gcc/ada/5ftaprop.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
   4 --                                                                          --
   5 --     S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S    --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --                                                                          --
  10 --         Copyright (C) 1992-2001, Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNARL was developed by the GNARL team at Florida State University. It is --
  31 -- now maintained by Ada Core Technologies, Inc. (http://www.gnat.com).     --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This is a IRIX (pthread library) version of this package.
  36
  37 --  This package contains all the GNULL primitives that interface directly
  38 --  with the underlying OS.
  39
  40 pragma Polling (Off);
  41 --  Turn off polling, we do not want ATC polling to take place during
  42 --  tasking operations. It causes infinite loops and other problems.
  43
  44 with Interfaces.C;
  45 --  used for int
  46 --           size_t
  47
  48 with System.Task_Info;
  49
  50 with System.Tasking.Debug;
  51 --  used for Known_Tasks
  52
  53 with System.IO;
  54 --  used for Put_Line
  55
  56 with System.Interrupt_Management;
  57 --  used for Keep_Unmasked
  58 --           Abort_Task_Interrupt
  59 --           Interrupt_ID
  60
  61 with System.Interrupt_Management.Operations;
  62 --  used for Set_Interrupt_Mask
  63 --           All_Tasks_Mask
  64 pragma Elaborate_All (System.Interrupt_Management.Operations);
  65
  66 with System.Parameters;
  67 --  used for Size_Type
  68
  69 with System.Tasking;
  70 --  used for Ada_Task_Control_Block
  71 --           Task_ID
  72
  73 with System.Soft_Links;
  74 --  used for Defer/Undefer_Abort
  75
  76 --  Note that we do not use System.Tasking.Initialization directly since
  77 --  this is a higher level package that we shouldn't depend on. For example
  78 --  when using the restricted run time, it is replaced by
  79 --  System.Tasking.Restricted.Initialization
  80
  81 with System.Program_Info;
  82 --  used for Default_Task_Stack
  83 --           Default_Time_Slice
  84 --           Stack_Guard_Pages
  85 --           Pthread_Sched_Signal
  86 --           Pthread_Arena_Size
  87
  88 with System.OS_Interface;
  89 --  used for various type, constant, and operations
  90
  91 with System.OS_Primitives;
  92 --  used for Delay_Modes
  93
  94 with Unchecked_Conversion;
  95 with Unchecked_Deallocation;
  96
  97 package body System.Task_Primitives.Operations is
  98
  99    use System.Tasking;
 100    use System.Tasking.Debug;
 101    use Interfaces.C;
 102    use System.OS_Interface;
 103    use System.OS_Primitives;
 104    use System.Parameters;
 105
 106    package SSL renames System.Soft_Links;
 107
 108    ------------------
 109    --  Local Data  --
 110    ------------------
 111
 112    --  The followings are logically constants, but need to be initialized
 113    --  at run time.
 114
 115    ATCB_Key : aliased pthread_key_t;
 116    --  Key used to find the Ada Task_ID associated with a thread
 117
 118    Single_RTS_Lock : aliased RTS_Lock;
 119    --  This is a lock to allow only one thread of control in the RTS at
 120    --  a time; it is used to execute in mutual exclusion from all other tasks.
 121    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
 122
 123    Environment_Task_ID : Task_ID;
 124    --  A variable to hold Task_ID for the environment task.
