diff --git a/docs/users_guide/runtime_control.rst b/docs/users_guide/runtime_control.rst
index 8ab6b2c8ea1a35d7d54eb4df97c6c2808bcbdf8b..370593d207e1658478479507ebc1c69c2b780c57 100644
--- a/docs/users_guide/runtime_control.rst
+++ b/docs/users_guide/runtime_control.rst
@@ -308,6 +308,23 @@ Miscellaneous RTS options
undue memory usage shown in reporting tools, so with this flag it can
be turned off.
+.. rts-flag:: --io-manager=(name)
+
+ Select the I/O manager to use. On some combinations of platform and
+ threaded/non-threaded RTS way there is a choice of more than one
+ implementation of I/O manager. This flag lets you override the default
+ and select one by name.
+
+ Currently the available I/O managers are:
+
+ ================ ========= ============
+ Name Platforms RTS way
+ ================ ========= ============
+ ``select`` Posix Non-threaded
+ ``mio`` All Threaded
+ ``win32-legacy`` Windows Non-threaded
+ ``winio`` Windows All
+ ================ ========= ============
.. rts-flag:: -xp
diff --git a/libraries/base/src/GHC/RTS/Flags.hs b/libraries/base/src/GHC/RTS/Flags.hs
index e9e2f00f185cd7ed912ba348ebc04395dd3b966e..24dd2203de745e0fc8956d440fead02de0d482b6 100644
--- a/libraries/base/src/GHC/RTS/Flags.hs
+++ b/libraries/base/src/GHC/RTS/Flags.hs
@@ -25,6 +25,7 @@ module GHC.RTS.Flags
, GCFlags (..)
, ConcFlags (..)
, MiscFlags (..)
+ , IoManagerFlag (..)
, DebugFlags (..)
, DoCostCentres (..)
, CCFlags (..)
@@ -35,12 +36,12 @@ module GHC.RTS.Flags
, TickyFlags (..)
, ParFlags (..)
, HpcFlags (..)
- , IoSubSystem (..)
+ , {-# DEPRECATED "import GHC.IO.SubSystem (IoSubSystem (..))" #-}
+ IoSubSystem (..)
, getRTSFlags
, getGCFlags
, getConcFlags
, getMiscFlags
- , getIoManagerFlag
, getDebugFlags
, getCCFlags
, getProfFlags
@@ -51,3 +52,4 @@ module GHC.RTS.Flags
) where
import GHC.Internal.RTS.Flags
+import GHC.Internal.IO.SubSystem (IoSubSystem(..))
diff --git a/libraries/ghc-internal/src/GHC/Internal/IO/SubSystem.hs b/libraries/ghc-internal/src/GHC/Internal/IO/SubSystem.hs
index e62e3e947332e0ffeaa521f9bdcd485637c09ecc..747e5a48b48c4f4d5fa801fc8bb3e32fdc9809ed 100644
--- a/libraries/ghc-internal/src/GHC/Internal/IO/SubSystem.hs
+++ b/libraries/ghc-internal/src/GHC/Internal/IO/SubSystem.hs
@@ -34,14 +34,27 @@ module GHC.Internal.IO.SubSystem (
) where
import GHC.Internal.Base
-import GHC.Internal.RTS.Flags
#if defined(mingw32_HOST_OS)
import GHC.Internal.IO.Unsafe
+import GHC.Internal.Foreign.Ptr
+import GHC.Internal.Foreign.Storable
+import GHC.Internal.Foreign.C.Types
+import GHC.Internal.Foreign.Marshal.Utils
#endif
infixl 7 <!>
+-- | The I/O SubSystem to use in the program.
+--
+-- @since base-4.9.0.0
+data IoSubSystem
+ = IoPOSIX -- ^ Use a POSIX I/O Sub-System
+ | IoNative -- ^ Use platform native Sub-System. For unix OSes this is the
+ -- same as IoPOSIX, but on Windows this means use the Windows
+ -- native APIs for I/O, including IOCP and RIO.
+ deriving (Eq)
+
-- | Conditionally execute an action depending on the configured I/O subsystem.
-- On POSIX systems always execute the first action.
-- On Windows execute the second action if WINIO as active, otherwise fall back to
@@ -64,10 +77,37 @@ conditional posix _ = posix
isWindowsNativeIO :: Bool
isWindowsNativeIO = False <!> True
+-- | The 'IoSubSystem' in use.
