gdb/osabi.c

   1 /* OS ABI variant handling for GDB.
   2
   3    Copyright (C) 2001, 2002, 2003, 2004, 2007, 2008, 2009
   4    Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22
  23 #include "gdb_assert.h"
  24 #include "gdb_string.h"
  25
  26 #include "osabi.h"
  27 #include "arch-utils.h"
  28 #include "gdbcmd.h"
  29 #include "command.h"
  30
  31 #include "elf-bfd.h"
  32
  33 #ifndef GDB_OSABI_DEFAULT
  34 #define GDB_OSABI_DEFAULT GDB_OSABI_UNKNOWN
  35 #endif
  36
  37 /* State for the "set osabi" command.  */
  38 static enum { osabi_auto, osabi_default, osabi_user } user_osabi_state;
  39 static enum gdb_osabi user_selected_osabi;
  40 static const char *gdb_osabi_available_names[GDB_OSABI_INVALID + 3] = {
  41   "auto",
  42   "default",
  43   "none",
  44   NULL
  45 };
  46 static const char *set_osabi_string;
  47
  48 /* This table matches the indices assigned to enum gdb_osabi.  Keep
  49    them in sync.  */
  50 static const char * const gdb_osabi_names[] =
  51 {
  52   "none",
  53
  54   "SVR4",
  55   "GNU/Hurd",
  56   "Solaris",
  57   "OSF/1",
  58   "GNU/Linux",
  59   "FreeBSD a.out",
  60   "FreeBSD ELF",
  61   "NetBSD a.out",
  62   "NetBSD ELF",
  63   "OpenBSD ELF",
  64   "Windows CE",
  65   "DJGPP",
  66   "Irix",
  67   "Interix",
  68   "HP/UX ELF",
  69   "HP/UX SOM",
  70
  71   "QNX Neutrino",
  72
  73   "Cygwin",
  74   "AIX",
  75   "DICOS",
  76   "Darwin",
  77
  78   "<invalid>"
  79 };
  80
  81 const char *
  82 gdbarch_osabi_name (enum gdb_osabi osabi)
  83 {
  84   if (osabi >= GDB_OSABI_UNKNOWN && osabi < GDB_OSABI_INVALID)
  85     return gdb_osabi_names[osabi];
  86
  87   return gdb_osabi_names[GDB_OSABI_INVALID];
  88 }
  89
  90 /* Lookup the OS ABI corresponding to the specified target description
  91    string.  */
  92
  93 enum gdb_osabi
  94 osabi_from_tdesc_string (const char *name)
  95 {
  96   int i;
  97
  98   for (i = 0; i < ARRAY_SIZE (gdb_osabi_names); i++)
  99     if (strcmp (name, gdb_osabi_names[i]) == 0)
 100       {
 101         /* See note above: the name table matches the indices assigned
 102            to enum gdb_osabi.  */
 103         enum gdb_osabi osabi = (enum gdb_osabi) i;
 104
 105         if (osabi == GDB_OSABI_INVALID)
 106           return GDB_OSABI_UNKNOWN;
 107         else
 108           return osabi;
 109       }
 110
 111   return GDB_OSABI_UNKNOWN;
 112 }
 113
 114 /* Handler for a given architecture/OS ABI pair.  There should be only
 115    one handler for a given OS ABI each architecture family.  */
 116 struct gdb_osabi_handler
 117 {
 118   struct gdb_osabi_handler *next;
 119   const struct bfd_arch_info *arch_info;
 120   enum gdb_osabi osabi;
 121   void (*init_osabi)(struct gdbarch_info, struct gdbarch *);
 122 };
 123
 124 static struct gdb_osabi_handler *gdb_osabi_handler_list;
 125
 126 void
 127 gdbarch_register_osabi (enum bfd_architecture arch, unsigned long machine,
 128                         enum gdb_osabi osabi,
 129                         void (*init_osabi)(struct gdbarch_info,
 130                                            struct gdbarch *))
 131 {
 132   struct gdb_osabi_handler **handler_p;
 133   const struct bfd_arch_info *arch_info = bfd_lookup_arch (arch, machine);
 134   const char **name_ptr;
 135
 136   /* Registering an OS ABI handler for "unknown" is not allowed.  */
 137   if (osabi == GDB_OSABI_UNKNOWN)
 138     {
 139       internal_error
 140         (__FILE__, __LINE__,
 141          _("gdbarch_register_osabi: An attempt to register a handler for "
 142          "OS ABI \"%s\" for architecture %s was made.  The handler will "
 143          "not be registered"),
 144          gdbarch_osabi_name (osabi),
 145          bfd_printable_arch_mach (arch, machine));
 146       return;
 147     }
 148
 149   gdb_assert (arch_info);
 150
