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1What: /sys/firmware/gsmi2Date: March 20113Contact: Mike Waychison <mikew@google.com>4Description:5 Some servers used internally at Google have firmware6 that provides callback functionality via explicit SMI7 triggers. Some of the callbacks are similar to those8 provided by the EFI runtime services page, but due to9 historical reasons this different entry-point has been10 used.11 12 The gsmi driver implements the kernel's abstraction for13 these firmware callbacks. Currently, this functionality14 is limited to handling the system event log and getting15 access to EFI-style variables stored in nvram.16 17 Layout:18 19 /sys/firmware/gsmi/vars:20 21 This directory has the same layout (and22 underlying implementation as /sys/firmware/efi/vars.23 See `Documentation/ABI/*/sysfs-firmware-efi-vars`24 for more information on how to interact with25 this structure.26 27 /sys/firmware/gsmi/append_to_eventlog - write-only:28 29 This file takes a binary blob and passes it onto30 the firmware to be timestamped and appended to31 the system eventlog. The binary format is32 interpreted by the firmware and may change from33 platform to platform. The only kernel-enforced34 requirement is that the blob be prefixed with a35 32bit host-endian type used as part of the36 firmware call.37 38 /sys/firmware/gsmi/clear_config - write-only:39 40 Writing any value to this file will cause the41 entire firmware configuration to be reset to42 "factory defaults". Callers should assume that43 a reboot is required for the configuration to be44 cleared.45 46 /sys/firmware/gsmi/clear_eventlog - write-only:47 48 This file is used to clear out a portion/the49 whole of the system event log. Values written50 should be values between 1 and 100 inclusive (in51 ASCII) representing the fraction of the log to52 clear. Not all platforms support fractional53 clearing though, and this writes to this file54 will error out if the firmware doesn't like your55 submitted fraction.56 57 Callers should assume that a reboot is needed58 for this operation to complete.59