ELFCTL(1)               FreeBSD General Commands Manual              ELFCTL(1)

NAME

     elfctl - change an ELF binary's feature control note

SYNOPSIS

     elfctl [-h | --help] [-i] [-l] [-e featurelist] file ...

DESCRIPTION

     The elfctl utility modifies feature flags in the feature control note in
     an ELF binary.

     The options are as follows:

     -h | --help
             Print a usage message and exit.

     -i      Ignore unknown feature flags in featurelist.

     -l      List known ELF feature flags.

     -e featurelist
             Edit features from the given comma separated list featurelist.
             featurelist starts with one of the three operations: "+" to turn
             on the features, "-" to turn off the features, "=" to only turn
             on the given features.  A comma separated list of feature names
             or numeric values follows the operation.

     If -e is not specified elfctl displays the status of each feature in the
     ELF note in each file ....

EXIT STATUS

     Exit status is 0 on success, and 1 if the command fails if a file does
     not exist, is too short, or fails to find or edit features note.

EXAMPLES

     The following is an example of a typical usage of the elfctl command:

           elfctl file
           elfctl -e +noaslr file

     Features may be specified as numerical values:

           elfctl -e =0x0001,0x0004 file

     Features may also be specified as a single combined value:

           elfctl -e =0x5 file

NOTES

     On amd64, on a machine with LA57 (5-level paging) mode supported and
     enabled, if both la57 and la48 feature flags are specified, the la57
     feature has priority over la48.  The vm.pmap.prefer_uva_la48 sysctl MIB
     defines the default user address space size for binaries which do not set
     either of these flags.

SEE ALSO

     mitigations(7)

HISTORY

     elfctl first appeared in FreeBSD 12.2.

AUTHORS

     elfctl was written by Bora Ozarslan borako.ozarslan@gmail.com under
     sponsorship from the FreeBSD Foundation.

FreeBSD 15.1-STABLE-HBSD        October 5, 2023                      ELFCTL(1)