set_thread_area(2) -- Linux man page
NAMEset_thread_area - Set a Thread Local Storage (TLS) area
- int set_thread_area (struct user_desc *u_info);
set_thread_area sets an entry in the current thread's Thread Local Storage (TLS) array. The TLS array entry set by set_thread_area corresponds to the value of u_info->entry_number passed in by the user. If this value is in bounds, set_thread_area copies the TLS descriptor pointed to by u_info into the thread's TLS array.
When set_thread_area is passed an entry_number of -1, it uses a free TLS entry. If set_thread_area finds a free TLS entry, the value of u_info->entry_number is set upon return to show which entry was changed.
set_thread_area returns 0 on success. Otherwise, it returns one of the errors listed in the "Errors" section.
u_info->entry_number is out of bounds.
u_info is an invalid pointer.
A free TLS entry could not be located.
set_thread_area is Linux specific and should not be used in programs that are intended to be portable.
A version of set_thread_area first appeared in Linux 2.5 in August, 2002.
set_thread_area was written by Ingo Molnar.