xref: /freebsd/share/man/man4/efidev.4 (revision d12d651f8692cfcaf6fd0a6e8264c29547f644c9)

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.Dd June 18, 2021
.Dt EFIDEV 4
.Os
.Sh NAME
.Nm efidev ,
.Nm efirtc
.Nd user-mode access to UEFI runtime services
.Sh SYNOPSIS
To compile this driver into the kernel, place the following lines in your
kernel configuration file:
.Bd -ragged -offset -indent
.Cd "options EFIRT"
.Ed
.Pp
Alternatively, to load the driver as a module at boot time, place the following
line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
efirt_load="YES"
.Ed
.Pp
The driver may be disabled by setting the
.Xr loader 8
tunable
.Va efi.rt.disabled
to
.Dq Li 1 .
.Sh DESCRIPTION
The
.Nm
device provides user-mode access to UEFI runtime services.
.Nm
also includes a driver to provide a time-of-day clock using the UEFI
real time clock (RTC).
However, the RTC may not always be available, based on the UEFI firmware.
If the RTC is not available, it will not be registered as a time-of-day clock
and the time related ioctls below will not be functional.
.Pp
.Nm
provides the following ioctls defined in
.In sys/efiio.h
with supplemental structures and constants defined in
.In sys/efi.h :
.Bl -tag -width indent
.It Dv EFIIOC_GET_TABLE Pq Vt "struct efi_get_table_ioc"
Copy the UEFI table specified by the
.Va uuid
field of the
.Vt struct efi_get_table_ioc
into the
.Va buf
field.
The memory size for the buf field can be queried by passing
.Dv NULL
pointer as a buf value.
The required size will be stored in the
.Va table_len
field.
The size of the allocated memory must be specified in the
.Va buf_len
field.
.Bd -literal -offset indent
struct efi_get_table_ioc {
	void *buf;
	struct uuid uuid;
	size_t table_len;
	size_t buf_len;
};
.Ed
.It Dv EFIIOC_GET_TIME Pq Vt "struct efi_tm"
Get the time from the RTC, if the RTC is available.
The
.Vt struct efi_tm
passed is populated with the current time, unless an error occurs.
.Bd -literal -offset indent
struct efi_tm {
	uint16_t	tm_year;
	uint8_t		tm_mon
	uint8_t		tm_mday
	uint8_t		tm_hour;
	uint8_t		tm_min;
	uint8_t		tm_sec;
	uint8_t		 __pad1;
	uint32_t	tm_nsec;
	int16_t		tm_tz;
	uint8_t		tm_dst;
	uint8_t		__pad2;
};
.Ed
.It Dv EFIIOC_SET_TIME Pq Vt "struct efi_tm"
Sets the time stored by the RTC, if the RTC is available.
.It Dv EFIIOC_VAR_GET Pq Vt "struct efi_var_ioc"
Gets data from the variable described by the vendor and name fields of the
.Vt struct efi_var_ioc
into the
.Fa data
field.
.Dv EFIIOC_VAR_GET Pq Vt "struct efi_var_ioc"
will also populate the
.Fa attrib
field.
.Bd -literal
struct efi_var_ioc {
	efi_char	*name;
	size_t		 namesize;
	struct uuid	 vendor;
	uint32_t	 attrib;
	void		*data;
	size_t		 datasize;
};
.Ed
.It Dv EFIIOC_VAR_NEXT Pq Vt "struct efi_var_ioc"
Used for enumerating all UEFI variables.
The initial call should use an empty string for the name attribute.
Subsequent calls should supply the vendor uuid and name of the last variable
returned.
.It Dv EFIIOC_VAR_SET Pq Vt "struct efi_var_ioc"
Sets data and attributes for the variable described by the name and vendor in
the
.Vt struct efi_var_ioc .
.El
.Sh FILES
.Bl -tag -width /dev/efi
.It Pa /dev/efi
.El
.Sh SEE ALSO
.Xr efivar 3 ,
.Xr efirt 9
.Sh HISTORY
A
.Nm
device first appeared in
.Fx 11.1 .
.Sh BUGS
.Nm
is currently only available on amd64 and arm64.