---
name: "mlx5io"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/mlx5io"
---

# mlx5io(4)

IOCTL interface to manage Connect-X 4/5/6 Mellanox network adapters

## NAME

**mlx5io** – IOCTL interface to manage Connect-X 4/5/6 Mellanox network adapters

## SYNOPSIS

**#include \<dev/mlx5/mlx5io.h\>**

## DESCRIPTION

The **mlx5io** interface is provided for management of the Connect-X4, 5 and 6 network adapters in the aspects not covered by the generic network configuration, mostly related to the PCIe attachment and internal card working. Interface consists of the commands, which are passed by means of [ioctl(2)](/ioctl/2.md) on the file descriptor, opened from the */dev/mlx5ctl* device node.

The following commands are implemented:

- MLX5\_FWDUMP\_FORCE

  Take the snapshot of the firmware registers state and store it in the kernel buffer. The buffer must be empty, in other words, no dumps should be written so far, or existing dump cleared with the MLX5\_FWDUMP\_RESET command for the specified device. The argument for the command should point to the *struct* *mlx5\_tool\_addr* structure, containing the PCIe bus address of the device.

  ```
  struct mlx5_tool_addr {
  	uint32_t domain;
  	uint8_t bus;
  	uint8_t slot;
  	uint8_t func;
  };
  ```

- MLX5\_FWDUMP\_RESET

  Clear the stored firmware dump, preparing the kernel buffer for the next dump. The argument for the command should point to the *struct* *mlx5\_tool\_addr* structure, containing the PCIe bus address of the device.

- MLX5\_FWDUMP\_GET

  Fetch the stored firmware dump into the user memory. The argument to the command should point to the input/output *struct* *mlx5\_fwdump\_get* structure. Its devaddr field specifies the address of the device, the buf fields points to the array of *struct* *mlx5\_fwdump\_reg* of records of the registers values, the size of the array is specified in the reg\_cnt field.

  ```
  struct mlx5_fwdump_get {
  	struct mlx5_tool_addr devaddr;
  	struct mlx5_fwdump_reg *buf;
  	size_t reg_cnt;
  	size_t reg_filled; /* out */
  };
  ```

  On successful return, the reg\_filled field reports the number of the buf array elements actually filled with the registers values. If buf contains the NULL pointer, no registers are filled, but reg\_filled still contains the number of registers that should be passed for the complete dump.

  The *struct* *mlx5\_fwdump\_reg* element contains the address of the register in the field addr, and its value in the field val.

  ```
  struct mlx5_fwdump_reg {
  	uint32_t addr;
  	uint32_t val;
  };
  ```

- MLX5\_FW\_UPDATE

  Requests firmware update (flash) on the adapter specified by the devaddr using the firmware image in MFA2 format. The argument for the ioctl command is the *struct* *mlx5\_fw\_update* with the following definition.

  ```
  struct mlx5_fw_update {
  	struct mlx5_tool_addr devaddr;
  	void *img_fw_data;
  	size_t img_fw_data_len;
  };
  ```

  Image address in memory is passed in img\_fw\_data, the length of the image is specified in img\_fw\_data\_len field.

- MLX5\_FW\_RESET

  Requests PCIe link-level reset on the device. The address of the device is specified by the *struct* *mlx5\_tool\_addr* structure, which should be passed as an argument.

- MLX5\_EEPROM\_GET

  Fetch EEPROM information. The argument to the command should point to the input/output *struct* *mlx5\_eeprom\_get* structure where, the devaddr field specifies the address of the device.

  ```
  struct mlx5_eeprom_get {
          struct mlx5_tool_addr devaddr;
          size_t eeprom_info_page_valid;
          uint32_t *eeprom_info_buf;
          size_t eeprom_info_out_len;
  };
  ```

  On successful return, the eeprom\_info\_out\_len field reports the length of the EEPROM information. eeprom\_info\_buf field contains the actual EEPROM information. eeprom\_info\_page\_valid field reports the third page validity.

## FILES

The */dev/mlx5ctl* [devfs(4)](/devfs/4.md) node is used to pass commands to the driver.

## RETURN VALUES

If successful, the IOCTL returns zero. Otherwise, -1 is returned and the global variable *errno* is set to indicate the error.

## SEE ALSO

[errno(2)](/errno/2.md), [ioctl(2)](/ioctl/2.md), [mlx5en(4)](/mlx5en/4.md), [mlx5ib(4)](/mlx5ib/4.md), [mlx5tool(8)](/mlx5tool/8.md) and [pci(9)](/pci/9.md).