<s>
The	O
basic	O
components	O
of	O
the	O
Linux	B-Operating_System
family	O
of	O
operating	O
systems	O
,	O
which	O
are	O
based	O
on	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
the	O
GNU	B-Language
C	I-Language
Library	I-Language
,	O
BusyBox	B-Application
or	O
forks	O
thereof	O
like	O
μClinux	B-Application
and	O
uClibc	B-Language
,	O
have	O
been	O
programmed	O
with	O
a	O
certain	O
level	O
of	O
abstraction	O
in	O
mind	O
.	O
</s>
<s>
Also	O
,	O
there	O
are	O
distinct	O
code	O
paths	O
in	O
the	O
assembly	B-Language
language	I-Language
or	O
C	B-Language
source	O
code	O
which	O
support	O
certain	O
hardware	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
source	O
code	O
can	O
be	O
successfully	O
compiled	B-Language
onor	O
cross-compiled	O
fora	O
great	O
number	O
of	O
computer	B-General_Concept
architectures	I-General_Concept
.	O
</s>
<s>
Furthermore	O
,	O
the	O
required	O
free	B-License
and	I-License
open-source	I-License
software	I-License
has	O
also	O
been	O
developed	O
to	O
interface	O
between	O
Linux	B-Operating_System
and	O
the	O
hardware	O
Linux	B-Operating_System
is	O
to	O
be	O
executed	O
on	O
.	O
</s>
<s>
For	O
example	O
,	O
compilers	B-Language
are	O
available	O
,	O
e.g.	O
</s>
<s>
GNU	B-Application
Compiler	I-Application
Collection	I-Application
(	O
GCC	B-Application
)	O
and	O
LLVM/Clang	O
.	O
</s>
<s>
For	O
cross-compilation	O
a	O
number	O
of	O
complete	O
toolchains	B-General_Concept
are	O
available	O
,	O
like	O
GNU	B-Application
toolchain	I-Application
,	O
OpenWrt	B-Application
Buildroot	I-Application
or	O
OpenEmbedded	B-Application
.	O
</s>
<s>
The	O
Yocto	B-Application
Project	I-Application
is	O
targeted	O
at	O
embedded	O
use	O
cases	O
.	O
</s>
<s>
The	O
portability	O
section	O
of	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
article	O
contains	O
information	O
and	O
references	O
to	O
technical	O
details	O
.	O
</s>
<s>
Note	O
that	O
further	O
components	O
like	O
a	O
display	O
server	O
,	O
or	O
programs	O
like	O
Blender	B-Application
,	O
can	O
be	O
present	O
or	O
absent	O
.	O
</s>
<s>
The	O
relevant	O
term	O
is	O
of	O
the	O
porting	O
target	O
is	O
computer	B-General_Concept
architecture	I-General_Concept
;	O
it	O
comprises	O
the	O
instruction	O
set(s )	O
and	O
the	O
microarchitecture(s )	O
of	O
the	O
processor(s )	O
,	O
at	O
least	O
of	O
the	O
CPU	B-General_Concept
.	O
</s>
<s>
The	O
target	O
also	O
comprises	O
the	O
"	O
system	O
design	O
"	O
of	O
the	O
entire	O
system	O
,	O
be	O
it	O
a	O
supercomputer	B-Architecture
,	O
a	O
desktop	B-Device
computer	I-Device
or	O
some	O
SoC	B-Architecture
,	O
e.g.	O
</s>
<s>
in	O
case	O
some	O
unique	O
bus	B-General_Concept
is	O
being	O
used	O
.	O
</s>
<s>
In	O
former	O
times	O
,	O
the	O
memory	B-General_Concept
controller	I-General_Concept
was	O
part	O
of	O
the	O
chipset	B-Device
on	O
the	O
motherboard	B-Device
and	O
not	O
on	O
the	O
CPU-die	O
.	O
</s>
<s>
Although	O
the	O
support	O
of	O
a	O
specific	O
instruction	B-General_Concept
set	I-General_Concept
is	O
the	O
task	O
of	O
the	O
compiler	B-Language
,	O
the	O
software	O
must	O
be	O
written	O
with	O
a	O
certain	O
level	O
of	O
abstraction	O
in	O
mind	O
to	O
make	O
this	O
portability	O
possible	O
.	O
</s>
<s>
Any	O
code	O
written	O
in	O
Assembly	B-Language
language	I-Language
will	O
be	O
specific	O
to	O
the	O
instruction	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
The	O
support	O
of	O
a	O
specific	O
microarchitecture	B-General_Concept
includes	O
optimizations	O
for	O
the	O
CPU	B-General_Concept
cache	I-General_Concept
hierarchy	O
,	O
the	O
TLB	B-Architecture
,	O
etc	O
.	O
</s>
<s>
ARM	B-Architecture
family	I-Architecture
of	I-Architecture
instruction	I-Architecture
sets	I-Architecture
(	O
32	O
-	O
and	O
64-bit	B-Device
)	O
(	O
arm	O
and	O
arm64	O
)	O
:	O
</s>
<s>
Freescale	O
's	O
(	O
formerly	O
Motorola	O
's	O
)	O
68k	B-Device
architecture	O
(	O
68020	O
,	O
68030	O
,	O
68040	O
,	O
68060	O
)	O
(	O
m68k	B-Device
)	O
:	O
</s>
<s>
x86	B-Operating_System
architecture	I-Operating_System
(	O
x86	B-Operating_System
)	O
:	O
</s>
<s>
IBM	O
PC	O
compatibles	O
using	O
IA-32	B-Device
and	O
x86-64	B-Device
processors	O
:	O
</s>
<s>
MIPS	B-Device
architecture	I-Device
(	O
mips	O
)	O
:	O
</s>
<s>
Power	B-Architecture
ISA	I-Architecture
:	O
</s>
<s>
PowerPC	B-Architecture
architecture	O
(	O
powerpc	B-Architecture
)	O
:	O
</s>
<s>
Project	O
BlackDog	B-Application
from	O
Realm	O
Systems	O
,	O
Inc	O
.	O
</s>
<s>
SPARC	B-Architecture
(	O
32-bit	O
)	O
:	O
</s>
<s>
UltraSPARC	O
(	O
64-bit	B-Device
)	O
:	O
</s>
<s>
Additional	O
processors	O
(	O
particularly	O
Freescale	O
's	O
68000	O
and	O
ColdFire	B-Device
)	O
are	O
supported	O
by	O
the	O
MMU-less	O
μClinux	B-Application
variant	O
.	O
</s>