 151   for (handler_p = &gdb_osabi_handler_list; *handler_p != NULL;
 152        handler_p = &(*handler_p)->next)
 153     {
 154       if ((*handler_p)->arch_info == arch_info
 155           && (*handler_p)->osabi == osabi)
 156         {
 157           internal_error
 158             (__FILE__, __LINE__,
 159              _("gdbarch_register_osabi: A handler for OS ABI \"%s\" "
 160              "has already been registered for architecture %s"),
 161              gdbarch_osabi_name (osabi),
 162              arch_info->printable_name);
 163           /* If user wants to continue, override previous definition.  */
 164           (*handler_p)->init_osabi = init_osabi;
 165           return;
 166         }
 167     }
 168
 169   (*handler_p)
 170     = (struct gdb_osabi_handler *) xmalloc (sizeof (struct gdb_osabi_handler));
 171   (*handler_p)->next = NULL;
 172   (*handler_p)->arch_info = arch_info;
 173   (*handler_p)->osabi = osabi;
 174   (*handler_p)->init_osabi = init_osabi;
 175
 176   /* Add this OS ABI to the list of enum values for "set osabi", if it isn't
 177      already there.  */
 178   for (name_ptr = gdb_osabi_available_names; *name_ptr; name_ptr ++)
 179     {
 180       if (*name_ptr == gdbarch_osabi_name (osabi))
 181         return;
 182     }
 183   *name_ptr++ = gdbarch_osabi_name (osabi);
 184   *name_ptr = NULL;
 185 }
 186 \f
 187
 188 /* Sniffer to find the OS ABI for a given file's architecture and flavour.
 189    It is legal to have multiple sniffers for each arch/flavour pair, to
 190    disambiguate one OS's a.out from another, for example.  The first sniffer
 191    to return something other than GDB_OSABI_UNKNOWN wins, so a sniffer should
 192    be careful to claim a file only if it knows for sure what it is.  */
 193 struct gdb_osabi_sniffer
 194 {
 195   struct gdb_osabi_sniffer *next;
 196   enum bfd_architecture arch;   /* bfd_arch_unknown == wildcard */
 197   enum bfd_flavour flavour;
 198   enum gdb_osabi (*sniffer)(bfd *);
 199 };
 200
 201 static struct gdb_osabi_sniffer *gdb_osabi_sniffer_list;
 202
 203 void
 204 gdbarch_register_osabi_sniffer (enum bfd_architecture arch,
 205                                 enum bfd_flavour flavour,
 206                                 enum gdb_osabi (*sniffer_fn)(bfd *))
 207 {
 208   struct gdb_osabi_sniffer *sniffer;
 209
 210   sniffer =
 211     (struct gdb_osabi_sniffer *) xmalloc (sizeof (struct gdb_osabi_sniffer));
 212   sniffer->arch = arch;
 213   sniffer->flavour = flavour;
 214   sniffer->sniffer = sniffer_fn;
 215
 216   sniffer->next = gdb_osabi_sniffer_list;
 217   gdb_osabi_sniffer_list = sniffer;
 218 }
 219 \f
 220
 221 enum gdb_osabi
 222 gdbarch_lookup_osabi (bfd *abfd)
 223 {
 224   struct gdb_osabi_sniffer *sniffer;
 225   enum gdb_osabi osabi, match;
 226   int match_specific;
 227
 228   /* If we aren't in "auto" mode, return the specified OS ABI.  */
 229   if (user_osabi_state == osabi_user)
 230     return user_selected_osabi;
 231
 232   /* If we don't have a binary, just return unknown.  The caller may
 233      have other sources the OSABI can be extracted from, e.g., the
 234      target description.  */
 235   if (abfd == NULL)
 236     return GDB_OSABI_UNKNOWN;
 237
 238   match = GDB_OSABI_UNKNOWN;
 239   match_specific = 0;
 240
 241   for (sniffer = gdb_osabi_sniffer_list; sniffer != NULL;
 242        sniffer = sniffer->next)
 243     {
 244       if ((sniffer->arch == bfd_arch_unknown /* wildcard */
 245            || sniffer->arch == bfd_get_arch (abfd))
 246           && sniffer->flavour == bfd_get_flavour (abfd))
 247         {
 248           osabi = (*sniffer->sniffer) (abfd);
 249           if (osabi < GDB_OSABI_UNKNOWN || osabi >= GDB_OSABI_INVALID)
 250             {
 251               internal_error
 252                 (__FILE__, __LINE__,
 253                  _("gdbarch_lookup_osabi: invalid OS ABI (%d) from sniffer "
