137 lines
4.3 KiB
Groff
137 lines
4.3 KiB
Groff
.\"-
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.\" Copyright (c) 2010 Marcel Moolenaar
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd Januari 29, 2010
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.Dt LIBEFI 3
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.Os
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.Sh NAME
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.Nm efi_getvar , efi_nextvarname , efi_setvar
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.Nd Interface for accessing the EFI variable services
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.Sh LIBRARY
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.Lb libefi
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.Sh SYNOPSIS
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.In libefi.h
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.Ft int
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.Fn efi_getvar "char *name" "uuid_t *vendor" "uint32_t *attrib" \
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"size_t *datasize" "void *data"
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.Ft int
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.Fn efi_nextvarname "size_t *namesize" "char *name" "uuid_t *vendor"
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.Ft int
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.Fn efi_setvar "char *name" "uuid_t *vendor" "uint32_t attrib" \
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"size_t datasize" "void *data"
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.Sh DESCRIPTION
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The
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.Nm libefi
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library provides access to a select set of the runtime services of the
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Extensible Firmware Interface (EFI).
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.Pp
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The
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.Fn efi_nextvarname
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function is used to enumerate the variables.
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The
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.Nm namesize
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parameter needs to be set to the size of the buffer pointed to by
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.Nm name .
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On return,
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.Nm namesize
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is set to the length of the variable name (including the terminating '\\0')
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irrespective of whether the buffer was big enough.
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The buffer pointed to by
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.Nm name
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contains the full or partial variable name on return.
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Only on successful completion of the request is the
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.Nm vendor
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updated.
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The values returned should be passed to successive calls to
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.Fn efi_nextvarname
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until all variables have been enumerated.
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.Pp
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The variable name and vendor as returned by
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.Fn efi_nextvarname
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can be passed to
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.Fn efi_getvar
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to obtain the value and attribute of the variable.
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The buffer that is to contain the value is specified by
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.Nm data
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and the size of the buffer is given by
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.Nm datasize .
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The attribute pointed to by
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.Nm attrib
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consists of the bit values defined by the EFI specification.
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.Pp
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Variables can be created, modified and deleted using the
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.Fn efi_setvar
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function.
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All new variables must be non-volatile and runtime accessable in
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order for the request to succeed.
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Note that for runtime accessable variables the boottime accessable bit must
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be set as well.
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To delete a variable, set
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.Nm datasize
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to 0.
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.Pp
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The vendor UUID is used to avoid collisions between variable names of
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different vendors.
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Variables created for use by FreeBSD should use the
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.Nm EFI_FREEBSD_VARIABLE
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UUID as defined in the
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.Nm libefi
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header file.
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.Sh RETURN VALUES
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Upon successful completion, these functions return 0.
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Otherwise, the error number is returned.
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These functions will fail if:
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.Bl -tag -width Er
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.It Bq Er EACCES
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Insufficient permissions to access the EFI services.
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.It Bq Er EILSEQ
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The variable name is not in UTF-8.
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.It Bq Er EINVAL
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The request has invalid parameters.
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.It Bq Er ENOENT
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The variable does not exist or no more variables exist.
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.It Bq Er ENOMEM
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Temporary storage could not be allocated.
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.It Bq Er EOVERFLOW
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The variable name is too long or the data is too big to fit in
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the buffer provided.
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.El
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.Sh SEE ALSO
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.Xr errno 2 ,
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.Xr uuid 3
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.Sh HISTORY
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The
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.Nm libefi
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library first appeared in
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.Fx 9
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for the ia64 architecture.
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.Sh AUTHORS
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The
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.Nm libefi
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library and corresponding manual page were written by
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.An Marcel Moolenaar Aq marcel@FreeBSD.org .
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