 125
 126    Locking_Policy : Character;
 127    pragma Import (C, Locking_Policy, "__gl_locking_policy");
 128
 129    Real_Time_Clock_Id : constant clockid_t := CLOCK_REALTIME;
 130
 131    Unblocked_Signal_Mask : aliased sigset_t;
 132
 133    -----------------------
 134    -- Local Subprograms --
 135    -----------------------
 136
 137    function To_Task_ID is new Unchecked_Conversion (System.Address, Task_ID);
 138
 139    function To_Address is new Unchecked_Conversion (Task_ID, System.Address);
 140
 141    procedure Abort_Handler (Sig : Signal);
 142
 143    -------------------
 144    -- Abort_Handler --
 145    -------------------
 146
 147    procedure Abort_Handler (Sig : Signal) is
 148       T       : Task_ID := Self;
 149       Result  : Interfaces.C.int;
 150       Old_Set : aliased sigset_t;
 151
 152    begin
 153       if T.Deferral_Level = 0
 154         and then T.Pending_ATC_Level < T.ATC_Nesting_Level
 155       then
 156          --  Make sure signals used for RTS internal purpose are unmasked
 157
 158          Result := pthread_sigmask
 159            (SIG_UNBLOCK,
 160             Unblocked_Signal_Mask'Unchecked_Access,
 161             Old_Set'Unchecked_Access);
 162          pragma Assert (Result = 0);
 163
 164          raise Standard'Abort_Signal;
 165       end if;
 166    end Abort_Handler;
 167
 168    -----------------
 169    -- Stack_Guard --
 170    -----------------
 171
 172    --  The underlying thread system sets a guard page at the
 173    --  bottom of a thread stack, so nothing is needed.
 174
 175    procedure Stack_Guard (T : ST.Task_ID; On : Boolean) is
 176    begin
 177       null;
 178    end Stack_Guard;
 179
 180    -------------------
 181    -- Get_Thread_Id --
 182    -------------------
 183
 184    function Get_Thread_Id (T : ST.Task_ID) return OSI.Thread_Id is
 185    begin
 186       return T.Common.LL.Thread;
 187    end Get_Thread_Id;
 188
 189    ----------
 190    -- Self --
 191    ----------
 192
 193    function Self return Task_ID is
 194       Result : System.Address;
 195
 196    begin
 197       Result := pthread_getspecific (ATCB_Key);
 198       pragma Assert (Result /= System.Null_Address);
 199
 200       return To_Task_ID (Result);
 201    end Self;
 202
 203    ---------------------
 204    -- Initialize_Lock --
 205    ---------------------
 206
 207    --  Note: mutexes and cond_variables needed per-task basis are
 208    --        initialized in Initialize_TCB and the Storage_Error is
 209    --        handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 210    --        used in RTS is initialized before any status change of RTS.
 211    --        Therefore rasing Storage_Error in the following routines
 212    --        should be able to be handled safely.
 213
 214    procedure Initialize_Lock
 215      (Prio : System.Any_Priority;
 216       L    : access Lock)
 217    is
 218       Attributes : aliased pthread_mutexattr_t;
 219       Result     : Interfaces.C.int;
 220
 221    begin
 222       Result := pthread_mutexattr_init (Attributes'Access);
 223       pragma Assert (Result = 0 or else Result = ENOMEM);
 224
 225       if Result = ENOMEM then
 226          raise Storage_Error;
 227       end if;
 228
 229       if Locking_Policy = 'C' then
 230          Result := pthread_mutexattr_setprotocol
 231            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 232          pragma Assert (Result = 0);
 233
 234          Result := pthread_mutexattr_setprioceiling
 235             (Attributes'Access, Interfaces.C.int (Prio));
 236          pragma Assert (Result = 0);
 237       end if;
 238
 239       Result := pthread_mutex_init (L, Attributes'Access);
 240       pragma Assert (Result = 0 or else Result = ENOMEM);
 241
 242       if Result = ENOMEM then
 243          Result := pthread_mutexattr_destroy (Attributes'Access);
 244          raise Storage_Error;
 245       end if;
 246
 247       Result := pthread_mutexattr_destroy (Attributes'Access);
 248       pragma Assert (Result = 0);
 249    end Initialize_Lock;
 250
 251    procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
 252       Attributes : aliased pthread_mutexattr_t;
 253       Result : Interfaces.C.int;
 254
 255    begin
 256       Result := pthread_mutexattr_init (Attributes'Access);