+--
+-- This is needed to optimize support for different IO Managers on Windows.
+-- GHC supports both the new WinIO manager as well as the old MIO (threaded),
+-- and ancient win32-legacy (non-threaded) ones. The WinIO manager uses native
+-- Win32 HANDLEs, whereas the other two use posix style FDs (via translation
+-- layers).
+--
+-- In many places in the I\/O base library code, for correctness or performance
+-- on Windows, we have to take different code paths depending on which style of
+-- IO manager is in use. The IO manager is set on RTS startup (and the default
+-- choice can be overridden using RTS flags). On Windows this value is obtained
+-- by reading a global variable that is set by the RTS IOManager on startup.
+--
+-- On non-Windows systems this value is always 'IoPOSIX'.
+--
ioSubSystem :: IoSubSystem
#if defined(mingw32_HOST_OS)
-{-# NOINLINE ioSubSystem #-}
-ioSubSystem = unsafeDupablePerformIO getIoManagerFlag
+{-# INLINE ioSubSystem #-}
+ioSubSystem =
+ case toBool ioManagerIsWin32NativeCBool of
+ False -> IoPOSIX
+ True -> IoNative
+
+{-# NOINLINE ioManagerIsWin32NativeCBool #-}
+ioManagerIsWin32NativeCBool :: CBool
+ioManagerIsWin32NativeCBool =
+ unsafeDupablePerformIO $ peek ioManagerIsWin32NativePtr
+
+foreign import ccall "&rts_IOManagerIsWin32Native"
+ ioManagerIsWin32NativePtr :: Ptr CBool
#else
ioSubSystem = IoPOSIX
#endif
diff --git a/libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc b/libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc
index 4a3e941762899ec6318fcf4c7a31c441cdd6b32c..c11346659a981f4e5dddd44fdb2819892f200347 100644
--- a/libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc
+++ b/libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc
@@ -27,6 +27,7 @@ module GHC.Internal.RTS.Flags
, GCFlags (..)
, ConcFlags (..)
, MiscFlags (..)
+ , IoManagerFlag (..)
, DebugFlags (..)
, DoCostCentres (..)
, CCFlags (..)
@@ -37,12 +38,10 @@ module GHC.Internal.RTS.Flags
, TickyFlags (..)
, ParFlags (..)
, HpcFlags (..)
- , IoSubSystem (..)
, getRTSFlags
, getGCFlags
, getConcFlags
, getMiscFlags
- , getIoManagerFlag
, getDebugFlags
, getCCFlags
, getProfFlags
@@ -103,32 +102,6 @@ instance Enum GiveGCStats where
toEnum #{const VERBOSE_GC_STATS} = VerboseGCStats
toEnum e = errorWithoutStackTrace ("invalid enum for GiveGCStats: " ++ show e)
--- | The I/O SubSystem to use in the program.
---
--- @since base-4.9.0.0
-data IoSubSystem
- = IoPOSIX -- ^ Use a POSIX I/O Sub-System
- | IoNative -- ^ Use platform native Sub-System. For unix OSes this is the
- -- same as IoPOSIX, but on Windows this means use the Windows
- -- native APIs for I/O, including IOCP and RIO.
- deriving (Eq, Show)
-
--- | @since base-4.9.0.0
-instance Enum IoSubSystem where
- fromEnum IoPOSIX = #{const IO_MNGR_POSIX}
- fromEnum IoNative = #{const IO_MNGR_NATIVE}
-
- toEnum #{const IO_MNGR_POSIX} = IoPOSIX
- toEnum #{const IO_MNGR_NATIVE} = IoNative
- toEnum e = errorWithoutStackTrace ("invalid enum for IoSubSystem: " ++ show e)
-
--- | @since base-4.9.0.0
-instance Storable IoSubSystem where
- sizeOf = sizeOf . fromEnum
- alignment = sizeOf . fromEnum
- peek ptr = fmap toEnum $ peek (castPtr ptr)
- poke ptr v = poke (castPtr ptr) (fromEnum v)
-
-- | Parameters of the garbage collector.
