<s>
UEFI	B-Architecture
(	O
Unified	B-Architecture
Extensible	I-Architecture
Firmware	I-Architecture
Interface	I-Architecture
)	O
is	O
a	O
set	O
of	O
specifications	O
written	O
by	O
the	O
UEFI	B-Device
Forum	I-Device
.	O
</s>
<s>
They	O
define	O
the	O
architecture	B-Architecture
of	O
the	O
platform	O
firmware	B-Application
used	O
for	O
booting	B-Operating_System
and	O
its	O
interface	B-Application
for	O
interaction	O
with	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Examples	O
of	O
firmware	B-Application
that	O
implement	O
these	O
specifications	O
are	O
AMI	O
Aptio	O
,	O
Phoenix	O
SecureCore	O
,	O
TianoCore	B-Language
EDK	I-Language
II	I-Language
and	O
InsydeH2O	O
.	O
</s>
<s>
UEFI	B-Architecture
replaces	O
the	O
BIOS	B-Operating_System
which	O
was	O
present	O
in	O
the	O
boot	B-General_Concept
ROM	I-General_Concept
of	O
all	O
personal	B-Device
computers	I-Device
that	O
are	O
IBM	O
PC-compatible	O
,	O
although	O
it	O
can	O
provide	O
backwards	B-General_Concept
compatibility	I-General_Concept
with	O
the	O
BIOS	B-Operating_System
using	O
CSM	O
booting	B-Operating_System
.	O
</s>
<s>
Intel	O
developed	O
the	O
original	O
Extensible	B-Architecture
Firmware	I-Architecture
Interface	I-Architecture
(	O
EFI	O
)	O
specifications	O
.	O
</s>
<s>
Some	O
of	O
the	O
EFI	O
's	O
practices	O
and	O
data	O
formats	O
mirror	O
those	O
of	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
In	O
2005	O
,	O
UEFI	B-Architecture
deprecated	O
EFI	O
1.10	O
(	O
the	O
final	O
release	O
of	O
EFI	O
)	O
.	O
</s>
<s>
UEFI	B-Architecture
is	O
independent	O
of	O
platform	O
and	O
programming	O
language	O
,	O
but	O
C	B-Language
is	O
used	O
for	O
the	O
reference	O
implementation	O
TianoCore	B-Language
EDKII	O
.	O
</s>
<s>
The	O
original	O
motivation	O
for	O
EFI	O
came	O
during	O
early	O
development	O
of	O
the	O
first	O
Intel	O
–	O
HP	O
Itanium	B-General_Concept
systems	O
in	O
the	O
mid-1990s	O
.	O
</s>
<s>
BIOS	B-Operating_System
limitations	O
(	O
such	O
as	O
16-bit	O
real	B-Application
mode	I-Application
,	O
1MB	O
addressable	O
memory	O
space	O
,	O
assembly	B-Language
language	I-Language
programming	O
,	O
and	O
PC	B-Operating_System
AT	I-Operating_System
hardware	O
)	O
had	O
become	O
too	O
restrictive	O
for	O
the	O
larger	O
server	O
platforms	O
Itanium	B-General_Concept
was	O
targeting	O
.	O
</s>
<s>
The	O
effort	O
to	O
address	O
these	O
concerns	O
began	O
in	O
1998	O
and	O
was	O
initially	O
called	O
Intel	B-Architecture
Boot	I-Architecture
Initiative	I-Architecture
.	O
</s>
<s>
It	O
was	O
later	O
renamed	O
to	O
Extensible	B-Architecture
Firmware	I-Architecture
Interface	I-Architecture
(	O
EFI	O
)	O
.	O
</s>
<s>
The	O
first	O
open	B-License
source	I-License
UEFI	B-Architecture
implementation	O
,	O
Tiano	B-Architecture
,	O
was	O
released	O
by	O
Intel	O
in	O
2004	O
.	O
</s>
<s>
Tiano	B-Architecture
has	O
since	O
then	O
been	O
superseded	O
by	O
EDK	O
and	O
EDK2	B-Language
and	O
is	O
now	O
maintained	O
by	O
the	O
TianoCore	B-Language
community	O
.	O
</s>
<s>
In	O
July	O
2005	O
,	O
Intel	O
ceased	O
its	O
development	O
of	O
the	O
EFI	O
specification	O
at	O
version	O
1.10	O
,	O
and	O
contributed	O
it	O
to	O
the	O
Unified	B-Device
EFI	I-Device
Forum	I-Device
,	O
which	O
has	O
developed	O
the	O
specification	O
as	O
the	O
Unified	B-Architecture
Extensible	I-Architecture
Firmware	I-Architecture
Interface	I-Architecture
(	O
UEFI	B-Architecture
)	O
.	O
</s>
<s>
The	O
original	O
EFI	O
specification	O
remains	O
owned	O
by	O
Intel	O
,	O
which	O
exclusively	O
provides	O
licenses	O
for	O
EFI-based	O
products	O
,	O
but	O
the	O
UEFI	B-Architecture
specification	O
is	O
owned	O
by	O
the	O
UEFI	B-Device
Forum	I-Device
.	O
</s>
<s>
Version	O
2.0	O
of	O
the	O
UEFI	B-Architecture
specification	O
was	O
released	O
on	O
31	O
January	O
2006	O
.	O
</s>
<s>
Version	O
2.1	O
of	O
the	O
UEFI	B-Architecture
specification	O
was	O
released	O
on	O
7	O
January	O
2007	O
.	O
</s>
<s>
It	O
added	O
network	O
authentication	O
and	O
the	O
user	B-Application
interface	I-Application
architecture	B-Architecture
( 	O
 '	O
Human	B-Application
Interface	I-Application
Infrastructure	O
 '	O
in	O
UEFI	B-Architecture
)	O
.	O
</s>
<s>
In	O
October	O
2018	O
,	O
Arm	B-Architecture
announced	O
,	O
a	O
compliance	O
certification	O
program	O
for	O
landing	O
the	O
generic	O
off-the-shelf	O
operating	B-General_Concept
systems	I-General_Concept
and	O
hypervisors	B-Operating_System
on	O
Arm-based	O
servers	O
.	O
</s>
<s>
The	O
program	O
requires	O
the	O
system	O
firmware	B-Application
to	O
comply	O
with	O
Server	O
Base	O
Boot	B-Operating_System
Requirements	O
(	O
SBBR	O
)	O
.	O
</s>
<s>
SBBR	O
requires	O
UEFI	B-Architecture
,	O
ACPI	B-Device
and	O
SMBIOS	O
compliance	O
.	O
</s>
<s>
In	O
October	O
2020	O
,	O
Arm	B-Architecture
announced	O
the	O
extension	O
of	O
the	O
program	O
to	O
the	O
edge	B-Device
and	O
IoT	B-Operating_System
market	O
.	O
</s>
<s>
Arm	B-Architecture
SystemReady	O
defined	O
the	O
Base	O
Boot	B-Operating_System
Requirements	O
(	O
)	O
specification	O
that	O
currently	O
provides	O
three	O
recipes	O
,	O
two	O
of	O
which	O
are	O
related	O
to	O
UEFI	B-Architecture
:	O
1	O
)	O
SBBR	O
:	O
which	O
requires	O
UEFI	B-Architecture
,	O
ACPI	B-Device
and	O
SMBIOS	O
compliance	O
suitable	O
for	O
enterprise	O
level	O
operating	O
environments	O
such	O
as	O
Windows	B-Application
,	O
Red	O
Hat	O
Enterprise	O
Linux	B-Operating_System
,	O
and	O
VMware	B-Operating_System
ESXi	I-Operating_System
;	O
and	O
2	O
)	O
EBBR	O
:	O
which	O
requires	O
compliance	O
to	O
a	O
set	O
of	O
UEFI	B-Architecture
interfaces	B-Application
as	O
defined	O
in	O
the	O
Embedded	O
Base	O
Boot	B-Operating_System
Requirements	O
(	O
)	O
suitable	O
for	O
embedded	O
environments	O
such	O
as	O
Yocto	O
.	O
</s>
<s>
Many	O
Linux	B-Operating_System
and	O
BSD	O
distros	O
can	O
support	O
both	O
recipes	O
.	O
</s>
<s>
In	O
December	O
2018	O
,	O
Microsoft	O
announced	O
Project	B-Language
Mu	I-Language
,	O
a	O
fork	O
of	O
TianoCore	B-Language
EDK2	B-Language
used	O
in	O
Microsoft	B-Device
Surface	I-Device
and	O
Hyper-V	O
products	O
.	O
</s>
<s>
The	O
project	O
promotes	O
the	O
idea	O
of	O
Firmware	B-Language
as	I-Language
a	I-Language
Service	I-Language
.	O
</s>
<s>
The	O
latest	O
UEFI	B-Architecture
specification	O
,	O
version	O
2.10	O
,	O
was	O
published	O
in	O
August	O
2022	B-Device
.	O
</s>
<s>
The	O
interface	B-Application
defined	O
by	O
the	O
EFI	O
specification	O
includes	O
data	O
tables	O
that	O
contain	O
platform	O
information	O
,	O
and	O
boot	B-Operating_System
and	O
runtime	O
services	O
that	O
are	O
available	O
to	O
the	O
OS	O
loader	O
and	O
OS	O
.	O
</s>
<s>
UEFI	B-Architecture
firmware	I-Architecture
provides	O
several	O
technical	O
advantages	O
over	O
a	O
traditional	O
BIOS	B-Operating_System
system	O
:	O
</s>
<s>
As	O
of	O
version	O
2.5	O
,	O
processor	O
bindings	O
exist	O
for	O
Itanium	B-General_Concept
,	O
x86	B-Operating_System
,	O
x86-64	B-Device
,	O
ARM	B-Architecture
(	O
AArch32	O
)	O
and	O
ARM64	B-Architecture
(	O
AArch64	B-Architecture
)	O
.	O
</s>
<s>
Unofficial	O
UEFI	B-Architecture
support	O
is	O
under	O
development	O
for	O
POWERPC64	O
by	O
implementing	O
TianoCore	B-Language
on	O
top	O
of	O
OPAL	O
,	O
the	O
OpenPOWER	O
abstraction	O
layer	O
,	O
running	O
in	O
little-endian	O
mode	O
.	O
</s>
<s>
Similar	O
projects	O
exist	O
for	O
MIPS	B-Device
and	O
RISC-V	B-Device
.	O
As	O
of	O
UEFI	B-Architecture
2.7	O
,	O
RISC-V	B-Device
processor	O
bindings	O
have	O
been	O
officially	O
established	O
for	O
32-	O
,	O
64	O
-	O
and	O
128-bit	O
modes	O
.	O
</s>
<s>
Standard	O
PC	B-Operating_System
BIOS	I-Operating_System
is	O
limited	O
to	O
a	O
16-bit	O
processor	O
mode	O
and	O
1MB	O
of	O
addressable	O
memory	O
space	O
,	O
resulting	O
from	O
the	O
design	O
based	O
on	O
the	O
IBM	B-Device
5150	I-Device
that	O
used	O
a	O
16-bit	O
Intel	B-Device
8088	I-Device
processor	O
.	O
</s>
<s>
In	O
comparison	O
,	O
the	O
processor	O
mode	O
in	O
a	O
UEFI	B-Architecture
environment	O
can	O
be	O
either	O
32-bit	O
(	O
x86-32	B-Device
,	O
AArch32	O
)	O
or	O
64-bit	B-Device
(	O
x86-64	B-Device
,	O
Itanium	B-General_Concept
,	O
and	O
AArch64	B-Architecture
)	O
.	O
</s>
<s>
64-bit	B-Device
UEFI	B-Architecture
firmware	I-Architecture
implementations	O
support	O
long	B-Application
mode	I-Application
,	O
which	O
allows	O
applications	O
in	O
the	O
preboot	O
environment	O
to	O
use	O
64-bit	B-Device
addressing	O
to	O
get	O
direct	O
access	O
to	O
all	O
of	O
the	O
machine	O
's	O
memory	O
.	O
</s>
<s>
UEFI	B-Architecture
requires	O
the	O
firmware	B-Application
and	O
operating	B-General_Concept
system	I-General_Concept
loader	O
(	O
or	O
kernel	B-Operating_System
)	O
to	O
be	O
size-matched	O
;	O
that	O
is	O
,	O
a	O
64-bit	B-Device
UEFI	B-Architecture
firmware	I-Architecture
implementation	O
can	O
load	O
only	O
a	O
64-bit	B-Device
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
