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Computer Group Literature Center Web Site
Falcon ECC Memory Controller Chipset
3
Error Logger Register
The Error Logger and Error Address Registers behave the same as the
other registers, in that data written to the upper Falcon is automatically
duplicated in the lower Falcon. They also behave the same as the other
registers, in that status read from the upper Falcon pertains to the upper
Falcon, and status read from the lower Falcon pertains to the lower Falcon.
Unlike most of the other registers, however, it is normal for this status to
differ between the two. This is due to the fact that each Falcon is connected
to its own set of DRAMs. The upper Falcon can log an error during a cycle
and the local Falcon not, or vice-versa. Or they can both log an error during
the same cycle and have the attributes of the errors differ.
Because of the above, software needs to monitor both the upper and lower
Falcon’s Error Logger and Error Address Registers. This includes
checking the elog bit from the upper Falcon and from the lower Falcon.
When the upper Falcon logs an error, it updates its attribute bits (escb,
embt, esbt, ERROR_SYNDROME, eblk0, eblk1, and
ERROR_ADDRESS) to match the results of the read cycle for its portion
of the DRAM array. When the lower Falcon logs an error, it updates its
attribute bits to match the results of the read cycle for its portion of the
DRAM array.
While the logging of errors by one Falcon in a pair does not affect the
logging of errors by the other, writing to the Error Logger Register control
bits affects both Falcons. This is of particular interest as regards the elog
bit. Writing a one to the elog bit clears the elog bit for both the upper and
lower Falcons. Because of this, software needs to check the status of both
upper and lower Error Logger and Error Address Registers before it clears
the elog bits. Otherwise, it could miss a logged error.
ADDRESS
$FEF80030
BIT
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
NAME
elo
g
0
0
0
es
cb
es
en
em
bt
es
bt
ERROR_SYNDROME
0
0
ebl
k0
ebl
k1
0
0
0
sc
of
SBE_COUNT
OPERATION
R/
C
R
R
R
R
R/
W
R
R
READ ONLY
R
R
R
R
R
R
R
R/
C
READ/WRITE
RESET
0 P
X
X
X
X P
0 PL
X P
X P
X P
X
X
X
X
X
X
X
0 P
0 P