--
-- @since base-4.8.0.0
@@ -191,12 +164,20 @@ data MiscFlags = MiscFlags
, linkerAlwaysPic :: Bool
, linkerMemBase :: Word
-- ^ address to ask the OS for memory for the linker, 0 ==> off
- , ioManager :: IoSubSystem
+ , ioManager :: IoManagerFlag
, numIoWorkerThreads :: Word32
} deriving ( Show -- ^ @since base-4.8.0.0
, Generic -- ^ @since base-4.15.0.0
)
+data IoManagerFlag =
+ IoManagerFlagAuto
+ | IoManagerFlagSelect -- ^ Unix only, non-threaded RTS only
+ | IoManagerFlagMIO -- ^ cross-platform, threaded RTS only
+ | IoManagerFlagWinIO -- ^ Windows only
+ | IoManagerFlagWin32Legacy -- ^ Windows only, non-threaded RTS only
+ deriving (Eq, Enum, Show)
+
-- | Flags to control debugging output & extra checking in various
-- subsystems.
--
@@ -552,36 +533,6 @@ getMiscFlags = do
<*> (fromIntegral
<$> (#{peek MISC_FLAGS, numIoWorkerThreads} ptr :: IO Word32))
-{- Note [The need for getIoManagerFlag]
- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
- GHC supports both the new WINIO manager
- as well as the old MIO one. In order to
- decide which code path to take we often
- have to inspect what the user selected at
- RTS startup.
-
- We could use getMiscFlags but then we end up with core containing
- reads for all MiscFlags. These won't be eliminated at the core level
- even if it's obvious we will only look at the ioManager part of the
- ADT.
-
- We could add a INLINE pragma, but that just means whatever we inline
- into is likely to be inlined. So rather than adding a dozen pragmas
- we expose a lean way to query this particular flag. It's not satisfying
- but it works well enough and allows these checks to be inlined nicely.
-
--}
-
-{-# INLINE getIoManagerFlag #-}
--- | Needed to optimize support for different IO Managers on Windows.
--- See Note [The need for getIoManagerFlag]
-getIoManagerFlag :: IO IoSubSystem
-getIoManagerFlag = do
- let ptr = (#ptr RTS_FLAGS, MiscFlags) rtsFlagsPtr
- mgrFlag <- (#{peek MISC_FLAGS, ioManager} ptr :: IO Word32)
- return $ (toEnum . fromIntegral) mgrFlag
-
getDebugFlags :: IO DebugFlags
getDebugFlags = do
let ptr = (#ptr RTS_FLAGS, DebugFlags) rtsFlagsPtr
diff --git a/rts/IOManager.c b/rts/IOManager.c
index 74d48ed5414e8c1868aacb7b1cbc284206066c72..2592ea4826de5c0cda9850694a31854b1e397e66 100644
--- a/rts/IOManager.c
+++ b/rts/IOManager.c
@@ -33,6 +33,174 @@
#include "win32/AsyncWinIO.h"
#endif
+#include <string.h>
+
+
+/* Global var to tell us which I/O manager impl we are using */
+IOManagerType iomgr_type;
+
+#if defined(mingw32_HOST_OS)
+/* Global var (only on Windows) that is exported to be shared with the I/O code
+ * in the base library to tell us which style of I/O manager we are using: one
+ * that uses the Windows native API HANDLEs, or one that uses Posix style fds.
+ */
+bool rts_IOManagerIsWin32Native = false;
+#endif
+
+enum IOManagerAvailability
+parseIOManagerFlag(const char *iomgrstr, IO_MANAGER_FLAG *flag)
+{
+ if (strcmp("select", iomgrstr) == 0) {
+#if defined(IOMGR_ENABLED_SELECT)
+ *flag = IO_MNGR_FLAG_SELECT;
+ return IOManagerAvailable;
+#else
+ return IOManagerUnavailable;
+#endif
+ }
+ else if (strcmp("mio", iomgrstr) == 0) {
+#if defined(IOMGR_ENABLED_MIO_POSIX) || defined(IOMGR_ENABLED_MIO_WIN32)
+ *flag = IO_MNGR_FLAG_MIO;
+ return IOManagerAvailable;
+#else
+ return IOManagerUnavailable;
+#endif
+ *flag = IO_MNGR_FLAG_MIO;
+ }
+ else if (strcmp("winio", iomgrstr) == 0) {
+#if defined(IOMGR_ENABLED_WINIO)
+ *flag = IO_MNGR_FLAG_WINIO;
+ return IOManagerAvailable;
+#else
+ return IOManagerUnavailable;
+#endif
+ }
+ else if (strcmp("win32-legacy", iomgrstr) == 0) {
+#if defined(IOMGR_ENABLED_WIN32_LEGACY)
+ *flag = IO_MNGR_FLAG_WIN32_LEGACY;
+ return IOManagerAvailable;
+#else
+ return IOManagerUnavailable;
+#endif
+ }
+ else if (strcmp("auto", iomgrstr) == 0) {
+ *flag = IO_MNGR_FLAG_AUTO;
+ return IOManagerAvailable;
+ }
+ /* Two deprecated aliases. These aliases only had any effect on Windows,
+ * but were available as RTS flags on all platforms. The "native" flag
+ * refers to the newer Windows WinIO IO manager (threaded or non-threaded),
+ * while (somewhat confusingly) the "posix" flag refers to the older
+ * Windows I/O managers (win32-legacy and mio). On non-Windows, we now make
+ * these flags equivalent to IO_MNGR_FLAG_AUTO.
