<s>
coreboot	B-Device
,	O
formerly	O
known	O
as	O
LinuxBIOS	B-Device
,	O
is	O
a	O
software	O
project	O
aimed	O
at	O
replacing	O
proprietary	O
firmware	B-Application
(	O
BIOS	B-Operating_System
or	O
UEFI	B-Architecture
)	O
found	O
in	O
most	O
computers	O
with	O
a	O
lightweight	O
firmware	B-Application
designed	O
to	O
perform	O
only	O
the	O
minimum	O
number	O
of	O
tasks	O
necessary	O
to	O
load	O
and	O
run	O
a	O
modern	O
32-bit	O
or	O
64-bit	B-Device
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Since	O
coreboot	B-Device
initializes	O
the	O
bare	O
hardware	O
,	O
it	O
must	O
be	O
ported	O
to	O
every	O
chipset	B-Device
and	O
motherboard	B-Device
that	O
it	O
supports	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
coreboot	B-Device
is	O
available	O
only	O
for	O
a	O
limited	O
number	O
of	O
hardware	O
platforms	O
and	O
motherboard	B-Device
models	O
.	O
</s>
<s>
One	O
of	O
the	O
coreboot	B-Device
variants	O
is	O
Libreboot	B-Device
,	O
a	O
software	B-Application
distribution	I-Application
fully	O
free	O
of	O
proprietary	O
blobs	O
,	O
aimed	O
at	O
end	O
users	O
.	O
</s>
<s>
The	O
coreboot	B-Device
project	O
began	O
in	O
the	O
winter	O
of	O
1999	O
in	O
the	O
Advanced	O
Computing	O
Laboratory	O
at	O
Los	O
Alamos	O
National	O
Laboratory	O
(	O
LANL	O
)	O
,	O
</s>
<s>
with	O
the	O
goal	O
of	O
creating	O
a	O
BIOS	B-Operating_System
that	O
would	O
start	O
fast	O
and	O
handle	O
errors	O
intelligently	O
.	O
</s>
<s>
It	O
is	O
licensed	O
under	O
the	O
terms	O
of	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
version	O
2	O
(	O
GPLv2	O
)	O
.	O
</s>
<s>
Main	O
contributors	O
include	O
LANL	O
,	O
SiS	O
,	O
AMD	O
,	O
Coresystems	O
and	O
Linux	B-Operating_System
Networx	O
,	O
Inc	O
,	O
as	O
well	O
as	O
motherboard	B-Device
vendors	O
MSI	O
,	O
Gigabyte	O
and	O
Tyan	O
,	O
which	O
offer	O
coreboot	B-Device
alongside	O
their	O
standard	B-Operating_System
BIOS	I-Operating_System
or	O
provide	O
specifications	O
of	O
the	O
hardware	O
interfaces	O
for	O
some	O
of	O
their	O
motherboards	B-Device
.	O
</s>
<s>
Google	B-Application
partly	O
sponsors	O
the	O
coreboot	B-Device
project	O
.	O
</s>
<s>
CME	O
Group	O
,	O
a	O
cluster	B-Architecture
of	O
futures	O
exchanges	O
,	O
began	O
supporting	O
the	O
coreboot	B-Device
project	O
in	O
2009	O
.	O
</s>
<s>
Coreboot	B-Device
was	O
accepted	O
in	O
seven	O
consecutive	O
years	O
(	O
2007	O
–	O
2014	O
)	O
for	O
the	B-Application
Google	I-Application
Summer	B-Application
of	I-Application
Code	I-Application
.	O
</s>
<s>
Other	O
than	O
the	O
first	O
three	O
models	O
,	O
all	O
Chromebooks	B-Operating_System
run	O
coreboot	B-Device
.	O
</s>
<s>
Code	O
from	O
