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Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-coreboot')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-coreboot | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-coreboot b/Documentation/ABI/testing/sysfs-bus-coreboot new file mode 100644 index 000000000000..8e8d6af24a4c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-coreboot @@ -0,0 +1,45 @@ +What: /sys/bus/coreboot +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + The coreboot bus provides a variety of virtual devices used to + access data structures created by the Coreboot BIOS. + +What: /sys/bus/coreboot/devices/cbmem-<id> +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + CBMEM is a downwards-growing memory region created by Coreboot, + and contains tagged data structures to be shared with payloads + in the boot process and the OS. Each CBMEM entry is given a + directory in /sys/bus/coreboot/devices based on its id. + A list of ids known to Coreboot can be found in the coreboot + source tree at + ``src/commonlib/bsd/include/commonlib/bsd/cbmem_id.h``. + +What: /sys/bus/coreboot/devices/cbmem-<id>/address +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + This is the physical memory address that the CBMEM entry's data + begins at, in hexadecimal (e.g., ``0x76ffe000``). + +What: /sys/bus/coreboot/devices/cbmem-<id>/size +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + This is the size of the CBMEM entry's data, in hexadecimal + (e.g., ``0x1234``). + +What: /sys/bus/coreboot/devices/cbmem-<id>/mem +Date: August 2022 +Contact: Jack Rosenthal <jrosenth@chromium.org> +Description: + A file exposing read/write access to the entry's data. Note + that this file does not support mmap(), as coreboot + does not guarantee that the data will be page-aligned. + + The mode of this file is 0600. While there shouldn't be + anything security-sensitive contained in CBMEM, read access + requires root privileges given this is exposing a small subset + of physical memory. |