+ */
+ else if (strcmp("native", iomgrstr) == 0) {
+#if defined(mingw32_HOST_OS)
+ /* On windows "native" is now an alias for IO_MNGR_FLAG_WINIO */
+#if defined(IOMGR_ENABLED_WINIO)
+ *flag = IO_MNGR_FLAG_WINIO;
+ return IOManagerAvailable;
+#else
+ return IOManagerUnavailable;
+#endif
+#else // !defined(mingw32_HOST_OS)
+ *flag = IO_MNGR_FLAG_AUTO;
+ return IOManagerAvailable;
+#endif
+ }
+ else if (strcmp("posix", iomgrstr) == 0) {
+#if defined(mingw32_HOST_OS)
+ /* On Windows "posix" is now an alias for either IO_MNGR_FLAG_MIO or
+ * IO_MNGR_FLAG_WIN32_LEGACY */
+#if defined(IOMGR_ENABLED_MIO_WIN32)
+ *flag = IO_MNGR_FLAG_MIO;
+ return IOManagerAvailable;
+#elif defined(IOMGR_ENABLED_WIN32_LEGACY)
+ *flag = IO_MNGR_FLAG_WIN32_LEGACY;
+ return IOManagerAvailable;
+#else
+ return IOManagerUnavailable;
+#endif
+#else // !defined(mingw32_HOST_OS)
+ *flag = IO_MNGR_FLAG_AUTO;
+ return IOManagerAvailable;
+#endif
+ }
+ else {
+ return IOManagerUnrecognised;
+ }
+}
+
+/* Based on the I/O manager RTS flag, select an I/O manager to use.
+ *
+ * This fills in the iomgr_type and rts_IOManagerIsWin32Native globals.
+ * Must be called before the I/O manager is started.
+ */
+static void selectIOManager(void)
+{
+ switch (RtsFlags.MiscFlags.ioManager) {
+ case IO_MNGR_FLAG_AUTO:
+#if defined(THREADED_RTS)
+#if defined(IOMGR_DEFAULT_THREADED_MIO)
+#if defined(mingw32_HOST_OS)
+ iomgr_type = IO_MANAGER_MIO_WIN32;
+#else
+ iomgr_type = IO_MANAGER_MIO_POSIX;
+#endif
+#elif defined(IOMGR_DEFAULT_THREADED_WINIO)
+ iomgr_type = IO_MANAGER_WINIO;
+#else
+#error No I/O default manager. See IOMGR_DEFAULT_THREADED_ flags
+#endif
+#else // !defined(THREADED_RTS)
+#if defined(IOMGR_DEFAULT_NON_THREADED_SELECT)
+ iomgr_type = IO_MANAGER_SELECT;
+#elif defined(IOMGR_DEFAULT_NON_THREADED_WINIO)
+ iomgr_type = IO_MANAGER_WINIO;
+#elif defined(IOMGR_DEFAULT_NON_THREADED_WIN32_LEGACY)
+ iomgr_type = IO_MANAGER_WIN32_LEGACY;
+#else
+#error No I/O default manager. See IOMGR_DEFAULT_NON_THREADED_ flags
+#endif
+#endif
+ break;
+
+#if defined(IOMGR_ENABLED_SELECT)
+ case IO_MNGR_FLAG_SELECT:
+ iomgr_type = IO_MANAGER_SELECT;
+ break;
+#endif
+
+#if defined(IOMGR_ENABLED_MIO_POSIX)
+ case IO_MNGR_FLAG_MIO:
+ iomgr_type = IO_MANAGER_MIO_POSIX;
+ break;
+#endif
+
+#if defined(IOMGR_ENABLED_MIO_WIN32)
+ case IO_MNGR_FLAG_MIO:
+ iomgr_type = IO_MANAGER_MIO_WIN32;
+ break;
+#endif
+
+#if defined(IOMGR_ENABLED_WINIO)
+ case IO_MNGR_FLAG_WINIO:
+ iomgr_type = IO_MANAGER_WINIO;
+ rts_IOManagerIsWin32Native = true;
+ break;
+#endif
+
+#if defined(IOMGR_ENABLED_WIN32_LEGACY)
+ case IO_MNGR_FLAG_WIN32_LEGACY:
+ iomgr_type = IO_MANAGER_WIN32_LEGACY;
+ break;
+#endif
+
+ default:
+ barf("selectIOManager: %d", RtsFlags.MiscFlags.ioManager);
+ }
+}
+
/* Allocate and initialise the per-capability CapIOManager that lives in each
* Capability. Called early in the RTS initialisation.
