| SPD511X(4D) | Devices | SPD511X(4D) |
spd511x — DDR5 hub
and serial presence detect driver
/dev/eeprom/spd511x/*/eeprom
/dev/sensors/temperature/i2c/spd511x*
The spd511x driver supports I2C devices
compliant with JEDEC Standard JESD300-5 which covers the hub and serial
presence detect data found on DDR5 DIMMs. The driver provides access to the
hub's built-in temperature sensor through the
ksensor(4D) driver and provides
read-only access to the SPD (serial presence detect) EEPROM through a
character device powered by the
eedev(4D) driver. These devices are
generally found at 7-bit addresses between 0x50 and 0x57. The lower three
bits of the address are used to indicate which DIMM the device is found on
(ranging from 0 to 7).
The SPD device contains 1024 bytes of memory that are organized into 16 blocks of 64 bytes each. A paging mechanism provides access to 128 bytes at a time. Devices can be found under /dev/eeprom/spd511x. Contents of the SPD data can be decoded with libjedec(3LIB).
The temperature sensor measures in units of 0.25
degrees Celsius and its accuracy varies depending on the current temperature
range. Temperature information is available to the system through the fault
ma management architecture (FMA). The file system location and programming
interface to the spd511x temperature sensors are
considered
volatile.
libjedec(3LIB), ee100x(4D), eedev(4D), ts511x(4D), i2cadm(8)
SPD5118 Hub and Serial Presence Detect Device Standard, JESD300-5B.01 Version 1.5.1, JEDEC Solid State Technology Association, May 2024.
| September 21, 2025 | OmniOS |