 254                  "for architecture %s flavour %d"),
 255                  (int) osabi,
 256                  bfd_printable_arch_mach (bfd_get_arch (abfd), 0),
 257                  (int) bfd_get_flavour (abfd));
 258             }
 259           else if (osabi != GDB_OSABI_UNKNOWN)
 260             {
 261               /* A specific sniffer always overrides a generic sniffer.
 262                  Croak on multiple match if the two matches are of the
 263                  same class.  If the user wishes to continue, we'll use
 264                  the first match.  */
 265               if (match != GDB_OSABI_UNKNOWN)
 266                 {
 267                   if ((match_specific && sniffer->arch != bfd_arch_unknown)
 268                    || (!match_specific && sniffer->arch == bfd_arch_unknown))
 269                     {
 270                       internal_error
 271                         (__FILE__, __LINE__,
 272                          _("gdbarch_lookup_osabi: multiple %sspecific OS ABI "
 273                          "match for architecture %s flavour %d: first "
 274                          "match \"%s\", second match \"%s\""),
 275                          match_specific ? "" : "non-",
 276                          bfd_printable_arch_mach (bfd_get_arch (abfd), 0),
 277                          (int) bfd_get_flavour (abfd),
 278                          gdbarch_osabi_name (match),
 279                          gdbarch_osabi_name (osabi));
 280                     }
 281                   else if (sniffer->arch != bfd_arch_unknown)
 282                     {
 283                       match = osabi;
 284                       match_specific = 1;
 285                     }
 286                 }
 287               else
 288                 {
 289                   match = osabi;
 290                   if (sniffer->arch != bfd_arch_unknown)
 291                     match_specific = 1;
 292                 }
 293             }
 294         }
 295     }
 296
 297   return match;
 298 }
 299
 300
 301 /* Return non-zero if architecture A can run code written for
 302    architecture B.  */
 303 static int
 304 can_run_code_for (const struct bfd_arch_info *a, const struct bfd_arch_info *b)
 305 {
 306   /* BFD's 'A->compatible (A, B)' functions return zero if A and B are
 307      incompatible.  But if they are compatible, it returns the 'more
 308      featureful' of the two arches.  That is, if A can run code
 309      written for B, but B can't run code written for A, then it'll
 310      return A.
 311
 312      struct bfd_arch_info objects are singletons: that is, there's
 313      supposed to be exactly one instance for a given machine.  So you
 314      can tell whether two are equivalent by comparing pointers.  */
 315   return (a == b || a->compatible (a, b) == a);
 316 }
 317
 318
 319 void
 320 gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
 321 {
 322   struct gdb_osabi_handler *handler;
 323
 324   if (info.osabi == GDB_OSABI_UNKNOWN)
 325     {
 326       /* Don't complain about an unknown OSABI.  Assume the user knows
 327          what they are doing.  */
 328       return;
 329     }
 330
 331   for (handler = gdb_osabi_handler_list; handler != NULL;
 332        handler = handler->next)
 333     {
 334       if (handler->osabi != info.osabi)
 335         continue;
 336
 337       /* If the architecture described by ARCH_INFO can run code for
 338          the architcture we registered the handler for, then the
 339          handler is applicable.  Note, though, that if the handler is
 340          for an architecture that is a superset of ARCH_INFO, we can't
 341          use that --- it would be perfectly correct for it to install
 342          gdbarch methods that refer to registers / instructions /
 343          other facilities ARCH_INFO doesn't have.