 257       pragma Assert (Result = 0 or else Result = ENOMEM);
 258
 259       if Result = ENOMEM then
 260          raise Storage_Error;
 261       end if;
 262
 263       if Locking_Policy = 'C' then
 264          Result := pthread_mutexattr_setprotocol
 265            (Attributes'Access, PTHREAD_PRIO_PROTECT);
 266          pragma Assert (Result = 0);
 267
 268          Result := pthread_mutexattr_setprioceiling
 269             (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));
 270          pragma Assert (Result = 0);
 271       end if;
 272
 273       Result := pthread_mutex_init (L, Attributes'Access);
 274
 275       pragma Assert (Result = 0 or else Result = ENOMEM);
 276
 277       if Result = ENOMEM then
 278          Result := pthread_mutexattr_destroy (Attributes'Access);
 279          raise Storage_Error;
 280       end if;
 281
 282       Result := pthread_mutexattr_destroy (Attributes'Access);
 283    end Initialize_Lock;
 284
 285    -------------------
 286    -- Finalize_Lock --
 287    -------------------
 288
 289    procedure Finalize_Lock (L : access Lock) is
 290       Result : Interfaces.C.int;
 291
 292    begin
 293       Result := pthread_mutex_destroy (L);
 294       pragma Assert (Result = 0);
 295    end Finalize_Lock;
 296
 297    procedure Finalize_Lock (L : access RTS_Lock) is
 298       Result : Interfaces.C.int;
 299
 300    begin
 301       Result := pthread_mutex_destroy (L);
 302       pragma Assert (Result = 0);
 303    end Finalize_Lock;
 304
 305    ----------------
 306    -- Write_Lock --
 307    ----------------
 308
 309    procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 310       Result : Interfaces.C.int;
 311    begin
 312       Result := pthread_mutex_lock (L);
 313       Ceiling_Violation := Result = EINVAL;
 314
 315       --  assumes the cause of EINVAL is a priority ceiling violation
 316
 317       pragma Assert (Result = 0 or else Result = EINVAL);
 318    end Write_Lock;
 319
 320    procedure Write_Lock
 321      (L : access RTS_Lock; Global_Lock : Boolean := False)
 322    is
 323       Result : Interfaces.C.int;
 324    begin
 325       if not Single_Lock or else Global_Lock then
 326          Result := pthread_mutex_lock (L);
 327          pragma Assert (Result = 0);
 328       end if;
 329    end Write_Lock;
 330
 331    procedure Write_Lock (T : Task_ID) is
 332       Result : Interfaces.C.int;
 333    begin
 334       if not Single_Lock then
 335          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 336          pragma Assert (Result = 0);
 337       end if;
 338    end Write_Lock;
 339
 340    ---------------
 341    -- Read_Lock --
 342    ---------------
 343
 344    procedure Read_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 345    begin
 346       Write_Lock (L, Ceiling_Violation);
 347    end Read_Lock;
 348
 349    ------------
 350    -- Unlock --
 351    ------------
 352
 353    procedure Unlock (L : access Lock) is
 354       Result : Interfaces.C.int;
 355    begin
 356       Result := pthread_mutex_unlock (L);
 357       pragma Assert (Result = 0);
 358    end Unlock;
 359
 360    procedure Unlock (L : access RTS_Lock; Global_Lock : Boolean := False) is
 361       Result : Interfaces.C.int;
 362    begin
 363       if not Single_Lock or else Global_Lock then
 364          Result := pthread_mutex_unlock (L);
 365          pragma Assert (Result = 0);
 366       end if;
 367    end Unlock;
 368
 369    procedure Unlock (T : Task_ID) is
 370       Result : Interfaces.C.int;
 371    begin
 372       if not Single_Lock then
 373          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 374          pragma Assert (Result = 0);
 375       end if;
 376    end Unlock;
 377
 378    -----------
 379    -- Sleep --
 380    -----------
 381
 382    procedure Sleep
 383      (Self_ID : ST.Task_ID;
 384       Reason  : System.Tasking.Task_States)
 385    is
 386       Result : Interfaces.C.int;
 387    begin
 388       if Single_Lock then
 389          Result := pthread_cond_wait
 390            (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 391       else
 392          Result := pthread_cond_wait
 393            (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 394       end if;
 395
 396       --  EINTR is not considered a failure.
