AC_ERROR([Linux kernel in $KBUILD26 is not version 2.6])
else
AC_ERROR([Linux kernel in build tree $KBUILD26 (source tree $KSRC26) is not version 2.6])
AC_ERROR([Linux kernel in $KBUILD26 is not version 2.6])
else
AC_ERROR([Linux kernel in build tree $KBUILD26 (source tree $KSRC26) is not version 2.6])