 344
 345          NOTE: kettenis/20021027: There may be more than one machine
 346          type that is compatible with the desired machine type.  Right
 347          now we simply return the first match, which is fine for now.
 348          However, we might want to do something smarter in the future.  */
 349       /* NOTE: cagney/2003-10-23: The code for "a can_run_code_for b"
 350          is implemented using BFD's compatible method (a->compatible
 351          (b) == a -- the lowest common denominator between a and b is
 352          a).  That method's definition of compatible may not be as you
 353          expect.  For instance the test "amd64 can run code for i386"
 354          (or more generally "64-bit ISA can run code for the 32-bit
 355          ISA").  BFD doesn't normally consider 32-bit and 64-bit
 356          "compatible" so it doesn't succeed.  */
 357       if (can_run_code_for (info.bfd_arch_info, handler->arch_info))
 358         {
 359           (*handler->init_osabi) (info, gdbarch);
 360           return;
 361         }
 362     }
 363
 364   warning
 365     ("A handler for the OS ABI \"%s\" is not built into this configuration\n"
 366      "of GDB.  Attempting to continue with the default %s settings.\n",
 367      gdbarch_osabi_name (info.osabi),
 368      info.bfd_arch_info->printable_name);
 369 }
 370 \f
 371 /* Limit on the amount of data to be read.  */
 372 #define MAX_NOTESZ      128
 373
 374 /* Return non-zero if NOTE matches NAME, DESCSZ and TYPE.  */
 375
 376 static int
 377 check_note (bfd *abfd, asection *sect, const char *note,
 378             const char *name, unsigned long descsz, unsigned long type)
 379 {
 380   unsigned long notesz;
 381
 382   /* Calculate the size of this note.  */
 383   notesz = strlen (name) + 1;
 384   notesz = ((notesz + 3) & ~3);
 385   notesz += descsz;
 386   notesz = ((notesz + 3) & ~3);
 387
 388   /* If this assertion triggers, increase MAX_NOTESZ.  */
 389   gdb_assert (notesz <= MAX_NOTESZ);
 390
 391   /* Check whether SECT is big enough to comtain the complete note.  */
 392   if (notesz > bfd_section_size (abfd, sect))
 393     return 0;
 394
 395   /* Check the note name.  */
 396   if (bfd_h_get_32 (abfd, note) != (strlen (name) + 1)
 397       || strcmp (note + 12, name) != 0)
 398     return 0;
 399
 400   /* Check the descriptor size.  */
 401   if (bfd_h_get_32 (abfd, note + 4) != descsz)
 402     return 0;
 403
 404   /* Check the note type.  */
 405   if (bfd_h_get_32 (abfd, note + 8) != type)
 406     return 0;
 407
 408   return 1;
 409 }
 410
 411 /* Generic sniffer for ELF flavoured files.  */
 412
 413 void
 414 generic_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect, void *obj)
 415 {
 416   enum gdb_osabi *osabi = obj;
 417   const char *name;
 418   unsigned int sectsize;
 419   char *note;
 420
 421   name = bfd_get_section_name (abfd, sect);
 422   sectsize = bfd_section_size (abfd, sect);
 423
 424   /* Limit the amount of data to read.  */
 425   if (sectsize > MAX_NOTESZ)
 426     sectsize = MAX_NOTESZ;
 427
 428   note = alloca (sectsize);
 429   bfd_get_section_contents (abfd, sect, note, 0, sectsize);
 430
 431   /* .note.ABI-tag notes, used by GNU/Linux and FreeBSD.  */
 432   if (strcmp (name, ".note.ABI-tag") == 0)
 433     {
 434       /* GNU.  */
 435       if (check_note (abfd, sect, note, "GNU", 16, NT_GNU_ABI_TAG))
 436         {
 437           unsigned int abi_tag = bfd_h_get_32 (abfd, note + 16);
 438
 439           switch (abi_tag)
 440             {
 441             case GNU_ABI_TAG_LINUX:
 442               *osabi = GDB_OSABI_LINUX;
 443               break;
 444
 445             case GNU_ABI_TAG_HURD:
