/*****************************************************************************\ * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC. * Copyright (C) 2007 The Regents of the University of California. * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). * Written by Brian Behlendorf . * UCRL-CODE-235197 * * This file is part of the SPL, Solaris Porting Layer. * For details, see . * * The SPL is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. * * The SPL is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * for more details. * * You should have received a copy of the GNU General Public License along * with the SPL. If not, see . \*****************************************************************************/ #ifndef _SPL_COMPILER_COMPAT_H #define _SPL_COMPILER_COMPAT_H #include #ifndef ACCESS_ONCE /* * Prevent the compiler from merging or refetching accesses. The compiler * is also forbidden from reordering successive instances of ACCESS_ONCE(), * but only when the compiler is aware of some particular ordering. One way * to make the compiler aware of ordering is to put the two invocations of * ACCESS_ONCE() in different C statements. * * This macro does absolutely -nothing- to prevent the CPU from reordering, * merging, or refetching absolutely anything at any time. Its main intended * use is to mediate communication between process-level code and irq/NMI * handlers, all running on the same CPU. */ /* Taken from 2.6.33.2 */ # define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) #endif #endif /* _SPL_COMPILER_COMPAT_H */