* sysdeps/posix/sysconf.c (__sysconf): Use #if _POSIX_FOO > 0

	rather than #ifdef _POSIX_FOO for options.  We should return -1
	at runtime for an option defined to 0 at compile time.

	* sysdeps/mach/hurd/bits/posix_opt.h: Define many missing options,
	many to -1 or 0.

2006-03-05  Roland McGrath  <roland@redhat.com>

	* sysdeps/unix/sysv/linux/sysconf.c (__sysconf)
	[__NR_clock_getres || HP_TIMING_AVAIL]: Handle _SC_CPUTIME,
	_SC_THREAD_CPUTIME.

3 files changed, 200 insertions, 92 deletions

diff --git a/sysdeps/mach/hurd/bits/posix_opt.h b/sysdeps/mach/hurd/bits/posix_opt.h
index 326bebff7f..6747bc276e 100644
--- a/sysdeps/mach/hurd/bits/posix_opt.h
+++ b/sysdeps/mach/hurd/bits/posix_opt.h
@@ -1,5 +1,5 @@
 /* Define POSIX options for GNU/Hurd.
-   Copyright (C) 1998,2000,2001,2002 Free Software Foundation, Inc.
+   Copyright (C) 1998,2000,2001,2002,2006 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -31,13 +31,6 @@
 /* Processes have a saved set-user-ID and a saved set-group-ID.  */
 #define	_POSIX_SAVED_IDS	1
 
-#if 0				/* XXX implement aio_* */
-/* Asynchronous I/O is supported.  */
-#define _POSIX_ASYNCHRONOUS_IO	1
-/* Alternative name for Unix98.  */
-#define _LFS_ASYNCHRONOUS_IO	_POSIX_ASYNCHRONOUS_IO
-#endif
-
 /* Synchronizing file data is supported, but msync is missing.  */
 #undef _POSIX_SYNCHRONIZED_IO
 
@@ -47,15 +40,15 @@
 /* Mapping of files to memory is supported.  */
 #define	_POSIX_MAPPED_FILES	200112L
 
+/* Locking of all memory could be supported in future.  */
+#define	_POSIX_MEMLOCK	0
+
 /* Locking of ranges of memory is supported.  */
 #define	_POSIX_MEMLOCK_RANGE	200112L
 
 /* Setting of memory protections is supported.  */
 #define	_POSIX_MEMORY_PROTECTION	200112L
 
-/* POSIX.4 shared memory objects are supported (using regular files).  */
-#define _POSIX_SHARED_MEMORY_OBJECTS	_POSIX_MAPPED_FILES
-
 /* Elements of the `c_cc' member of `struct termios' structure
    can be disabled by using the value _POSIX_VDISABLE.  */
 #define _POSIX_VDISABLE			((unsigned char) -1)
@@ -67,13 +60,106 @@
 #undef _POSIX_NO_TRUNC		/* Overlong file names get error?  */
 #undef _POSIX_SYNC_IO		/* File supports O_SYNC et al?  */
 
+
+/* We do not have the POSIX threads interface.  */
+#define _POSIX_THREADS	-1
+
+/* We have the reentrant functions described in POSIX.  */
+#define _POSIX_REENTRANT_FUNCTIONS      1
+#define _POSIX_THREAD_SAFE_FUNCTIONS	200112L
+
+/* These are all things that won't be supported when _POSIX_THREADS is not.  */
+#define _POSIX_THREAD_PRIORITY_SCHEDULING	-1
+#define _POSIX_THREAD_ATTR_STACKSIZE		-1
+#define _POSIX_THREAD_ATTR_STACKADDR		-1
+#define _POSIX_SEMAPHORES			-1
+
+/* Real-time signals are not yet supported.  */
+#define _POSIX_REALTIME_SIGNALS	-1
+
+/* Asynchronous I/O might supported with the existing ABI.  */
+#define _POSIX_ASYNCHRONOUS_IO	0
+/* Alternative name for Unix98.  */
+#define _LFS_ASYNCHRONOUS_IO	_POSIX_ASYNCHRONOUS_IO
+
+/* The LFS support in asynchronous I/O is also available.  */
+#define _LFS64_ASYNCHRONOUS_IO	_POSIX_ASYNCHRONOUS_IO
+
+/* The rest of the LFS is also available.  */
+#define _LFS_LARGEFILE		1
+#define _LFS64_LARGEFILE	1
+#define _LFS64_STDIO		1
+
+/* POSIX.4 shared memory objects are supported (using regular files).  */
+#define _POSIX_SHARED_MEMORY_OBJECTS	_POSIX_MAPPED_FILES
+
+/* CPU-time clocks support needs to be checked at runtime.  */
+#define _POSIX_CPUTIME	0
+
+/* Clock support in threads must be also checked at runtime.  */
+#define _POSIX_THREAD_CPUTIME	0
+
 /* GNU libc provides regular expression handling.  */
 #define _POSIX_REGEXP	1
 
