--- old/usr/src/lib/libc/i386/fp/fpstart.c
          +++ new/usr/src/lib/libc/i386/fp/fpstart.c

   1    1  /*
   2    2   * CDDL HEADER START
   3    3   *
   4    4   * The contents of this file are subject to the terms of the
   5    5   * Common Development and Distribution License (the "License").
   6    6   * You may not use this file except in compliance with the License.
   7    7   *
   8    8   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9    9   * or http://www.opensolaris.org/os/licensing.
  10   10   * See the License for the specific language governing permissions
  11   11   * and limitations under the License.
  12   12   *
  13   13   * When distributing Covered Code, include this CDDL HEADER in each
  14   14   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15   15   * If applicable, add the following below this CDDL HEADER, with the
  16   16   * fields enclosed by brackets "[]" replaced with your own identifying
  17   17   * information: Portions Copyright [yyyy] [name of copyright owner]
  18   18   *
  19   19   * CDDL HEADER END
  20   20   */
  21   21  
  22   22  /*
  23   23   * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24   24   * Use is subject to license terms.
  25   25   */
  26   26  
  27   27  /*
  28   28   *      Copyright (c) 1990, 1991 UNIX System Laboratories, Inc.
  29   29   *      Copyright (c) 1988 AT&T
  30   30   *        All Rights Reserved
  31   31   */
  32   32  
  33   33  /*
  34   34   * Copyright 2023 Oxide Computer Company
  35   35   */
  36   36  
  37   37  /*
  38   38   * Establish the default settings for the floating-point state for a C language
  39   39   * program:
  40   40   *      rounding mode           -- round to nearest default by OS,
  41   41   *      exceptions enabled      -- all masked
  42   42   *      sticky bits             -- all clear by default by OS.
  43   43   *      precision control       -- double extended
  44   44   * Set _fp_hw according to what floating-point hardware is available.
  45   45   * Set _sse_hw according to what SSE hardware is available.
  46   46   * Set __flt_rounds according to the rounding mode.
  47   47   */
  48   48  
  49   49  #pragma weak _fpstart = __fpstart
  50   50  
  51   51  #include        "lint.h"
  52   52  #include        <sys/types.h>
  53   53  #include        <sys/sysi86.h>  /* for SI86FPHW/SI86FPSTART definitions */
  54   54  #include        <sys/fp.h>      /* for FPU_CW_INIT and SSE_MXCSR_INIT */
  55   55  #include        <upanic.h>
  56   56  
  57   57  extern int      __fltrounds();
  58   58  
  59   59  int     _fp_hw;                 /* default: bss: 0 == no hardware */
  60   60  int     _sse_hw;                /* default: bss: 0 == no sse */
  61   61  int     __flt_rounds;           /* ANSI rounding mode */
  62   62  
  63   63  #define UPANIC_MSG      "32-bit FPU init failed!"
  64   64  
  65   65  void
  66   66  __fpstart()
  67   67  {
  68   68          /*
  69   69           * query OS for HW status and ensure the x87 and (optional)
  70   70           * SSE control words are (will be) set correctly.
  71   71           */
  72   72          if ((_sse_hw = sysi86(SI86FPSTART,
  73   73              &_fp_hw, FPU_CW_INIT, SSE_MXCSR_INIT)) == -1) {
  74   74                  /*
  75   75                   * Because the system only supports a 64-bit kernel, the above
  76   76                   * should always work (we assume it does in 64-bit libc). If it
  77   77                   * should fail, we upanic. Note, because the FPU state is
  78   78                   * unknown, we use a static message below and don't rely upon
  79   79                   * strlen(), but rather constant time lengths.
  80   80                   */
  81   81                  upanic(UPANIC_MSG, sizeof (UPANIC_MSG));
  82   82          }
  83   83  
  84   84          /*
  85   85           * At this point the x87 fp environment that has been (or more
  86   86           * hopefully, will be) established by the kernel is:
  87   87           *
  88   88           * affine infinity      0x1000
  89   89           * round to nearest     0x0000
  90   90           * 64-bit doubles       0x0300
  91   91           * precision, underflow, overflow, zero-divide, denorm, invalid masked
  92   92           *                      0x003f
  93   93           *
  94   94           * which conforms to the 4th edition i386 ABI definition.
  95   95           *
  96   96           * Additionally, if we have SSE hardware, we've also masked all
  97   97           * the same traps, and have round to nearest.
  98   98           */
  99   99  
 100  100          __flt_rounds = 1;       /* ANSI way of saying round-to-nearest */
 101  101  }

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