boot	B-Application
loader	I-Application
or	O
kernel	B-Operating_System
(	O
unless	O
the	O
CSM-based	O
Legacy	O
boot	B-Operating_System
is	O
used	O
)	O
and	O
the	O
same	O
applies	O
to	O
32-bit	O
.	O
</s>
<s>
After	O
the	O
system	O
transitions	O
from	O
"	O
Boot	B-Operating_System
Services	O
"	O
to	O
"	O
Runtime	O
Services	O
"	O
,	O
the	O
operating	B-Operating_System
system	I-Operating_System
kernel	I-Operating_System
takes	O
over	O
.	O
</s>
<s>
At	O
this	O
point	O
,	O
the	O
kernel	B-Operating_System
can	O
change	O
processor	O
modes	O
if	O
it	O
desires	O
,	O
but	O
this	O
bars	O
usage	O
of	O
the	O
runtime	O
services	O
(	O
unless	O
the	O
kernel	B-Operating_System
switches	O
back	O
again	O
)	O
.	O
</s>
<s>
As	O
of	O
version	O
3.15	O
,	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
supports	O
64-bit	B-Device
kernels	B-Operating_System
to	O
be	O
booted	B-Operating_System
on	O
32-bit	O
UEFI	B-Architecture
firmware	I-Architecture
implementations	O
running	O
on	O
x86-64	B-Device
CPUs	O
,	O
with	O
UEFI	B-Architecture
handover	O
support	O
from	O
a	O
UEFI	B-Architecture
boot	B-Application
loader	I-Application
as	O
the	O
requirement	O
.	O
</s>
<s>
UEFI	B-Architecture
handover	O
protocol	O
deduplicates	B-General_Concept
the	O
UEFI	B-Architecture
initialization	O
code	O
between	O
the	O
kernel	B-Operating_System
and	O
UEFI	B-Architecture
boot	B-Application
loaders	I-Application
,	O
leaving	O
the	O
initialization	O
to	O
be	O
performed	O
only	O
by	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
's	O
UEFI	B-Architecture
boot	B-Operating_System
stub	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
standard	O
PC	O
disk	O
partition	O
scheme	O
that	O
uses	O
a	O
master	B-Device
boot	I-Device
record	I-Device
(	O
MBR	B-Device
)	O
,	O
UEFI	B-Architecture
also	O
works	O
with	O
the	O
GUID	B-Application
Partition	I-Application
Table	I-Application
(	O
GPT	B-Application
)	O
partitioning	O
scheme	O
,	O
which	O
is	O
free	O
from	O
many	O
of	O
the	O
limitations	O
of	O
MBR	B-Device
.	O
</s>
<s>
In	O
particular	O
,	O
the	O
MBR	B-Device
limits	O
on	O
the	O
number	O
and	O
size	O
of	O
disk	O
partitions	O
(	O
up	O
to	O
four	O
primary	O
partitions	O
per	O
disk	O
,	O
and	O
up	O
to	O
2TB	O
per	O
disk	O
)	O
are	O
relaxed	O
.	O
</s>
<s>
More	O
specifically	O
,	O
GPT	B-Application
allows	O
for	O
a	O
maximum	O
disk	O
and	O
partition	O
size	O
of	O
8ZB	O
.	O
</s>
<s>
Support	O
for	O
GPT	B-Application
in	O
Linux	B-Operating_System
is	O
enabled	O
by	O
turning	O
on	O
the	O
option	O
CONFIG_EFI_PARTITION	O
(	O
EFI	O
GUID	O
Partition	O
Support	O
)	O
during	O
kernel	B-Operating_System
configuration	O
.	O
</s>
<s>
This	O
option	O
allows	O
Linux	B-Operating_System
to	O
recognize	O
and	O
use	O
GPT	B-Application
disks	I-Application
after	O
the	O
system	O
firmware	B-Application
passes	O
control	O
over	O
the	O
system	O
to	O
Linux	B-Operating_System
.	O
</s>
<s>
For	O
reverse	O
compatibility	O
,	O
Linux	B-Operating_System
can	O
use	O
GPT	B-Application
disks	I-Application
in	O
BIOS-based	O
systems	O
for	O
both	O
data	B-General_Concept
storage	I-General_Concept
and	O
booting	B-Operating_System
,	O
as	O
both	O
GRUB	B-Application
2	I-Application
and	O
Linux	B-Operating_System
are	O
GPT-aware	O
.	O
</s>
<s>
Such	O
a	O
setup	O
is	O
usually	O
referred	O
to	O
as	O
BIOS-GPT	O
.	O
</s>
<s>
As	O
GPT	B-Application
incorporates	O
the	O
protective	O
MBR	B-Device
,	O
a	O
BIOS-based	O
computer	O
can	O
boot	B-Operating_System
from	O
a	O
GPT	B-Application
disk	I-Application
using	O
a	O
GPT-aware	O
boot	B-Application
loader	I-Application
stored	O
in	O
the	O
protective	O
MBR	B-Device
's	O
bootstrap	O
code	O
area	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
GRUB	B-Application
,	O
such	O
a	O
configuration	O
requires	O
a	O
BIOS	B-Device
boot	I-Device
partition	I-Device
for	O
GRUB	B-Application
to	O
embed	O
its	O
second-stage	O
code	O
due	O
to	O
absence	O
of	O
the	O
post-MBR	O
gap	O
in	O
GPT	B-Application
partitioned	O
disks	O
(	O
which	O
is	O
taken	O
over	O
by	O
the	O
GPT	B-Application
's	O
Primary	O
Header	O
and	O
Primary	O
Partition	O
Table	O
)	O
.	O
</s>
<s>
Commonly	O
1MB	O
in	O
size	O
,	O
this	O
partition	O
's	O
Globally	O
Unique	O
Identifier	O
(	O
GUID	O
)	O
in	O
GPT	B-Application
scheme	O
is	O
and	O
is	O
used	O
by	O
GRUB	B-Application
only	O
in	O
BIOS-GPT	O
setups	O
.	O
</s>
<s>
From	O
GRUB	B-Application
's	O
perspective	O
,	O
no	O
such	O
partition	O
type	B-Device
exists	O
in	O
case	O
of	O
MBR	B-Device
partitioning	O
.	O
</s>
<s>
This	O
partition	O
is	O
not	O
required	O
if	O
the	O
system	O
is	O
UEFI-based	O
because	O
no	O
embedding	O
of	O
the	O
second-stage	O
code	O
is	O
needed	O
in	O
that	O
case	O
.	O
</s>
<s>
UEFI	B-Architecture
systems	O
can	O
access	O
GPT	B-Application
disks	I-Application
and	O
boot	B-Operating_System
directly	O
from	O
them	O
,	O
which	O
allows	O
Linux	B-Operating_System
to	O
use	O
UEFI	B-Architecture
boot	B-Operating_System
methods	O
.	O
</s>
<s>
Booting	B-Operating_System
Linux	B-Operating_System
from	O
GPT	B-Application
disks	I-Application
on	O
UEFI	B-Architecture
systems	O
involves	O
creation	O
of	O
an	O
EFI	B-Device
system	I-Device
partition	I-Device
(	O
ESP	O
)	O
,	O
which	O
contains	O
UEFI	B-Architecture
applications	O
such	O
as	O
bootloaders	B-Application
,	O
operating	B-Operating_System
system	I-Operating_System
kernels	I-Operating_System
,	O
and	O
utility	O
software	O
.	O
</s>
<s>
Such	O
a	O
setup	O
is	O
usually	O
referred	O
to	O
as	O
UEFI-GPT	O
,	O
while	O
ESP	O
is	O
recommended	O
to	O
be	O
at	O
least	O
512MB	O
in	O
size	O
and	O
formatted	O
with	O
a	O
FAT32	B-Application
filesystem	O
for	O
maximum	O
compatibility	O
.	O
</s>
<s>
For	O
backward	B-General_Concept
compatibility	I-General_Concept
,	O
some	O
UEFI	B-Architecture
implementations	O
also	O
support	O
booting	B-Operating_System
from	O
MBR-partitioned	O
disks	O
through	O
the	O
Compatibility	O
Support	O
Module	B-Application
(	O
CSM	O
)	O
that	O
provides	O
legacy	B-Operating_System
BIOS	I-Operating_System
compatibility	O
.	O
</s>
<s>
In	O
that	O
case	O
,	O
booting	B-Operating_System
Linux	B-Operating_System
on	O
UEFI	B-Architecture
systems	O
is	O
the	O
same	O
as	O
on	O
legacy	O
BIOS-based	O
systems	O
.	O
</s>
<s>
The	O
64-bit	B-Device
versions	O
of	O
Windows	B-Application
Vista	I-Application
SP1	O
and	O
later	O
and	O
32-bit	O
versions	O
of	O
Windows	B-Application
8	I-Application
,	O
8.1	B-Device
,	O
and	O
10	B-Operating_System
can	O
boot	B-Operating_System
from	O
a	O
GPT	B-Application
disk	I-Application
that	O
is	O
larger	O
than	O
2TB	O
.	O
</s>
<s>
EFI	O
defines	O
two	O
types	O
of	O
services	O
:	O
boot	B-Operating_System
services	O
and	O
runtime	O
services	O
.	O
</s>
<s>
Boot	B-Operating_System
services	O
are	O
available	O
only	O
while	O
the	O
firmware	B-Application
owns	O
the	O
platform	O
(	O
i.e.	O
,	O
before	O
the	O
ExitBootServices( )	O
call	O
)	O
,	O
and	O
they	O
include	O
text	O
and	O
graphical	O
consoles	O
on	O
various	O
devices	O
,	O
and	O
bus	O
,	O
block	O
and	O
file	O
services	O
.	O
</s>
<s>
Runtime	O
services	O
are	O
still	O
accessible	O
while	O
the	O
operating	B-General_Concept
system	I-General_Concept
is	O
running	O
;	O
they	O
include	O
services	O
such	O
as	O
date	O
,	O
time	B-Device
and	O
NVRAM	B-General_Concept
access	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
is	O
permitted	O
to	O
directly	O
write	O
to	O
the	O
framebuffer	O
provided	O
by	O
GOP	O
during	O
runtime	O
mode	O
.	O
</s>
<s>
UEFI	B-Architecture
variables	O
provide	O
a	O
way	O
to	O
store	O
data	O
,	O
in	O
particular	O
non-volatile	B-General_Concept
data	O
.	O
</s>
<s>
Some	O
UEFI	B-Architecture
variables	O
are	O
shared	O
between	O
platform	O
firmware	B-Application
and	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
UEFI	B-Architecture
variables	O
can	O
be	O
used	O
to	O
keep	O
crash	O
messages	O
in	O
NVRAM	B-General_Concept
after	O
a	O
crash	O
for	O
the	O
operating	B-General_Concept
system	I-General_Concept
to	O
retrieve	O
after	O
a	O
reboot	O
.	O
</s>
<s>
UEFI	B-Architecture
provides	O
time	B-Device
services	O
.	O
</s>
<s>
Time	B-Device
services	O
include	O
support	O
for	O
time	B-Device
zone	O
and	O
daylight	O
saving	O
fields	O
,	O
which	O
allow	O
the	O
hardware	O
real-time	O
clock	O
to	O
be	O
set	O
to	O
local	O
time	B-Device
or	O
UTC	O
.	O
</s>
<s>
On	O
machines	O
using	O
a	O
PC-AT	O
real-time	O
clock	O
,	O
by	O
default	O
the	O
hardware	O
clock	O
still	O
has	O
to	O
be	O
set	O
to	O
local	O
time	B-Device
for	O
compatibility	O
with	O
BIOS-based	O
Windows	B-Application
,	O
unless	O
using	O
recent	O
versions	O
and	O
an	O
entry	O
in	O
the	O
Windows	B-Protocol
registry	I-Protocol
is	O
set	O
to	O
indicate	O
the	O
use	O
of	O
UTC	O
.	O
</s>
<s>
Beyond	O
loading	O
an	O
OS	O
,	O
UEFI	B-Architecture
can	O
run	O
UEFI	B-Architecture
applications	O
,	O
which	O
reside	O
as	O