+/* Reader/Writer locks are not available.  */
+#define _POSIX_READER_WRITER_LOCKS	-1
+
 /* We have a POSIX shell.  */
 #define _POSIX_SHELL	1
 
+/* We cannot support the Timeouts option without _POSIX_THREADS.  */
+#define _POSIX_TIMEOUTS	-1
+
 /* The `spawn' function family is supported.  */
 #define _POSIX_SPAWN	200112L
 
+/* We do not have POSIX timers, but could in future without ABI change.  */
+#define _POSIX_TIMERS	0
+
+/* The barrier functions are not available.  */
+#define _POSIX_BARRIERS	-1
+
+/* POSIX message queues could be available in future.  */
+#define	_POSIX_MESSAGE_PASSING	0
+
+/* Thread process-shared synchronization is not supported.  */
+#define _POSIX_THREAD_PROCESS_SHARED	-1
+
+/* The monotonic clock might be available.  */
+#define _POSIX_MONOTONIC_CLOCK	0
+
+/* The clock selection interfaces are available.  */
+#define _POSIX_CLOCK_SELECTION	200112L
+
+/* Advisory information interfaces could be available in future.  */
+#define _POSIX_ADVISORY_INFO	0
+
+/* IPv6 support is available.  */
+#define _POSIX_IPV6	200112L
+
+/* Raw socket support is available.  */
+#define _POSIX_RAW_SOCKETS	200112L
+
+/* We have at least one terminal.  */
+#define _POSIX2_CHAR_TERM	200112L
+
+/* Neither process nor thread sporadic server interfaces is available.  */
+#define _POSIX_SPORADIC_SERVER	-1
+#define _POSIX_THREAD_SPORADIC_SERVER	-1
+
+/* trace.h is not available.  */
+#define _POSIX_TRACE	-1
+#define _POSIX_TRACE_EVENT_FILTER	-1
+#define _POSIX_TRACE_INHERIT	-1
+#define _POSIX_TRACE_LOG	-1
+
+/* Typed memory objects are not available.  */
+#define _POSIX_TYPED_MEMORY_OBJECTS	-1
+
+/* No support for priority inheritance or protection so far.  */
+#define _POSIX_THREAD_PRIO_INHERIT	-1
+#define _POSIX_THREAD_PRIO_PROTECT	-1
+
+
 #endif /* bits/posix_opt.h */
diff --git a/sysdeps/posix/sysconf.c b/sysdeps/posix/sysconf.c
index cb5137cd76..5a355925da 100644
--- a/sysdeps/posix/sysconf.c
+++ b/sysdeps/posix/sysconf.c
@@ -95,112 +95,112 @@ __sysconf (name)
       return MAX (__tzname_max (), _POSIX_TZNAME_MAX);
 
     case _SC_JOB_CONTROL:
-#ifdef	_POSIX_JOB_CONTROL
-      return 1;
+#if _POSIX_JOB_CONTROL > 0
+      return _POSIX_JOB_CONTROL;
 #else
       return -1;
 #endif
 
     case _SC_SAVED_IDS:
-#ifdef	_POSIX_SAVED_IDS
+#if _POSIX_SAVED_IDS > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_REALTIME_SIGNALS:
-#ifdef	_POSIX_REALTIME_SIGNALS
+#if _POSIX_REALTIME_SIGNALS > 0
       return _POSIX_REALTIME_SIGNALS;
 #else
       return -1;
 #endif
 
