<s>
A	O
machine	B-Device
check	I-Device
exception	I-Device
(	O
MCE	O
)	O
is	O
a	O
type	O
of	O
computer	B-Error_Name
error	I-Error_Name
that	O
occurs	O
when	O
a	O
problem	O
involving	O
the	O
computer	O
's	O
hardware	B-Architecture
is	O
detected	O
.	O
</s>
<s>
With	O
most	O
mass-market	O
personal	O
computers	O
,	O
an	O
MCE	O
indicates	O
faulty	O
or	O
misconfigured	O
hardware	B-Architecture
.	O
</s>
<s>
The	O
nature	O
and	O
causes	O
of	O
MCEs	O
can	O
vary	O
by	O
architecture	B-General_Concept
and	O
generation	O
of	O
system	O
.	O
</s>
<s>
In	O
some	O
designs	O
,	O
an	O
MCE	O
is	O
always	O
an	O
unrecoverable	O
error	O
,	O
that	O
halts	O
the	O
machine	O
,	O
requiring	O
a	O
reboot	B-Device
.	O
</s>
<s>
In	O
other	O
architectures	O
,	O
some	O
MCEs	O
may	O
be	O
non-fatal	O
,	O
such	O
as	O
for	O
single-bit	O
errors	O
corrected	O
by	O
ECC	B-General_Concept
memory	I-General_Concept
.	O
</s>
<s>
On	O
some	O
architectures	O
,	O
such	O
as	O
PowerPC	B-Architecture
,	O
certain	O
software	O
bugs	O
can	O
cause	O
MCEs	O
,	O
such	O
as	O
an	O
invalid	O
memory	B-Architecture
access	O
.	O
</s>
<s>
On	O
other	O
architectures	O
,	O
such	O
as	O
x86	B-Operating_System
,	O
MCEs	O
typically	O
originate	O
from	O
hardware	B-Architecture
only	O
.	O
</s>
<s>
IBM	B-Application
System/360	I-Application
Operating	I-Application
System	I-Application
(	O
OS/360	B-Application
)	O
records	O
input/output	O
errors	O
in	O
a	O
dataset	O
called	O
SYS1.LOGREC	O
.	O
</s>
<s>
Since	O
then	O
IBM	O
has	O
coined	O
the	O
term	O
error	O
recording	O
data	O
set	O
(	O
ERDS	O
)	O
for	O
successor	O
versions	O
that	O
allow	O
the	O
installation	O
to	O
choose	O
the	O
name	O
and	O
for	O
operating	O
systems	O
not	O
derived	O
from	O
OS/360	B-Application
.	O
</s>
<s>
In	O
OS/360	B-Application
,	O
the	O
installation	O
can	O
choose	O
several	O
levels	O
of	O
support	O
for	O
handling	O
machine	B-Device
checks	I-Device
.	O
</s>
<s>
The	O
most	O
sophisticated	O
,	O
Machine	B-Device
Check	I-Device
Handler	O
(	O
MCH	O
)	O
,	O
records	O
failure	O
data	O
on	O
SYS1.LOGREC	O
and	O
attempts	O
recovery	O
.	O
</s>
<s>
The	O
MCH	O
can	O
handle	O
memory	B-Architecture
failures	O
in	O
refreshable	O
nucleus	O
control	O
sections	O
by	O
reading	O
a	O
fresh	O
copy	O
from	O
SYS1.ASRLIB	O
and	O
can	O
handle	O
memory	B-Architecture
errors	O
in	O
SVC	O
transient	O
areas	O
by	O
reading	O
a	O
fresh	O
copy	O
of	O
the	O
SVC	O
module	O
from	O
SYS1.SVCLIB	O
.	O
</s>
<s>
As	O
with	O
OS/360	B-Application
,	O
the	O
installation	O
uses	O
EREP	O
to	O
print	O
those	O
data	O
;	O
SEREP	O
is	O
no	O
longer	O
available	O
.	O
</s>
<s>
The	O
MCH	O
is	O
no	O
