I2C Complaints - Sun Microsystems Netra ct Service Manual

A soft hang occurs when a component such as a power supply sends a level high
interrupt and keeps it high. The kernel notices and polls the devices. Each device
answers negative, including the culprit power supply. Meanwhile, the CPU
continues with minimal work before returning to the querying process. This is a
serious problem because the failing component remains unidentified.
Action
Completely power the server off and then on again using the instructions in
Chapter 2. When the system boots, it always boots interrupts low (masked), and
attaches the drivers one by one. You can also use OpenBoot PROM commands to
probe the components and determine which one has failed.
2
C.3 I C Complaints
Message
NO ADDERSS ACK 80
Cause
2
This message indicates a problem with I C, and often it's the pcf8584 driver that
complains, followed by the address it was trying to access (for example, NO
ADDRESS ACK 80. indicates a problem with address 80, which is the fixed address
of the system controller board.
Most of the Sun drivers print a secondary error message, but the principal error
message comes from pcf8584. The interface to this is through an ioctl, so its done
through software. This message indicates a problem, but not the severity. Sometimes
such a message is normal.
For example when a power supply is removed, the Present line goes low and the
SCB sets the bit high (interrupt. The kernel pcf8584 goes down the device line
querying for interrupts in the order in which the devices boot, each one answering.
The message 8584 NO ADDR ACK 0x9E occurs when the device is removed.
Because it happened after the driver tried to query the hardware, this spurious error
message occurs. This happens with fans and power supplies.
Appendix C Error Messages C-9