     case _SC_PRIORITY_SCHEDULING:
-#ifdef	_POSIX_PRIORITY_SCHEDULING
+#if _POSIX_PRIORITY_SCHEDULING > 0
       return _POSIX_PRIORITY_SCHEDULING;
 #else
       return -1;
 #endif
 
     case _SC_TIMERS:
-#ifdef	_POSIX_TIMERS
+#if _POSIX_TIMERS > 0
       return _POSIX_TIMERS;
 #else
       return -1;
 #endif
 
     case _SC_ASYNCHRONOUS_IO:
-#ifdef	_POSIX_ASYNCHRONOUS_IO
+#if _POSIX_ASYNCHRONOUS_IO > 0
       return _POSIX_ASYNCHRONOUS_IO;
 #else
       return -1;
 #endif
 
     case _SC_PRIORITIZED_IO:
-#ifdef	_POSIX_PRIORITIZED_IO
+#if _POSIX_PRIORITIZED_IO > 0
       return _POSIX_PRIORITIZED_IO;
 #else
       return -1;
 #endif
 
     case _SC_SYNCHRONIZED_IO:
-#ifdef	_POSIX_SYNCHRONIZED_IO
+#if _POSIX_SYNCHRONIZED_IO > 0
       return _POSIX_SYNCHRONIZED_IO;
 #else
       return -1;
 #endif
 
     case _SC_FSYNC:
-#ifdef	_POSIX_FSYNC
+#if _POSIX_FSYNC > 0
       return _POSIX_FSYNC;
 #else
       return -1;
 #endif
 
     case _SC_MAPPED_FILES:
-#ifdef	_POSIX_MAPPED_FILES
+#if _POSIX_MAPPED_FILES > 0
       return _POSIX_MAPPED_FILES;
 #else
       return -1;
 #endif
 
     case _SC_MEMLOCK:
-#ifdef	_POSIX_MEMLOCK
+#if _POSIX_MEMLOCK > 0
       return _POSIX_MEMLOCK;
 #else
       return -1;
 #endif
 
     case _SC_MEMLOCK_RANGE:
-#ifdef	_POSIX_MEMLOCK_RANGE
+#if _POSIX_MEMLOCK_RANGE > 0
       return _POSIX_MEMLOCK_RANGE;
 #else
       return -1;
 #endif
 
     case _SC_MEMORY_PROTECTION:
-#ifdef	_POSIX_MEMORY_PROTECTION
+#if _POSIX_MEMORY_PROTECTION > 0
       return _POSIX_MEMORY_PROTECTION;
 #else
       return -1;
 #endif
 
     case _SC_MESSAGE_PASSING:
-#ifdef	_POSIX_MESSAGE_PASSING
+#if _POSIX_MESSAGE_PASSING > 0
       return _POSIX_MESSAGE_PASSING;
 #else
       return -1;
 #endif
 
     case _SC_SEMAPHORES:
-#ifdef	_POSIX_SEMAPHORES
+#if _POSIX_SEMAPHORES > 0
       return _POSIX_SEMAPHORES;
 #else
       return -1;
 #endif
 
     case _SC_SHARED_MEMORY_OBJECTS:
-#ifdef	_POSIX_SHARED_MEMORY_OBJECTS
+#if _POSIX_SHARED_MEMORY_OBJECTS > 0
       return _POSIX_SHARED_MEMORY_OBJECTS;
 #else
       return -1;
@@ -353,49 +353,49 @@ __sysconf (name)
 #endif
 
     case _SC_PII:
-#ifdef	_POSIX_PII
+#if _POSIX_PII > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_PII_XTI:
-#ifdef	_POSIX_PII_XTI
+#if _POSIX_PII_XTI > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_PII_SOCKET:
-#ifdef	_POSIX_PII_SOCKET
+#if _POSIX_PII_SOCKET > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_PII_INTERNET:
-#ifdef	_POSIX_PII_INTERNET
+#if _POSIX_PII_INTERNET > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_PII_OSI:
-#ifdef	_POSIX_PII_OSI
+#if _POSIX_PII_OSI > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_POLL:
-#ifdef	_POSIX_POLL
+#if _POSIX_POLL > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_SELECT:
-#ifdef	_POSIX_SELECT
+#if _POSIX_SELECT > 0
       return 1;
 #else
       return -1;
@@ -410,35 +410,35 @@ __sysconf (name)
 #endif
 
