.\" Copyright 2020, Dave Martin <Dave.Martin@arm.com>
.\" Copyright 2020, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Copyright 2024, Alejandro Colomar <alx@kernel.org>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH PR_SVE_GET_VL 2const 2024-06-02 "Linux man-pages 6.9.1"
.SH NAME
PR_SVE_GET_VL
\-
get the thread's SVE vector length
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.BR "#include <linux/prctl.h>" "  /* Definition of " PR_* " constants */"
.B #include <sys/prctl.h>
.P
.B int prctl(PR_SVE_GET_VL);
.fi
.SH DESCRIPTION
Get the thread's current SVE vector length configuration.
.P
This operation returns
a nonnegative value that describes the
.I current
configuration.
The bits corresponding to
.B PR_SVE_VL_LEN_MASK
contain the currently configured vector length in bytes.
The bit corresponding to
.B PR_SVE_VL_INHERIT
indicates whether the vector length will be inherited
across
.BR execve (2).
.SH RETURN VALUE
On success,
.BR PR_SVE_GET_VL ,
return the nonnegative values described above.
On error, \-1 is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EINVAL
SVE is not available on this platform.
.SH STANDARDS
Linux.
arm64 only.
.SH HISTORY
Linux 4.15 (arm64).
.SH CAVEATS
There is no way to determine whether there is
a pending vector length change that has not yet taken effect.
.SH SEE ALSO
.BR prctl (2),
.BR PR_SVE_SET_VL (2const)
.P
For more information, see the kernel source file
.I Documentation/arm64/sve.rst
.\"commit b693d0b372afb39432e1c49ad7b3454855bc6bed
(or
.I Documentation/arm64/sve.txt
before Linux 5.3).