What: /sys/firmware/gsmi
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Date: March 2011
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Contact: Mike Waychison <mikew@google.com>
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Description:
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Some servers used internally at Google have firmware
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that provides callback functionality via explicit SMI
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triggers. Some of the callbacks are similar to those
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provided by the EFI runtime services page, but due to
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historical reasons this different entry-point has been
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used.
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The gsmi driver implements the kernel's abstraction for
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these firmware callbacks. Currently, this functionality
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is limited to handling the system event log and getting
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access to EFI-style variables stored in nvram.
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Layout:
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/sys/firmware/gsmi/vars:
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This directory has the same layout (and
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underlying implementation as /sys/firmware/efi/vars.
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See `Documentation/ABI/*/sysfs-firmware-efi-vars`
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for more information on how to interact with
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this structure.
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/sys/firmware/gsmi/append_to_eventlog - write-only:
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This file takes a binary blob and passes it onto
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the firmware to be timestamped and appended to
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the system eventlog. The binary format is
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interpreted by the firmware and may change from
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platform to platform. The only kernel-enforced
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requirement is that the blob be prefixed with a
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32bit host-endian type used as part of the
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firmware call.
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/sys/firmware/gsmi/clear_config - write-only:
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Writing any value to this file will cause the
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entire firmware configuration to be reset to
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"factory defaults". Callers should assume that
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a reboot is required for the configuration to be
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cleared.
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/sys/firmware/gsmi/clear_eventlog - write-only:
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This file is used to clear out a portion/the
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whole of the system event log. Values written
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should be values between 1 and 100 inclusive (in
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ASCII) representing the fraction of the log to
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clear. Not all platforms support fractional
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clearing though, and this writes to this file
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will error out if the firmware doesn't like your
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submitted fraction.
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Callers should assume that a reboot is needed
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for this operation to complete.
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