Service manual

5-48 AlphaServer 4000/4100 Service Manual
5.4.4 PIO Buffer Overflow Error (PIO_OVFL)
Step 5
Enter the value of the CAP_CTRL register bits<19:16> (Actual_PEND_NUM) in the
following formula. Compare the results as indicated in Table 5-7 to determine the
most likely cause of the error. When an IOD is implicated in the analysis of the
error, replace the one that capturered the error in its CAP Error Register.
Expected_PEND_NUM = 12 - ((2 * (X - 1)) + Y)
Where: X = Number of PCIs
Y = Number of CPUs
Table 5-7 Cause of PIO_OVFL Error
Comparison Most Likely Cause Action
Actual_PEND_NUM =
Expected_PEND_NUM
Broken hardware on IOD Replace IOD
Actual_PEND_NUM <
Expected_PEND_NUM
Broken hardware on IOD Replace IOD
Actual_PEND_NUM >
Expected_PEND_NUM
PEND_NUM setup incorrect Fix the software
NOTE: IOD0 = B3040-AA bridge module; IOD1 = B3040-AB bridge module.