| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 1 | What: /dev/wmi/dell-smbios |
| 2 | Date: November 2017 |
| 3 | KernelVersion: 4.15 |
| 4 | Contact: "Mario Limonciello" <mario.limonciello@dell.com> |
| 5 | Description: |
| 6 | Perform SMBIOS calls on supported Dell machines. |
| 7 | through the Dell ACPI-WMI interface. |
| 8 | |
| 9 | IOCTL's and buffer formats are defined in: |
| 10 | <uapi/linux/wmi.h> |
| 11 | |
| 12 | 1) To perform an SMBIOS call from userspace, you'll need to |
| 13 | first determine the minimum size of the calling interface |
| 14 | buffer for your machine. |
| 15 | Platforms that contain larger buffers can return larger |
| 16 | objects from the system firmware. |
| 17 | Commonly this size is either 4k or 32k. |
| 18 | |
| 19 | To determine the size of the buffer read() a u64 dword from |
| 20 | the WMI character device /dev/wmi/dell-smbios. |
| 21 | |
| 22 | 2) After you've determined the minimum size of the calling |
| 23 | interface buffer, you can allocate a structure that represents |
| 24 | the structure documented above. |
| 25 | |
| 26 | 3) In the 'length' object store the size of the buffer you |
| 27 | determined above and allocated. |
| 28 | |
| 29 | 4) In this buffer object, prepare as necessary for the SMBIOS |
| 30 | call you're interested in. Typically SMBIOS buffers have |
| 31 | "class", "select", and "input" defined to values that coincide |
| 32 | with the data you are interested in. |
| 33 | Documenting class/select/input values is outside of the scope |
| 34 | of this documentation. Check with the libsmbios project for |
| 35 | further documentation on these values. |
| 36 | |
| 37 | 6) Run the call by using ioctl() as described in the header. |
| 38 | |
| 39 | 7) The output will be returned in the buffer object. |
| 40 | |
| 41 | 8) Be sure to free up your allocated object. |