@@ -62,6 +230,7 @@ void initCapabilityIOManager(CapIOManager **piomgr)
void
initIOManager(void)
{
+ selectIOManager();
#if defined(THREADED_RTS)
/* Posix implementation in posix/Signals.c
@@ -217,3 +386,18 @@ void insertIntoSleepingQueue(Capability *cap, StgTSO *tso, LowResTime target)
}
}
#endif
+
+/* Temporary compat helper function used in the Win32 I/O managers.
+ * TODO: replace by consulting the iomgr_type global instead.
+ */
+bool is_io_mng_native_p (void)
+{
+ switch (iomgr_type) {
+#if defined(IOMGR_ENABLED_WINIO)
+ case IO_MANAGER_WINIO:
+ return true;
+#endif
+ default:
+ return false;
+ }
+}
diff --git a/rts/IOManager.h b/rts/IOManager.h
index df5f72cdd840c0135673541f56b82d7fc0a026b9..1e34d6b16650391229216529794aa425ce7e00e0 100644
--- a/rts/IOManager.h
+++ b/rts/IOManager.h
@@ -122,6 +122,60 @@
IOMGR_ENABLED_STR_WINIO \
IOMGR_ENABLED_STR_WIN32_LEGACY
+/* An enumeration of all the available I/O managers. We use conditional
+ * compilation to help us optimise out unavailable choices. To help us
+ * do that correctly, we only define choices that are available.
+ */
+typedef enum {
+#if defined(IOMGR_ENABLED_SELECT)
+ IO_MANAGER_SELECT,
+#endif
+#if defined(IOMGR_ENABLED_MIO_POSIX)
+ IO_MANAGER_MIO_POSIX,
+#endif
+#if defined(IOMGR_ENABLED_MIO_WIN32)
+ IO_MANAGER_MIO_WIN32,
+#endif
+#if defined(IOMGR_ENABLED_WINIO)
+ IO_MANAGER_WINIO,
+#endif
+#if defined(IOMGR_ENABLED_WIN32_LEGACY)
+ IO_MANAGER_WIN32_LEGACY,
+#endif
+} IOManagerType;
+
+/* Global var to tell us which I/O manager impl we are using */
+extern IOManagerType iomgr_type;
+
+#if defined(mingw32_HOST_OS)
+/* Global var (only on Windows) that is exported to be shared with the I/O code
+ * in the base library to tell us which style of I/O manager we are using: one
+ * that uses the Windows native API HANDLEs, or one that uses Posix style fds.
+ */
+extern bool rts_IOManagerIsWin32Native;
+#endif
+
+
+/* Parse the I/O manager flag value, returning if is available, unavailable or
+ * unrecognised.
+ *
+ * If it is available, the passed-in IO_MANAGER_FLAG value will be filled in
+ * to record what was requested.
+ *
+ * Called in the RTS flag processing by procRtsOpts.
+ */
+enum IOManagerAvailability {
+ IOManagerAvailable,
+ IOManagerUnavailable,
+ IOManagerUnrecognised
+};
+enum IOManagerAvailability
+parseIOManagerFlag(const char *iomgrstr, IO_MANAGER_FLAG *flag);
+
+/* Temporary compat helper function used in the Win32 I/O managers.
+ * TODO: replace by consulting the iomgr_type global instead.
+ */
+bool is_io_mng_native_p (void);
/* The per-capability data structures belonging to the I/O manager.