longer	O
optional	O
,	O
and	O
handles	O
many	O
more	O
failure	O
modes	O
than	O
the	O
OS/360	B-Application
MCH	O
.	O
</s>
<s>
On	O
Microsoft	B-Application
Windows	I-Application
platforms	O
,	O
in	O
the	O
event	O
of	O
an	O
unrecoverable	O
MCEs	O
,	O
the	O
system	O
generates	O
a	O
BugCheck	O
—	O
also	O
called	O
a	O
STOP	O
error	O
,	O
or	O
a	O
Blue	O
Screen	O
of	O
Death	O
.	O
</s>
<s>
More	O
recent	O
versions	O
of	O
Windows	O
use	O
the	O
Windows	O
Hardware	B-Architecture
Error	O
Architecture	B-General_Concept
(	O
WHEA	O
)	O
,	O
and	O
generate	O
STOP	O
code	O
0x124	O
,	O
WHEA_UNCORRECTABLE_ERROR	O
.	O
</s>
<s>
Older	O
versions	O
of	O
Windows	O
use	O
the	O
Machine	B-Device
Check	I-Device
Architecture	I-Device
,	O
with	O
STOP	O
code	O
0x9C	O
,	O
MACHINE_CHECK_EXCEPTION	O
.	O
</s>
<s>
On	O
Linux	B-Application
,	O
the	O
kernel	B-Operating_System
writes	O
messages	O
about	O
MCEs	O
to	O
the	O
kernel	B-Operating_System
message	O
log	O
and	O
the	O
system	B-Device
console	I-Device
.	O
</s>
<s>
When	O
the	O
MCEs	O
are	O
not	O
fatal	O
,	O
they	O
will	O
also	O
typically	O
be	O
copied	O
to	O
the	O
system	B-Protocol
log	I-Protocol
and/or	O
systemd	O
journal	O
.	O
</s>
<s>
Some	O
of	O
the	O
main	O
hardware	B-Architecture
problems	O
that	O
cause	O
MCEs	O
include	O
:	O
</s>
<s>
System	B-Architecture
bus	I-Architecture
errors	O
:	O
(	O
error	O
communicating	O
between	O
the	O
processor	O
and	O
the	O
motherboard	B-Device
)	O
.	O
</s>
<s>
Memory	B-Architecture
errors	O
:	O
parity	B-Error_Name
checking	I-Error_Name
detects	O
when	O
a	O
memory	B-Architecture
error	O
has	O
occurred	O
.	O
</s>
<s>
Error	B-Error_Name
correction	I-Error_Name
code	I-Error_Name
(	O
ECC	O
)	O
can	O
correct	O
limited	O
memory	B-Architecture
errors	O
so	O
that	O
processing	O
can	O
continue	O
.	O
</s>
<s>
CPU	B-General_Concept
cache	I-General_Concept
errors	O
in	O
the	O
processor	O
.	O
</s>
<s>
Machine	B-Device
checks	I-Device
are	O
a	O
hardware	B-Architecture
problem	O
,	O
not	O
a	O
software	O
problem	O
.	O
</s>
<s>
They	O
are	O
often	O
the	O
result	O
of	O
overclocking	B-Application
or	O
overheating	O
.	O
</s>
<s>
But	O
they	O
can	O
also	O
be	O
caused	O
by	O
bus	O
errors	O
introduced	O
by	O
other	O
failing	O
components	O
,	O
like	O
memory	B-Architecture
or	O
I/O	O
devices	O
.	O
</s>
<s>
Poor	O
CPU	B-General_Concept
cooling	I-General_Concept
due	O
to	O
a	O
CPU	B-General_Concept
heatsink	I-General_Concept
and	O
case	B-Application
fans	I-Application
(	O
or	O
filters	O
)	O
that	O
's	O
clogged	O
with	O
dust	O
or	O
has	O
come	O
loose	O
.	O
</s>
<s>
Overclocking	B-Application
beyond	O
the	O
highest	O
clock	O