Das	B-Language
U-Boot	I-Language
has	O
been	O
assimilated	O
to	O
enable	O
support	O
for	O
processors	O
based	O
on	O
the	O
ARM	B-Architecture
instruction	I-Architecture
set	I-Architecture
.	O
</s>
<s>
In	O
June	O
2019	O
,	O
Coreboot	B-Device
began	O
to	O
use	O
the	O
NSA	O
software	O
Ghidra	B-Language
for	O
its	O
reverse	O
engineering	O
efforts	O
on	O
firmware-specific	B-Application
problems	O
following	O
the	O
release	O
of	O
the	O
suite	O
as	O
free	B-Application
and	I-Application
open	I-Application
source	I-Application
software	I-Application
.	O
</s>
<s>
CPU	B-General_Concept
architectures	O
supported	O
by	O
coreboot	B-Device
include	O
IA-32	B-Device
,	O
x86-64	B-Device
,	O
ARM	B-Architecture
,	O
ARM64	B-Architecture
,	O
MIPS	B-Device
and	O
RISC-V	B-Device
.	O
</s>
<s>
Supported	O
system-on-a-chip	B-Architecture
(	O
SOC	O
)	O
platforms	O
include	O
AMD	B-Device
Geode	I-Device
,	O
starting	O
with	O
the	O
Geode	B-Device
GX	I-Device
processor	O
developed	O
for	O
the	O
OLPC	O
.	O
</s>
<s>
Artec	O
Group	O
added	O
Geode	B-Device
LX	I-Device
support	O
for	O
its	O
ThinCan	B-Application
model	O
DBE61	O
;	O
that	O
code	O
was	O
adopted	O
by	O
AMD	O
and	O
further	O
improved	O
for	O
the	O
OLPC	O
after	O
it	O
was	O
upgraded	O
to	O
the	O
Geode	B-Device
LX	I-Device
platform	O
,	O
and	O
is	O
further	O
developed	O
by	O
the	O
coreboot	B-Device
community	O
to	O
support	O
other	O
Geode	B-Device
variants	O
.	O
</s>
<s>
Coreboot	B-Device
can	O
be	O
flashed	O
onto	O
a	O
Geode	B-Device
platform	O
using	O
Flashrom	B-Device
.	O
</s>
<s>
From	O
that	O
initial	O
development	O
on	O
AMD	B-Device
Geode	I-Device
based	O
platforms	O
,	O
coreboot	B-Device
support	O
has	O
been	O
extended	O
onto	O
many	O
AMD	O
processors	O
and	O
chipsets	B-Device
.	O
</s>
<s>
The	O
processor	O
list	O
includes	O
Family	O
0Fh	O
and	O
10h	O
(	O
K8	B-Device
core	O
)	O
,	O
and	O
recently	O
Family	O
14h	O
(	O
Bobcat	O
core	O
,	O
Fusion	B-Architecture
APU	I-Architecture
)	O
.	O
</s>
<s>
Coreboot	B-Device
support	O
also	O
extends	O
to	O
AMD	O
chipsets	B-Device
:	O
RS690	O
,	O
RS7xx	O
,	O
SB600	B-Device
,	O
and	O
SB8xx	O
.	O
</s>
<s>
AMD	B-Device
Generic	I-Device
Encapsulated	I-Device
Software	I-Device
Architecture	I-Device
(	O
AGESA	B-Device
)	O
a	O
bootstrap	B-Application
protocol	O
by	O
which	O
system	O
devices	O
on	O
AMD64	B-Device
mainboards	B-Device
are	O
initializedwas	O
open	O
sourced	O
in	O
early	O
2011	O
,	O
aiming	O
to	O
provide	O
required	O
functionality	O
for	O
coreboot	B-Device
system	O
initialization	O
on	O
AMD64	B-Device
hardware	O
.	O
</s>
<s>
some	O
x86-based	O
Chromebooks	B-Operating_System
,	O
</s>
<s>
the	O
Libre	O
T440p	O
and	O