*
diff --git a/rts/RtsFlags.c b/rts/RtsFlags.c
index 9e26df76f5e0ebb9ec72e7d5445b287a8fddd2df..e74499954badb1c1497fc39b5ba6c674f23c571d 100644
--- a/rts/RtsFlags.c
+++ b/rts/RtsFlags.c
@@ -269,11 +269,7 @@ void initRtsFlagsDefaults(void)
RtsFlags.MiscFlags.internalCounters = false;
RtsFlags.MiscFlags.linkerAlwaysPic = DEFAULT_LINKER_ALWAYS_PIC;
RtsFlags.MiscFlags.linkerMemBase = 0;
-#if defined(DEFAULT_NATIVE_IO_MANAGER)
- RtsFlags.MiscFlags.ioManager = IO_MNGR_NATIVE;
-#else
- RtsFlags.MiscFlags.ioManager = IO_MNGR_POSIX;
-#endif
+ RtsFlags.MiscFlags.ioManager = IO_MNGR_FLAG_AUTO;
#if defined(THREADED_RTS) && defined(mingw32_HOST_OS)
RtsFlags.MiscFlags.numIoWorkerThreads = getNumberOfProcessors();
#else
@@ -533,8 +529,10 @@ usage_text[] = {
" fatal error. When symbols are available an attempt will be",
" made to resolve addresses to names. (default: yes)",
#endif
-" --io-manager=<native|posix>",
-" The I/O manager subsystem to use. (default: posix)",
+" --io-manager=<name>",
+" The I/O manager to use.",
+" Options available: auto" IOMGRS_ENABLED_STR
+ " (default: " IOMGR_DEFAULT_STR ")",
#if defined(THREADED_RTS)
#if defined(mingw32_HOST_OS)
" --io-manager-threads=<num>",
@@ -1013,15 +1011,23 @@ error = true;
OPTION_SAFE;
RtsFlags.MiscFlags.internalCounters = true;
}
- else if (strequal("io-manager=native",
- &rts_argv[arg][2])) {
- OPTION_UNSAFE;
- RtsFlags.MiscFlags.ioManager = IO_MNGR_NATIVE;
- }
- else if (strequal("io-manager=posix",
- &rts_argv[arg][2])) {
+ else if (!strncmp("io-manager=",
+ &rts_argv[arg][2], 11)) {
OPTION_UNSAFE;
- RtsFlags.MiscFlags.ioManager = IO_MNGR_POSIX;
+ char *iomgrstr = &rts_argv[arg][13];
+ IO_MANAGER_FLAG iomgrflag;
+ enum IOManagerAvailability availability;
+ availability = parseIOManagerFlag(iomgrstr, &iomgrflag);
+ if (availability == IOManagerAvailable) {
+ RtsFlags.MiscFlags.ioManager = iomgrflag;
+ } else {
+ errorBelch("%s choice '%s' for --io-manager=\n"
+ "The choices are: auto%s",
+ availability == IOManagerUnavailable ?
+ "unavailable" : "unrecognised",
+ iomgrstr, IOMGRS_ENABLED_STR);
+ stg_exit(EXIT_FAILURE);
+ }
}
else if (strequal("info",
&rts_argv[arg][2])) {
@@ -2722,16 +2728,6 @@ files like <progname>.eventlog, not arbitrary files.
Helper utilities to query state.
