This feature is currently present only on gnu/Linux native hosts.
gdb reads in some cases thread debugging library from places specific to the inferior (see set libthread-db-search-path).
The special ‘libthread-db-search-path’ entry ‘$sdir’ is processed without checking this ‘set auto-load libthread-db’ switch as system libraries have to be trusted in general. In all other cases of ‘libthread-db-search-path’ entries gdb checks first if ‘set auto-load libthread-db’ is enabled before trying to open such thread debugging library.
Note that loading of this debugging library also requires accordingly configured
auto-load safe-path (see Auto-loading safe path).
set auto-load libthread-db [on|off]
show auto-load libthread-db
info auto-load libthread-db