915GM Datasheet, PDF (18/48 Pages) Intel Corporation – 915GM/PM/GME/GMS and 910GML/GMLE Express Chipset

Errata
8.
PCI Express Common Mode Voltage Noise Immediately following
Receiver Detect Sequence
Problem:
The PCI Express Common Mode Voltage is not stable immediately after Receiver
Detect Sequence when entering Polling.Active from Detect.Active states.
Implication: Common Mode Voltage noise may result in bit errors early in Polling.Active state. May
result in additional training time before transitioning on to Polling.Configuration.
Performance impact expected to be minimal.
Workaround: None
Status:
For the steppings affected, see the Summary Tables of Changes.
9.
GMCH Does Not Ignore a PCI Express Null Packet
Problem:
If the GMCH receives a PCI Express Null packet, it should drop the packet and not
perform sequence number checking or respond with any Ack or Nak DLLP. The issue is
that the GMCH still performs sequence number checks for Null packets and may
respond with an ACK or NAK depending on the result of the check.
Implication: GMCH may send ACK or NAK DLLPs in response to a Null packet if the sequence
number is not as expected. This may cause unnecessary retries, but Null packets are
expected to be rare on the link.
Workaround: None
Status:
For the steppings affected, see the Summary Tables of Changes.
10.
Data Payload Byte Count Supplied during an Unsupported Upstream
Configuration Read Is Not 4 Bytes
Problem:
During configuration reads to unsupported PCI Express configuration space, the byte
count for data payload is not 4.
Implication: Data payload byte count is 5 and not the expected 4.
Workaround: Do not perform unsupported upstream PCI Express configuration cycles.
Status:
For the steppings affected, see the Summary Tables of Changes.
11.
PCI Express Replay Timer Register Default Setting Is Incorrect
Problem:
The default Replay timer value is too aggressive and does not properly account for L0s
exit latency or internal pipeline delays. As a result the GMCH may initiate a replay
sooner than expected.
Implication: The GMCH may initiate a replay sooner than expected. This should not happen as long
as the downstream device complies with the PCI Express Ack Latency requirement.
Workaround: It is possible for BIOS to contain a workaround. Contact your Intel Field
Representative for more details.
Status:
For the steppings affected, see the Summary Tables of Changes.
18
Specification Update