------------------------------------------------------------------------- */
-bool is_io_mng_native_p (void)
-{
-#if defined(mingw32_HOST_OS)
- return RtsFlags.MiscFlags.ioManager == IO_MNGR_NATIVE;
-#else
- return false;
-#endif
-}
-
-
#if defined(PROFILING)
bool
doingLDVProfiling( void )
diff --git a/rts/RtsFlags.h b/rts/RtsFlags.h
index 05a00af4e773fa3b35f25c01a658e0c191fad22d..2395a03aaa07c63036df50d413fedcff3cd73fb4 100644
--- a/rts/RtsFlags.h
+++ b/rts/RtsFlags.h
@@ -23,7 +23,6 @@ char** getUTF8Args(int* argc);
void initRtsFlagsDefaults (void);
void setupRtsFlags (int *argc, char *argv[], RtsConfig rtsConfig);
void freeRtsArgs (void);
-bool is_io_mng_native_p (void);
#if defined(PROFILING)
bool doingLDVProfiling (void);
bool doingRetainerProfiling(void);
diff --git a/rts/RtsSymbols.c b/rts/RtsSymbols.c
index 9b908ee227c0d147ec82aed5f6f5554e6a6f3db3..285049a3066cc4cb2d401bfa463d16810924d88c 100644
--- a/rts/RtsSymbols.c
+++ b/rts/RtsSymbols.c
@@ -28,6 +28,7 @@
#include <io.h>
#include <windows.h>
#include <shfolder.h> /* SHGetFolderPathW */
+#include "IOManager.h"
#include "win32/AsyncWinIO.h"
#endif
@@ -166,6 +167,7 @@ extern char **environ;
SymI_HasProto(stg_asyncWritezh) \
SymI_HasProto(stg_asyncDoProczh) \
SymI_HasProto(rts_InstallConsoleEvent) \
+ SymI_HasProto(rts_IOManagerIsWin32Native) \
SymI_HasProto(rts_ConsoleHandlerDone) \
SymI_NeedsProto(__mingw_module_is_dll) \
RTS_WIN32_ONLY(SymI_NeedsProto(___chkstk_ms)) \
diff --git a/rts/configure.ac b/rts/configure.ac
index d1ae16fe407c638edf7369ef60d8dfb31fd43f13..5819e68d29b8952da403df84d3dd335e017c362b 100644
--- a/rts/configure.ac
+++ b/rts/configure.ac
@@ -37,16 +37,6 @@ if test "$enable_asserts_all_ways" = "yes" ; then
AC_DEFINE([USE_ASSERTS_ALL_WAYS], [1], [Compile-in ASSERTs in all ways.])
fi
-AC_ARG_ENABLE(native-io-manager,
-[AS_HELP_STRING([--enable-native-io-manager],
- [Enable the native I/O manager by default.])],
- [FP_CAPITALIZE_YES_NO(["$enableval"], [EnableNativeIOManager])],
- [EnableNativeIOManager=NO]
-)
-if test "$EnableNativeIOManager" = "YES"; then
- AC_DEFINE_UNQUOTED([DEFAULT_NATIVE_IO_MANAGER], [1], [Enable Native I/O manager as default.])
-fi
-
# We have to run these unconditionally, but we may discard their
# results in the following code
AC_CANONICAL_BUILD
diff --git a/rts/include/rts/Flags.h b/rts/include/rts/Flags.h
index 66f8fa568ecf98669230619de908145cc9c64b1e..ca9520ef8a88c451cf4d9b28d04e41f153e8bdda 100644
--- a/rts/include/rts/Flags.h
+++ b/rts/include/rts/Flags.h
@@ -233,8 +233,22 @@ typedef struct _CONCURRENT_FLAGS {
#define DEFAULT_LINKER_ALWAYS_PIC false
#endif
-/* Which I/O Manager to use in the target program. */
-typedef enum _IO_MANAGER { IO_MNGR_NATIVE, IO_MNGR_POSIX } IO_MANAGER;
+/* Which I/O Manager to use in the target program. */
+typedef enum _IO_MANAGER_FLAG {
+
+ /* Select an I/O manager automatically. This will pick the one determined
+ * at configure time, for the RTS way. This can also fall back to other
+ * available I/O managers if the first choice cannot be initialised,
+ * if platform support turns out to be unavailable (e.g. too old a kernel).
+ */
+ IO_MNGR_FLAG_AUTO,
+
+ /* All other choices pick only the requested one, with no fallback. */
+ IO_MNGR_FLAG_SELECT, /* Unix only, non-threaded RTS only */
+ IO_MNGR_FLAG_MIO, /* cross-platform, threaded RTS only */
+ IO_MNGR_FLAG_WINIO, /* Windows only */
+ IO_MNGR_FLAG_WIN32_LEGACY, /* Windows only, non-threaded RTS only */
+ } IO_MANAGER_FLAG;
/* See Note [Synchronization of flags and base APIs] */
typedef struct _MISC_FLAGS {
@@ -254,7 +268,7 @@ typedef struct _MISC_FLAGS {
bool linkerAlwaysPic; /* Assume the object code is always PIC */
StgWord linkerMemBase; /* address to ask the OS for memory
* for the linker, NULL ==> off */
- IO_MANAGER ioManager; /* The I/O manager to use. */
+ IO_MANAGER_FLAG ioManager; /* The I/O manager to use. */
uint32_t numIoWorkerThreads; /* Number of I/O worker threads to use. */
} MISC_FLAGS;