 446               *osabi = GDB_OSABI_HURD;
 447               break;
 448
 449             case GNU_ABI_TAG_SOLARIS:
 450               *osabi = GDB_OSABI_SOLARIS;
 451               break;
 452
 453             case GNU_ABI_TAG_FREEBSD:
 454               *osabi = GDB_OSABI_FREEBSD_ELF;
 455               break;
 456
 457             case GNU_ABI_TAG_NETBSD:
 458               *osabi = GDB_OSABI_NETBSD_ELF;
 459               break;
 460
 461             default:
 462               internal_error (__FILE__, __LINE__, _("\
 463 generic_elf_osabi_sniff_abi_tag_sections: unknown OS number %d"),
 464                               abi_tag);
 465             }
 466           return;
 467         }
 468
 469       /* FreeBSD.  */
 470       if (check_note (abfd, sect, note, "FreeBSD", 4, NT_FREEBSD_ABI_TAG))
 471         {
 472           /* There is no need to check the version yet.  */
 473           *osabi = GDB_OSABI_FREEBSD_ELF;
 474           return;
 475         }
 476
 477       return;
 478     }
 479
 480   /* .note.netbsd.ident notes, used by NetBSD.  */
 481   if (strcmp (name, ".note.netbsd.ident") == 0
 482       && check_note (abfd, sect, note, "NetBSD", 4, NT_NETBSD_IDENT))
 483     {
 484       /* There is no need to check the version yet.  */
 485       *osabi = GDB_OSABI_NETBSD_ELF;
 486       return;
 487     }
 488
 489   /* .note.openbsd.ident notes, used by OpenBSD.  */
 490   if (strcmp (name, ".note.openbsd.ident") == 0
 491       && check_note (abfd, sect, note, "OpenBSD", 4, NT_OPENBSD_IDENT))
 492     {
 493       /* There is no need to check the version yet.  */
 494       *osabi = GDB_OSABI_OPENBSD_ELF;
 495       return;
 496     }
 497
 498   /* .note.netbsdcore.procinfo notes, used by NetBSD.  */
 499   if (strcmp (name, ".note.netbsdcore.procinfo") == 0)
 500     {
 501       *osabi = GDB_OSABI_NETBSD_ELF;
 502       return;
 503     }
 504 }
 505
 506 static enum gdb_osabi
 507 generic_elf_osabi_sniffer (bfd *abfd)
 508 {
 509   unsigned int elfosabi;
 510   enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
 511
 512   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
 513
 514   switch (elfosabi)
 515     {
 516     case ELFOSABI_NONE:
 517       /* When the EI_OSABI field in the ELF header is ELFOSABI_NONE
 518          (0), then the ELF structures in the file are conforming to
 519          the base specification for that machine (there are no
 520          OS-specific extensions).  In order to determine the real OS
 521          in use we must look for OS-specific notes.  */
 522       bfd_map_over_sections (abfd,
 523                              generic_elf_osabi_sniff_abi_tag_sections,
 524                              &osabi);
 525       break;
 526
 527     case ELFOSABI_FREEBSD:
 528       osabi = GDB_OSABI_FREEBSD_ELF;
 529       break;
 530
 531     case ELFOSABI_NETBSD:
 532       osabi = GDB_OSABI_NETBSD_ELF;
 533       break;
 534
 535     case ELFOSABI_LINUX:
 536       osabi = GDB_OSABI_LINUX;
 537       break;
 538
 539     case ELFOSABI_HURD:
 540       osabi = GDB_OSABI_HURD;
 541       break;
 542
 543     case ELFOSABI_SOLARIS:
 544       osabi = GDB_OSABI_SOLARIS;
 545       break;
 546
 547     case ELFOSABI_HPUX:
 548       /* For some reason the default value for the EI_OSABI field is
 549          ELFOSABI_HPUX for all PA-RISC targets (with the exception of
 550          GNU/Linux).  We use HP-UX ELF as the default, but let any
 551          OS-specific notes override this.  */
 552       osabi = GDB_OSABI_HPUX_ELF;
 553       bfd_map_over_sections (abfd,
 554                              generic_elf_osabi_sniff_abi_tag_sections,
 555                              &osabi);
 556       break;
 557     }