X230	O
(	O
rebranded	O
ThinkPad	B-Operating_System
T440p	O
and	O
X230	O
,	O
respectively	O
,	O
available	O
from	O
Minifree	O
,	O
previously	O
known	O
as	O
Gluglug	O
)	O
,,	O
</s>
<s>
OLPC	B-Application
XO	I-Application
from	O
the	O
One	O
Laptop	O
per	O
Child	O
initiative	O
,	O
</s>
<s>
ThinCan	B-Application
models	O
DBE61	O
,	O
DBE62	O
and	O
DBE63	O
,	O
and	O
fanless	O
server/router	O
hardware	O
manufactured	O
by	O
PC	B-General_Concept
Engines	I-General_Concept
.	O
</s>
<s>
All	O
Purism	O
Librem	B-Device
laptops	O
come	O
with	O
coreboot	B-Device
.	O
</s>
<s>
Some	O
System76	O
PCs	O
use	O
coreboot	B-Device
TianoCore	B-Language
firmware	B-Application
,	O
including	O
open	O
source	O
Embedded	B-Architecture
Controller	I-Architecture
firmware	B-Application
.	O
</s>
<s>
StarLabs	O
Systems	O
use	O
Coreboot	B-Device
firmware	B-Application
,	O
as	O
an	O
alternative	O
.	O
</s>
<s>
Coreboot	B-Device
typically	O
loads	O
a	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
but	O
it	O
can	O
load	O
any	O
other	O
stand-alone	B-General_Concept
ELF	O
executable	O
,	O
such	O
as	O
iPXE	B-Device
,	O
gPXE	B-Device
or	O
Etherboot	B-Device
that	O
can	O
boot	O
a	O
Linux	B-Operating_System
kernel	I-Operating_System
over	B-Device
a	I-Device
network	I-Device
,	O
or	O
SeaBIOS	B-Language
that	O
can	O
load	O
a	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
Windows	B-Application
2000	I-Application
and	O
later	O
,	O
and	O
BSDs	O
;	O
Windows	O
2000/XP	O
and	O
OpenBSD	B-Operating_System
support	O
was	O
previously	O
provided	O
by	O
ADLO	O
.	O
</s>
<s>
Coreboot	B-Device
can	O
also	O
load	O
a	O
kernel	B-Operating_System
from	O
any	O
supported	O
device	O
,	O
such	O
as	O
Myrinet	O
,	O
Quadrics	O
,	O
or	O
SCI	O
cluster	B-Architecture
interconnects	O
.	O
</s>
<s>
Booting	O
other	O
kernels	B-Operating_System
directly	O
is	O
also	O
possible	O
,	O
such	O
as	O
a	O
Plan	B-Operating_System
9	I-Operating_System
kernel	I-Operating_System
.	O
</s>
<s>
Instead	O
of	O
loading	O
a	O
kernel	B-Operating_System
directly	O
,	O
coreboot	B-Device
can	O
pass	O
control	O
to	O
a	O
dedicated	O
boot	O
loader	O
,	O
such	O
as	O
a	O
coreboot-capable	O
version	O
of	O
GNU	B-Application
GRUB	I-Application
2	O
.	O
</s>
<s>
Coreboot	B-Device
is	O
written	O
primarily	O
in	O
C	B-Language
,	O
with	O
a	O
small	O
amount	O
of	O
assembly	B-Language
code	I-Language
.	O
</s>
<s>
Choosing	O
C	B-Language
as	O
the	O
primary	O
programming	O
language	O
enables	O
easier	O
code	O
audits	O
when	O
compared	O
to	O
contemporary	O
PC	B-Operating_System
BIOS	I-Operating_System
that	O
was	O
generally	O
written	O
in	O
assembly	B-Language
,	O
which	O
results	O
in	O