files	O
on	O
the	O
EFI	B-Device
System	I-Device
Partition	I-Device
.	O
</s>
<s>
They	O
can	O
be	O
executed	O
from	O
the	O
UEFI	B-Architecture
Shell	O
,	O
by	O
the	O
firmware	B-Application
's	O
boot	B-Application
manager	I-Application
,	O
or	O
by	O
other	O
UEFI	B-Architecture
applications	O
.	O
</s>
<s>
UEFI	B-Architecture
applications	O
can	O
be	O
developed	O
and	O
installed	O
independently	O
of	O
the	O
original	O
equipment	O
manufacturers	O
(	O
OEMs	O
)	O
.	O
</s>
<s>
A	O
type	B-Device
of	O
UEFI	B-Architecture
application	O
is	O
an	O
OS	O
boot	B-Application
loader	I-Application
such	O
as	O
GRUB	B-Application
,	O
rEFInd	B-Device
,	O
Gummiboot	B-Application
,	O
and	O
Windows	B-Operating_System
Boot	I-Operating_System
Manager	I-Operating_System
;	O
which	O
loads	O
some	O
OS	O
files	O
into	O
memory	O
and	O
executes	O
them	O
.	O
</s>
<s>
Also	O
,	O
an	O
OS	O
boot	B-Application
loader	I-Application
can	O
provide	O
a	O
user	B-Application
interface	I-Application
to	O
allow	O
the	O
selection	O
of	O
another	O
UEFI	B-Architecture
application	O
to	O
run	O
.	O
</s>
<s>
Utilities	O
like	O
the	O
UEFI	B-Architecture
Shell	O
are	O
also	O
UEFI	B-Architecture
applications	O
.	O
</s>
<s>
EFI	O
defines	O
protocols	O
as	O
a	O
set	O
of	O
software	O
interfaces	B-Application
used	O
for	O
communication	O
between	O
two	O
binary	O
modules	B-Application
.	O
</s>
<s>
The	O
EFI	O
Protocols	O
are	O
similar	O
to	O
the	O
BIOS	B-Device
interrupt	I-Device
calls	I-Device
.	O
</s>
<s>
In	O
addition	O
to	O
standard	O
instruction	O
set	O
architecture-specific	O
device	B-Application
drivers	I-Application
,	O
EFI	O
provides	O
for	O
a	O
ISA-independent	O
device	B-Application
driver	I-Application
stored	O
in	O
non-volatile	B-General_Concept
memory	I-General_Concept
as	O
EFI	O
byte	B-Application
code	O
or	O
EBC	O
.	O
</s>
<s>
System	O
firmware	B-Application
has	O
an	O
interpreter	O
for	O
EBC	O
images	O
.	O
</s>
<s>
In	O
that	O
sense	O
,	O
EBC	O
is	O
analogous	O
to	O
Open	B-Architecture
Firmware	I-Architecture
,	O
the	O
ISA-independent	O
firmware	B-Application
used	O
in	O
PowerPC-based	O
Apple	B-Device
Macintosh	I-Device
and	O
Sun	O
Microsystems	O
SPARC	B-Architecture
computers	O
,	O
among	O
others	O
.	O
</s>
<s>
Some	O
architecture-specific	O
(	O
non-EFI	O
Byte	B-Application
Code	O
)	O
EFI	O
drivers	O
for	O
some	O
device	O
types	O
can	O
have	O
interfaces	B-Application
for	O
use	O
by	O
the	O
OS	O
.	O
</s>
<s>
In	O
other	O
cases	O
,	O
the	O
EFI	O
driver	O
can	O
be	O
filesystem	O
drivers	O
that	O
allow	O
for	O
booting	B-Operating_System
from	O
other	O
types	O
of	O
disk	O
volumes	O
.	O
</s>
<s>
Examples	O
include	O
efifs	O
for	O
37	O
file	O
systems	O
(	O
based	O
on	O
GRUB2	O
code	O
)	O
,	O
used	O
by	O
Rufus	B-Application
for	O
chain-loading	O
NTFS	O
ESPs	O
.	O
</s>
<s>
UEFI	B-Architecture
did	O
not	O
include	O
UGA	O
and	O
replaced	O
it	O
with	O
GOP	O
(	O
Graphics	O
Output	O
Protocol	O
)	O
.	O
</s>
<s>
UEFI	B-Architecture
2.1	O
defined	O
a	O
"	O
Human	B-Application
Interface	I-Application
Infrastructure	O
"	O
(	O
HII	O
)	O
to	O
manage	O
user	O
input	O
,	O
localized	O
strings	O
,	O
fonts	O
,	O
and	O
forms	O
(	O
in	O
the	O
HTML	B-Language
sense	O
)	O
.	O
</s>
<s>
These	O
enable	O
original	O
equipment	O
manufacturers	O
(	O
OEMs	O
)	O
or	O
independent	O
BIOS	B-Operating_System
vendors	O
(	O
IBVs	O
)	O
to	O
design	O
graphical	O
interfaces	B-Application
for	O
pre-boot	O
configuration	O
.	O
</s>
<s>
Most	O
early	O
UEFI	B-Architecture
firmware	I-Architecture
implementations	O
were	O
console-based	O
.	O
</s>
<s>
Today	O
many	O
UEFI	B-Architecture
firmware	I-Architecture
implementations	O
are	O
GUI-based	O
.	O
</s>
<s>
An	O
EFI	B-Device
system	I-Device
partition	I-Device
,	O
often	O
abbreviated	O
to	O
ESP	O
,	O
is	O
a	O
data	B-General_Concept
storage	I-General_Concept
device	I-General_Concept
partition	O
that	O
is	O
used	O
in	O
computers	O
adhering	O
to	O
the	O
UEFI	B-Architecture
specification	O
.	O
</s>
<s>
Accessed	O
by	O
the	O
UEFI	B-Architecture
firmware	I-Architecture
when	O
a	O
computer	O
is	O
powered	O
up	O
,	O
it	O
stores	O
UEFI	B-Architecture
applications	O
and	O
the	O
files	O
these	O
applications	O
need	O
to	O
run	O
,	O
including	O
operating	B-General_Concept
system	I-General_Concept
boot	B-Application
loaders	I-Application
.	O
</s>
<s>
Supported	O
partition	O
table	O
schemes	O
include	O
MBR	B-Device
and	O
GPT	B-Application
,	O
as	O
well	O
as	O
El	B-Device
Torito	I-Device
volumes	O
on	O
optical	O
discs	O
.	O
</s>
<s>
For	O
use	O
on	O
ESPs	O
,	O
UEFI	B-Architecture
defines	O
a	O
specific	O
version	O
of	O
the	O
FAT	B-Application
file	I-Application
system	I-Application
,	O
which	O
is	O
maintained	O
as	O
part	O
of	O
the	O
UEFI	B-Architecture
specification	O
and	O
independently	O
from	O
the	O
original	O
FAT	O
specification	O
,	O
encompassing	O
the	O
FAT32	B-Application
,	O
FAT16	B-Application
and	O
FAT12	B-Application
file	O
systems	O
.	O
</s>
<s>
The	O
ESP	O
also	O
provides	O
space	O
for	O
a	O
boot	B-Device
sector	I-Device
as	O
part	O
of	O
the	O
backward	O
BIOS	B-Operating_System
compatibility	O
.	O
</s>
<s>
Unlike	O
the	O
legacy	O
PC	B-Operating_System
BIOS	I-Operating_System
,	O
UEFI	B-Architecture
does	O
not	O
rely	O
on	O
boot	B-Device
sectors	I-Device
,	O
defining	O
instead	O
a	O
boot	B-Application
manager	I-Application
as	O
part	O
of	O
the	O
UEFI	B-Architecture
specification	O
.	O
</s>
<s>
When	O
a	O
computer	O
is	O
powered	O
on	O
,	O
the	O
boot	B-Application
manager	I-Application
checks	O
the	O
boot	B-Operating_System
configuration	O
and	O
,	O
based	O
on	O
its	O
settings	O
,	O
then	O
executes	O
the	O
specified	O
OS	O
boot	B-Application
loader	I-Application
or	O
operating	B-Operating_System
system	I-Operating_System
kernel	I-Operating_System
(	O
usually	O
boot	B-Application
loader	I-Application
)	O
.	O
</s>
<s>
The	O
boot	B-Operating_System
configuration	O
is	O
defined	O
by	O
variables	O
stored	O
in	O
NVRAM	B-General_Concept
,	O
including	O
variables	O
that	O
indicate	O
the	O
file	O
system	O
paths	O
to	O
OS	O
loaders	O
or	O
OS	B-Operating_System
kernels	I-Operating_System
.	O
</s>
<s>
OS	O
boot	B-Application
loaders	I-Application
can	O
be	O
automatically	O
detected	O
by	O
UEFI	B-Architecture
,	O
which	O
enables	O
easy	O
booting	B-Operating_System
from	O
removable	O
devices	O
such	O
as	O
USB	O
flash	O
drives	O
.	O
</s>
<s>
This	O
automated	O
detection	O
relies	O
on	O
standardized	O
file	O
paths	O
to	O
the	O
OS	O
boot	B-Application
loader	I-Application
,	O
with	O
the	O
path	O
varying	O
depending	O
on	O
the	O
computer	B-General_Concept
architecture	I-General_Concept
.	O
</s>
<s>
The	O
format	O
of	O
the	O
file	O
path	O
is	O
defined	O
as	O
;	O
for	O
example	O
,	O
the	O
file	O
path	O
to	O
the	O
OS	O
loader	O
on	O
an	O
x86-64	B-Device
system	O
is	O
,	O
and	O
on	O
ARM64	B-Architecture
architecture	B-Architecture
.	O
</s>
<s>
Booting	B-Operating_System
UEFI	B-Architecture
systems	O
from	O
GPT-partitioned	O
disks	O
is	O
commonly	O
called	O
UEFI-GPT	O
booting	B-Operating_System
.	O
</s>
<s>
Despite	O
the	O
fact	O
that	O
the	O
UEFI	B-Architecture
specification	O
requires	O
MBR	B-Device
partition	O
tables	O
to	O
be	O
fully	O
supported	O
,	O
some	O
UEFI	B-Architecture
firmware	I-Architecture
implementations	O
immediately	O
switch	O
to	O
the	O
BIOS-based	O
CSM	O
booting	B-Operating_System
depending	O
on	O
the	O
type	B-Device
of	O
boot	B-Operating_System
disk	O
's	O
partition	O
table	O
,	O
effectively	O
preventing	O
UEFI	B-Architecture
booting	B-Operating_System
to	O
be	O
performed	O
from	O
EFI	B-Device
System	I-Device
Partition	I-Device
on	O
MBR-partitioned	O
disks	O
.	O
</s>
<s>
Such	O
a	O
boot	B-Operating_System
scheme	O
is	O
commonly	O
called	O
UEFI-MBR	O
.	O
</s>
<s>
It	O
is	O
also	O
common	O
for	O
a	O
boot	B-Application
manager	I-Application
to	O
have	O
a	O
textual	O
user	B-Application
interface	I-Application
so	O
the	O
user	O
can	O
select	O
the	O
desired	O
OS	O
(	O
or	O
setup	O
utility	O
)	O
from	O
a	O
list	O
of	O
available	O
boot	B-Operating_System
options	O
.	O
</s>
<s>
To	O
ensure	O
backward	B-General_Concept
compatibility	I-General_Concept
,	O
UEFI	B-Architecture
firmware	I-Architecture
implementations	O
on	O
PC-class	O
machines	O
could	O
support	O
booting	B-Operating_System
in	O
legacy	B-Operating_System
BIOS	I-Operating_System
mode	O
from	O
MBR-partitioned	O
disks	O
through	O
the	O
Compatibility	O
Support	O
Module	B-Application
(	O
CSM	O
)	O
that	O
provides	O
legacy	B-Operating_System
BIOS	I-Operating_System
compatibility	O
.	O
</s>
<s>
In	O
this	O
scenario	O
,	O
booting	B-Operating_System
is	O
performed	O
in	O
the	O
same	O
way	O
as	O
on	O
legacy	O
BIOS-based	O
systems	O
,	O
by	O
ignoring	O
the	O
partition	O
table	O
and	O
relying	O
on	O
the	O
content	O
of	O
a	O
boot	B-Device
sector	I-Device
.	O
</s>
<s>
BIOS-style	O
booting	B-Operating_System
from	O
