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1 dnl ----------------------------------------------------------------------
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2 dnl This whole bit snagged from libgomp.
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3
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4 dnl
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5 dnl GCC_LINUX_FUTEX
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6 dnl (SHELL-CODE_HANDLER)
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7 dnl
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8 AC_DEFUN([GCC_LINUX_FUTEX],[dnl
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9 GCC_ENABLE(linux-futex,default, ,[use the Linux futex system call],
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10 permit yes|no|default)
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11 case "$target" in
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12 *-linux*)
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13 case "$enable_linux_futex" in
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14 default)
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15 # If headers don't have gettid/futex syscalls definition, then
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16 # default to no, otherwise there will be compile time failures.
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17 # Otherwise, default to yes. If we don't detect we are
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18 # compiled/linked against NPTL and not cross-compiling, check
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19 # if programs are run by default against NPTL and if not, issue
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20 # a warning.
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21 enable_linux_futex=no
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22 AC_LINK_IFELSE(
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23 [AC_LANG_PROGRAM(
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24 [#include <sys/syscall.h>
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25 int lk;],
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26 [syscall (SYS_gettid); syscall (SYS_futex, &lk, 0, 0, 0);])],
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27 [save_LIBS="$LIBS"
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28 LIBS="-lpthread $LIBS"
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29 AC_LINK_IFELSE(
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30 [AC_LANG_PROGRAM(
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31 [#ifndef _GNU_SOURCE
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32 #define _GNU_SOURCE 1
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33 #endif
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34 #include <pthread.h>
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35 pthread_t th; void *status;],
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36 [pthread_tryjoin_np (th, &status);])],[enable_linux_futex=yes],
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37 [if test x$cross_compiling = xno; then
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38 if getconf GNU_LIBPTHREAD_VERSION 2>/dev/null \
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39 | LC_ALL=C grep -i NPTL > /dev/null 2>/dev/null; then :; else
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40 AC_MSG_WARN([The kernel might not support futex or gettid syscalls.
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41 If so, please configure with --disable-linux-futex])
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42 fi
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43 fi
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44 enable_linux_futex=yes])
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45 LIBS="$save_LIBS"])
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46 ;;
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47 yes)
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48 AC_LINK_IFELSE(
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49 [AC_LANG_PROGRAM(
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50 [#include <sys/syscall.h>
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51 int lk;],
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52 [syscall (SYS_gettid); syscall (SYS_futex, &lk, 0, 0, 0);])],[],
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53 [AC_MSG_ERROR([SYS_gettid and SYS_futex required for --enable-linux-futex])])
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54 ;;
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55 esac
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56 ;;
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57 *)
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58 enable_linux_futex=no
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59 ;;
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60 esac
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61 if test x$enable_linux_futex = xyes; then
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62 $1
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63 fi
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64 ])
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