 397
 398       pragma Assert (Result = 0 or else Result = EINTR);
 399    end Sleep;
 400
 401    -----------------
 402    -- Timed_Sleep --
 403    -----------------
 404
 405    procedure Timed_Sleep
 406      (Self_ID  : Task_ID;
 407       Time     : Duration;
 408       Mode     : ST.Delay_Modes;
 409       Reason   : Task_States;
 410       Timedout : out Boolean;
 411       Yielded  : out Boolean)
 412    is
 413       Check_Time : constant Duration := Monotonic_Clock;
 414       Abs_Time   : Duration;
 415       Request    : aliased timespec;
 416       Result     : Interfaces.C.int;
 417
 418    begin
 419       Timedout := True;
 420       Yielded  := False;
 421
 422       if Mode = Relative then
 423          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 424       else
 425          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 426       end if;
 427
 428       if Abs_Time > Check_Time then
 429          Request := To_Timespec (Abs_Time);
 430
 431          loop
 432             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 433               or else Self_ID.Pending_Priority_Change;
 434
 435             if Single_Lock then
 436                Result := pthread_cond_timedwait
 437                  (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access,
 438                   Request'Access);
 439
 440             else
 441                Result := pthread_cond_timedwait
 442                  (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access,
 443                   Request'Access);
 444             end if;
 445
 446             exit when Abs_Time <= Monotonic_Clock;
 447
 448             if Result = 0 or else errno = EINTR then
 449                Timedout := False;
 450                exit;
 451             end if;
 452          end loop;
 453       end if;
 454    end Timed_Sleep;
 455
 456    -----------------
 457    -- Timed_Delay --
 458    -----------------
 459
 460    --  This is for use in implementing delay statements, so
 461    --  we assume the caller is abort-deferred but is holding
 462    --  no locks.
 463
 464    procedure Timed_Delay
 465      (Self_ID : Task_ID;
 466       Time    : Duration;
 467       Mode    : ST.Delay_Modes)
 468    is
 469       Check_Time : constant Duration := Monotonic_Clock;
 470       Abs_Time   : Duration;
 471       Request    : aliased timespec;
 472       Result     : Interfaces.C.int;
 473
 474    begin
 475       --  Only the little window between deferring abort and
 476       --  locking Self_ID is the reason we need to
 477       --  check for pending abort and priority change below! :(
 478
 479       SSL.Abort_Defer.all;
 480
 481       if Single_Lock then
 482          Lock_RTS;
 483       end if;
 484
 485       Write_Lock (Self_ID);
 486
 487       if Mode = Relative then
 488          Abs_Time := Time + Check_Time;
 489       else
 490          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 491       end if;
 492
 493       if Abs_Time > Check_Time then
 494          Request := To_Timespec (Abs_Time);
 495          Self_ID.Common.State := Delay_Sleep;
 496
 497          loop
 498             if Self_ID.Pending_Priority_Change then
 499                Self_ID.Pending_Priority_Change := False;
 500                Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority;
 501                Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
 502             end if;
 503
 504             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 505
 506             Result := pthread_cond_timedwait (Self_ID.Common.LL.CV'Access,
 507               Self_ID.Common.LL.L'Access, Request'Access);
 508             exit when Abs_Time <= Monotonic_Clock;
 509
 510             pragma Assert (Result = 0
 511               or else Result = ETIMEDOUT
 512               or else Result = EINTR);
 513          end loop;
 514
 515          Self_ID.Common.State := Runnable;
 516       end if;
 517
 518       Unlock (Self_ID);
 519
 520       if Single_Lock then
 521          Unlock_RTS;
 522       end if;
 523
 524       Yield;
 525       SSL.Abort_Undefer.all;
 526    end Timed_Delay;
 527
 528    ---------------------
 529    -- Monotonic_Clock --
 530    ---------------------
 531
 532    function Monotonic_Clock return Duration is
 533       TS     : aliased timespec;
 534       Result : Interfaces.C.int;
 535
 536    begin
 537       Result := clock_gettime (Real_Time_Clock_Id, TS'Unchecked_Access);
 538       pragma Assert (Result = 0);
 539       return To_Duration (TS);
 540    end Monotonic_Clock;
 541
 542    -------------------
 543    -- RT_Resolution --
 544    -------------------
 545
 546    function RT_Resolution return Duration is
 547    begin
 548       --  The clock_getres (Real_Time_Clock_Id) function appears to return
 549       --  the interrupt resolution of the realtime clock and not the actual
 550       --  resolution of reading the clock. Even though this last value is
 551       --  only guaranteed to be 100 Hz, at least the Origin 200 appears to
 552       --  have a microsecond resolution or better.