MBR-partitioned	O
disks	O
is	O
commonly	O
called	O
BIOS-MBR	O
,	O
regardless	O
of	O
it	O
being	O
performed	O
on	O
UEFI	B-Architecture
or	O
legacy	O
BIOS-based	O
systems	O
.	O
</s>
<s>
Furthermore	O
,	O
booting	B-Operating_System
legacy	O
BIOS-based	O
systems	O
from	O
GPT	B-Application
disks	I-Application
is	O
also	O
possible	O
,	O
and	O
such	O
a	O
boot	B-Operating_System
scheme	O
is	O
commonly	O
called	O
BIOS-GPT	O
.	O
</s>
<s>
The	O
Compatibility	O
Support	O
Module	B-Application
allows	O
legacy	O
operating	B-General_Concept
systems	I-General_Concept
and	O
some	O
legacy	O
option	O
ROMs	O
that	O
do	O
not	O
support	O
UEFI	B-Architecture
to	O
still	O
be	O
used	O
.	O
</s>
<s>
It	O
also	O
provides	O
required	O
legacy	O
System	B-Architecture
Management	I-Architecture
Mode	I-Architecture
(	O
SMM	B-Architecture
)	O
functionality	O
,	O
called	O
CompatibilitySmm	O
,	O
as	O
an	O
addition	O
to	O
features	O
provided	O
by	O
the	O
UEFI	B-Architecture
SMM	B-Architecture
.	O
</s>
<s>
An	O
example	O
of	O
such	O
a	O
legacy	O
SMM	B-Architecture
functionality	O
is	O
providing	O
USB	O
legacy	O
support	O
for	O
keyboard	O
and	O
mouse	O
,	O
by	O
emulating	O
their	O
classic	O
PS/2	B-Protocol
counterparts	O
.	O
</s>
<s>
In	O
July	O
,	O
of	O
2022	B-Device
,	O
Kaspersky	O
Labs	O
published	O
information	O
regarding	O
a	O
Rootkit	O
designed	O
to	O
chain	O
boot	B-Operating_System
malicious	O
code	O
on	O
machines	O
using	O
Intel	O
's	O
H81	O
chipset	O
and	O
the	O
Compatibility	O
Support	O
module	B-Application
of	O
affected	O
motherboards	B-Device
.	O
</s>
<s>
The	O
UEFI	B-Architecture
specification	O
includes	O
support	O
for	O
booting	B-Operating_System
over	O
network	O
via	O
the	O
Preboot	B-Device
eXecution	I-Device
Environment	I-Device
(	O
PXE	O
)	O
.	O
</s>
<s>
PXE	O
booting	B-Operating_System
network	O
protocols	O
include	O
Internet	B-Protocol
Protocol	I-Protocol
(	O
IPv4	B-Protocol
and	O
IPv6	B-Protocol
)	O
,	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	O
)	O
,	O
Dynamic	B-Protocol
Host	I-Protocol
Configuration	I-Protocol
Protocol	I-Protocol
(	O
DHCP	B-Protocol
)	O
,	O
Trivial	B-Device
File	I-Device
Transfer	I-Device
Protocol	I-Device
(	O
TFTP	B-Device
)	O
and	O
iSCSI	B-Protocol
.	O
</s>
<s>
OS	O
images	O
can	O
be	O
remotely	O
stored	O
on	O
storage	O
area	O
networks	O
(	O
SANs	O
)	O
,	O
with	O
Internet	B-Protocol
Small	I-Protocol
Computer	I-Protocol
System	I-Protocol
Interface	I-Protocol
(	O
iSCSI	B-Protocol
)	O
and	O
Fibre	B-Protocol
Channel	I-Protocol
over	I-Protocol
Ethernet	I-Protocol
(	O
FCoE	B-Protocol
)	O
as	O
supported	O
protocols	O
for	O
accessing	O
the	O
SANs	O
.	O
</s>
<s>
Version	O
2.5	O
of	O
the	O
UEFI	B-Architecture
specification	O
adds	O
support	O
for	O
accessing	O
boot	B-Operating_System
images	O
over	O
the	O
HTTP	B-Protocol
protocol	I-Protocol
.	O
</s>
<s>
The	O
UEFI	B-Architecture
specification	O
defines	O
a	O
protocol	O
known	O
as	O
Secure	O
Boot	B-Operating_System
,	O
which	O
can	O
secure	O
the	O
boot	B-Operating_System
process	I-Operating_System
by	O
preventing	O
the	O
loading	O
of	O
UEFI	B-Architecture
drivers	O
or	O
OS	O
boot	B-Application
loaders	I-Application
that	O
are	O
not	O
signed	B-Application
with	O
an	O
acceptable	O
digital	O
signature	O
.	O
</s>
<s>
The	O
mechanical	O
details	O
of	O
how	O
precisely	O
these	O
drivers	O
are	O
to	O
be	O
signed	B-Application
are	O
not	O
specified	O
.	O
</s>
<s>
When	O
Secure	O
Boot	B-Operating_System
is	O
enabled	O
,	O
it	O
is	O
initially	O
placed	O
in	O
"	O
setup	O
"	O
mode	O
,	O
which	O
allows	O
a	O
public	B-Application
key	I-Application
known	O
as	O
the	O
"	O
platform	O
key	O
"	O
(	O
PK	O
)	O
to	O
be	O
written	O
to	O
the	O
firmware	B-Application
.	O
</s>
<s>
Once	O
the	O
key	O
is	O
written	O
,	O
Secure	O
Boot	B-Operating_System
enters	O
"	O
User	O
"	O
mode	O
,	O
where	O
only	O
UEFI	B-Architecture
drivers	O
and	O
OS	O
boot	B-Application
loaders	I-Application
signed	B-Application
with	O
the	O
platform	O
key	O
can	O
be	O
loaded	O
by	O
the	O
firmware	B-Application
.	O
</s>
<s>
Secure	O
Boot	B-Operating_System
can	O
also	O
be	O
placed	O
in	O
"	O
Custom	O
"	O
mode	O
,	O
where	O
additional	O
public	B-Application
keys	I-Application
can	O
be	O
added	O
to	O
the	O
system	O
that	O
do	O
not	O
match	O
the	O
private	B-Application
key	I-Application
.	O
</s>
<s>
Secure	O
Boot	B-Operating_System
is	O
supported	O
by	O
Windows	B-Application
8	I-Application
and	O
8.1	B-Device
,	O
Windows	B-Device
Server	I-Device
2012	I-Device
and	O
2012	O
R2	O
,	O
Windows	B-Operating_System
10	I-Operating_System
,	O
Windows	B-Device
Server	I-Device
2016	I-Device
,	O
2019	B-Device
,	O
and	O
2022	B-Device
,	O
and	O
Windows	B-Application
11	I-Application
,	O
VMware	B-Application
vSphere	I-Application
6.5	O
and	O
a	O
number	O
of	O
Linux	B-Application
distributions	I-Application
including	O
Fedora	O
(	O
since	O
version	O
18	O
)	O
,	O
openSUSE	B-Operating_System
(	O
since	O
version	O
12.3	O
)	O
,	O
RHEL	O
(	O
since	O
version	O
7	O
)	O
,	O
CentOS	O
(	O
since	O
version	O
7	O
)	O
,	O
Debian	O
(	O
since	O
version	O
10	B-Operating_System
)	O
,	O
and	O
Ubuntu	B-Operating_System
(	O
since	O
version	O
12.04.2	O
)	O
.	O
</s>
<s>
,	O
FreeBSD	B-Operating_System
support	O
is	O
in	O
a	O
planning	O
stage	O
.	O
</s>
<s>
UEFI	B-Architecture
provides	O
a	O
shell	B-Operating_System
environment	I-Operating_System
,	O
which	O
can	O
be	O
used	O
to	O
execute	O
other	O
UEFI	B-Architecture
applications	O
,	O
including	O
UEFI	B-Architecture
boot	B-Application
loaders	I-Application
.	O
</s>
<s>
Apart	O
from	O
that	O
,	O
commands	B-Application
available	O
in	O
the	O
UEFI	B-Architecture
shell	O
can	O
be	O
used	O
for	O
obtaining	O
various	O
other	O
information	O
about	O
the	O
system	O
or	O
the	O
firmware	B-Application
,	O
including	O
getting	O
the	O
memory	B-General_Concept
map	I-General_Concept
(	O
memmap	O
)	O
,	O
modifying	O
boot	B-Application
manager	I-Application
variables	O
(	O
bcfg	O
)	O
,	O
running	O
partitioning	O
programs	O
(	O
diskpart	O
)	O
,	O
loading	O
UEFI	B-Architecture
drivers	O
,	O
and	O
editing	O
text	O
files	O
(	O
edit	O
)	O
.	O
</s>
<s>
Source	O
code	O
for	O
a	O
UEFI	B-Architecture
shell	O
can	O
be	O
downloaded	O
from	O
the	O
Intel	O
's	O
TianoCore	B-Language
UDK/EDK2	O
project	O
.	O
</s>
<s>
Shell	O
v2	O
works	O
best	O
in	O
UEFI	B-Architecture
2.3	O
+	O
systems	O
and	O
is	O
recommended	O
over	O
Shell	O
v1	O
in	O
those	O
systems	O
.	O
</s>
<s>
Shell	O
v1	O
should	O
work	O
in	O
all	O
UEFI	B-Architecture
systems	O
.	O
</s>
<s>
Methods	O
used	O
for	O
launching	O
UEFI	B-Architecture
shell	O
depend	O
on	O
the	O
manufacturer	O
and	O
model	O
of	O
the	O
system	O
motherboard	B-Device
.	O
</s>
<s>
Some	O
of	O
them	O
already	O
provide	O
a	O
direct	O
option	O
in	O
firmware	B-Application
setup	O
for	O
launching	O
,	O
e.g.	O
</s>
<s>
compiled	O
x86-64	B-Device
version	O
of	O
the	O
shell	O
needs	O
to	O
be	O
made	O
available	O
as	O
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1/SHELLX64.EFI	O
.	O
</s>
<s>
Some	O
other	O
systems	O
have	O
an	O
already	O
embedded	O
UEFI	B-Architecture
shell	O
which	O
can	O
be	O
launched	O
by	O
appropriate	O
key	O
press	O
combinations	O
.	O
</s>
<s>
For	O
other	O
systems	O
,	O
the	O
solution	O
is	O
either	O
creating	O
an	O
appropriate	O
USB	O
flash	O
drive	O
or	O
adding	O
manually	O
(	O
bcfg	O
)	O
a	O
boot	B-Operating_System
option	O
associated	O
with	O
the	O
compiled	O
version	O
of	O
shell	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
list	O
of	O
commands	B-Application
supported	O
by	O
the	O
EFI	O
shell	O
.	O
</s>
<s>
Extensions	O
to	O
UEFI	B-Architecture
can	O
be	O
loaded	O
from	O
virtually	O
any	O
non-volatile	B-General_Concept
storage	I-General_Concept
device	O
attached	O
to	O
the	O
computer	O
.	O
</s>
<s>
For	O
example	O
,	O
an	O
original	O
equipment	O
manufacturer	O
(	O
OEM	O
)	O
can	O
distribute	O
systems	O
with	O
an	O
EFI	B-Device
system	I-Device
partition	I-Device
on	O
the	O
hard	O
drive	O
,	O
which	O
would	O
add	O
additional	O
functions	O
to	O
the	O
standard	O
UEFI	B-Architecture
firmware	I-Architecture
stored	O
on	O
the	O
motherboard	B-Device
's	O
ROM	B-Device
.	O
</s>
<s>
UEFI	B-Architecture
Capsule	O
defines	O
a	O
Firmware-to-OS	O
firmware	B-Application
update	O
interface	B-Application
,	O
marketed	O
as	O
modern	O
and	O
secure	O
.	O
</s>
<s>
Windows	B-Application
8	I-Application
,	O
Windows	B-Device
8.1	I-Device
,	O
Windows	B-Operating_System
10	I-Operating_System
,	O
and	O
Fwupd	B-Application
for	O
Linux	B-Operating_System
each	O
support	O
the	O
UEFI	B-Architecture
Capsule	O
.	O
</s>
<s>
Like	O
BIOS	B-Operating_System
,	O
UEFI	B-Architecture
initializes	O
and	O
tests	O
system	O
hardware	O
components	O
(	O
e.g.	O
</s>
<s>
Memory	O
training	O
,	O
PCIe	O
link	O
training	O
,	O
USB	O
link	O
training	O
)	O
,	O
and	O
then	O
loads	O
the	O
boot	B-Application
loader	I-Application