     case _SC_PII_INTERNET_STREAM:
-#ifdef	_POSIX_PII_INTERNET_STREAM
+#if _POSIX_PII_INTERNET_STREAM > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_PII_INTERNET_DGRAM:
-#ifdef	_POSIX_PII_INTERNET_DGRAM
+#if _POSIX_PII_INTERNET_DGRAM > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_PII_OSI_COTS:
-#ifdef	_POSIX_PII_OSI_COTS
+#if _POSIX_PII_OSI_COTS > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_PII_OSI_CLTS:
-#ifdef	_POSIX_PII_OSI_CLTS
+#if _POSIX_PII_OSI_CLTS > 0
       return 1;
 #else
       return -1;
 #endif
 
     case _SC_PII_OSI_M:
-#ifdef	_POSIX_PII_OSI_M
+#if _POSIX_PII_OSI_M > 0
       return 1;
 #else
       return -1;
@@ -519,14 +519,14 @@ __sysconf (name)
 
       /* POSIX 1003.1c (POSIX Threads).  */
     case _SC_THREADS:
-#ifdef	_POSIX_THREADS
+#if _POSIX_THREADS > 0
       return _POSIX_THREADS;
 #else
       return -1;
 #endif
 
     case _SC_THREAD_SAFE_FUNCTIONS:
-#ifdef	_POSIX_THREAD_SAFE_FUNCTIONS
+#if _POSIX_THREAD_SAFE_FUNCTIONS > 0
       return _POSIX_THREAD_SAFE_FUNCTIONS;
 #else
       return -1;
@@ -553,7 +553,7 @@ __sysconf (name)
 #endif
 
     case _SC_THREAD_DESTRUCTOR_ITERATIONS:
-#ifdef	_POSIX_THREAD_DESTRUCTOR_ITERATIONS
+#if _POSIX_THREAD_DESTRUCTOR_ITERATIONS > 0
       return _POSIX_THREAD_DESTRUCTOR_ITERATIONS;
 #else
       return -1;
@@ -581,42 +581,42 @@ __sysconf (name)
 #endif
 
     case _SC_THREAD_ATTR_STACKADDR:
-#ifdef	_POSIX_THREAD_ATTR_STACKADDR
+#if _POSIX_THREAD_ATTR_STACKADDR > 0
       return _POSIX_THREAD_ATTR_STACKADDR;
 #else
       return -1;
 #endif
 
     case _SC_THREAD_ATTR_STACKSIZE:
-#ifdef	_POSIX_THREAD_ATTR_STACKSIZE
+#if _POSIX_THREAD_ATTR_STACKSIZE > 0
       return _POSIX_THREAD_ATTR_STACKSIZE;
 #else
       return -1;
 #endif
 
     case _SC_THREAD_PRIORITY_SCHEDULING:
-#ifdef	_POSIX_THREAD_PRIORITY_SCHEDULING
+#if _POSIX_THREAD_PRIORITY_SCHEDULING > 0
       return _POSIX_THREAD_PRIORITY_SCHEDULING;
 #else
       return -1;
 #endif
 
     case _SC_THREAD_PRIO_INHERIT:
-#ifdef	_POSIX_THREAD_PRIO_INHERIT
+#if _POSIX_THREAD_PRIO_INHERIT > 0
       return _POSIX_THREAD_PRIO_INHERIT;
 #else
       return -1;
 #endif
 
     case _SC_THREAD_PRIO_PROTECT:
-#ifdef	_POSIX_THREAD_PRIO_PROTECT
+#if _POSIX_THREAD_PRIO_PROTECT > 0
       return _POSIX_THREAD_PRIO_PROTECT;
 #else
       return -1;
 #endif
 
     case _SC_THREAD_PROCESS_SHARED:
-#ifdef	_POSIX_THREAD_PROCESS_SHARED
+#if _POSIX_THREAD_PROCESS_SHARED > 0
       return _POSIX_THREAD_PROCESS_SHARED;
 #else
       return -1;
@@ -816,25 +816,25 @@ __sysconf (name)
 #endif
 
