levelzero: remove the setting of ZES_ENABLE_SYSMAN=1

Now that zesInit() is widely available, remove all the stuff trying
to set ZES_ENABLE_SYSMAN=1 in the environment early.
If people really cannot use a recent runtime with zesInit(),
they should take care of setting ZES_ENABLE_SYSMAN=1.

Signed-off-by: Brice Goglin <[email protected]>

hwloc/topology-levelzero.c

@@ -533,25 +533,8 @@ hwloc_levelzero_discover(struct hwloc_backend *backend, struct hwloc_disc_status
     }
     return 0;
   }
-#else /* !HWLOC_HAVE_ZESINIT */
-  /* Tell L0 to create sysman devices.
-   * If somebody already initialized L0 without Sysman,
-   * zesDeviceGetProperties() will fail and warn in hwloc__levelzero_properties_get().
-   * The lib constructor and Windows DllMain tried to set ZES_ENABLE_SYSMAN=1 early (see topology.c),
-   * we try again in case they didn't.
-   */
- {
-  char *env = getenv("ZES_ENABLE_SYSMAN");
-  if (!env) {
-    /* setenv() is safer than putenv() but not available on Windows */
-#ifdef HWLOC_WIN_SYS
-    putenv("ZES_ENABLE_SYSMAN=1");
-#else
-    setenv("ZES_ENABLE_SYSMAN", "1", 1);
-#endif
-  }
- }
 #endif /* !HWLOC_HAVE_ZESINIT */
+  /* if !HWLOC_HAVE_ZESINIT, the user must set ZES_ENABLE_SYSMAN=1 in his environment */
 
   res = zeInit(0);
   if (res != ZE_RESULT_SUCCESS) {

hwloc/topology.c

@@ -54,57 +54,6 @@
 #endif
 
 
-#if (defined HWLOC_HAVE_LEVELZERO) && !(defined HWLOC_HAVE_ZESINIT)
-/*
- * Define ZES_ENABLE_SYSMAN=1 early so that the LevelZero backend gets Sysman enabled.
- * This is only for old releases (<1.5) without zesInit().
- *
- * Only if the levelzero was enabled in this build so that we don't enable sysman
- * for external levelzero users when hwloc doesn't need it. If somebody ever loads
- * an external levelzero plugin in a hwloc library built without levelzero (unlikely),
- * he may have to manually set ZES_ENABLE_SYSMAN=1.
- *
- * Use the constructor if supported and/or the Windows DllMain callback.
- * Do it in the main hwloc library instead of the levelzero component because
- * the latter could be loaded later as a plugin.
- *
- * L0 seems to be using getenv() to check this variable on Windows
- * (at least in the Intel Compute-Runtime of March 2021),
- * but setenv() doesn't seem to exist on Windows, hence use putenv() to set the variable.
- *
- * For the record, Get/SetEnvironmentVariable() is not exactly the same as getenv/putenv():
- * - getenv() doesn't see what was set with SetEnvironmentVariable()
- * - GetEnvironmentVariable() doesn't see putenv() in cygwin (while it does in MSVC and MinGW).
- * Hence, if L0 ever switches from getenv() to GetEnvironmentVariable(),
- * it will break in cygwin, we'll have to use both putenv() and SetEnvironmentVariable().
- * Hopefully L0 will provide a way to enable Sysman without env vars before it happens.
- */
-#if HWLOC_HAVE_ATTRIBUTE_CONSTRUCTOR
-static void hwloc_constructor(void) __attribute__((constructor));
-static void hwloc_constructor(void)
-{
-  if (!getenv("ZES_ENABLE_SYSMAN"))
-#ifdef HWLOC_WIN_SYS
-    putenv("ZES_ENABLE_SYSMAN=1");
-#else
-    setenv("ZES_ENABLE_SYSMAN", "1", 1);
-#endif
-}
-#endif
-#ifdef HWLOC_WIN_SYS
-BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved)
-{
-  if (fdwReason == DLL_PROCESS_ATTACH) {
-    if (!getenv("ZES_ENABLE_SYSMAN"))
-      /* Windows does not have a setenv, so use putenv. */
-      putenv((char *) "ZES_ENABLE_SYSMAN=1");
-  }
-  return TRUE;
-}
-#endif
-#endif /* HWLOC_HAVE_LEVELZERO && !HWLOC_HAVE_ZESINIT */
-
-
 unsigned hwloc_get_api_version(void)
 {
   return HWLOC_API_VERSION;

tests/hwloc/levelzero.c

@@ -28,16 +28,15 @@ int main(void)
     fprintf(stderr, "Failed to initialize LevelZero in zesInit(): %d\n", (int)res);
     return 0;
   }
-#else
-  putenv((char *) "ZES_ENABLE_SYSMAN=1");
 #endif
+  /* if !HWLOC_HAVE_ZESINIT, the user must set ZES_ENABLE_SYSMAN=1 in his environment */
 
   res = zeInit(0);
   if (res != ZE_RESULT_SUCCESS) {
     fprintf(stderr, "Failed to initialize LevelZero in zeInit(): %d\n", (int)res);
     return 0;
   }
-  
+
   hwloc_topology_init(&topology);
   hwloc_topology_set_io_types_filter(topology, HWLOC_TYPE_FILTER_KEEP_IMPORTANT);
   hwloc_topology_load(topology);