improved	O
security	O
.	O
</s>
<s>
There	O
is	O
build	O
and	O
runtime	O
support	O
to	O
write	O
parts	O
of	O
coreboot	B-Device
in	O
Ada	B-Language
to	O
further	O
raise	O
the	O
security	O
bar	O
,	O
but	O
it	O
is	O
currently	O
only	O
sporadically	O
used	O
.	O
</s>
<s>
The	O
source	O
code	O
is	O
released	O
under	O
the	O
GNU	B-License
GPL	I-License
version	O
2	O
license	O
.	O
</s>
<s>
Coreboot	B-Device
performs	O
the	O
absolute	O
minimal	O
amount	O
of	O
hardware	O
initialization	O
and	O
then	O
passes	O
control	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
As	O
a	O
result	O
,	O
there	O
is	O
no	O
coreboot	B-Device
code	O
running	O
once	O
the	O
operating	B-General_Concept
system	I-General_Concept
has	O
taken	O
control	O
.	O
</s>
<s>
A	O
feature	O
of	O
coreboot	B-Device
is	O
that	O
the	O
x86	B-Operating_System
version	O
runs	O
in	O
32-bit	O
mode	O
after	O
executing	O
only	O
ten	O
instructions	O
(	O
almost	O
all	O
other	O
x86	B-Operating_System
BIOSes	O
run	O
exclusively	O
in	O
16-bit	B-Device
mode	O
)	O
.	O
</s>
<s>
This	O
is	O
similar	O
to	O
the	O
modern	O
UEFI	B-Architecture
firmware	I-Architecture
,	O
which	O
is	O
used	O
on	O
newer	O
PC	O
hardware	O
.	O
</s>
<s>
By	O
itself	O
,	O
coreboot	B-Device
does	O
not	O
provide	O
BIOS	B-Device
call	I-Device
services	O
.	O
</s>
<s>
The	O
SeaBIOS	B-Language
payload	O
can	O
be	O
used	O
to	O
provide	O
BIOS	B-Device
calls	I-Device
and	O
thus	O
allow	O
coreboot	B-Device
to	O
load	O
operating	B-General_Concept
systems	I-General_Concept
that	O
require	O
those	O
services	O
,	O
such	O
as	O
Windows	O
2000/XP/Vista/7	O
and	O
BSDs	O
.	O
</s>
<s>
However	O
,	O
most	O
modern	O
operating	B-General_Concept
systems	I-General_Concept
access	O
hardware	O
in	O
another	O
manner	O
and	O
use	O
BIOS	B-Device
calls	I-Device
only	O
during	O
early	O
initialization	O
and	O
as	O
a	O
fallback	O
mechanism	O
.	O
</s>
<s>
The	O
most	O
difficult	O
hardware	O
that	O
coreboot	B-Device
initializes	O
is	O
the	O
DRAM	O
controllers	O
and	O
DRAM	O
.	O
</s>
<s>
RAM	B-Architecture
initialization	O
is	O
particularly	O
difficult	O
because	O
before	O
the	O
RAM	B-Architecture
is	O
initialized	O
it	O
cannot	O
be	O
used	O
.	O
</s>
<s>
Therefore	O
,	O
to	O
initialize	O
DRAM	O
controllers	O
and	O
DRAM	O
,	O
the	O
initialization	O
code	O
may	O
have	O
only	O
the	O
CPU	B-General_Concept
's	O
general	B-General_Concept
purpose	I-General_Concept
registers	I-General_Concept
or	O
Cache-as-RAM	O
as	O
temporary	O
storage	O
.	O
</s>
<s>
romcc	O
,	O
a	O
C	B-Language
compiler	B-Language
that	O
uses	O
registers	O
instead	O
of	O
RAM	B-Architecture
,	O
eases	O
the	O
task	O
.	O
</s>
<s>
Using	O
romcc	O
,	O
it	O