from	O
a	O
mass	B-Device
storage	I-Device
device	I-Device
or	O
through	O
a	O
network	B-Device
connection	I-Device
.	O
</s>
<s>
In	O
x86	B-Operating_System
systems	O
,	O
the	O
UEFI	B-Architecture
firmware	I-Architecture
is	O
usually	O
stored	O
in	O
the	O
NOR	O
flash	O
chip	O
of	O
the	O
motherboard	B-Device
.	O
</s>
<s>
UEFI	B-Architecture
machines	O
can	O
have	O
one	O
of	O
the	O
following	O
classes	O
,	O
which	O
were	O
used	O
to	O
help	B-Protocol
ease	O
the	O
transition	O
to	O
UEFI	B-Architecture
:	O
</s>
<s>
Class	O
1	O
:	O
UEFI	B-Architecture
with	O
a	O
CSM	O
interface	B-Application
and	O
no	O
external	O
UEFI	B-Architecture
interface	B-Application
.	O
</s>
<s>
The	O
only	O
UEFI	B-Architecture
interfaces	B-Application
are	O
internal	O
to	O
the	O
firmware	B-Application
.	O
</s>
<s>
Starting	O
from	O
the	O
10th	O
Gen	O
Intel	O
Core	O
,	O
Intel	O
no	O
longer	O
provides	O
Legacy	O
Video	B-Device
BIOS	I-Device
for	O
the	O
iGPU	O
(	O
Intel	B-Application
Graphics	I-Application
Technology	I-Application
)	O
.	O
</s>
<s>
Legacy	O
boot	B-Operating_System
with	O
those	O
CPUs	O
requires	O
a	O
Legacy	O
Video	B-Device
BIOS	I-Device
,	O
which	O
can	O
still	O
be	O
provided	O
by	O
a	O
video	O
card	O
.	O
</s>
<s>
This	O
is	O
the	O
first	O
stage	O
of	O
the	O
UEFI	B-Architecture
boot	B-Operating_System
but	O
may	O
have	O
platform	O
specific	O
binary	O
code	O
that	O
precedes	O
it	O
.	O
</s>
<s>
(	O
e.g.	O
,	O
Intel	B-Device
ME	I-Device
,	O
AMD	B-Device
PSP	I-Device
,	O
CPU	O
microcode	B-Device
)	O
.	O
</s>
<s>
It	O
consists	O
of	O
minimal	O
code	O
written	O
in	O
assembly	B-Language
language	I-Language
for	O
the	O
specific	O
architecture	B-Architecture
.	O
</s>
<s>
The	O
second	O
stage	O
of	O
UEFI	B-Architecture
boot	B-Operating_System
consists	O
of	O
a	O
dependency-aware	O
dispatcher	O
that	O
loads	O
and	O
runs	O
PEI	O
modules	B-Application
(	O
PEIMs	O
)	O
to	O
handle	O
early	O
hardware	O
initialization	O
tasks	O
such	O
as	O
main	O
memory	O
initialization	O
and	O
firmware	B-Application
recovery	O
operations	O
.	O
</s>
<s>
Additionally	O
,	O
it	O
is	O
responsible	O
for	O
discovery	O
of	O
the	O
current	O
boot	B-Operating_System
mode	O
and	O
handling	O
many	O
ACPI	B-Device
S0ix/ACPI	O
S3	O
operations	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
ACPI	B-Device
S0ix/ACPI	O
S3	O
resume	O
,	O
it	O
is	O
responsible	O
for	O
restoring	O
many	O
hardware	O
registers	O
to	O
a	O
pre-sleep	O
state	O
.	O
</s>
<s>
This	O
stage	O
consist	O
of	O
C	B-Language
modules	B-Application
and	O
a	O
dependency-aware	O
dispatcher	O
.	O
</s>
<s>
With	O
main	O
memory	O
now	O
available	O
,	O
CPU	O
,	O
chipset	O
,	O
mainboard	B-Device
and	O
boot	B-Operating_System
devices	O
are	O
initialized	O
in	O
DXE	O
and	O
BDS	O
.	O
</s>
<s>
In	O
this	O
stage	O
,	O
boot	B-Operating_System
devices	O
are	O
initialized	O
,	O
UEFI	B-Architecture
drivers	O
or	O
Option	O
ROMs	O
of	O
PCI	O
devices	O
are	O
executed	O
according	O
to	O
system	O
configuration	O
,	O
and	O
boot	B-Operating_System
options	O
are	O
processed	O
.	O
</s>
<s>
This	O
is	O
the	O
stage	O
between	O
boot	B-Operating_System
device	O
selection	O
and	O
hand-off	O
to	O
the	O
OS	O
.	O
</s>
<s>
At	O
this	O
point	O
one	O
may	O
enter	O
UEFI	B-Architecture
shell	O
,	O
or	O
execute	O
an	O
UEFI	B-Architecture
application	O
such	O
as	O
the	O
OS	O
boot	B-Application
loader	I-Application
.	O
</s>
<s>
The	O
UEFI	B-Architecture
hands	O
off	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
after	O
is	O
executed	O
.	O
</s>
<s>
A	O
UEFI	B-Architecture
compatible	O
OS	O
is	O
now	O
responsible	O
for	O
exiting	O
boot	B-Operating_System
services	O
triggering	O
the	O
firmware	B-Application
to	O
unload	O
all	O
no	O
longer	O
needed	O
code	O
and	O
data	O
,	O
leaving	O
only	O
runtime	O
services	O
code/data	O
,	O
e.g.	O
</s>
<s>
SMM	B-Architecture
and	O
ACPI	B-Device
.	O
</s>
<s>
A	O
typical	O
modern	O
OS	O
will	O
prefer	O
to	O
use	O
its	O
own	O
programs	O
(	O
such	O
as	O
kernel	B-Application
drivers	I-Application
)	O
to	O
control	O
hardware	O
devices	O
.	O
</s>
<s>
When	O
a	O
legacy	O
OS	O
is	O
used	O
,	O
CSM	O
will	O
handle	O
this	O
call	O
ensuring	O
the	O
system	O
is	O
compatible	O
with	O
legacy	B-Operating_System
BIOS	I-Operating_System
expectations	O
.	O
</s>
<s>
Intel	O
's	O
implementation	O
of	O
EFI	O
is	O
the	O
Intel	O
Platform	O
Innovation	O
Framework	O
,	O
codenamed	O
Tiano	B-Architecture
.	O
</s>
<s>
Tiano	B-Architecture
runs	O
on	O
Intel	O
's	O
XScale	B-Application
,	O
Itanium	B-General_Concept
,	O
x86-32	B-Device
and	O
x86-64	B-Device
processors	O
,	O
and	O
is	O
proprietary	O
software	O
,	O
although	O
a	O
portion	O
of	O
the	O
code	O
has	O
been	O
released	O
under	O
the	O
BSD	B-Operating_System
license	I-Operating_System
or	O
Eclipse	B-License
Public	I-License
License	I-License
(	O
EPL	O
)	O
as	O
TianoCore	B-Language
EDK	I-Language
II	I-Language
.	O
</s>
<s>
TianoCore	B-Language
can	O
be	O
used	O
as	O
a	O
payload	O
for	O
coreboot	B-Device
.	O
</s>
<s>
Phoenix	O
Technologies	O
 '	O
implementation	O
of	O
UEFI	B-Architecture
is	O
branded	O
as	O
SecureCore	O
Technology	O
(	O
SCT	O
)	O
.	O
</s>
<s>
American	O
Megatrends	O
offers	O
its	O
own	O
UEFI	B-Architecture
firmware	I-Architecture
implementation	O
known	O
as	O
Aptio	O
,	O
while	O
Insyde	O
Software	O
offers	O
InsydeH2O	O
.	O
</s>
<s>
In	O
December	O
2018	O
,	O
Microsoft	O
released	O
an	O
open	B-License
source	I-License
version	O
of	O
its	O
TianoCore	B-Language
EDK2-based	O
UEFI	B-Architecture
implementation	O
from	O
the	O
Surface	B-Device
line	O
,	O
Project	B-Language
Mu	I-Language
.	O
</s>
<s>
An	O
implementation	O
of	O
the	O
UEFI	B-Architecture
API	O
was	O
introduced	O
into	O
the	O
Universal	O
Boot	B-Application
Loader	I-Application
(	O
Das	B-Language
U-Boot	I-Language
)	O
in	O
2017	O
.	O
</s>
<s>
On	O
the	O
ARMv8	O
architecture	B-Architecture
Linux	B-Application
distributions	I-Application
use	O
the	O
U-Boot	O
UEFI	B-Architecture
implementation	O
in	O
conjunction	O
with	O
GNU	B-Application
GRUB	I-Application
for	O
booting	B-Operating_System
(	O
e.g.	O
</s>
<s>
SUSE	O
Linux	B-Operating_System
)	O
,	O
the	O
same	O
holds	O
true	O
for	O
OpenBSD	B-Operating_System
.	O
</s>
<s>
For	O
booting	B-Operating_System
from	O
iSCSI	B-Protocol
iPXE	B-Device
can	O
be	O
used	O
as	O
a	O
UEFI	B-Architecture
application	O
loaded	O
by	O
U-Boot	O
.	O
</s>
<s>
Intel	O
's	O
first	O
Itanium	B-General_Concept
workstations	O
and	O
servers	O
,	O
released	O
in	O
2000	O
,	O
implemented	O
EFI	O
1.02	O
.	O
</s>
<s>
Hewlett-Packard	O
'	O
s	O
first	O
Itanium	B-General_Concept
2	O
systems	O
,	O
released	O
in	O
2002	O
,	O
implemented	O
EFI	O
1.10	O
;	O
they	O
were	O
able	O
to	O
boot	B-Operating_System
Windows	B-Application
,	O
Linux	B-Operating_System
,	O
FreeBSD	B-Operating_System
and	O
HP-UX	B-Application
;	O
OpenVMS	B-Operating_System
added	O
UEFI	B-Architecture
capability	O
in	O
June	O
2003	O
.	O
</s>
<s>
In	O
January	O
2006	O
,	O
Apple	O
Inc	O
.	O
shipped	O
its	O
first	O
Intel-based	B-Device
Macintosh	I-Device
computers	I-Device
.	O
</s>
<s>
These	O
systems	O
used	O
EFI	O
instead	O
of	O
Open	B-Architecture
Firmware	I-Architecture
,	O
which	O
had	O
been	O
used	O
on	O
its	O
previous	O
PowerPC-based	O
systems	O
.	O
</s>
<s>
On	O
5	O
April	O
2006	O
,	O
Apple	O
first	O
released	O
Boot	B-Application
Camp	I-Application
,	O
which	O
produces	O
a	O
Windows	B-Application
drivers	O
disk	O
and	O
a	O
non-destructive	O
partitioning	O
tool	O
to	O
allow	O
the	O
installation	O
of	O
Windows	B-Application
XP	O
or	O
Vista	B-Application
without	O
requiring	O
a	O
reinstallation	O
of	O
Mac	B-Device
OS	O
X	O
.	O
</s>
<s>
A	O
firmware	B-Application
update	O
was	O
also	O
released	O
that	O
added	O
BIOS	B-Operating_System
compatibility	O
to	O
its	O
EFI	O
implementation	O
.	O
</s>
<s>
Subsequent	O
Macintosh	B-Device
models	O
shipped	O
with	O
the	O
newer	O
firmware	B-Application
.	O
</s>
<s>
During	O
2005	O
,	O
more	O
than	O
one	O
million	O
Intel	O
systems	O
shipped	O
with	O
Intel	O
's	O
implementation	O
of	O
UEFI	B-Architecture
.	O
</s>
<s>
New	O
mobile	O
,	O
desktop	O
and	O
server	O
products	O
,	O
using	O
Intel	O
's	O
implementation	O
of	O
UEFI	B-Architecture
,	O
started	O
shipping	O
in	O
2006	O
.	O
</s>
<s>
For	O
instance	O
,	O
boards	O
that	O
use	O
the	O
Intel	O
945	O
chipset	O
series	O
use	O
Intel	O
's	O
UEFI	B-Architecture
firmware	I-Architecture
implementation	O
.	O
</s>
<s>
Since	O
2005	O
,	O
EFI	O
has	O
also	O
been	O
implemented	O
on	O
non-PC	O
architectures	O
,	O
such	O
as	O
embedded	B-Architecture
systems	I-Architecture
based	O
on	O
XScale	B-Application
cores	O
.	O
</s>
<s>
The	O
EDK	O
(	O
EFI	B-Architecture
Developer	I-Architecture
Kit	I-Architecture
)	O
includes	O
an	O
NT32	O
target	O
,	O
which	O
allows	O
EFI	O
firmware	B-Application
and	O
EFI	O
applications	O
to	O
run	O
within	O
a	O
Windows	B-Application
