config/kernel.m4

   1 dnl #
   2 dnl # Default ZFS kernel configuration
   3 dnl #
   4 AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
   5         ZFS_AC_KERNEL
   6         ZFS_AC_SPL
   7         ZFS_AC_TEST_MODULE
   8         ZFS_AC_KERNEL_CONFIG
   9         ZFS_AC_KERNEL_BDEV_BLOCK_DEVICE_OPERATIONS
  10         ZFS_AC_KERNEL_TYPE_FMODE_T
  11         ZFS_AC_KERNEL_KOBJ_NAME_LEN
  12         ZFS_AC_KERNEL_3ARG_BLKDEV_GET
  13         ZFS_AC_KERNEL_BLKDEV_GET_BY_PATH
  14         ZFS_AC_KERNEL_OPEN_BDEV_EXCLUSIVE
  15         ZFS_AC_KERNEL_LOOKUP_BDEV
  16         ZFS_AC_KERNEL_INVALIDATE_BDEV_ARGS
  17         ZFS_AC_KERNEL_BDEV_LOGICAL_BLOCK_SIZE
  18         ZFS_AC_KERNEL_BDEV_PHYSICAL_BLOCK_SIZE
  19         ZFS_AC_KERNEL_BIO_FAILFAST
  20         ZFS_AC_KERNEL_BIO_FAILFAST_DTD
  21         ZFS_AC_KERNEL_REQ_FAILFAST_MASK
  22         ZFS_AC_KERNEL_BIO_END_IO_T_ARGS
  23         ZFS_AC_KERNEL_BIO_RW_SYNC
  24         ZFS_AC_KERNEL_BIO_RW_SYNCIO
  25         ZFS_AC_KERNEL_REQ_SYNC
  26         ZFS_AC_KERNEL_BLK_END_REQUEST
  27         ZFS_AC_KERNEL_BLK_QUEUE_FLUSH
  28         ZFS_AC_KERNEL_BLK_QUEUE_MAX_HW_SECTORS
  29         ZFS_AC_KERNEL_BLK_QUEUE_MAX_SEGMENTS
  30         ZFS_AC_KERNEL_BLK_QUEUE_PHYSICAL_BLOCK_SIZE
  31         ZFS_AC_KERNEL_BLK_QUEUE_IO_OPT
  32         ZFS_AC_KERNEL_BLK_QUEUE_NONROT
  33         ZFS_AC_KERNEL_BLK_QUEUE_DISCARD
  34         ZFS_AC_KERNEL_BLK_FETCH_REQUEST
  35         ZFS_AC_KERNEL_BLK_REQUEUE_REQUEST
  36         ZFS_AC_KERNEL_BLK_RQ_BYTES
  37         ZFS_AC_KERNEL_BLK_RQ_POS
  38         ZFS_AC_KERNEL_BLK_RQ_SECTORS
  39         ZFS_AC_KERNEL_GET_DISK_RO
  40         ZFS_AC_KERNEL_GET_GENDISK
  41         ZFS_AC_KERNEL_RQ_IS_SYNC
  42         ZFS_AC_KERNEL_RQ_FOR_EACH_SEGMENT
  43         ZFS_AC_KERNEL_DISCARD_GRANULARITY
  44         ZFS_AC_KERNEL_CONST_XATTR_HANDLER
  45         ZFS_AC_KERNEL_XATTR_HANDLER_GET
  46         ZFS_AC_KERNEL_XATTR_HANDLER_SET
  47         ZFS_AC_KERNEL_SHOW_OPTIONS
  48         ZFS_AC_KERNEL_FSYNC
  49         ZFS_AC_KERNEL_EVICT_INODE
  50         ZFS_AC_KERNEL_DIRTY_INODE_WITH_FLAGS
  51         ZFS_AC_KERNEL_NR_CACHED_OBJECTS
  52         ZFS_AC_KERNEL_FREE_CACHED_OBJECTS
  53         ZFS_AC_KERNEL_FALLOCATE
  54         ZFS_AC_KERNEL_MKDIR_UMODE_T
  55         ZFS_AC_KERNEL_LOOKUP_NAMEIDATA
  56         ZFS_AC_KERNEL_CREATE_NAMEIDATA
  57         ZFS_AC_KERNEL_TRUNCATE_RANGE
  58         ZFS_AC_KERNEL_AUTOMOUNT
  59         ZFS_AC_KERNEL_ENCODE_FH_WITH_INODE