is	O
relatively	O
easy	O
to	O
make	O
SMBus	B-Algorithm
accesses	O
to	O
the	O
SPD	B-General_Concept
ROMs	O
of	O
the	O
DRAM	O
DIMMs	B-General_Concept
,	O
that	O
allows	O
the	O
RAM	B-Architecture
to	O
be	O
used	O
.	O
</s>
<s>
With	O
newer	O
x86	B-Operating_System
processors	O
,	O
the	O
processor	O
cache	O
can	O
be	O
used	O
as	O
RAM	B-Architecture
until	O
DRAM	O
is	O
initialized	O
.	O
</s>
<s>
The	O
processor	O
cache	O
has	O
to	O
be	O
initialized	O
into	O
Cache-as-RAM	O
mode	O
as	O
well	O
,	O
but	O
this	O
needs	O
fewer	O
instructions	O
than	O
initializing	O
DRAM	O
.	O
</s>
<s>
Also	O
,	O
the	O
Cache-as-RAM	O
mode	O
initialization	O
is	O
specific	O
to	O
CPU	B-General_Concept
architectures	O
,	O
thus	O
more	O
generic	O
than	O
DRAM	O
initialization	O
,	O
which	O
is	O
specific	O
to	O
each	O
chipset	B-Device
and	O
mainboard	B-Device
.	O
</s>
<s>
For	O
most	O
modern	O
x86	B-Operating_System
platforms	O
,	O
closed	O
source	O
binary-only	O
components	O
provided	O
by	O
the	O
vendor	O
are	O
used	O
for	O
DRAM	O
setup	O
.	O
</s>
<s>
Binary	O
AGESA	B-Device
is	O
currently	O
used	O
for	O
proprietary	O
UEFI	B-Architecture
firmware	I-Architecture
on	O
AMD	O
systems	O
,	O
and	O
this	O
model	O
is	O
expected	O
to	O
carry	O
over	O
to	O
any	O
future	O
AMD-related	O
coreboot	B-Device
support	O
.	O
</s>
<s>
Since	O
coreboot	B-Device
must	O
initialize	O
the	O
bare	O
hardware	O
,	O
it	O
must	O
be	O
ported	O
to	O
every	O
chipset	B-Device
and	O
motherboard	B-Device
that	O
it	O
supports	O
.	O
</s>
<s>
Before	O
initializing	O
RAM	B-Architecture
,	O
coreboot	B-Device
initializes	O
the	O
serial	B-Protocol
port	I-Protocol
(	O
addressing	O
cache	O
and	O
registers	O
only	O
)	O
,	O
so	O
it	O
can	O
send	O
out	O
debug	O
text	O
to	O
a	O
connected	O
terminal	B-General_Concept
.	O
</s>
<s>
It	O
can	O
also	O
send	O
byte	O
codes	O
to	O
port	O
0x80	O
that	O
are	O
displayed	O
on	O
a	O
two-hex-digit	O
display	O
of	O
a	O
connected	O
POST	B-Device
card	I-Device
.	O
</s>
<s>
Another	O
porting	O
aid	O
was	O
the	O
commercial	O
"	O
RD1	O
BIOS	B-Operating_System
Savior	O
"	O
product	O
from	O
www.ioss.com.tw	O
,	O
(	O
not	O
to	O
be	O
confused	O
with	O
US	O
Interagency	O
OPSEC	O
Support	O
Staff	O
at	O
www.iad.gov/ioss/	O
)	O
which	O
was	O
a	O
combination	O
of	O
two	O
boot	O
memory	O
devices	O
that	O
plugs	O
into	O
the	O
boot	O
memory	O
socket	O
and	O
has	O
a	O
manual	O
switch	O
to	O
select	O
between	O
the	O
two	O
devices	O
.	O
</s>
<s>
A	O
more	O
expensive	O
alternative	O
is	O
an	O
external	O
EEPROM/NOR	O
flash	O
programmer	O
.	O
</s>
<s>
There	O
are	O
also	O
CPU	B-General_Concept
emulators	B-Application
that	O
either	O
replace	O
the	O