application	O
.	O
</s>
<s>
In	O
2008	O
,	O
more	O
x86-64	B-Device
systems	O
adopted	O
UEFI	B-Architecture
.	O
</s>
<s>
While	O
many	O
of	O
these	O
systems	O
still	O
allow	O
booting	B-Operating_System
only	O
the	O
BIOS-based	O
OSes	O
via	O
the	O
Compatibility	O
Support	O
Module	B-Application
(	O
CSM	O
)	O
(	O
thus	O
not	O
appearing	O
to	O
the	O
user	O
to	O
be	O
UEFI-based	O
)	O
,	O
other	O
systems	O
started	O
to	O
allow	O
booting	B-Operating_System
UEFI-based	O
OSes	O
.	O
</s>
<s>
For	O
example	O
,	O
IBM	O
x3450	O
server	O
,	O
MSI	O
motherboards	B-Device
with	O
ClickBIOS	O
,	O
HP	O
EliteBook	O
Notebook	O
PCs	B-Device
.	O
</s>
<s>
In	O
2009	O
,	O
IBM	O
shipped	O
System	B-Operating_System
x	I-Operating_System
machines	O
(	O
x3550	O
M2	O
,	O
x3650	O
M2	O
,	O
iDataPlex	O
dx360	O
M2	O
)	O
and	O
BladeCenter	B-General_Concept
HS22	O
with	O
UEFI	B-Architecture
capability	O
.	O
</s>
<s>
Dell	O
shipped	O
PowerEdge	O
T610	O
,	O
R610	O
,	O
R710	O
,	O
M610	O
and	O
M710	O
servers	O
with	O
UEFI	B-Architecture
capability	O
.	O
</s>
<s>
More	O
commercially	O
available	O
systems	O
are	O
mentioned	O
in	O
a	O
UEFI	B-Architecture
whitepaper	O
.	O
</s>
<s>
In	O
2011	O
,	O
major	O
vendors	O
(	O
such	O
as	O
ASRock	O
,	O
Asus	O
,	O
Gigabyte	O
,	O
and	O
MSI	O
)	O
launched	O
several	O
consumer-oriented	O
motherboards	B-Device
using	O
the	O
Intel	O
6-series	O
LGA	B-Device
1155	I-Device
chipset	O
and	O
AMD	O
9	O
Series	O
AM3+	O
chipsets	O
with	O
UEFI	B-Architecture
.	O
</s>
<s>
With	O
the	O
release	O
of	O
Windows	B-Application
8	I-Application
in	O
October	O
2012	O
,	O
Microsoft	O
's	O
certification	O
requirements	O
now	O
require	O
that	O
computers	O
include	O
firmware	B-Application
that	O
implements	O
the	O
UEFI	B-Architecture
specification	O
.	O
</s>
<s>
Furthermore	O
,	O
if	O
the	O
computer	O
supports	O
the	O
"	O
Connected	B-Device
Standby	I-Device
"	O
feature	O
of	O
Windows	B-Application
8	I-Application
(	O
which	O
allows	O
devices	O
to	O
have	O
power	O
management	O
comparable	O
to	O
smartphones	B-Application
,	O
with	O
an	O
almost	O
instantaneous	O
return	O
from	O
standby	O
mode	O
)	O
,	O
then	O
the	O
firmware	B-Application
is	O
not	O
permitted	O
to	O
contain	O
a	O
Compatibility	O
Support	O
Module	B-Application
(	O
CSM	O
)	O
.	O
</s>
<s>
As	O
such	O
,	O
systems	O
that	O
support	O
Connected	B-Device
Standby	I-Device
are	O
incapable	O
of	O
booting	B-Operating_System
Legacy	B-Operating_System
BIOS	I-Operating_System
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
In	O
October	O
2017	O
,	O
Intel	O
announced	O
that	O
it	O
would	O
remove	O
legacy	O
PC	B-Operating_System
BIOS	I-Operating_System
support	O
from	O
all	O
its	O
products	O
by	O
2020	O
,	O
in	O
favor	O
of	O
UEFI	B-Architecture
Class	O
3	O
.	O
</s>
<s>
An	O
operating	B-General_Concept
system	I-General_Concept
that	O
can	O
be	O
booted	B-Operating_System
from	O
a	O
(	O
U	O
)	O
EFI	O
is	O
called	O
a	O
(	O
U	O
)	O
EFI-aware	O
operating	B-General_Concept
system	I-General_Concept
,	O
defined	O
by	O
(	O
U	O
)	O
EFI	O
specification	O
.	O
</s>
<s>
Here	O
the	O
term	O
booted	B-Operating_System
from	O
a	O
(	O
U	O
)	O
EFI	O
means	O
directly	O
booting	B-Operating_System
the	O
system	O
using	O
a	O
(	O
U	O
)	O
EFI	O
operating	B-General_Concept
system	I-General_Concept
loader	O
stored	O
on	O
any	O
storage	O
device	O
.	O
</s>
<s>
The	O
default	O
location	O
for	O
the	O
operating	B-General_Concept
system	I-General_Concept
loader	O
is	O
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1.EFI	O
,	O
where	O
short	O
name	O
of	O
the	O
machine	O
type	B-Device
can	O
be	O
IA32	B-Device
,	O
X64	B-Device
,	O
IA64	B-General_Concept
,	O
ARM	B-Architecture
or	O
AA64	O
.	O
</s>
<s>
Some	O
operating	B-General_Concept
systems	I-General_Concept
vendors	O
may	O
have	O
their	O
own	O
boot	B-Application
loaders	I-Application
.	O
</s>
<s>
They	O
may	O
also	O
change	O
the	O
default	O
boot	B-Operating_System
location	O
.	O
</s>
<s>
The	O
Linux	B-Operating_System
kernel	I-Operating_System
has	O
been	O
able	O
to	O
use	O
EFI	O
at	O
boot	B-Operating_System
time	I-Operating_System
since	O
early	O
2000s	O
,	O
using	O
the	O
elilo	O
EFI	O
boot	B-Application
loader	I-Application
or	O
,	O
more	O
recently	O
,	O
EFI	O
versions	O
of	O
GRUB	B-Application
.	O
</s>
<s>
Grub+Linux	O
also	O
supports	O
booting	B-Operating_System
from	O
a	O
GUID	B-Application
partition	I-Application
table	I-Application
without	O
UEFI	B-Architecture
.	O
</s>
<s>
The	O
distribution	O
Ubuntu	B-Operating_System
added	O
support	O
for	O
UEFI	B-Architecture
Secure	O
Boot	B-Operating_System
as	O
of	O
version	O
12.10	O
.	O
</s>
<s>
Furthermore	O
,	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
can	O
be	O
compiled	O
with	O
the	O
option	O
to	O
run	O
as	O
an	O
EFI	O
bootloader	B-Application
on	O
its	O
own	O
through	O
the	O
EFI	O
bootstub	O
feature	O
.	O
</s>
<s>
HP-UX	B-Application
has	O
used	O
(	O
U	O
)	O
EFI	O
as	O
its	O
boot	B-Operating_System
mechanism	O
on	O
IA-64	B-General_Concept
systems	O
since	O
2002	O
.	O
</s>
<s>
OpenVMS	B-Operating_System
has	O
used	O
EFI	O
on	O
IA-64	B-General_Concept
since	O
its	O
initial	O
evaluation	O
release	O
in	O
December	O
2003	O
,	O
and	O
for	O
production	O
releases	O
since	O
January	O
2005	O
.	O
</s>
<s>
The	O
x86-64	B-Device
port	O
of	O
OpenVMS	B-Operating_System
also	O
uses	O
UEFI	B-Architecture
to	O
boot	B-Operating_System
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Apple	O
uses	O
EFI	O
for	O
its	O
line	O
of	O
Intel-based	B-Device
Macs	I-Device
.	O
</s>
<s>
Mac	B-Application
OS	I-Application
X	I-Application
v10.4	I-Application
Tiger	I-Application
and	O
Mac	B-Application
OS	I-Application
X	I-Application
v10.5	I-Application
Leopard	B-Application
implement	O
EFI	O
v1.10	O
in	O
32-bit	O
mode	O
even	O
on	O
newer	O
64-bit	B-Device
CPUs	I-Device
,	O
but	O
full	O
support	O
arrived	O
with	O
OS	B-Operating_System
X	I-Operating_System
v10.8	I-Operating_System
Mountain	I-Operating_System
Lion	I-Operating_System
.	O
</s>
<s>
The	O
Itanium	B-General_Concept
versions	O
of	O
Windows	B-Application
2000	I-Application
(	O
Advanced	O
Server	O
Limited	O
Edition	O
and	O
Datacenter	O
Server	O
Limited	O
Edition	O
)	O
implemented	O
EFI	O
1.10	O
in	O
2002	O
.	O
</s>
<s>
MS	B-Application
Windows	I-Application
Server	O
2003	O
for	O
IA-64	B-General_Concept
,	O
MS	B-Application
Windows	I-Application
XP	O
64-bit	B-Device
Edition	O
and	O
Windows	B-Application
2000	I-Application
Advanced	O
Server	O
Limited	O
Edition	O
,	O
all	O
of	O
which	O
are	O
for	O
the	O
Intel	B-General_Concept
Itanium	I-General_Concept
family	O
of	O
processors	O
,	O
implement	O
EFI	O
,	O
a	O
requirement	O
of	O
the	O
platform	O
through	O
the	O
DIG64	O
specification	O
.	O
</s>
<s>
Microsoft	O
introduced	O
UEFI	B-Architecture
for	O
x64	B-Device
Windows	B-Application
operating	I-Application
systems	I-Application
with	O
Windows	B-Application
Vista	I-Application
SP1	O
and	O
Windows	B-Device
Server	I-Device
2008	I-Device
however	O
only	O
UGA	O
(	O
Universal	O
Graphic	O
Adapter	O
)	O
1.1	O
or	O
Legacy	B-Operating_System
BIOS	I-Operating_System
INT	B-Device
10h	I-Device
is	O
supported	O
;	O
Graphics	O
Output	O
Protocol	O
(	O
GOP	O
)	O
is	O
not	O
supported	O
.	O
</s>
<s>
Therefore	O
,	O
PCs	B-Device
running	O
64-bit	B-Device
versions	O
of	O
Windows	B-Application
Vista	I-Application
SP1	O
,	O
Windows	B-Application
Vista	I-Application
SP2	O
,	O
Windows	B-Device
7	I-Device
,	O
Windows	B-Device
Server	I-Device
2008	I-Device
and	O
Windows	B-Device
Server	I-Device
2008	I-Device
R2	I-Device
are	O
compatible	O
with	O
UEFI	B-Architecture
Class	O
2	O
.	O
</s>
<s>
32-bit	O
UEFI	B-Architecture
was	O
originally	O
not	O
supported	O
since	O
vendors	O
did	O
not	O
have	O
any	O
interest	O
in	O
producing	O
native	O
32-bit	O
UEFI	B-Architecture
firmware	I-Architecture
because	O
of	O
the	O
mainstream	O
status	O
of	O
64-bit	B-Device
computing	I-Device
.	O
</s>
<s>
Windows	B-Application
8	I-Application
finally	O
introduced	O
further	O
optimizations	O
for	O
UEFI	B-Architecture
systems	O
,	O
including	O
Graphics	O
Output	O
Protocol	O
(	O
GOP	O
)	O
support	O
,	O
a	O
faster	O
startup	O
,	O
32-bit	O
UEFI	B-Architecture
support	O
,	O
and	O
Secure	O
Boot	B-Operating_System
support	O
.	O
</s>
<s>
Microsoft	O
began	O
requiring	O
UEFI	B-Architecture
to	O
run	O
Windows	B-Application
with	O
Windows	B-Application
11	I-Application
.	O
</s>
<s>
On	O
5	O
March	O
2013	O
,	O
the	B-Application
FreeBSD	I-Application
Foundation	I-Application
awarded	O
a	O
grant	O
to	O
a	O
developer	O
seeking	O
to	O
add	O
UEFI	B-Architecture
support	O
to	O
the	O
FreeBSD	B-Operating_System
kernel	B-Operating_System
and	O
bootloader	B-Application
.	O
</s>
<s>
The	O
changes	O
were	O
initially	O
stored	O
in	O
a	O
discrete	O
branch	O
of	O
the	O
FreeBSD	B-Operating_System
source	O
code	O
,	O
but	O
were	O
merged	O
into	O
the	O
mainline	O