 553       --  ??? We should figure out a method to return the right value on
 554       --  all SGI hardware.
 555
 556       return 0.000_001; --  Assume microsecond resolution of clock
 557    end RT_Resolution;
 558
 559    ------------
 560    -- Wakeup --
 561    ------------
 562
 563    procedure Wakeup (T : ST.Task_ID; Reason : System.Tasking.Task_States) is
 564       Result : Interfaces.C.int;
 565    begin
 566       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 567       pragma Assert (Result = 0);
 568    end Wakeup;
 569
 570    -----------
 571    -- Yield --
 572    -----------
 573
 574    procedure Yield (Do_Yield : Boolean := True) is
 575       Result : Interfaces.C.int;
 576    begin
 577       if Do_Yield then
 578          Result := sched_yield;
 579       end if;
 580    end Yield;
 581
 582    ------------------
 583    -- Set_Priority --
 584    ------------------
 585
 586    procedure Set_Priority
 587      (T                   : Task_ID;
 588       Prio                : System.Any_Priority;
 589       Loss_Of_Inheritance : Boolean := False)
 590    is
 591       Result       : Interfaces.C.int;
 592       Param        : aliased struct_sched_param;
 593       Sched_Policy : Interfaces.C.int;
 594
 595       use type System.Task_Info.Task_Info_Type;
 596
 597       function To_Int is new Unchecked_Conversion
 598         (System.Task_Info.Thread_Scheduling_Policy, Interfaces.C.int);
 599
 600    begin
 601       T.Common.Current_Priority := Prio;
 602       Param.sched_priority := Interfaces.C.int (Prio);
 603
 604       if T.Common.Task_Info /= null then
 605          Sched_Policy := To_Int (T.Common.Task_Info.Policy);
 606       else
 607          Sched_Policy := SCHED_FIFO;
 608       end if;
 609
 610       Result := pthread_setschedparam (T.Common.LL.Thread, Sched_Policy,
 611         Param'Access);
 612       pragma Assert (Result = 0);
 613    end Set_Priority;
 614
 615    ------------------
 616    -- Get_Priority --
 617    ------------------
 618
 619    function Get_Priority (T : Task_ID) return System.Any_Priority is
 620    begin
 621       return T.Common.Current_Priority;
 622    end Get_Priority;
 623
 624    ----------------
 625    -- Enter_Task --
 626    ----------------
 627
 628    procedure Enter_Task (Self_ID : Task_ID) is
 629       Result : Interfaces.C.int;
 630
 631       function To_Int is new Unchecked_Conversion
 632         (System.Task_Info.CPU_Number, Interfaces.C.int);
 633
 634       use System.Task_Info;
 635
 636    begin
 637       Self_ID.Common.LL.Thread := pthread_self;
 638       Result := pthread_setspecific (ATCB_Key, To_Address (Self_ID));
 639       pragma Assert (Result = 0);
 640
 641       if Self_ID.Common.Task_Info /= null
 642         and then Self_ID.Common.Task_Info.Scope = PTHREAD_SCOPE_SYSTEM
 643         and then Self_ID.Common.Task_Info.Runon_CPU /= ANY_CPU
 644       then
 645          Result := pthread_setrunon_np
 646            (To_Int (Self_ID.Common.Task_Info.Runon_CPU));
 647          pragma Assert (Result = 0);
 648       end if;
 649
 650       Lock_RTS;
 651
 652       for J in Known_Tasks'Range loop
 653          if Known_Tasks (J) = null then
 654             Known_Tasks (J) := Self_ID;
 655             Self_ID.Known_Tasks_Index := J;
 656             exit;
 657          end if;
 658       end loop;
 659
 660       Unlock_RTS;
 661    end Enter_Task;
 662
 663    --------------
 664    -- New_ATCB --
 665    --------------
 666
 667    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_ID is
 668    begin
 669       return new Ada_Task_Control_Block (Entry_Num);
 670    end New_ATCB;
 671
 672    --------------------
 673    -- Initialize_TCB --
 674    --------------------
 675
 676    procedure Initialize_TCB (Self_ID : Task_ID; Succeeded : out Boolean) is
 677       Result    : Interfaces.C.int;
 678       Cond_Attr : aliased pthread_condattr_t;
 679
 680    begin
 681       if not Single_Lock then
 682          Initialize_Lock (Self_ID.Common.LL.L'Access, ATCB_Level);
 683       end if;