  60         ZFS_AC_KERNEL_COMMIT_METADATA
  61         ZFS_AC_KERNEL_CLEAR_INODE
  62         ZFS_AC_KERNEL_INSERT_INODE_LOCKED
  63         ZFS_AC_KERNEL_D_MAKE_ROOT
  64         ZFS_AC_KERNEL_D_OBTAIN_ALIAS
  65         ZFS_AC_KERNEL_D_SET_D_OP
  66         ZFS_AC_KERNEL_D_REVALIDATE_NAMEIDATA
  67         ZFS_AC_KERNEL_CONST_DENTRY_OPERATIONS
  68         ZFS_AC_KERNEL_CHECK_DISK_SIZE_CHANGE
  69         ZFS_AC_KERNEL_TRUNCATE_SETSIZE
  70         ZFS_AC_KERNEL_6ARGS_SECURITY_INODE_INIT_SECURITY
  71         ZFS_AC_KERNEL_CALLBACK_SECURITY_INODE_INIT_SECURITY
  72         ZFS_AC_KERNEL_MOUNT_NODEV
  73         ZFS_AC_KERNEL_SHRINK
  74         ZFS_AC_KERNEL_S_D_OP
  75         ZFS_AC_KERNEL_BDI
  76         ZFS_AC_KERNEL_BDI_SETUP_AND_REGISTER
  77         ZFS_AC_KERNEL_SET_NLINK
  78         ZFS_AC_KERNEL_ELEVATOR_CHANGE
  79         ZFS_AC_KERNEL_5ARG_SGET
  80
  81         AS_IF([test "$LINUX_OBJ" != "$LINUX"], [
  82                 KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS O=$LINUX_OBJ"
  83         ])
  84         AC_SUBST(KERNELMAKE_PARAMS)
  85
  86
  87         dnl # -Wall -fno-strict-aliasing -Wstrict-prototypes and other
  88         dnl # compiler options are added by the kernel build system.
  89         KERNELCPPFLAGS="$KERNELCPPFLAGS $NO_UNUSED_BUT_SET_VARIABLE"
  90         KERNELCPPFLAGS="$KERNELCPPFLAGS -DHAVE_SPL -D_KERNEL"
  91         KERNELCPPFLAGS="$KERNELCPPFLAGS -DTEXT_DOMAIN=\\\"zfs-linux-kernel\\\""
  92
  93         AC_SUBST(KERNELCPPFLAGS)
  94 ])
  95
  96 dnl #
  97 dnl # Detect name used for Module.symvers file in kernel
  98 dnl #
  99 AC_DEFUN([ZFS_AC_MODULE_SYMVERS], [
 100         modpost=$LINUX/scripts/Makefile.modpost
 101         AC_MSG_CHECKING([kernel file name for module symbols])
 102         AS_IF([test "x$enable_linux_builtin" != xyes -a -f "$modpost"], [
 103                 AS_IF([grep -q Modules.symvers $modpost], [
 104                         LINUX_SYMBOLS=Modules.symvers
 105                 ], [
 106                         LINUX_SYMBOLS=Module.symvers
 107                 ])
 108
 109                 AS_IF([test ! -f "$LINUX_OBJ/$LINUX_SYMBOLS"], [
 110                         AC_MSG_ERROR([
 111         *** Please make sure the kernel devel package for your distribution
 112         *** is installed.  If you are building with a custom kernel, make sure the
 113         *** kernel is configured, built, and the '--with-linux=PATH' configure
 114         *** option refers to the location of the kernel source.])