 558
 559   if (osabi == GDB_OSABI_UNKNOWN)
 560     {
 561       /* The FreeBSD folks have been naughty; they stored the string
 562          "FreeBSD" in the padding of the e_ident field of the ELF
 563          header to "brand" their ELF binaries in FreeBSD 3.x.  */
 564       if (memcmp (&elf_elfheader (abfd)->e_ident[8],
 565                   "FreeBSD", sizeof ("FreeBSD")) == 0)
 566         osabi = GDB_OSABI_FREEBSD_ELF;
 567     }
 568
 569   return osabi;
 570 }
 571 \f
 572 static void
 573 set_osabi (char *args, int from_tty, struct cmd_list_element *c)
 574 {
 575   struct gdbarch_info info;
 576
 577   if (strcmp (set_osabi_string, "auto") == 0)
 578     user_osabi_state = osabi_auto;
 579   else if (strcmp (set_osabi_string, "default") == 0)
 580     {
 581       user_selected_osabi = GDB_OSABI_DEFAULT;
 582       user_osabi_state = osabi_user;
 583     }
 584   else if (strcmp (set_osabi_string, "none") == 0)
 585     {
 586       user_selected_osabi = GDB_OSABI_UNKNOWN;
 587       user_osabi_state = osabi_user;
 588     }
 589   else
 590     {
 591       int i;
 592       for (i = 1; i < GDB_OSABI_INVALID; i++)
 593         if (strcmp (set_osabi_string, gdbarch_osabi_name (i)) == 0)
 594           {
 595             user_selected_osabi = i;
 596             user_osabi_state = osabi_user;
 597             break;
 598           }
 599       if (i == GDB_OSABI_INVALID)
 600         internal_error (__FILE__, __LINE__,
 601                         _("Invalid OS ABI \"%s\" passed to command handler."),
 602                         set_osabi_string);
 603     }
 604
 605   /* NOTE: At some point (true multiple architectures) we'll need to be more
 606      graceful here.  */
 607   gdbarch_info_init (&info);
 608   if (! gdbarch_update_p (info))
 609     internal_error (__FILE__, __LINE__, _("Updating OS ABI failed."));
 610 }
 611
 612 static void
 613 show_osabi (struct ui_file *file, int from_tty, struct cmd_list_element *c,
 614             const char *value)
 615 {
 616   if (user_osabi_state == osabi_auto)
 617     fprintf_filtered (file,
 618                       _("The current OS ABI is \"auto\" (currently \"%s\").\n"),
 619                       gdbarch_osabi_name (gdbarch_osabi (get_current_arch ())));
 620   else
 621     fprintf_filtered (file, _("The current OS ABI is \"%s\".\n"),
 622                       gdbarch_osabi_name (user_selected_osabi));
 623
 624   if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN)
 625     fprintf_filtered (file, _("The default OS ABI is \"%s\".\n"),
 626                       gdbarch_osabi_name (GDB_OSABI_DEFAULT));
 627 }
 628 \f
 629 extern initialize_file_ftype _initialize_gdb_osabi; /* -Wmissing-prototype */
 630
 631 void
 632 _initialize_gdb_osabi (void)
 633 {
 634   struct cmd_list_element *c;
 635
 636   if (strcmp (gdb_osabi_names[GDB_OSABI_INVALID], "<invalid>") != 0)
 637     internal_error
 638       (__FILE__, __LINE__,
 639        _("_initialize_gdb_osabi: gdb_osabi_names[] is inconsistent"));
 640
 641   /* Register a generic sniffer for ELF flavoured files.  */
 642   gdbarch_register_osabi_sniffer (bfd_arch_unknown,
 643                                   bfd_target_elf_flavour,
 644                                   generic_elf_osabi_sniffer);
 645
 646   /* Register the "set osabi" command.  */
 647   add_setshow_enum_cmd ("osabi", class_support, gdb_osabi_available_names,
 648                         &set_osabi_string, _("\
 649 Set OS ABI of target."), _("\
 650 Show OS ABI of target."), NULL,
 651                         set_osabi,
 652                         show_osabi,
 653                         &setlist, &showlist);
 654   user_osabi_state = osabi_auto;
 655 }