source	O
on	O
4	O
April	O
2014	O
(	O
revision	O
264095	O
)	O
;	O
the	O
changes	O
include	O
support	O
in	O
the	O
installer	O
as	O
well	O
.	O
</s>
<s>
UEFI	B-Architecture
boot	B-Operating_System
support	O
for	O
amd64	B-Device
first	O
appeared	O
in	O
FreeBSD	B-Operating_System
10.1	O
and	O
for	O
arm64	B-Architecture
in	O
FreeBSD	B-Operating_System
11.0	O
.	O
</s>
<s>
Oracle	B-Application
Solaris	I-Application
11.1	O
and	O
later	O
support	O
UEFI	B-Architecture
boot	B-Operating_System
for	O
x86	B-Operating_System
systems	O
with	O
UEFI	B-Architecture
firmware	I-Architecture
version	O
2.1	O
or	O
later	O
.	O
</s>
<s>
GRUB	B-Application
2	I-Application
is	O
used	O
as	O
the	O
boot	B-Application
loader	I-Application
on	O
x86	B-Operating_System
.	O
</s>
<s>
OpenBSD	B-Operating_System
5.9	O
introduced	O
UEFI	B-Architecture
boot	B-Operating_System
support	O
for	O
64-bit	B-Device
x86	I-Device
systems	O
using	O
its	O
own	O
custom	O
loader	O
,	O
OpenBSD	B-Operating_System
6.0	O
extended	O
that	O
support	O
to	O
include	O
ARMv7	O
.	O
</s>
<s>
HP	B-Device
Integrity	I-Device
Virtual	I-Device
Machines	I-Device
provides	O
UEFI	B-Architecture
boot	B-Operating_System
on	O
HP	O
Integrity	O
Servers	O
.	O
</s>
<s>
It	O
also	O
provides	O
a	O
virtualized	O
UEFI	B-Architecture
environment	O
for	O
the	O
guest	O
UEFI-aware	O
OSes	O
.	O
</s>
<s>
Intel	O
hosts	O
an	O
Open	O
Virtual	O
Machine	O
Firmware	B-Application
project	O
on	O
SourceForge	B-Application
.	O
</s>
<s>
VMware	B-Operating_System
Fusion	I-Operating_System
3	I-Operating_System
software	O
for	O
Mac	B-Device
OS	O
X	O
can	O
boot	B-Operating_System
Mac	B-Device
OS	O
X	O
Server	O
virtual	O
machines	O
using	O
UEFI	B-Architecture
.	O
</s>
<s>
VMware	B-Operating_System
Workstation	I-Operating_System
prior	O
to	O
version	O
11	O
unofficially	O
supports	O
UEFI	B-Architecture
,	O
but	O
is	O
manually	O
enabled	O
by	O
editing	O
the	O
.vmx	B-Operating_System
file	O
.	O
</s>
<s>
VMware	B-Operating_System
Workstation	I-Operating_System
version	O
11	O
and	O
above	O
supports	O
UEFI	B-Architecture
,	O
independently	O
of	O
whether	O
the	O
physical	O
host	O
system	O
is	O
UEFI-based	O
.	O
</s>
<s>
VMware	B-Operating_System
Workstation	I-Operating_System
14	O
(	O
and	O
accordingly	O
,	O
Fusion	O
10	B-Operating_System
)	O
adds	O
support	O
for	O
the	O
Secure	O
Boot	B-Operating_System
feature	O
of	O
UEFI	B-Architecture
.	O
</s>
<s>
The	O
vSphere	O
ESXi	B-Operating_System
5.0	O
hypervisor	B-Operating_System
officially	O
supports	O
UEFI	B-Architecture
.	O
</s>
<s>
Version	O
6.5	O
adds	O
support	O
for	O
Secure	O
Boot	B-Operating_System
.	O
</s>
<s>
VirtualBox	B-Operating_System
has	O
implemented	O
UEFI	B-Architecture
since	O
3.1	O
,	O
but	O
is	O
limited	O
to	O
Unix/Linux	O
operating	O
systems	O
and	O
Windows	B-Application
8	I-Application
and	O
later	O
(	O
does	O
not	O
work	O
with	O
Windows	B-Application
Vista	I-Application
x64	B-Device
and	O
Windows	B-Device
7	I-Device
x64	B-Device
)	O
.	O
</s>
<s>
QEMU/KVM	O
can	O
be	O
used	O
with	O
the	O
Open	O
Virtual	O
Machine	O
Firmware	B-Application
(	O
OVMF	O
)	O
provided	O
by	O
TianoCore	B-Language
.	O
</s>
<s>
The	O
VMware	B-Operating_System
ESXi	I-Operating_System
version	O
5	O
hypervisor	B-Operating_System
,	O
part	O
of	O
VMware	B-Application
vSphere	I-Application
,	O
supports	O
virtualized	O
UEFI	B-Architecture
as	O
an	O
alternative	O
to	O
the	O
legacy	O
PC	B-Operating_System
BIOS	I-Operating_System
inside	O
a	O
virtual	O
machine	O
.	O
</s>
<s>
The	O
second	O
generation	O
of	O
the	O
Microsoft	O
Hyper-V	O
virtual	O
machine	O
supports	O
virtualized	O
UEFI	B-Architecture
.	O
</s>
<s>
Google	B-General_Concept
Cloud	I-General_Concept
Platform	I-General_Concept
Shielded	O
VMs	B-Operating_System
support	O
virtualized	O
UEFI	B-Architecture
to	O
enable	O
Secure	O
Boot	B-Operating_System
.	O
</s>
<s>
EDK2	B-Language
Application	O
Development	O
Kit	O
(	O
EADK	O
)	O
makes	O
it	O
possible	O
to	O
use	O
standard	B-Language
C	I-Language
library	I-Language
functions	O
in	O
UEFI	B-Architecture
applications	O
.	O
</s>
<s>
EADK	O
can	O
be	O
freely	O
downloaded	O
from	O
the	O
Intel	O
's	O
TianoCore	B-Language
UDK	O
/	O
EDK2	B-Language
SourceForge	B-Application
project	O
.	O
</s>
<s>
As	O
an	O
example	O
,	O
a	O
port	O
of	O
the	O
Python	B-Language
interpreter	O
is	O
made	O
available	O
as	O
a	O
UEFI	B-Architecture
application	O
by	O
using	O
the	O
EADK	O
.	O
</s>
<s>
The	O
development	O
has	O
moved	O
to	O
GitHub	B-Application
since	O
UDK2015	O
.	O
</s>
<s>
A	O
minimalistic	O
"	O
hello	O
,	O
world	O
"	O
C	B-Language
program	I-Language
written	O
using	O
EADK	O
looks	O
similar	O
to	O
its	O
usual	O
C	B-Language
counterpart	O
:	O
</s>
<s>
Numerous	O
digital	O
rights	O
activists	O
have	O
protested	O
against	O
UEFI	B-Architecture
.	O
</s>
<s>
Ronald	O
G	O
.	O
Minnich	O
,	O
a	O
co-author	O
of	O
coreboot	B-Device
,	O
and	O
Cory	O
Doctorow	O
,	O
a	O
digital	O
rights	O
activist	O
,	O
have	O
criticized	O
UEFI	B-Architecture
as	O
an	O
attempt	O
to	O
remove	O
the	O
ability	O
of	O
the	O
user	O
to	O
truly	O
control	O
the	O
computer	O
.	O
</s>
<s>
It	O
does	O
not	O
solve	O
the	O
BIOS	B-Operating_System
's	O
long-standing	O
problems	O
of	O
requiring	O
two	O
different	O
drivers	O
—	O
one	O
for	O
the	O
firmware	B-Application
and	O
one	O
for	O
the	O
operating	B-General_Concept
system	I-General_Concept
—	O
for	O
most	O
hardware	O
.	O
</s>
<s>
Open-source	B-License
project	O
TianoCore	B-Language
also	O
provides	O
UEFI	B-Architecture
interfaces	B-Application
.	O
</s>
<s>
TianoCore	B-Language
lacks	O
the	O
specialized	O
drivers	O
that	O
initialize	O
chipset	O
functions	O
,	O
which	O
are	O
instead	O
provided	O
by	O
coreboot	B-Device
,	O
of	O
which	O
TianoCore	B-Language
is	O
one	O
of	O
many	O
payload	O
options	O
.	O
</s>
<s>
The	O
development	O
of	O
coreboot	B-Device
requires	O
cooperation	O
from	O
chipset	O
manufacturers	O
to	O
provide	O
the	O
specifications	O
needed	O
to	O
develop	O
initialization	O
drivers	O
.	O
</s>
<s>
In	O
2011	O
,	O
Microsoft	O
announced	O
that	O
computers	O
certified	O
to	O
run	O
its	O
Windows	B-Application
8	I-Application
operating	B-General_Concept
system	I-General_Concept
had	O
to	O
ship	O
with	O
Microsoft	O
's	O
public	B-Application
key	I-Application
enrolled	O
and	O
Secure	O
Boot	B-Operating_System
enabled	O
.	O
</s>
<s>
Following	O
the	O
announcement	O
,	O
the	O
company	O
was	O
accused	O
by	O
critics	O
and	O
free	O
software/open	O
source	O
advocates	O
(	O
including	O
the	B-Operating_System
Free	I-Operating_System
Software	I-Operating_System
Foundation	I-Operating_System
)	O
of	O
trying	O
to	O
use	O
the	O
Secure	O
Boot	B-Operating_System
functionality	O
of	O
UEFI	B-Architecture
to	O
hinder	O
or	O
outright	O
prevent	O
the	O
installation	O
of	O
alternative	O
operating	B-General_Concept
systems	I-General_Concept
such	O
as	O
Linux	B-Operating_System
.	O
</s>
<s>
Microsoft	O
denied	O
that	O
the	O
Secure	O
Boot	B-Operating_System
requirement	O
was	O
intended	O
to	O
serve	O
as	O
a	O
form	O
of	O
lock-in	O
,	O
and	O
clarified	O
its	O
requirements	O
by	O
stating	O
that	O
x86-based	B-Operating_System
systems	I-Operating_System
certified	O
for	O
Windows	B-Application
8	I-Application
must	O
allow	O
Secure	O
Boot	B-Operating_System
to	O
enter	O
custom	O
mode	O
or	O
be	O
disabled	O
,	O
but	O
not	O
on	O
systems	O
using	O
the	O
ARM	B-Architecture
architecture	I-Architecture
.	O
</s>
<s>
Windows	B-Operating_System
10	I-Operating_System
allows	O
OEMs	O
to	O
decide	O
whether	O
or	O
not	O
Secure	O
Boot	B-Operating_System
can	O
be	O
managed	O
by	O
users	O
of	O
their	O
x86	B-Operating_System
systems	O
.	O
</s>
<s>
Other	O
developers	O
raised	O
concerns	O
about	O
the	O
legal	O
and	O
practical	O
issues	O
of	O
implementing	O
support	O
for	O
Secure	O
Boot	B-Operating_System
on	O
Linux	B-Operating_System
systems	O
in	O
general	O
.	O
</s>
<s>
Former	O
Red	O
Hat	O
developer	O
Matthew	O
Garrett	O
noted	O
that	O
conditions	O
in	O
the	O
GNU	O
General	O
Public	O
License	O
version	O
3	O
may	O
prevent	O
the	O
use	O
of	O
the	O
GNU	B-Application
GRand	I-Application
Unified	I-Application
Bootloader	I-Application
without	O
a	O
distribution	O
's	O
developer	O
disclosing	O
the	O
private	B-Application
key	I-Application
(	O
however	O
,	O
the	B-Operating_System
Free	I-Operating_System
Software	I-Operating_System
Foundation	I-Operating_System
has	O
since	O
clarified	O
its	O
position	O
,	O
assuring	O
that	O
the	O
responsibility	O
to	O
make	O
keys	O
available	O
was	O
held	O
by	O
the	O
hardware	O
manufacturer	O
)	O
,	O
and	O
that	O
it	O
would	O
also	O
be	O
difficult	O
for	O
advanced	O
users	O
to	O
build	O
custom	O
kernels	B-Operating_System
that	O
could	O
function	O
with	O
Secure	O
Boot	B-Operating_System
enabled	O
without	O
self-signing	O
them	O
.	O
</s>
<s>
Other	O
developers	O
suggested	O
that	O
signed	B-Application
builds	O