 115                 ])
 116         ], [
 117                 LINUX_SYMBOLS=NONE
 118         ])
 119         AC_MSG_RESULT($LINUX_SYMBOLS)
 120         AC_SUBST(LINUX_SYMBOLS)
 121 ])
 122
 123 dnl #
 124 dnl # Detect the kernel to be built against
 125 dnl #
 126 AC_DEFUN([ZFS_AC_KERNEL], [
 127         AC_ARG_WITH([linux],
 128                 AS_HELP_STRING([--with-linux=PATH],
 129                 [Path to kernel source]),
 130                 [kernelsrc="$withval"])
 131
 132         AC_ARG_WITH(linux-obj,
 133                 AS_HELP_STRING([--with-linux-obj=PATH],
 134                 [Path to kernel build objects]),
 135                 [kernelbuild="$withval"])
 136
 137         AC_MSG_CHECKING([kernel source directory])
 138         AS_IF([test -z "$kernelsrc"], [
 139                 AS_IF([test -e "/lib/modules/$(uname -r)/source"], [
 140                         headersdir="/lib/modules/$(uname -r)/source"
 141                         sourcelink=$(readlink -f "$headersdir")
 142                 ], [test -e "/lib/modules/$(uname -r)/build"], [
 143                         headersdir="/lib/modules/$(uname -r)/build"
 144                         sourcelink=$(readlink -f "$headersdir")
 145                 ], [
 146                         sourcelink=$(ls -1d /usr/src/kernels/* \
 147                                      /usr/src/linux-* \
 148                                      2>/dev/null | grep -v obj | tail -1)
 149                 ])
 150
 151                 AS_IF([test -n "$sourcelink" && test -e ${sourcelink}], [
 152                         kernelsrc=`readlink -f ${sourcelink}`
 153                 ], [
 154                         kernelsrc="[Not found]"
 155                 ])
 156         ], [
 157                 AS_IF([test "$kernelsrc" = "NONE"], [
 158                         kernsrcver=NONE
 159                 ])
 160         ])
 161
 162         AC_MSG_RESULT([$kernelsrc])
 163         AS_IF([test ! -d "$kernelsrc"], [
 164                 AC_MSG_ERROR([
 165         *** Please make sure the kernel devel package for your distribution
 166         *** is installed and then try again.  If that fails, you can specify the
 167         *** location of the kernel source with the '--with-linux=PATH' option.])
 168         ])
 169
 170         AC_MSG_CHECKING([kernel build directory])
 171         AS_IF([test -z "$kernelbuild"], [
 172                 AS_IF([test -e "/lib/modules/$(uname -r)/build"], [
 173                         kernelbuild=`readlink -f /lib/modules/$(uname -r)/build`
 174                 ], [test -d ${kernelsrc}-obj/${target_cpu}/${target_cpu}], [
 175                         kernelbuild=${kernelsrc}-obj/${target_cpu}/${target_cpu}
 176                 ], [test -d ${kernelsrc}-obj/${target_cpu}/default], [
 177                         kernelbuild=${kernelsrc}-obj/${target_cpu}/default
 178                 ], [test -d `dirname ${kernelsrc}`/build-${target_cpu}], [
 179                         kernelbuild=`dirname ${kernelsrc}`/build-${target_cpu}
 180                 ], [
 181                         kernelbuild=${kernelsrc}
 182                 ])
 183         ])
 184         AC_MSG_RESULT([$kernelbuild])
 185
 186         AC_MSG_CHECKING([kernel source version])
 187         utsrelease1=$kernelbuild/include/linux/version.h
 188         utsrelease2=$kernelbuild/include/linux/utsrelease.h
 189         utsrelease3=$kernelbuild/include/generated/utsrelease.h
 190         AS_IF([test -r $utsrelease1 && fgrep -q UTS_RELEASE $utsrelease1], [
 191                 utsrelease=linux/version.h
 192         ], [test -r $utsrelease2 && fgrep -q UTS_RELEASE $utsrelease2], [
 193                 utsrelease=linux/utsrelease.h
 194         ], [test -r $utsrelease3 && fgrep -q UTS_RELEASE $utsrelease3], [
 195                 utsrelease=generated/utsrelease.h
 196         ])
 197
 198         AS_IF([test "$utsrelease"], [
 199                 kernsrcver=`(echo "#include <$utsrelease>";
 200                              echo "kernsrcver=UTS_RELEASE") |
 201                              cpp -I $kernelbuild/include |
 202                              grep "^kernsrcver=" | cut -d \" -f 2`
 203
 204                 AS_IF([test -z "$kernsrcver"], [
 205                         AC_MSG_RESULT([Not found])
 206                         AC_MSG_ERROR([*** Cannot determine kernel version.])
 207                 ])
 208         ], [
 209                 AC_MSG_RESULT([Not found])
 210                 if test "x$enable_linux_builtin" != xyes; then
 211                         AC_MSG_ERROR([*** Cannot find UTS_RELEASE definition.])
 212                 else
 213                         AC_MSG_ERROR([
 214         *** Cannot find UTS_RELEASE definition.
