46 lines
1.7 KiB
Plaintext
46 lines
1.7 KiB
Plaintext
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What: /sys/bus/coreboot
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Date: August 2022
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Contact: Jack Rosenthal <jrosenth@chromium.org>
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Description:
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The coreboot bus provides a variety of virtual devices used to
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access data structures created by the Coreboot BIOS.
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What: /sys/bus/coreboot/devices/cbmem-<id>
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Date: August 2022
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Contact: Jack Rosenthal <jrosenth@chromium.org>
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Description:
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CBMEM is a downwards-growing memory region created by Coreboot,
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and contains tagged data structures to be shared with payloads
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in the boot process and the OS. Each CBMEM entry is given a
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directory in /sys/bus/coreboot/devices based on its id.
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A list of ids known to Coreboot can be found in the coreboot
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source tree at
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``src/commonlib/bsd/include/commonlib/bsd/cbmem_id.h``.
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What: /sys/bus/coreboot/devices/cbmem-<id>/address
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Date: August 2022
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Contact: Jack Rosenthal <jrosenth@chromium.org>
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Description:
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This is the pyhsical memory address that the CBMEM entry's data
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begins at, in hexadecimal (e.g., ``0x76ffe000``).
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What: /sys/bus/coreboot/devices/cbmem-<id>/size
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Date: August 2022
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Contact: Jack Rosenthal <jrosenth@chromium.org>
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Description:
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This is the size of the CBMEM entry's data, in hexadecimal
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(e.g., ``0x1234``).
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What: /sys/bus/coreboot/devices/cbmem-<id>/mem
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Date: August 2022
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Contact: Jack Rosenthal <jrosenth@chromium.org>
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Description:
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A file exposing read/write access to the entry's data. Note
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that this file does not support mmap(), as coreboot
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does not guarantee that the data will be page-aligned.
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The mode of this file is 0600. While there shouldn't be
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anything security-sensitive contained in CBMEM, read access
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requires root privileges given this is exposing a small subset
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of physical memory.
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