 684
 685       Result := pthread_condattr_init (Cond_Attr'Access);
 686       pragma Assert (Result = 0 or else Result = ENOMEM);
 687
 688       if Result = 0 then
 689          Result := pthread_cond_init (Self_ID.Common.LL.CV'Access,
 690            Cond_Attr'Access);
 691          pragma Assert (Result = 0 or else Result = ENOMEM);
 692       end if;
 693
 694       if Result = 0 then
 695          Succeeded := True;
 696       else
 697          if not Single_Lock then
 698             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 699             pragma Assert (Result = 0);
 700          end if;
 701
 702          Succeeded := False;
 703       end if;
 704
 705       Result := pthread_condattr_destroy (Cond_Attr'Access);
 706       pragma Assert (Result = 0);
 707    end Initialize_TCB;
 708
 709    -----------------
 710    -- Create_Task --
 711    -----------------
 712
 713    procedure Create_Task
 714      (T          : Task_ID;
 715       Wrapper    : System.Address;
 716       Stack_Size : System.Parameters.Size_Type;
 717       Priority   : System.Any_Priority;
 718       Succeeded  : out Boolean)
 719    is
 720       use System.Task_Info;
 721
 722       Attributes          : aliased pthread_attr_t;
 723       Sched_Param         : aliased struct_sched_param;
 724       Adjusted_Stack_Size : Interfaces.C.size_t;
 725       Result              : Interfaces.C.int;
 726
 727       function Thread_Body_Access is new
 728         Unchecked_Conversion (System.Address, Thread_Body);
 729
 730       function To_Int is new Unchecked_Conversion
 731         (System.Task_Info.Thread_Scheduling_Scope, Interfaces.C.int);
 732       function To_Int is new Unchecked_Conversion
 733         (System.Task_Info.Thread_Scheduling_Inheritance, Interfaces.C.int);
 734       function To_Int is new Unchecked_Conversion
 735         (System.Task_Info.Thread_Scheduling_Policy, Interfaces.C.int);
 736
 737    begin
 738       if Stack_Size = System.Parameters.Unspecified_Size then
 739          Adjusted_Stack_Size :=
 740            Interfaces.C.size_t (System.Program_Info.Default_Task_Stack);
 741
 742       elsif Stack_Size < Size_Type (Minimum_Stack_Size) then
 743          Adjusted_Stack_Size :=
 744            Interfaces.C.size_t (Minimum_Stack_Size);
 745
 746       else
 747          Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size);
 748       end if;
 749
 750       Result := pthread_attr_init (Attributes'Access);
 751       pragma Assert (Result = 0 or else Result = ENOMEM);
 752
 753       if Result /= 0 then
 754          Succeeded := False;
 755          return;
 756       end if;
 757
 758       Result := pthread_attr_setdetachstate
 759         (Attributes'Access, PTHREAD_CREATE_DETACHED);
 760       pragma Assert (Result = 0);
 761
 762       Result := pthread_attr_setstacksize
 763         (Attributes'Access, Interfaces.C.size_t (Adjusted_Stack_Size));
 764       pragma Assert (Result = 0);
 765
 766       if T.Common.Task_Info /= null then
 767          Result := pthread_attr_setscope
 768            (Attributes'Access, To_Int (T.Common.Task_Info.Scope));
 769          pragma Assert (Result = 0);
 770
 771          Result := pthread_attr_setinheritsched
 772            (Attributes'Access, To_Int (T.Common.Task_Info.Inheritance));
 773          pragma Assert (Result = 0);
 774
 775          Result := pthread_attr_setschedpolicy
 776            (Attributes'Access, To_Int (T.Common.Task_Info.Policy));
 777          pragma Assert (Result = 0);
 778
 779          Sched_Param.sched_priority :=
 780            Interfaces.C.int (T.Common.Task_Info.Priority);
 781
 782          Result := pthread_attr_setschedparam
 783            (Attributes'Access, Sched_Param'Access);
 784          pragma Assert (Result = 0);
 785       end if;
 786
 787       --  Since the initial signal mask of a thread is inherited from the
 788       --  creator, and the Environment task has all its signals masked, we
 789       --  do not need to manipulate caller's signal mask at this point.