 215         *** Please run 'make prepare' inside the kernel source tree.])
 216                 fi
 217         ])
 218
 219         AC_MSG_RESULT([$kernsrcver])
 220
 221         LINUX=${kernelsrc}
 222         LINUX_OBJ=${kernelbuild}
 223         LINUX_VERSION=${kernsrcver}
 224
 225         AC_SUBST(LINUX)
 226         AC_SUBST(LINUX_OBJ)
 227         AC_SUBST(LINUX_VERSION)
 228
 229         ZFS_AC_MODULE_SYMVERS
 230 ])
 231
 232 dnl #
 233 dnl # Detect name used for the additional SPL Module.symvers file.  If one
 234 dnl # does not exist this is likely because the SPL has been configured
 235 dnl # but not built.  The '--with-spl-timeout' option can be passed
 236 dnl # to pause here, waiting for the file to appear from a concurrently
 237 dnl # building SPL package.  If the file does not appear in time, a good
 238 dnl # guess is made as to what this file will be named based on what it
 239 dnl # is named in the kernel build products.  This file will first be
 240 dnl # used at link time so if the guess is wrong the build will fail
 241 dnl # then.  This unfortunately means the ZFS package does not contain a
 242 dnl # reliable mechanism to detect symbols exported by the SPL at
 243 dnl # configure time.
 244 dnl #
 245 AC_DEFUN([ZFS_AC_SPL_MODULE_SYMVERS], [
 246         AC_ARG_WITH([spl-timeout],
 247                 AS_HELP_STRING([--with-spl-timeout=SECS],
 248                 [Wait SECS for symvers file to appear  @<:@default=0@:>@]),
 249                 [timeout="$withval"], [timeout=0])
 250
 251         AC_MSG_CHECKING([spl file name for module symbols])
 252         SPL_SYMBOLS=NONE
 253
 254         while true; do
 255                 AS_IF([test -r $SPL_OBJ/Module.symvers], [
 256                         SPL_SYMBOLS=Module.symvers
 257                 ], [test -r $SPL_OBJ/Modules.symvers], [
 258                         SPL_SYMBOLS=Modules.symvers
 259                 ], [test -r $SPL_OBJ/module/Module.symvers], [
 260                         SPL_SYMBOLS=Module.symvers
 261                 ], [test -r $SPL_OBJ/module/Modules.symvers], [
 262                         SPL_SYMBOLS=Modules.symvers
 263                 ])
 264
 265                 AS_IF([test $SPL_SYMBOLS != NONE -o $timeout -le 0], [
 266                         break;
 267                 ], [
 268                         sleep 1
 269                         timeout=$((timeout-1))
 270                 ])
 271         done
 272
 273         AS_IF([test "$SPL_SYMBOLS" = NONE], [
 274                 SPL_SYMBOLS=$LINUX_SYMBOLS
 275         ])
 276
 277         AC_MSG_RESULT([$SPL_SYMBOLS])
 278         AC_SUBST(SPL_SYMBOLS)
 279 ])
 280
 281 dnl #
 282 dnl # Detect the SPL module to be built against
 283 dnl #
 284 AC_DEFUN([ZFS_AC_SPL], [
 285         AC_ARG_WITH([spl],
 286                 AS_HELP_STRING([--with-spl=PATH],
 287                 [Path to spl source]),
 288                 [splsrc="$withval"])
 289
 290         AC_ARG_WITH([spl-obj],
 291                 AS_HELP_STRING([--with-spl-obj=PATH],
 292                 [Path to spl build objects]),
 293                 [splbuild="$withval"])
 294
 295         dnl #
 296         dnl # The existence of spl.release.in is used to identify a valid
 297         dnl # source directory.  In order of preference:
 298         dnl #
 299         splsrc0="/var/lib/dkms/spl/${VERSION}/build"
 300         splsrc1="/usr/src/spl-${VERSION}/${LINUX_VERSION}"
 301         splsrc2="/usr/src/spl-${VERSION}"
 302         splsrc3="../spl/"
 303         splsrc4="$LINUX"
 304
 305         AC_MSG_CHECKING([spl source directory])
 306         AS_IF([test -z "${splsrc}"], [