of	O
Linux	B-Operating_System
with	O
another	O
key	O
could	O
be	O
provided	O
,	O
but	O
noted	O
that	O
it	O
would	O
be	O
difficult	O
to	O
persuade	O
OEMs	O
to	O
ship	O
their	O
computers	O
with	O
the	O
required	O
key	O
alongside	O
the	O
Microsoft	O
key	O
.	O
</s>
<s>
Several	O
major	O
Linux	B-Application
distributions	I-Application
have	O
developed	O
different	O
implementations	O
for	O
Secure	O
Boot	B-Operating_System
.	O
</s>
<s>
Garrett	O
himself	O
developed	O
a	O
minimal	O
bootloader	B-Application
known	O
as	O
a	O
shim	O
,	O
which	O
is	O
a	O
precompiled	O
,	O
signed	B-Application
bootloader	B-Application
that	O
allows	O
the	O
user	O
to	O
individually	O
trust	O
keys	O
provided	O
by	O
Linux	B-Application
distributions	I-Application
.	O
</s>
<s>
Ubuntu	B-Operating_System
12.10	I-Operating_System
uses	O
an	O
older	O
version	O
of	O
shim	O
pre-configured	O
for	O
use	O
with	O
Canonical	O
's	O
own	O
key	O
that	O
verifies	O
only	O
the	O
bootloader	B-Application
and	O
allows	O
unsigned	O
kernels	B-Operating_System
to	O
be	O
loaded	O
;	O
developers	O
believed	O
that	O
the	O
practice	O
of	O
signing	O
only	O
the	O
bootloader	B-Application
is	O
more	O
feasible	O
,	O
since	O
a	O
trusted	O
kernel	B-Operating_System
is	O
effective	O
at	O
securing	O
only	O
the	O
user	B-Operating_System
space	I-Operating_System
,	O
and	O
not	O
the	O
pre-boot	O
state	O
for	O
which	O
Secure	O
Boot	B-Operating_System
is	O
designed	O
to	O
add	O
protection	O
.	O
</s>
<s>
That	O
also	O
allows	O
users	O
to	O
build	O
their	O
own	O
kernels	B-Operating_System
and	O
use	O
custom	O
kernel	B-Application
modules	I-Application
as	O
well	O
,	O
without	O
the	O
need	O
to	O
reconfigure	O
the	O
system	O
.	O
</s>
<s>
Canonical	O
also	O
maintains	O
its	O
own	O
private	B-Application
key	I-Application
to	O
sign	O
installations	O
of	O
Ubuntu	B-Operating_System
pre-loaded	O
on	O
certified	O
OEM	O
computers	O
that	O
run	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
and	O
also	O
plans	O
to	O
enforce	O
a	O
Secure	O
Boot	B-Operating_System
requirement	O
as	O
wellrequiring	O
both	O
a	O
Canonical	O
key	O
and	O
a	O
Microsoft	O
key	O
(	O
for	O
compatibility	O
reasons	O
)	O
to	O
be	O
included	O
in	O
their	O
firmware	B-Application
.	O
</s>
<s>
Fedora	O
also	O
uses	O
shim	O
,	O
but	O
requires	O
that	O
both	O
the	O
kernel	B-Operating_System
and	O
its	O
modules	B-Application
be	O
signed	B-Application
as	O
well	O
.	O
</s>
<s>
It	O
has	O
been	O
disputed	O
whether	O
the	O
operating	B-Operating_System
system	I-Operating_System
kernel	I-Operating_System
and	O
its	O
modules	B-Application
must	O
be	O
signed	B-Application
as	O
well	O
;	O
while	O
the	O
UEFI	B-Architecture
specifications	O
do	O
not	O
require	O
it	O
,	O
Microsoft	O
has	O
asserted	O
that	O
their	O
contractual	O
requirements	O
do	O
,	O
and	O
that	O
it	O
reserves	O
the	O
right	O
to	O
revoke	O
any	O
certificates	O
used	O
to	O
sign	O
code	O
that	O
can	O
be	O
used	O
to	O
compromise	O
the	O
security	O
of	O
the	O
system	O
.	O
</s>
<s>
In	O
Windows	B-Application
,	O
only	O
WHQL	O
kernel	B-Application
driver	I-Application
is	O
allowed	O
if	O
Secure	O
Boot	B-Operating_System
enabled	O
.	O
</s>
<s>
In	O
February	O
2013	O
,	O
another	O
Red	O
Hat	O
developer	O
attempted	O
to	O
submit	O
a	O
patch	O
to	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
that	O
would	O
allow	O
it	O
to	O
parse	O
Microsoft	O
's	O
authenticode	O
signing	O
using	O
a	O
master	O
X.509	O
key	O
embedded	O
in	O
PE	O
files	O
signed	B-Application
by	O
Microsoft	O
.	O
</s>
<s>
However	O
,	O
the	O
proposal	O
was	O
criticized	O
by	O
Linux	B-Operating_System
creator	O
Linus	O
Torvalds	O
,	O
who	O
attacked	O
Red	O
Hat	O
for	O
supporting	O
Microsoft	O
's	O
control	O
over	O
the	O
Secure	O
Boot	B-Operating_System
infrastructure	O
.	O
</s>
<s>
On	O
26	O
March	O
2013	O
,	O
the	O
Spanish	O
free	O
software	O
development	O
group	O
Hispalinux	O
filed	O
a	O
formal	O
complaint	O
with	O
the	O
European	O
Commission	O
,	O
contending	O
that	O
Microsoft	O
's	O
Secure	O
Boot	B-Operating_System
requirements	O
on	O
OEM	O
systems	O
were	O
"	O
obstructive	O
"	O
and	O
anti-competitive	O
.	O
</s>
<s>
At	O
the	O
Black	O
Hat	O
conference	O
in	O
August	O
2013	O
,	O
a	O
group	O
of	O
security	O
researchers	O
presented	O
a	O
series	O
of	O
exploits	O
in	O
specific	O
vendor	O
implementations	O
of	O
UEFI	B-Architecture
that	O
could	O
be	O
used	O
to	O
exploit	O
Secure	O
Boot	B-Operating_System
.	O
</s>
<s>
In	O
August	O
2016	O
it	O
was	O
reported	O
that	O
two	O
security	O
researchers	O
had	O
found	O
the	O
"	O
golden	O
key	O
"	O
security	O
key	O
Microsoft	O
uses	O
in	O
signing	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Technically	O
,	O
no	O
key	O
was	O
exposed	O
,	O
however	O
,	O
an	O
exploitable	O
binary	O
signed	B-Application
by	O
the	O
key	O
was	O
.	O
</s>
<s>
This	O
allows	O
any	O
software	O
to	O
run	O
as	O
though	O
it	O
was	O
genuinely	O
signed	B-Application
by	O
Microsoft	O
and	O
exposes	O
the	O
possibility	O
of	O
rootkit	O
and	O
bootkit	O
attacks	O
.	O
</s>
<s>
This	O
also	O
makes	O
patching	O
the	O
fault	O
impossible	O
,	O
since	O
any	O
patch	O
can	O
be	O
replaced	O
(	O
downgraded	O
)	O
by	O
the	O
(	O
signed	B-Application
)	O
exploitable	O
binary	O
.	O
</s>
<s>
Microsoft	O
responded	O
in	O
a	O
statement	O
that	O
the	O
vulnerability	O
only	O
exists	O
in	O
ARM	B-Architecture
architecture	I-Architecture
and	O
Windows	B-Operating_System
RT	I-Operating_System
devices	O
,	O
and	O
has	O
released	O
two	O
patches	O
;	O
however	O
,	O
the	O
patches	O
do	O
not	O
(	O
and	O
cannot	O
)	O
remove	O
the	O
vulnerability	O
,	O
which	O
would	O
require	O
key	O
replacements	O
in	O
end	O
user	O
firmware	B-Application
to	O
fix	O
.	O
</s>
<s>
On	O
March	O
1st	O
,	O
2023	O
,	O
researchers	O
from	O
ESET	O
Cybersecurity	O
Firm	O
reported	O
“	O
The	O
first	O
in-the-wild	O
UEFI	B-Architecture
bootkit	O
bypassing	O
UEFI	B-Architecture
Secure	O
Boot	B-Operating_System
”	O
named	O
‘	O
BlackLotus’	O
in	O
their	O
public	O
analyses	O
findings	O
describing	O
the	O
theory	O
behind	O
it	O
’s	O
mechanics	O
exploiting	O
the	O
patches	O
that	O
“	O
do	O
not	O
(	O
and	O
cannot	O
)	O
remove	O
the	O
vulnerability	O
”	O
.	O
</s>
<s>
Many	O
Linux	B-Application
distributions	I-Application
support	O
UEFI	B-Architecture
Secure	O
Boot	B-Operating_System
now	O
,	O
such	O
as	O
RHEL	O
(	O
RHEL	O
7	O
and	O
later	O
)	O
,	O
CentOS	O
(	O
CentOS	O
7	O
and	O
later	O
)	O
,	O
Ubuntu	B-Operating_System
,	O
Fedora	O
,	O
Debian	O
(	O
Debian	O
10	B-Operating_System
and	O
later	O
)	O
,	O
OpenSUSE	B-Operating_System
,	O
SUSE	O
Linux	B-Operating_System
.	O
</s>
<s>
The	O
increased	O
prominence	O
of	O
UEFI	B-Architecture
firmware	I-Architecture
in	O
devices	O
has	O
also	O
led	O
to	O
a	O
number	O
of	O
technical	O
problems	O
blamed	O
on	O
their	O
respective	O
implementations	O
.	O
</s>
<s>
Following	O
the	O
release	O
of	O
Windows	B-Application
8	I-Application
in	O
late	O
2012	O
,	O
it	O
was	O
discovered	O
that	O
certain	O
Lenovo	O
computer	O
models	O
with	O
Secure	O
Boot	B-Operating_System
had	O
firmware	B-Application
that	O
was	O
hardcoded	O
to	O
allow	O
only	O
executables	O
named	O
"	O
Windows	B-Operating_System
Boot	I-Operating_System
Manager	I-Operating_System
"	O
or	O
"	O
Red	O
Hat	O
Enterprise	O
Linux	B-Operating_System
"	O
to	O
load	O
,	O
regardless	O
of	O
any	O
other	O
setting	O
.	O
</s>
<s>
Other	O
problems	O
were	O
encountered	O
by	O
several	O
Toshiba	O
laptop	O
models	O
with	O
Secure	O
Boot	B-Operating_System
that	O
were	O
missing	O
certain	O
certificates	O
required	O
for	O
its	O
proper	O
operation	O
.	O
</s>
<s>
In	O
January	O
2013	O
,	O
a	O
bug	O
surrounding	O
the	O
UEFI	B-Architecture
implementation	O
on	O
some	O
Samsung	B-Application
laptops	O
was	O
publicized	O
,	O
which	O
caused	O
them	O
to	O
be	O
bricked	O
after	O
installing	O
a	O
Linux	B-Application
distribution	I-Application
in	O
UEFI	B-Architecture
mode	O
.	O
</s>
<s>
While	O
potential	O
conflicts	O
with	O
a	O
kernel	B-Application
module	I-Application
designed	O
to	O
access	O
system	O
features	O
on	O
Samsung	B-Application
laptops	O
were	O
initially	O
blamed	O
(	O
also	O
prompting	O
kernel	B-Operating_System
maintainers	O
to	O
disable	O
the	O
module	B-Application
on	O
UEFI	B-Architecture
systems	O
as	O
a	O
safety	O
measure	O
)	O
,	O
Matthew	O
Garrett	O
discovered	O
that	O
the	O
bug	O
was	O
actually	O
triggered	O
by	O
storing	O
too	O
many	O
UEFI	B-Architecture
variables	O
to	O
memory	O
,	O
and	O
that	O
the	O
bug	O
could	O
also	O
be	O
triggered	O
under	O
Windows	B-Application
under	O
certain	O
conditions	O
.	O
</s>
<s>
In	O
conclusion	O
,	O
he	O
determined	O
that	O
the	O
offending	O
kernel	B-Application
module	I-Application
had	O
caused	O
kernel	B-Operating_System
message	O
dumps	O
to	O
be	O
written	O
to	O
the	O
firmware	B-Application
,	O
thus	O
triggering	O
the	O
bug	O
.	O
</s>
