1 /*
   2  * Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2012, 2018 SAP SE. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #ifndef OS_AIX_GLOBALS_AIX_HPP
  27 #define OS_AIX_GLOBALS_AIX_HPP
  28 
  29 //
  30 // Declare Aix specific flags. They are not available on other platforms.
  31 //
  32 // (Please keep the switches sorted alphabetically.)
  33 #include "runtime/flags/jvmFlag.hpp"
  34 
  35     //  Whether to allow the VM to run if EXTSHM=ON. EXTSHM is an environment 
  36     //  variable used on AIX to activate certain hacks which allow more shm segments 
  37     //  for 32bit processes. For 64bit processes, it is pointless and may have 
  38     //  harmful side effects (e.g. for some reasonn prevents allocation of 64k pages 
  39     //  via shmctl). 
  40     //  Per default we quit with an error if that variable is found; for certain 
  41     //  customer scenarios, we may want to be able to run despite that variable. 
  42 PRODUCT_FLAG(bool,     AllowExtshm, false, JVMFlag::DEFAULT,
  43                        "Allow VM to run with EXTSHM=ON.");
  44 
  45 
  46     //   Maximum expected size of the data segment. That correlates with the      
  47     //   to the maximum C Heap consumption we expect.                             
  48     //   We need to know this because we need to leave "breathing space" for the  
  49     //   data segment when placing the java heap. If that space is too small, we  
  50     //   reduce our chance of getting a low heap address (needed for compressed   
  51     //   Oops).                                                                   
  52 PRODUCT_FLAG(uintx,    MaxExpectedDataSegmentSize, 8*G, JVMFlag::DEFAULT,
  53                        "Maximum expected Data Segment Size.");
  54 
  55 
  56     //  Use optimized addresses for the polling page.                             
  57 PRODUCT_FLAG(bool,     OptimizePollingPageLocation, true, JVMFlag::DEFAULT,
  58                        "Optimize the location of the polling page used for Safepoints");
  59 
  60 
  61     //  Use 64K pages for virtual memory (shmat). 
  62 PRODUCT_FLAG(bool,     Use64KPages, true, JVMFlag::DEFAULT,
  63                        "Use 64K pages if available.");
  64 
  65 
  66     //   If VM uses 64K paged memory (shmat) for virtual memory: threshold below  
  67     //   which virtual memory allocations are done with 4K memory (mmap). This is 
  68     //   mainly for test purposes.                                                
  69 DEVELOP_FLAG(uintx,    Use64KPagesThreshold, 0, JVMFlag::DEFAULT,
  70                        "4K/64K page allocation threshold.");
  71 
  72 
  73     //  Normally AIX commits memory on touch, but sometimes it is helpful to have 
  74     //  explicit commit behaviour. This flag, if true, causes the VM to touch     
  75     //  memory on os::commit_memory() (which normally is a noop).                 
  76 PRODUCT_FLAG(bool,     UseExplicitCommit, false, JVMFlag::DEFAULT,
  77                        "Explicit commit for virtual memory.");
  78 
  79 //
  80 // Define Aix-specific default values. The flags are available on all
  81 // platforms, but they may have different default values on other platforms.
  82 //
  83 
  84 // UseLargePages means nothing, for now, on AIX.
  85 // Use Use64KPages or Use16MPages instead.
  86 define_pd_global(bool, UseLargePages, false);
  87 define_pd_global(bool, UseLargePagesIndividualAllocation, false);
  88 define_pd_global(bool, UseOSErrorReporting, false);
  89 define_pd_global(bool, UseThreadPriorities, true) ;
  90 
  91 #endif // OS_AIX_GLOBALS_AIX_HPP