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.
/dev/eeprom/spd511x/*/eeprom EEPROM character device file.
/dev/sensors/temperature/i2c/spd511x*
Hub temperature sensor.
/kernel/drv/amd64/spd511x Device driver (x86)
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.
illumos September 21, 2025 illumos
NAME
spd511x - DDR5 hub and serial presence detect driver
SYNOPSIS
/dev/eeprom/spd511x/*/eeprom
/dev/sensors/temperature/i2c/spd511x*
DESCRIPTION
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.
FILES
/dev/eeprom/spd511x/*/eeprom EEPROM character device file.
/dev/sensors/temperature/i2c/spd511x*
Hub temperature sensor.
/kernel/drv/amd64/spd511x Device driver (x86)
SEE ALSO
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.
illumos September 21, 2025 illumos