 790       --  All tasks in RTS will have All_Tasks_Mask initially.
 791
 792       Result := pthread_create
 793         (T.Common.LL.Thread'Access,
 794          Attributes'Access,
 795          Thread_Body_Access (Wrapper),
 796          To_Address (T));
 797
 798       if Result /= 0
 799         and then T.Common.Task_Info /= null
 800         and then T.Common.Task_Info.Scope = PTHREAD_SCOPE_SYSTEM
 801       then
 802          --  The pthread_create call may have failed because we
 803          --  asked for a system scope pthread and none were
 804          --  available (probably because the program was not executed
 805          --  by the superuser). Let's try for a process scope pthread
 806          --  instead of raising Tasking_Error.
 807
 808          System.IO.Put_Line
 809            ("Request for PTHREAD_SCOPE_SYSTEM in Task_Info pragma for task");
 810          System.IO.Put ("""");
 811          System.IO.Put (T.Common.Task_Image.all);
 812          System.IO.Put_Line (""" could not be honored. ");
 813          System.IO.Put_Line ("Scope changed to PTHREAD_SCOPE_PROCESS");
 814
 815          T.Common.Task_Info.Scope := PTHREAD_SCOPE_PROCESS;
 816          Result := pthread_attr_setscope
 817            (Attributes'Access, To_Int (T.Common.Task_Info.Scope));
 818          pragma Assert (Result = 0);
 819
 820          Result := pthread_create
 821            (T.Common.LL.Thread'Access,
 822             Attributes'Access,
 823             Thread_Body_Access (Wrapper),
 824             To_Address (T));
 825       end if;
 826
 827       pragma Assert (Result = 0 or else Result = EAGAIN);
 828
 829       Succeeded := Result = 0;
 830
 831       Set_Priority (T, Priority);
 832
 833       Result := pthread_attr_destroy (Attributes'Access);
 834       pragma Assert (Result = 0);
 835    end Create_Task;
 836
 837    ------------------
 838    -- Finalize_TCB --
 839    ------------------
 840
 841    procedure Finalize_TCB (T : Task_ID) is
 842       Result : Interfaces.C.int;
 843       Tmp    : Task_ID := T;
 844
 845       procedure Free is new
 846         Unchecked_Deallocation (Ada_Task_Control_Block, Task_ID);
 847
 848    begin
 849       if not Single_Lock then
 850          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
 851          pragma Assert (Result = 0);
 852       end if;
 853
 854       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
 855       pragma Assert (Result = 0);
 856
 857       if T.Known_Tasks_Index /= -1 then
 858          Known_Tasks (T.Known_Tasks_Index) := null;
 859       end if;
 860
 861       Free (Tmp);
 862    end Finalize_TCB;
 863
 864    ---------------
 865    -- Exit_Task --
 866    ---------------
 867
 868    procedure Exit_Task is
 869    begin
 870       pthread_exit (System.Null_Address);
 871    end Exit_Task;
 872
 873    ----------------
 874    -- Abort_Task --
 875    ----------------
 876
 877    procedure Abort_Task (T : Task_ID) is
 878       Result : Interfaces.C.int;
 879    begin
 880       Result := pthread_kill (T.Common.LL.Thread,
 881         Signal (System.Interrupt_Management.Abort_Task_Interrupt));
 882       pragma Assert (Result = 0);
 883    end Abort_Task;
 884
 885    ----------------
 886    -- Check_Exit --
 887    ----------------
 888
 889    --  Dummy versions. The only currently working versions is for solaris
 890    --  (native).
