<s>
e820	B-Device
is	O
shorthand	O
for	O
the	O
facility	O
by	O
which	O
the	O
BIOS	B-Operating_System
of	O
x86-based	O
computer	O
systems	O
reports	O
the	O
memory	B-General_Concept
map	I-General_Concept
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
or	O
boot	B-Application
loader	I-Application
.	O
</s>
<s>
It	O
is	O
accessed	O
via	O
the	O
int	B-Device
15h	O
call	B-Device
,	O
by	O
setting	O
the	O
register	O
to	O
value	O
E820	B-Device
in	O
hexadecimal	O
.	O
</s>
<s>
It	O
reports	O
which	O
memory	O
address	O
ranges	O
are	O
usable	O
and	O
which	O
are	O
reserved	O
for	O
use	O
by	O
the	O
BIOS	B-Operating_System
.	O
</s>
<s>
BIOS-e820	O
is	O
often	O
the	O
first	O
thing	O
reported	O
by	O
a	O
booting	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
and	O
it	O
can	O
also	O
be	O
seen	O
with	O
the	O
dmesg	B-Device
command	O
.	O
</s>
