| Dave Young | 5039e31 | 2013-12-20 18:02:21 +0800 | [diff] [blame] | 1 | What: /sys/kernel/boot_params |
| 2 | Date: December 2013 |
| 3 | Contact: Dave Young <dyoung@redhat.com> |
| 4 | Description: The /sys/kernel/boot_params directory contains two |
| 5 | files: "data" and "version" and one subdirectory "setup_data". |
| 6 | It is used to export the kernel boot parameters of an x86 |
| 7 | platform to userspace for kexec and debugging purpose. |
| 8 | |
| 9 | If there's no setup_data in boot_params the subdirectory will |
| 10 | not be created. |
| 11 | |
| 12 | "data" file is the binary representation of struct boot_params. |
| 13 | |
| 14 | "version" file is the string representation of boot |
| 15 | protocol version. |
| 16 | |
| 17 | "setup_data" subdirectory contains the setup_data data |
| 18 | structure in boot_params. setup_data is maintained in kernel |
| 19 | as a link list. In "setup_data" subdirectory there's one |
| 20 | subdirectory for each link list node named with the number |
| 21 | of the list nodes. The list node subdirectory contains two |
| 22 | files "type" and "data". "type" file is the string |
| 23 | representation of setup_data type. "data" file is the binary |
| 24 | representation of setup_data payload. |
| 25 | |
| 26 | The whole boot_params directory structure is like below: |
| 27 | /sys/kernel/boot_params |
| 28 | |__ data |
| 29 | |__ setup_data |
| 30 | | |__ 0 |
| 31 | | | |__ data |
| 32 | | | |__ type |
| 33 | | |__ 1 |
| 34 | | |__ data |
| 35 | | |__ type |
| 36 | |__ version |
| 37 | |
| 38 | Users: Kexec |