 891
 892    function Check_Exit (Self_ID : ST.Task_ID) return Boolean is
 893    begin
 894       return True;
 895    end Check_Exit;
 896
 897    --------------------
 898    -- Check_No_Locks --
 899    --------------------
 900
 901    function Check_No_Locks (Self_ID : ST.Task_ID) return Boolean is
 902    begin
 903       return True;
 904    end Check_No_Locks;
 905
 906    ----------------------
 907    -- Environment_Task --
 908    ----------------------
 909
 910    function Environment_Task return Task_ID is
 911    begin
 912       return Environment_Task_ID;
 913    end Environment_Task;
 914
 915    --------------
 916    -- Lock_RTS --
 917    --------------
 918
 919    procedure Lock_RTS is
 920    begin
 921       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
 922    end Lock_RTS;
 923
 924    ----------------
 925    -- Unlock_RTS --
 926    ----------------
 927
 928    procedure Unlock_RTS is
 929    begin
 930       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
 931    end Unlock_RTS;
 932
 933    ------------------
 934    -- Suspend_Task --
 935    ------------------
 936
 937    function Suspend_Task
 938      (T           : ST.Task_ID;
 939       Thread_Self : Thread_Id) return Boolean is
 940    begin
 941       return False;
 942    end Suspend_Task;
 943
 944    -----------------
 945    -- Resume_Task --
 946    -----------------
 947
 948    function Resume_Task
 949      (T           : ST.Task_ID;
 950       Thread_Self : Thread_Id) return Boolean is
 951    begin
 952       return False;
 953    end Resume_Task;
 954
 955    ----------------
 956    -- Initialize --
 957    ----------------
 958
 959    procedure Initialize (Environment_Task : Task_ID) is
 960       act     : aliased struct_sigaction;
 961       old_act : aliased struct_sigaction;
 962       Tmp_Set : aliased sigset_t;
 963       Result  : Interfaces.C.int;
 964
 965    begin
 966       Environment_Task_ID := Environment_Task;
 967
 968       --  Initialize the lock used to synchronize chain of all ATCBs.
 969       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
 970
 971       Enter_Task (Environment_Task);
 972
 973       --  Install the abort-signal handler
 974
 975       act.sa_flags := 0;
 976       act.sa_handler := Abort_Handler'Address;
 977
 978       Result := sigemptyset (Tmp_Set'Access);
 979       pragma Assert (Result = 0);
 980       act.sa_mask := Tmp_Set;
 981
 982       Result :=
 983         sigaction (
 984           Signal (System.Interrupt_Management.Abort_Task_Interrupt),
 985           act'Unchecked_Access,
 986           old_act'Unchecked_Access);
 987       pragma Assert (Result = 0);
 988    end Initialize;
 989
 990 begin
 991    declare
 992       Result : Interfaces.C.int;
 993    begin
 994       --  Mask Environment task for all signals. The original mask of the
 995       --  Environment task will be recovered by Interrupt_Server task
 996       --  during the elaboration of s-interr.adb.
 997
 998       System.Interrupt_Management.Operations.Set_Interrupt_Mask
 999         (System.Interrupt_Management.Operations.All_Tasks_Mask'Access);
1000
1001       --  Prepare the set of signals that should unblocked in all tasks
1002
1003       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1004       pragma Assert (Result = 0);
1005
1006       for J in Interrupt_Management.Interrupt_ID loop
1007          if System.Interrupt_Management.Keep_Unmasked (J) then
1008             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1009             pragma Assert (Result = 0);
1010          end if;
1011       end loop;
1012
1013       Result := pthread_key_create (ATCB_Key'Access, null);
1014       pragma Assert (Result = 0);
1015
1016       --  Pick the highest resolution Clock for Clock_Realtime
1017       --  ??? This code currently doesn't work (see c94007[ab] for example)
1018       --
1019       --  if syssgi (SGI_CYCLECNTR_SIZE) = 64 then
1020       --     Real_Time_Clock_Id := CLOCK_SGI_CYCLE;
1021       --  else
1022       --     Real_Time_Clock_Id := CLOCK_REALTIME;
1023       --  end if;
1024    end;
1025 end System.Task_Primitives.Operations;