Figure 34-3 on page 996 illustrates what the specification refers to as an actively managed chassis. It is comprised of the following elements:
Embedded switch.This switch is embedded in the chassis. It is connected to each of the installed IBA modules via one or two IBA links and is connected to the external IBA fabric, in this example, by a single link (there could be more than one external link). The embedded switch incorporates the following entities:
-
IB-ML Agent.Permits the MME to send and receive transactions over a dedicated, point-to-point IB-ML channel with the Chassis Management Entity (CME).
-
CME.
Provides the following functions:
- Permits access to the ChassisInfoSEEPROM (Serial EEPROM) to obtain information about the chassis. See Table 34-1 on this page.
- The CME may also have access to other chassis-specific devices, such as temperature monitoring logic, fan control logic, etc.
- The CME has a series of dedicated, point-to-point IB-ML channels connecting it to each chassis module slot. This permits the CME to monitor the IB-ML interrupt line from each module so it can receive alerts regarding module-related situations. The CME can send and receive messages with each module over the dedicated, point-to-point IB-ML channels.
- In the example, the CME can also communicate with another chassis via a dedicated, point-to-point IB-ML channel.
The example chassis also incorporates two embedded IBA devices connected to the switch via IBA links.
Figure 34-3. Major Baseboard Management Elements (Actively Managed Chassis)
Table 34-1. ChassisInfo Content
Field Size (bytes)
Description
8
ChassisGUID.
EUI-64 ID that identifies this chassis.
1
SlotCount.
Total number of module slots available in this chassis.
1 or more
SlotNumbers.
One or more 8-bit fields indicating which slot numbers are valid for the chassis. Slot numbers do not have to be sequential and must be in the range from 1 through 254. 0 is assigned to the CME and the chassis containing the CME.
Bit 7:
- 1 = There is at least one other SlotNumbers field byte following this one.
- 0 = This is the last byte of the SlotNumbers field in this record.
Bit 6 is reserved.
Bits[5:0]: Each of the three bit-pairs represents one of three corresponding slot numbers, with bits 1:0 of the first SlotNumbers field corresponding to slot number 1.
- 00b = Chassis does not implement this slot number.
- 01b = Chassis provides one backplane connector to this standard slot.
- 10b = Chassis provides one backplane connector to this tall slot.
- 11b = Chassis provides two backplane connectors to this tall slot.
1 or more
CMEAccess.
One or more contiguous 8-bit fields indicating which module slots in this chassis provide CME access via their primary port (i.e., port 1). If this record is for the CME itself (slot number = 0) then this indicates the number of IB-MLs connected to the CME.
Bit 7:
- 1 = There is at least one other CMEAccess field byte following this one.
- 0 = This is the last byte of the CMEAccess field in this record.
Bits [6:0]. Each bit represents 1 of 7 corresponding slot numbers, with bit 1 of the first CMEAccess field corresponding to slot number 1. Bit 0 of the first CMEAccess field indicates whether a CME is present.
- 0 = slot does not provide CME access.
- 1 = slot provides CME access.
1
SlotNumber.
Chassis-assigned slot number for the slot through which this ChassisInfo SEEPROM device is being accessed. Slot numbers must be in the range 1 through 254. A 0 is assigned to the CME and to the chassis containing the CME. FFh = unspecified and is used to support non-module applications of this record.
Bits [7:6]. CMEAccess:
- 00b = unspecified (used to support non-module applications of this record).
- 01b = A CME is accessible via the primary port (i.e., port 1) of this slot. If this info is for a non-module, this bit indicates that a CME is accessible by BM MADs to the port used to access this VPD Device.
- 10b = A CME is not accessible from this slot/port.
- 11b = Reserved
Bit 5. ProxyAccess:
- 0 = There is no CME proxy access to other slots via the slot or port used to access this VPD Device.
- 1 = This slot or port provides access to a CME that provides proxy access to other slots.
Bit 4. Reserved.
Bits [3:2]. LockDrivesCTR (Lock Drives Clear to Remove). Indicates whether the lock (if present) keeps CME_CTR (Chassis Management Entity Clear to Remove) deasserted (0) until the lock is released.
- 00b = unspecified (used to support non-module applications of this record).
- 01b = CME only uses the state of the lock to drive CME_CTR.
- 10b = CME_CTR will not be asserted unless the lock is released, but CME has other criteria that can also cause CME_CTR to be kept de-asserted.
- 11b = Reserved.
Bits [1:0]. MechanicalLockPresent. Indicates whether there is a mechanical lock associated with this slot. A mechanical lock physically prevents removal of the module from the slot. The implementation of the lock can be purely mechanical (e.g., a mechanical key lock) or electro-mechanical (e.g., a solenoid).
- 00b = Unspecified (used to support non-module applications of this record).
- 01b = Mechanical lock present.
- 10b = No mechanical lock on this slot.
- 11b = Reserved.
variable
OEM fields.
A group of one or more OEM fields. Must be preceded with an OEM Prefix field. Please note that the specification doesn't define what an OEM Prefix field consists of.
1
C0h (Encoding/Length byte encoded to indicate no more info fields). Only required when space exists between the end of the last field and the Checksum. Please note that the specification doesn't define the encoding of this field.
variable
PAD (0 to n bytes).
An implementation is allowed to pad records with FFh values.