 307                 AS_IF([ test -e "${splsrc0}/spl.release.in"], [
 308                         splsrc=${splsrc0}
 309                 ], [ test -e "${splsrc1}/spl.release.in"], [
 310                         splsrc=${splsrc1}
 311                 ], [ test -e "${splsrc2}/spl.release.in"], [
 312                         splsrc=${splsrc2}
 313                 ], [ test -e "${splsrc3}/spl.release.in"], [
 314                         splsrc=$(readlink -f "${splsrc3}")
 315                 ], [ test -e "${splsrc4}/spl.release.in" ], [
 316                         splsrc=${splsrc4}
 317                 ], [
 318                         splsrc="[Not found]"
 319                 ])
 320         ], [
 321                 AS_IF([test "$splsrc" = "NONE"], [
 322                         splbuild=NONE
 323                         splsrcver=NONE
 324                 ])
 325         ])
 326
 327         AC_MSG_RESULT([$splsrc])
 328         AS_IF([ test ! -e "$splsrc/spl.release.in"], [
 329                 AC_MSG_ERROR([
 330         *** Please make sure the kmod spl devel package for your distribution
 331         *** is installed then try again.  If that fails you can specify the
 332         *** location of the spl source with the '--with-spl=PATH' option.])
 333         ])
 334
 335         dnl #
 336         dnl # The existence of the spl_config.h is used to identify a valid
 337         dnl # spl object directory.  In many cases the object and source
 338         dnl # directory are the same, however the objects may also reside
 339         dnl # is a subdirectory named after the kernel version.
 340         dnl #
 341         AC_MSG_CHECKING([spl build directory])
 342         AS_IF([test -z "$splbuild"], [
 343                 AS_IF([ test -e "${splsrc}/${LINUX_VERSION}/spl_config.h" ], [
 344                         splbuild="${splsrc}/${LINUX_VERSION}"
 345                 ], [ test -e "${splsrc}/spl_config.h" ], [
 346                         splbuild="${splsrc}"
 347                 ], [
 348                         splbuild="[Not found]"
 349                 ])
 350         ])
 351
 352         AC_MSG_RESULT([$splbuild])
 353         AS_IF([ ! test -e "$splbuild/spl_config.h"], [
 354                 AC_MSG_ERROR([
 355         *** Please make sure the kmod spl devel <kernel> package for your
 356         *** distribution is installed then try again.  If that fails you
 357         *** can specify the location of the spl objects with the
 358         *** '--with-spl-obj=PATH' option.])
 359         ])
 360
 361         AC_MSG_CHECKING([spl source version])
 362         AS_IF([test -r $splbuild/spl_config.h &&
 363                 fgrep -q SPL_META_VERSION $splbuild/spl_config.h], [
 364
 365                 splsrcver=`(echo "#include <spl_config.h>";
 366                             echo "splsrcver=SPL_META_VERSION-SPL_META_RELEASE") |
 367                             cpp -I $splbuild |
 368                             grep "^splsrcver=" | tr -d \" | cut -d= -f2`
 369         ])
 370
 371         AS_IF([test -z "$splsrcver"], [
 372                 AC_MSG_RESULT([Not found])
 373                 AC_MSG_ERROR([
 374         *** Cannot determine the version of the spl source.
 375         *** Please prepare the spl source before running this script])
 376         ])
 377
 378         AC_MSG_RESULT([$splsrcver])
 379
 380         SPL=${splsrc}
 381         SPL_OBJ=${splbuild}
 382         SPL_VERSION=${splsrcver}
 383
 384         AC_SUBST(SPL)
 385         AC_SUBST(SPL_OBJ)
 386         AC_SUBST(SPL_VERSION)
 387
 388         ZFS_AC_SPL_MODULE_SYMVERS
 389 ])
 390
 391 dnl #
 392 dnl # Basic toolchain sanity check.
