1 /* Definition for thread-local data handling.  Generic version.
2    Copyright (C) 2002 Free Software Foundation, Inc.
3    This file is part of the GNU C Library.
4 
5    The GNU C Library is free software; you can redistribute it and/or
6    modify it under the terms of the GNU Lesser General Public
7    License as published by the Free Software Foundation; either
8    version 2.1 of the License, or (at your option) any later version.
9 
10    The GNU C Library is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13    Lesser General Public License for more details.
14 
15    You should have received a copy of the GNU Lesser General Public
16    License along with the GNU C Library; if not, see
17    <http://www.gnu.org/licenses/>.  */
18 
19 /* By default no TLS support is available.  This is signaled by the
20    absence of the symbol USE_TLS.  */
21 #undef USE_TLS
22 
23 
24 /* An architecture-specific version of this file has to defined a
25    number of symbols:
26 
27      TLS_TCB_AT_TP  or  TLS_DTV_AT_TP
28 
29      The presence of one of these symbols signals which variant of
30      the TLS ABI is used.  There are in the moment two variants
31      available:
32 
33      * the thread pointer points to a thread control block
34 
35      * the thread pointer points to the dynamic thread vector
36 
37 
38      TLS_TCB_SIZE
39 
40      This is the size of the thread control block structure.  How
41      this is actually defined depends on the ABI.  The thread control
42      block could be internal descriptor of the thread library or
43      just a data structure which allows finding the DTV.
44 
45      TLS_INIT_TCB_SIZE
46 
47      Similarly, but this value is only used at startup and in the
48      dynamic linker itself.  There are no threads in use at that time.
49 
50 
51      TLS_TCB_ALIGN
52 
53      Alignment requirements for the TCB structure.
54 
55      TLS_INIT_TCB_ALIGN
56 
57      Similarly, but for the structure used at startup time.
58 
59 
60      INSTALL_DTV(tcb, init_dtv)
61 
62      This macro must install the given initial DTV into the thread control
63      block TCB.  The normal runtime functionality must then be able to
64      use the value.
65 
66 
67      TLS_INIT_TP(tcb, firstcall)
68 
69      This macro must initialize the thread pointer to enable normal TLS
70      operation.  The first parameter is a pointer to the thread control
71      block.  The second parameter specifies whether this is the first
72      call for the TCB.  ld.so calls this macro more than once.
73 
74 
75      THREAD_DTV()
76 
77      This macro returns the address of the DTV of the current thread.
78      This normally is done using the the thread register which points
79      to the dtv or the TCB (from which the DTV can found).
80   */
81