     case _SC_V6_ILP32_OFF32:
-#ifdef _POSIX_V6_ILP32_OFF32
+#if _POSIX_V6_ILP32_OFF32 > 0
       return _POSIX_V6_ILP32_OFF32;
 #else
       return __sysconf_check_spec ("ILP32_OFF32");
 #endif
     case _SC_V6_ILP32_OFFBIG:
-#ifdef _POSIX_V6_ILP32_OFFBIG
+#if _POSIX_V6_ILP32_OFFBIG > 0
       return _POSIX_V6_ILP32_OFFBIG;
 #else
       return __sysconf_check_spec ("ILP32_OFFBIG");
 #endif
     case _SC_V6_LP64_OFF64:
-#ifdef _POSIX_V6_LP64_OFF64
+#if _POSIX_V6_LP64_OFF64 > 0
       return _POSIX_V6_LP64_OFF64;
 #else
       return __sysconf_check_spec ("LP64_OFF64");
 #endif
     case _SC_V6_LPBIG_OFFBIG:
-#ifdef _POSIX_V6_LPBIG_OFFBIG
+#if _POSIX_V6_LPBIG_OFFBIG > 0
       return _POSIX_V6_LPBIG_OFFBIG;
 #else
       return __sysconf_check_spec ("LPBIG_OFFBIG");
@@ -857,40 +857,40 @@ __sysconf (name)
 #endif
 
     case _SC_ADVISORY_INFO:
-#ifdef _POSIX_ADVISORY_INFO
+#if _POSIX_ADVISORY_INFO > 0
       return _POSIX_ADVISORY_INFO;
 #else
       return -1;
 #endif
 
     case _SC_BARRIERS:
-#ifdef _POSIX_BARRIERS
+#if _POSIX_BARRIERS > 0
       return _POSIX_BARRIERS;
 #else
       return -1;
 #endif
 
     case _SC_BASE:
-#ifdef _POSIX_BASE
+#if _POSIX_BASE > 0
       return _POSIX_BASE;
 #else
       return -1;
 #endif
     case _SC_C_LANG_SUPPORT:
-#ifdef _POSIX_C_LANG_SUPPORT
+#if _POSIX_C_LANG_SUPPORT > 0
       return _POSIX_C_LANG_SUPPORT;
 #else
       return -1;
 #endif
     case _SC_C_LANG_SUPPORT_R:
-#ifdef _POSIX_C_LANG_SUPPORT_R
+#if _POSIX_C_LANG_SUPPORT_R > 0
       return _POSIX_C_LANG_SUPPORT_R;
 #else
       return -1;
 #endif
 
     case _SC_CLOCK_SELECTION:
-#ifdef _POSIX_CLOCK_SELECTION
+#if _POSIX_CLOCK_SELECTION > 0
       return _POSIX_CLOCK_SELECTION;
 #else
       return -1;
@@ -904,58 +904,58 @@ __sysconf (name)
 #endif
 
     case _SC_DEVICE_IO:
-#ifdef _POSIX_DEVICE_IO
+#if _POSIX_DEVICE_IO > 0
       return _POSIX_DEVICE_IO;
 #else
       return -1;
 #endif
     case _SC_DEVICE_SPECIFIC:
-#ifdef _POSIX_DEVICE_SPCIFIC
+#if _POSIX_DEVICE_SPCIFIC > 0
       return _POSIX_DEVICE_SPECIFIC;
 #else
       return -1;
 #endif
     case _SC_DEVICE_SPECIFIC_R:
-#ifdef _POSIX_DEVICE_SPCIFIC_R
+#if _POSIX_DEVICE_SPCIFIC_R > 0
       return _POSIX_DEVICE_SPECIFIC_R;
 #else
       return -1;
 #endif
 
     case _SC_FD_MGMT:
-#ifdef _POSIX_FD_MGMT
+#if _POSIX_FD_MGMT > 0
       return _POSIX_FD_MGMT;
 #else
       return -1;
 #endif
 
     case _SC_FIFO:
-#ifdef _POSIX_FIFO
+#if _POSIX_FIFO > 0
       return _POSIX_FIFO;
 #else
       return -1;
 #endif
     case _SC_PIPE:
-#ifdef _POSIX_PIPE
+#if _POSIX_PIPE > 0
       return _POSIX_PIPE;
 #else
       return -1;
 #endif
 