 393 dnl #
 394 AC_DEFUN([ZFS_AC_TEST_MODULE],
 395         [AC_MSG_CHECKING([whether modules can be built])
 396         ZFS_LINUX_TRY_COMPILE([],[],[
 397                 AC_MSG_RESULT([yes])
 398         ],[
 399                 AC_MSG_RESULT([no])
 400                 if test "x$enable_linux_builtin" != xyes; then
 401                         AC_MSG_ERROR([*** Unable to build an empty module.])
 402                 else
 403                         AC_MSG_ERROR([
 404         *** Unable to build an empty module.
 405         *** Please run 'make scripts' inside the kernel source tree.])
 406                 fi
 407         ])
 408 ])
 409
 410 dnl #
 411 dnl # Certain kernel build options are not supported.  These must be
 412 dnl # detected at configure time and cause a build failure.  Otherwise
 413 dnl # modules may be successfully built that behave incorrectly.
 414 dnl #
 415 AC_DEFUN([ZFS_AC_KERNEL_CONFIG], [
 416
 417         AS_IF([test "$ZFS_META_LICENSE" = GPL], [
 418                 AC_DEFINE([HAVE_GPL_ONLY_SYMBOLS], [1],
 419                         [Define to 1 if licensed under the GPL])
 420         ])
 421
 422         ZFS_AC_KERNEL_CONFIG_DEBUG_LOCK_ALLOC
 423 ])
 424
 425 dnl #
 426 dnl # Check CONFIG_DEBUG_LOCK_ALLOC
 427 dnl #
 428 dnl # This is typically only set for debug kernels because it comes with
 429 dnl # a performance penalty.  However, when it is set it maps the non-GPL
 430 dnl # symbol mutex_lock() to the GPL-only mutex_lock_nested() symbol.
 431 dnl # This will cause a failure at link time which we'd rather know about
 432 dnl # at compile time.
 433 dnl #
 434 dnl # Since we plan to pursue making mutex_lock_nested() a non-GPL symbol
 435 dnl # with the upstream community we add a check to detect this case.
 436 dnl #
 437 AC_DEFUN([ZFS_AC_KERNEL_CONFIG_DEBUG_LOCK_ALLOC], [
 438
 439         ZFS_LINUX_CONFIG([DEBUG_LOCK_ALLOC], [
 440                 AC_MSG_CHECKING([whether mutex_lock() is GPL-only])
 441                 tmp_flags="$EXTRA_KCFLAGS"
 442                 ZFS_LINUX_TRY_COMPILE([
 443                         #include <linux/module.h>
 444                         #include <linux/mutex.h>
 445
 446                         MODULE_LICENSE("$ZFS_META_LICENSE");
 447                 ],[
 448                         struct mutex lock;
 449
 450                         mutex_init(&lock);
 451                         mutex_lock(&lock);
 452                         mutex_unlock(&lock);
 453                 ],[
 454                         AC_MSG_RESULT(no)
 455                 ],[
 456                         AC_MSG_RESULT(yes)
 457                         AC_MSG_ERROR([
 458         *** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is incompatible
 459         *** with the CDDL license and will prevent the module linking stage
 460         *** from succeeding.  You must rebuild your kernel without this
 461         *** option enabled.])
 462                 ])
 463                 EXTRA_KCFLAGS="$tmp_flags"
 464         ], [])
 465 ])
 466
 467 dnl #
 468 dnl # ZFS_LINUX_CONFTEST
 469 dnl #
 470 AC_DEFUN([ZFS_LINUX_CONFTEST], [
 471 cat confdefs.h - <<_ACEOF >conftest.c
 472 $1
 473 _ACEOF
 474 ])
 475
 476 dnl #
 477 dnl # ZFS_LANG_PROGRAM(C)([PROLOGUE], [BODY])
 478 dnl #
 479 m4_define([ZFS_LANG_PROGRAM], [
 480 $1
 481 int
 482 main (void)
 483 {
 484 dnl Do *not* indent the following line: there may be CPP directives.
 485 dnl Don't move the `;' right after for the same reason.
