— get and set the address of the thread
control block of the current thread
() functions are for use by libpthread
and other parts of the C runtime to retrieve and set the address of the
current thread's thread control block (TCB). This is used to locate per-thread
data such as errno
. Each kernel-level thread
in a process has a separate value for this address, which can be obtained and
changed via these system calls.
The initial thread of a new process created using
inherits the TCB address
of the thread that created it. A thread created using
starts with the TCB
address specified in that call.
resets the thread's
TCB address to zero.
On some platforms, this address is also directly mapped to a CPU register which
can be accessed from userspace.
() returns the address of the thread
control block of the current thread.
() system calls appeared in