     case _SC_FILE_ATTRIBUTES:
-#ifdef _POSIX_FILE_ATTRIBUTES
+#if _POSIX_FILE_ATTRIBUTES > 0
       return _POSIX_FILE_ATTRIBUTES;
 #else
       return -1;
 #endif
     case _SC_FILE_LOCKING:
-#ifdef _POSIX_FILE_LOCKING
+#if _POSIX_FILE_LOCKING > 0
       return _POSIX_FILE_LOCKING;
 #else
       return -1;
 #endif
     case _SC_FILE_SYSTEM:
-#ifdef _POSIX_FILE_SYSTEM
+#if _POSIX_FILE_SYSTEM > 0
       return _POSIX_FILE_SYSTEM;
 #else
       return -1;
@@ -969,53 +969,53 @@ __sysconf (name)
 #endif
 
     case _SC_MULTI_PROCESS:
-#ifdef _POSIX_MULTI_PROCESS
+#if _POSIX_MULTI_PROCESS > 0
       return _POSIX_MULTI_PROCESS;
 #else
       return -1;
 #endif
     case _SC_SINGLE_PROCESS:
-#ifdef _POSIX_SINGLE_PROCESS
+#if _POSIX_SINGLE_PROCESS > 0
       return _POSIX_SINGLE_PROCESS;
 #else
       return -1;
 #endif
 
     case _SC_NETWORKING:
-#ifdef _POSIX_NETWORKING
+#if _POSIX_NETWORKING > 0
       return _POSIX_NETWORKING;
 #else
       return -1;
 #endif
 
     case _SC_READER_WRITER_LOCKS:
-#ifdef _POSIX_READER_WRITER_LOCKS
+#if _POSIX_READER_WRITER_LOCKS > 0
       return _POSIX_READER_WRITER_LOCKS;
 #else
       return -1;
 #endif
     case _SC_SPIN_LOCKS:
-#ifdef _POSIX_SPIN_LOCKS
+#if _POSIX_SPIN_LOCKS > 0
       return _POSIX_SPIN_LOCKS;
 #else
       return -1;
 #endif
 
     case _SC_REGEXP:
-#ifdef _POSIX_REGEXP
+#if _POSIX_REGEXP > 0
       return _POSIX_REGEXP;
 #else
       return -1;
 #endif
     case _SC_REGEX_VERSION:
-#ifdef _POSIX_REGEX_VERSION
+#if _POSIX_REGEX_VERSION > 0
       return _POSIX_REGEX_VERSION;
 #else
       return -1;
 #endif
 
     case _SC_SHELL:
-#ifdef _POSIX_SHELL
+#if _POSIX_SHELL > 0
       return _POSIX_SHELL;
 #else
       return -1;
@@ -1029,33 +1029,33 @@ __sysconf (name)
 #endif
 
     case _SC_SPAWN:
-#ifdef _POSIX_SPAWN
+#if _POSIX_SPAWN > 0
       return _POSIX_SPAWN;
 #else
       return -1;
 #endif
 
     case _SC_SPORADIC_SERVER:
-#ifdef _POSIX_SPORADIC_SERVER
+#if _POSIX_SPORADIC_SERVER > 0
       return _POSIX_SPORADIC_SERVER;
 #else
       return -1;
 #endif
     case _SC_THREAD_SPORADIC_SERVER:
-#ifdef _POSIX_THREAD_SPORADIC_SERVER
+#if _POSIX_THREAD_SPORADIC_SERVER > 0
       return _POSIX_THREAD_SPORADIC_SERVER;
 #else
       return -1;
 #endif
 
     case _SC_SYSTEM_DATABASE:
-#ifdef _POSIX_SYSTEM_DATABASE
+#if _POSIX_SYSTEM_DATABASE > 0
       return _POSIX_SYSTEM_DATABASE;
 #else
       return -1;
 #endif
     case _SC_SYSTEM_DATABASE_R:
-#ifdef _POSIX_SYSTEM_DATABASE_R
+#if _POSIX_SYSTEM_DATABASE_R > 0
       return _POSIX_SYSTEM_DATABASE_R;
 #else
       return -1;
@@ -1069,27 +1069,27 @@ __sysconf (name)
 #endif
 