 486 $2
 487   ;
 488   return 0;
 489 }
 490 ])
 491
 492 dnl #
 493 dnl # ZFS_LINUX_COMPILE_IFELSE / like AC_COMPILE_IFELSE
 494 dnl #
 495 AC_DEFUN([ZFS_LINUX_COMPILE_IFELSE], [
 496         m4_ifvaln([$1], [ZFS_LINUX_CONFTEST([$1])])
 497         rm -Rf build && mkdir -p build && touch build/conftest.mod.c
 498         echo "obj-m := conftest.o" >build/Makefile
 499         modpost_flag=''
 500         test "x$enable_linux_builtin" = xyes && modpost_flag='modpost=true' # fake modpost stage
 501         AS_IF(
 502                 [AC_TRY_COMMAND(cp conftest.c build && make [$2] -C $LINUX_OBJ EXTRA_CFLAGS="-Werror $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build $modpost_flag) >/dev/null && AC_TRY_COMMAND([$3])],
 503                 [$4],
 504                 [_AC_MSG_LOG_CONFTEST m4_ifvaln([$5],[$5])]
 505         )
 506         rm -Rf build
 507 ])
 508
 509 dnl #
 510 dnl # ZFS_LINUX_TRY_COMPILE like AC_TRY_COMPILE
 511 dnl #
 512 AC_DEFUN([ZFS_LINUX_TRY_COMPILE],
 513         [ZFS_LINUX_COMPILE_IFELSE(
 514         [AC_LANG_SOURCE([ZFS_LANG_PROGRAM([[$1]], [[$2]])])],
 515         [modules],
 516         [test -s build/conftest.o],
 517         [$3], [$4])
 518 ])
 519
 520 dnl #
 521 dnl # ZFS_LINUX_CONFIG
 522 dnl #
 523 AC_DEFUN([ZFS_LINUX_CONFIG],
 524         [AC_MSG_CHECKING([whether Linux was built with CONFIG_$1])
 525         ZFS_LINUX_TRY_COMPILE([
 526                 #include <linux/module.h>
 527         ],[
 528                 #ifndef CONFIG_$1
 529                 #error CONFIG_$1 not #defined
 530                 #endif
 531         ],[
 532                 AC_MSG_RESULT([yes])
 533                 $2
 534         ],[
 535                 AC_MSG_RESULT([no])
 536                 $3
 537         ])
 538 ])
 539
 540 dnl #
 541 dnl # ZFS_CHECK_SYMBOL_EXPORT
 542 dnl # check symbol exported or not
 543 dnl #
 544 AC_DEFUN([ZFS_CHECK_SYMBOL_EXPORT], [
 545         grep -q -E '[[[:space:]]]$1[[[:space:]]]' \
 546                 $LINUX_OBJ/$LINUX_SYMBOLS 2>/dev/null
 547         rc=$?
 548         if test $rc -ne 0; then
 549                 export=0
 550                 for file in $2; do
 551                         grep -q -E "EXPORT_SYMBOL.*($1)" \
 552                                 "$LINUX/$file" 2>/dev/null
 553                         rc=$?
 554                         if test $rc -eq 0; then
 555                                 export=1
 556                                 break;
 557                         fi
 558                 done
 559                 if test $export -eq 0; then :
 560                         $4
 561                 else :
 562                         $3
 563                 fi
 564         else :
 565                 $3
 566         fi
 567 ])
 568
 569 dnl #
 570 dnl # ZFS_LINUX_TRY_COMPILE_SYMBOL
 571 dnl # like ZFS_LINUX_TRY_COMPILE, except ZFS_CHECK_SYMBOL_EXPORT
 572 dnl # is called if not compiling for builtin
 573 dnl #
 574 AC_DEFUN([ZFS_LINUX_TRY_COMPILE_SYMBOL], [
 575         ZFS_LINUX_TRY_COMPILE([$1], [$2], [rc=0], [rc=1])
 576         if test $rc -ne 0; then :
 577                 $6
 578         else
 579                 if test "x$enable_linux_builtin" != xyes; then
 580                         ZFS_CHECK_SYMBOL_EXPORT([$3], [$4], [rc=0], [rc=1])
 581                 fi
 582                 if test $rc -ne 0; then :
 583                         $6
 584                 else :
 585                         $5
 586                 fi
 587         fi
 588 ])