rate	O
at	O
which	O
the	O
CPU	O
is	O
still	O
reliable	O
.	O
</s>
<s>
Failing	O
motherboard	B-Device
.	O
</s>
<s>
Failing	O
memory	B-Architecture
.	O
</s>
<s>
Failing	O
I/O	O
controllers	O
,	O
on	O
either	O
the	O
motherboard	B-Device
or	O
separate	O
cards	O
.	O
</s>
<s>
A	O
failing	O
motherboard	B-Device
or	O
processor	O
can	O
be	O
identified	O
by	O
swapping	O
them	O
with	O
functioning	O
parts	O
.	O
</s>
<s>
Memory	B-Architecture
can	O
be	O
checked	O
by	O
booting	O
to	O
a	O
diagnostic	O
tool	O
,	O
like	O
memtest86	B-Application
.	O
</s>
<s>
For	O
IA-32	O
and	O
Intel	O
64	O
processors	O
,	O
consult	O
the	O
Intel	O
64	O
and	O
IA-32	O
Architectures	O
Software	O
Developer	O
's	O
Manual	O
Chapter	O
15	O
(	O
Machine-Check	O
Architecture	B-General_Concept
)	O
,	O
or	O
the	O
Microsoft	O
KB	O
Article	O
on	O
Windows	O
Exceptions	O
.	O
</s>
<s>
rasdaemon	O
is	O
a	O
RAS	O
(	O
reliability	B-General_Concept
,	I-General_Concept
availability	I-General_Concept
and	I-General_Concept
serviceability	I-General_Concept
)	O
logging	O
tool	O
for	O
Linux	B-Application
.	O
</s>
<s>
It	O
records	O
memory	B-Architecture
errors	O
,	O
using	O
the	O
EDAC	O
tracing	O
events	O
.	O
</s>
<s>
EDAC	O
is	O
a	O
Linux	B-Operating_System
kernel	I-Operating_System
subsystem	O
with	O
handles	O
detection	O
of	O
ECC	O
errors	O
from	O
memory	B-Architecture
controllers	O
for	O
most	O
chipsets	O
on	O
i386	O
and	O
x86_64	O
architectures	O
.	O
</s>
<s>
It	O
is	O
recommended	O
to	O
use	O
rasdaemon	O
to	O
gather	O
MCE	O
information	O
on	O
Linux	B-Application
systems	O
because	O
mcelog	B-Device
has	O
been	O
deprecated	O
as	O
of	O
2017	O
.	O
</s>
<s>
mcelog	B-Device
is	O
a	O
Linux	B-Application
daemon	O
by	O
Andi	O
Kleen	O
to	O
handle	O
MCEs	O
for	O
x86	B-Operating_System
processors	O
.	O
</s>
<s>
mcelog	B-Device
can	O
also	O
decode	O
machine	B-Device
checks	I-Device
.	O
</s>
<s>
mcelog	B-Device
is	O
considered	O
functionally	O
obsolete	O
as	O
of	O
2017	O
.	O
</s>
<s>
The	O
replacement	O
of	O
mcelog	B-Device
for	O
Linux	B-Application
systems	O
is	O
rasdaemon	O
.	O
</s>
<s>
parsemce	O
is	O
a	O
Linux	B-Application
program	O
by	O
Dave	O
Jones	O
to	O
decode	O
MCEs	O
from	O
AMD	B-Architecture
K7	I-Architecture
processors	O
.	O
</s>
<s>
mced	O
(	O
mcedaemon	O
)	O
is	O
a	O
Linux	B-Application
program	O
by	O
Tim	O
Hockin	O
to	O
gather	O
MCEs	O
from	O
the	O
kernel	B-Operating_System
and	O
alert	O
interested	O
applications	O
.	O
</s>
<s>
mcat	O
is	O
a	O
Windows	O
command-line	O
program	O
from	O
AMD	O
to	O
decode	O
MCEs	O
from	O
AMD	B-Device
K8	I-Device
,	O
Family	O
0x10	O
and	O
0x11	O
processors	O
.	O
</s>
