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/*********************************************************
* Copyright (C) 2006 VMware, Inc. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation version 2.1 and no later version.
*
* This program 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 Lesser GNU General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
*********************************************************/
/*
* atomic.c --
*
* Support for atomic instructions.
*
* This is the user-level version.
* The monitor-only version is in vmcore/vmm/main.
*/
#include "vmware.h"
#include "vm_atomic.h"
#include "x86cpuid.h"
#include "vm_basic_asm.h"
Bool AtomicUseFence;
Bool atomicFenceInitialized;
/*
*-----------------------------------------------------------------------------
*
* AtomicInitFence --
*
* Compute AtomicUseFence.
*
* This version of fence initialization doesn't take into account
* the number of CPUs. Code that cares uses Atomic_SetFence() directly.
* See Atomic_Init in vm_atomic.h.
*
* This code is rather weird because while the logic belongs
* in x86cpuid.h, it's almost impossible to put this whole function
* there, so here it is. -- edward
*
* Results:
* None.
*
* Side effects:
* As described.
*
*-----------------------------------------------------------------------------
*/
void
AtomicInitFence(void)
{
CPUIDRegs regs;
Bool needFence;
ASSERT(!atomicFenceInitialized);
needFence = FALSE;
#if defined(__i386__) || defined(__x86_64__)
__GET_CPUID(0, ®s);
if (CPUID_ID0RequiresFence(®s)) {
__GET_CPUID(1, ®s);
if (CPUID_ID1RequiresFence(®s)) {
needFence = TRUE;
}
}
#endif
Atomic_SetFence(needFence);
}
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