     case _SC_TIMEOUTS:
-#ifdef _POSIX_TIMEOUTS
+#if _POSIX_TIMEOUTS > 0
       return _POSIX_TIMEOUTS;
 #else
       return -1;
 #endif
 
     case _SC_TYPED_MEMORY_OBJECTS:
-#ifdef _POSIX_TYPED_MEMORY_OBJECTS
+#if _POSIX_TYPED_MEMORY_OBJECTS > 0
       return _POSIX_TYPED_MEMORY_OBJECTS;
 #else
       return -1;
 #endif
 
     case _SC_USER_GROUPS:
-#ifdef _POSIX_USER_GROUPS
+#if _POSIX_USER_GROUPS > 0
       return _POSIX_USER_GROUPS;
 #else
       return -1;
 #endif
     case _SC_USER_GROUPS_R:
-#ifdef _POSIX_USER_GROUPS_R
+#if _POSIX_USER_GROUPS_R > 0
       return _POSIX_USER_GROUPS_R;
 #else
       return -1;
@@ -1154,25 +1154,25 @@ __sysconf (name)
 #endif
 
     case _SC_TRACE:
-#ifdef _POSIX_TRACE
+#if _POSIX_TRACE > 0
       return _POSIX_TRACE;
 #else
       return -1;
 #endif
     case _SC_TRACE_EVENT_FILTER:
-#ifdef _POSIX_TRACE_EVENT_FILTER
+#if _POSIX_TRACE_EVENT_FILTER > 0
       return _POSIX_TRACE_EVENT_FILTER;
 #else
       return -1;
 #endif
     case _SC_TRACE_INHERIT:
-#ifdef _POSIX_TRACE_INHERIT
+#if _POSIX_TRACE_INHERIT > 0
       return _POSIX_TRACE_INHERIT;
 #else
       return -1;
 #endif
     case _SC_TRACE_LOG:
-#ifdef _POSIX_TRACE_LOG
+#if _POSIX_TRACE_LOG > 0
       return _POSIX_TRACE_LOG;
 #else
       return -1;
@@ -1198,14 +1198,14 @@ __sysconf (name)
       return 0;
 
     case _SC_IPV6:
-#ifdef _POSIX_IPV6
+#if _POSIX_IPV6 > 0
       return _POSIX_IPV6;
 #else
       return -1;
 #endif
 
     case _SC_RAW_SOCKETS:
-#ifdef _POSIX_RAW_SOCKETS
+#if _POSIX_RAW_SOCKETS > 0
       return _POSIX_RAW_SOCKETS;
 #else
       return -1;
diff --git a/sysdeps/unix/sysv/linux/sysconf.c b/sysdeps/unix/sysv/linux/sysconf.c
index 3cf6aa70bb..f9f6f1bfa5 100644
--- a/sysdeps/unix/sysv/linux/sysconf.c
+++ b/sysdeps/unix/sysv/linux/sysconf.c
@@ -1,5 +1,5 @@
 /* Get file-specific information about a file.  Linux version.
-   Copyright (C) 2003, 2004 Free Software Foundation, Inc.
+   Copyright (C) 2003, 2004, 2006 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -48,6 +48,28 @@ __sysconf (int name)
       }
 #endif
 
+#if defined __NR_clock_getres || HP_TIMING_AVAIL
+    case _SC_CPUTIME:
+    case _SC_THREAD_CPUTIME:
+      {
+	/* If we have HP_TIMING, we will fall back on that if the system
+	   call does not work, so we support it either way.  */
+# if !HP_TIMING_AVAIL
+	/* Check using the clock_getres system call.  */
+	struct timespec ts;
+	INTERNAL_SYSCALL_DECL (err);
+	int r = INTERNAL_SYSCALL (clock_getres, err, 2,
+				  (name == _SC_CPUTIME
+				   ? CLOCK_PROCESS_CPUTIME_ID
+				   : CLOCK_THREAD_CPUTIME_ID),
+				  &ts);
+	if (INTERNAL_SYSCALL_ERROR_P (r, err))
+	  return -1;
+# endif
+	return _POSIX_VERSION;
+      }
+#endif
+
     case _SC_NGROUPS_MAX:
       /* Try to read the information from the /proc/sys/kernel/ngroups_max
 	 file.  */