_System
3.9	O
(	O
released	O
)	O
.	O
</s>
<s>
In	O
2007	O
,	O
the	O
framework	O
was	O
ported	O
to	O
FreeBSD	B-Operating_System
as	O
part	O
of	O
a	O
Google	B-Application
Summer	I-Application
of	I-Application
Code	I-Application
grant	O
;	O
it	O
has	O
been	O
adopted	O
by	O
DragonFly	B-Application
BSD	I-Application
later	O
that	O
year	O
.	O
</s>
<s>
The	O
usability	O
of	O
the	O
,	O
the	O
sensors	O
monitoring	O
daemon	O
,	O
has	O
been	O
vastly	O
improved	O
in	O
2007	O
,	O
partly	O
due	O
to	O
same	O
GSoC	B-Application
grant	O
.	O
</s>
<s>
,	O
the	O
total	O
number	O
of	O
drivers	O
stood	O
at	O
68	O
in	O
OpenBSD	B-Operating_System
4.4	O
;	O
growing	O
by	O
7	O
drivers	O
in	O
a	O
6-month	O
release	O
cycle	O
.	O
</s>
<s>
This	O
level	O
of	O
growth	O
,	O
of	O
one	O
new	O
driver	O
per	O
month	O
on	O
average	O
,	O
has	O
been	O
common	O
throughout	O
the	O
history	O
of	O
the	O
framework	O
since	O
OpenBSD	B-Operating_System
3.9	O
.	O
</s>
<s>
The	O
values	O
exported	O
by	O
the	O
drivers	O
through	O
the	O
framework	O
are	O
read-only	O
;	O
however	O
,	O
an	O
external	O
patch	O
exists	O
that	O
implements	O
the	O
fan	B-Device
control	I-Device
functionality	O
in	O
both	O
the	O
framework	O
as	O
well	O
as	O
one	O
of	O
the	O
drivers	O
for	O
the	O
most	O
popular	O
family	O
of	O
Super	B-Device
I/O	I-Device
chips	O
;	O
this	O
patchset	O
was	O
provided	O
for	O
both	O
OpenBSD	B-Operating_System
and	O
DragonFly	B-Application
BSD	I-Application
.	O
</s>