CPU	B-General_Concept
or	O
connect	O
via	O
a	O
JTAG	O
port	O
,	O
with	O
the	O
Sage	O
SmartProbe	O
being	O
an	O
example	O
.	O
</s>
<s>
Code	O
can	O
be	O
built	O
on	O
,	O
or	O
downloaded	O
to	O
,	O
BIOS	B-Operating_System
emulators	B-Application
rather	O
than	O
flashing	O
the	O
BIOS	B-Operating_System
device	O
.	O
</s>
<s>
Coreboot	B-Device
can	O
load	O
a	O
payload	O
,	O
which	O
may	O
be	O
written	O
using	O
the	O
helper	O
library	O
.	O
</s>
<s>
One	O
physical	O
meeting	O
is	O
the	O
European	O
Coreboot	B-Device
Conference	O
which	O
was	O
organized	O
in	O
October	O
2017	O
and	O
lasted	O
for	O
three	O
days	O
.	O
</s>
<s>
Coreboot	B-Device
is	O
open	O
source	O
,	O
and	O
third-parties	O
such	O
as	O
Chromebooks	B-Operating_System
,	O
PC	B-General_Concept
Engines	I-General_Concept
,	O
Star	O
Labs	O
,	O
System76	O
and	O
Purism	O
ship	O
their	O
hardware	O
with	O
coreboot	B-Device
.	O
</s>
<s>
Coreboot	B-Device
has	O
a	O
number	O
of	O
variants	O
from	O
its	O
original	O
code	O
base	O
each	O
with	O
slightly	O
different	O
objectives	O
:	O
</s>
<s>
librecore	O
-	O
A	O
variant	O
with	O
more	O
focus	O
on	O
freedom	O
,	O
non-x86	O
instruction	B-General_Concept
set	I-General_Concept
computers	O
,	O
and	O
firmware	B-Application
development	O
frameworks	O
.	O
</s>
<s>
Libreboot	B-Device
-	O
A	O
variant	O
with	O
a	O
primary	O
focus	O
to	O
remove	O
all	O
binary	O
blobs	O
.	O
</s>
<s>
osboot	O
-	O
A	O
variant	O
similar	O
to	O
Libreboot	B-Device
that	O
scrapped	O
its	O
no	O
blob	O
policy	O
to	O
increase	O
hardware	O
support	O
and	O
stability	O
.	O
</s>
<s>
As	O
of	O
November	O
2022	O
merged	O
with	O
libreboot	B-Device
.	O
</s>
<s>
Libreboot	B-Device
has	O
been	O
established	O
as	O
a	O
distribution	O
of	O
coreboot	B-Device
without	O
proprietary	O
binary	O
blobs	O
.	O
</s>
<s>
Libreboot	B-Device
is	O
not	O
a	O
straight	O
fork	B-Application
of	O
coreboot	B-Device
;	O
instead	O
,	O
it	O
is	O
a	O
parallel	O
effort	O
that	O
works	O
closely	O
with	O
and	O
re-bases	B-Library
every	O
so	O
often	O
on	O
the	O
latest	O
coreboot	B-Device
as	O
the	O
upstream	O
supplier	O
,	O
with	O
patches	O
merged	O
upstream	O
whenever	O
possible	O
.	O
</s>
<s>
In	O
addition	O
to	O
removing	O
proprietary	O
software	O
,	O
libreboot	B-Device
also	O
attempts	O
to	O
make	O
coreboot	B-Device
easy	O
to	O
use	O
by	O
automating	O
the	O
build	O
and	O
installation	O
processes	O
.	O
</s>
<s>
The	O
Libreboot	B-Device
project	O
made	O
possible	O
the	O
required	O
modifications	O
for	O
completely	O
libre	O
variants	O
of	O
some	O
ThinkPad	B-Operating_System
,	O
MacBook	B-Device
and	O
ARM	B-Architecture
Chromebook	B-Operating_System
laptops	O
.	O
</s>
