1.\" Copyright 2016 Netflix, Inc. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD: head/lib/libefivar/efivar.3 343755 2019-02-04 21:28:25Z imp $ 26.\" 27.Dd July 3, 2020 28.Dt LIBEFIVAR 3 29.Os 30.Sh NAME 31.Nm libefivar 32.Nd EFI Non Volatile Variable Support 33.Sh LIBRARY 34.Lb libefivar 35.Sh SYNOPSIS 36.In efivar.h 37.Ft int 38.Fn efi_append_variable "efi_guid_t guid" "const char *name" "uint8_t *data" "size_t data_size" "uint32_t attributes" 39.Ft int 40.Fn efi_del_variable "efi_guid_t guid" "const char *name" 41.Ft int 42.Fn efi_get_variable "efi_guid_t guid" "const char *name" "uint8_t **data" "size_t *data_size" "uint32_t *attributes" 43.Ft int 44.Fn efi_get_variable_attributes "efi_guid_t guid" "const char *name" "uint32_t *attributes" 45.Ft int 46.Fn efi_get_variable_size "efi_guid_t guid" "const char *name" "size_t *size" 47.Ft int 48.Fn efi_get_next_variable_name "efi_guid_t **guid" "char **name" 49.Ft int 50.Fn efi_guid_to_name "efi_guid_t *guid" "char **name" 51.Ft int 52.Fn efi_guid_to_symbol "efi_guid_t *guid" "char **symbol" 53.Ft int 54.Fn efi_guid_to_str "const efi_guid_t *guid" "char **sp" 55.Ft int 56.Fn efi_name_to_guid "const char *name" "efi_guid_t *guid" 57.Ft int 58.Fn efi_set_variable "efi_guid_t guid" "const char *name" "uint8_t *data" "size_t data_size" "uint32_t attributes" 59.Ft int 60.Fn efi_str_to_guid "const char *s" "efi_guid_t *guid" 61.Ft int 62.Fn efi_variables_supported "void" 63.Sh DESCRIPTION 64The 65.Nm 66library implements access to EFI Variables via the EFI Runtime 67Services. 68All 69.Vt "char *" 70strings are converted to 16-bit UTF strings before passing 71them to EFI. 72.Pp 73.Fn efi_variables_supported 74returns non-zero if the current machine supports setting of EFI firmware 75variables and the kernel support for doing so is present. 76Otherwise zero is returned. 77.Pp 78.Fn efi_del_variable 79deletes the EFI variable selected by 80.Fa guid 81and 82.Fa name . 83.Pp 84The following functions have not been implemented yet: 85.Bl -dash -offset indent -compact 86.It 87.Fn efi_append_variable 88.It 89.Fn efi_get_next_variable_name 90.It 91.Fn efi_get_variable 92.It 93.Fn efi_get_variable_attributes 94.It 95.Fn efi_get_variable_size 96.It 97.Fn efi_guid_to_name 98.It 99.Fn efi_guid_to_str 100.It 101.Fn efi_guid_to_symbol 102.It 103.Fn efi_name_to_guid 104.It 105.Fn efi_set_variable 106.It 107.Fn efi_str_to_guid 108.El 109.Sh SEE ALSO 110.Xr efidev 4 , 111.Xr efidp 8 , 112.Xr efivar 8 113.Sh HISTORY 114The 115.Nm 116library first appeared in 117.Fx 12.0 . 118.Sh AUTHORS 119.An -nosplit 120This software was originally written by 121.An Warner Losh . 122.Sh BUGS 123No facilities exist to process the strings as native UTF. 124This is a limitation in the Linux 125.Nm 126library interface. 127